Direct characterization of subvisible particles in drug products with non-invasive MIE-scattering-based light sheet technology

Abstract

Described herein are systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product. The systems may comprise a Mie-scattering-based light sheet (MSLS) liquid particle analyzer. Described herein are method for determining an absence, or presence and size of particles in a liquid pharmaceutical product.

Description

[0001] DIRECT CHARACTERIZATION OF SUBVISIBLE PARTICLES IN DRUG PRODUCTS WITH NON-INVASIVE MIE-SCATTERING-BASED LIGHT SHEET TECHNOLOGY

[0002] Reference to Related Application

[0003] The present application claims the benefit of US Provisional Application No. 63 / 610,811, filed Dec. 15, 2023, which is hereby incorporated by reference in its entirety.

[0004] Field

[0005] Embodiments herein relate to methods and systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product.

[0006] Background

[0007] The characteristics of subvisible particles (SVPs) in the 1-100 pm range are critical quality attributes in pharmaceutical industry. Common sources of SVPs include random-sourced particles, contaminants, protein aggregates, surfactant degradants, and silicone oil droplets. It has been reported that the presence of certain types of SVPs in parental DPs can trigger immunogenicity thus causing safety concerns. According to the standards set by United States Pharmacopeial Convention (USP) in chapter <787>, <788> and <1788> standards, and corresponding EP and JP monographs, SVP testing is required for all final therapeutic protein products.

[0008] Summary

[0009] The following embodiments are described herein:

[0010] El. A method for determining an absence, or presence and size of particles in a liquid pharmaceutical product, the method comprising: providing the liquid pharmaceutical product in a shelf keeping unit (SKU) container suitable for administration to a patient, said SKU container comprising a cylindrical vessel in which the pharmaceutical product is disposed therein; illuminating the cylindrical vessel with a sheet of electromagnetic radiation, thereby producing side scatter light; and determining a presence or absence, and if present, a concentration and size, of a particle in the liquid pharmaceutical product in the cylindrical vessel, wherein said determining utilizes on Mie scattering theory, wherein analyzed liquid pharmaceutical product in the SKU container remains suitable for administration to a patient after said determining the absence, or the presence and size of particles in the liquid pharmaceutical product.

[0011] E2. A method as described herein, for example the method of El, wherein said illuminating illuminates the cylindrical vessel disposed in a solid housing that conforms to the cylindrical vessel, said solid housing comprising: an inner surface that conforms to the convex curved surface of the cylindrical vessel; and an outer surface comprising a facet that is flat or substantially flat, wherein a first difference between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product, optionally wherein the method further comprises disposing the cylindrical vessel in the solid housing prior to the illuminating.

[0012] E3. A method as described herein, for example the method of any one of E1-E2, wherein the size of the particle is determined based on side-scattering light intensity, and not subvisible particle morphology.

[0013] E4. A method as described herein, for example the method of any one of E1-E3, wherein said determining comprises: obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation; and template mapping the input image to a template.

[0014] E5. A method as described herein, for example the method of E4, further comprising: downsizing the input image by a factor, such as about 10, wherein the template is also downsized by the factor; Gaussian blurring the downsized input image and downsized template; and cross-correlating between the Gaussian blurred and downsized input image and template image.

[0015] E6. A method as described herein, for example the method of E5, wherein the template image is downsized prior to obtaining the input image.

[0016] E7. A method as described herein, for example the method of any one of E1-E6, comprising using astigmatism as an estimator of the particle's axial position and determining the incident light intensity for that particle.

[0017] E8. A method as described herein, for example the method of any one of E1-E7, further comprising categorizing detected subvisible particles according to particle diameter bins, such as bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

[0018] E9. A method as described herein, for example the method of any one of E1-E8, wherein the determining is repeated for additional particles.

[0019] E10. A system for determining an absence, or presence and size of particles in a liquid pharmaceutical product, the system comprising: a Mie-scattering-based light sheet (MSLS) liquid particle analyzer comprising an illumination source and a detector; and a solid housing that conforms to a cylindrical vessel configured to contain a liquid pharmaceutical product, said solid housing comprising: an inner surface that conforms to the convex curved surface of the cylindrical vessel; and an outer surface that is flat or substantially flat, wherein a first difference, between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product; and a processor configured to determine a presence or absence, and if present a concentration and size, of particles in the liquid pharmaceutical product in the cylindrical vessel, wherein said determining utilizes on Mie scattering theory, wherein the illumination source is configured to illuminate the solid housing configured to contain a SKU container comprising a cylindrical vessel containing a liquid pharmaceutical product, wherein the detector is configured to receive side scatter light from the illuminated solid housing, and wherein the system is configured for the liquid pharmaceutical product in the SKU container to remain suitable for administration to a patient after said absence, or said presence and size of particles in the liquid pharmaceutical product has been determined.

[0020] Ell. A system as described herein, for example the system of E10, wherein the processor is configured to determine the size of the particles based on side-scattering light intensity, and not subvisible particle morphology.

[0021] E12. A system as described herein, for example the system of any one of E1O-E11, wherein the determination of the size of the particles by the processor comprises: obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation; and template mapping the input image to a template.

[0022] E13. A system as described herein, for example the system of E12, wherein the determination by the processor further comprises downsizing the input image by a factor, such as about 10, wherein the template is also downsized by the factor;

[0023] Gaussian blurring the downsized input image and downsized template; and cross-correlating between the Gaussian blurred and downsized input image and template image.

[0024] E14. A system as described herein, for example the system of any one of E10-E13, wherein the processor is configured to categorize the detected subvisible particles according to particle diameter bins, such as bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

[0025] E15. A method or system as described herein, for example the method of any one of E2-E9 or the system of any one of E10-E14, wherein the solid housing has a refractive index of about 1.1 to about 1.7, such as about 1.2 to about 1.6, or about 1.4. E16. A method or system as described herein, for example the method of any one of E2-E9 or E15, or the system of any one of E10-15, wherein the solid housing comprises or consists of polydimethylsiloxane (PDMS) elastomer.

[0026] E17. A method or system as described herein, for example the method of any one of E2-E9 or E15-E16, or the system of any one of E10-E16, wherein the solid housing comprises two or more facets that are each flat or substantially flat.

[0027] E18. A method or system as described herein, for example the method of any one of E2-E9 or E15-E17 or system of any one of E10-E17 wherein the particle is or particles are a subvisible particle.

[0028] E19. A method or system as described herein, for example the method of any one of E2-E9 or E15-E18 or system of any one of E10-E18 wherein the particle has or particles have an average diameter of about 1 pm to 100 pm, or about 2 pm to 100 pm.

[0029] E20. A method or system as described herein, for example the method of any one of E2- E9 or E15-E19 or system of any one of E10-E19 wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the liquid pharmaceutical product remaining sealed in the SKU container.

[0030] E21. A method or system as described herein, for example the method of any one of E2- E9 or E15-E20 or system of any one of E10-E20 wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the SKU container remaining intact.

[0031] E22. A method or system as described herein, for example the method of any one of E2-E9 or E15-E21 or system of any one of E10-E21 wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the liquid pharmaceutical product remaining sterile.

[0032] E23. A method or system as described herein, for example the method of any one of E2-E9 or E15-E22 or system of any one of E10-E22, wherein in addition to remaining suitable for administration to a patient, the liquid pharmaceutical product in the SKU container further remains suitable for continued storage under specified conditions, such as stability, temperature cycling, mechanical stresses, and / or light stress.

[0033] E24. A method or system as described herein, for example the method of any one of E2-E9 or E15-E23 or system of any one of E10-E23 wherein the SKU container comprises a vial, syringe, or autoinjector.

[0034] E25. A method or system as described herein, for example the method of any one of E2-E9 or E15-E24 or system of any one of E10-E24 wherein the liquid pharmaceutical product comprises a therapeutic protein, such as an antigen binding protein or a fusion protein.

[0035] E26. A method or system as described herein, for example the method of any one of E2-E9 or E15-E25 or system of any one of E10-E25, wherein the antigen binding protein comprises or consists of a monoclonal antibody or binding fragment thereof.

[0036] E27. A method or system as described herein, for example the method of any one of E2-E9 or E15-E26 or system of any one of E10-E26 wherein the liquid pharmaceutical product comprises a liquid drug product or a reconstituted lyophilized drug product.

[0037] Brief Description of Drawings

[0038] FIG. 1A-C are schematic drawings of MSLS analyzer set up and workflow. FIG. 1A depicts a simplified MSLS analyzer schematic, which refers to an example system according to some embodiments herein. FIG. IB depicts a typical light sheet image captured by the MSLS analyzer. Scale bar: 50 pm. FIG. 1C depicts a data processing workflow to extract SVP size, concentration, and distribution.

[0039] FIG. 2 is a schematic graph depicting a demonstration of the sample housings compensating astigmatism.

[0040] FIG. 3 is a schematic illustration of a particle detection process according to some embodiments herein.

[0041] FIG. 4 is a schematic illustration of a particle sizing process according to some embodiments herein.

[0042] FIGs. 5A-B are graphs illustrating functionality of the MSLS analyzer according to some embodiments herein. FIG. 5A illustrates results of the ISO 6R vial samples. FIG. 5B illustrates results of the ISO 2R vial samples. FIG. 5C is a series of images illustrating typical errors (close or overlapping imprints) encountered in the MSLS analyzer. Scale bar: 50 pm.

[0043] FIG. 6 is a flow diagram illustrating a method for determining an absence, or presence and size of particles in a liquid pharmaceutical product according to some embodiments.

[0044] Detailed Description

[0045] Conventional compendial SVP testing methods, namely the light obstruction (LO) method and the membrane microscope method, are destructive and wasteful of the target samples. These conventional methods necessitate the removal of the liquid testing sample from the original DP containers and subsequent follow-up procedures. The LO method and the flow imaging method involve flowing the target fluid through the testing systems and into waste receptacle. The membrane microscope requires the particles of interest to be filtered out from the liquid sample for observation. As a result, the DP unit(s), and the liquid testing sample itself are destroyed as part of the method sample preparation and testing procedure. This results in a significant amount of waste. In contrast to conventional SVP testing methods, described herein are non-invasive and non-destructive particle analysis methods and system that are compatible with typical drug product (DP) containers, targeting particles between 2 to 100 pm. The systems and methods according to some embodiments herein reduce cylindrical container associated aberrations through the use of custom holders and capture the side-scattered light from the intact sample vial in a light sheet illumination geometry. Particle sizes may be determined using Mie scattering theory and particle concentration calculated from the scattering volume. Advantageously, in accordance with systems and methods described herein, after the determination of an absence, or presence and size of particles in a liquid pharmaceutical product, the liquid pharmaceutical product in the SKU container remains suitable for administration to a patient. As such, the systems and methods herein avoid contamination and / or waste of liquid pharmaceutical product and SKU containers.

[0046] Described herein are methods and systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product. The particles may be subvisible particles. By way of example, the particles may have an average diameter of about 1 pm to 100 pm, or about 2 pm to 100 pm.

[0047] The methods and systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product describe herein may be useful for a variety of liquid pharmaceutical products. For some methods and systems, the liquid pharmaceutical product may comprise a therapeutic protein, such as an antigen binding protein or a fusion protein. For example, the antigen binding protein may comprise or consist of a monoclonal antibody or binding fragment thereof. For some methods and systems, the liquid pharmaceutical product comprises a liquid drug product or a reconstituted lyophilized drug product.

[0048] The methods and systems for determining an absence, or presence and size of particles for liquid pharmaceutical products are suitable for liquid pharmaceutical products in a variety of SKU containers. The SKU containers may comprise or consist of a cylindrical vessel. For example, the SKU container may comprise a vial, syringe, or autoinjector. Without being limited by theory, the cylindrical shape of the vessel of the SKU container may introduce astigmatism. However, for the methods and systems described herein, the housings that conform to the cylindrical shape may compensate for the astigmatism introduced by the SKU container's vessel's cylindrical geometry.

[0049] Systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product

[0050] Described herein are systems for determining an absence, or presence and size of particles in a liquid pharmaceutical product. The systems comprise a Mie-scattering-based light sheet (MSLS) liquid particle analyzer comprising an illumination source and a detector. The systems may further comprise a solid housing that conforms to a cylindrical vessel configured to contain a liquid pharmaceutical product. Without being limited by theory, a solid housing with an inner surface that conforms to the outer surface of a cylindrical vessel may compensate for the astigmatism introduced by the vessel's cylindrical geometry. By way of example, the solid housing may comprise an inner surface that conforms to the convex curved surface of the cylindrical vessel and an outer surface that is flat or substantially flat. A first difference, between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product. The systems further comprise processor. The processor may be configured to determine a presence or absence, and (if present) a concentration and size, of particles in the liquid pharmaceutical product in the cylindrical vessel, wherein said determining utilizes on Mie scattering theory. The illumination source of the system is configured to illuminate the solid housing configured to contain a shelf keeping unit (SKU) container comprising a cylindrical vessel containing a liquid pharmaceutical product. The detector of the system is configured to receive side scatter light from the illuminated solid housing. The system may be configured for the liquid pharmaceutical product in the SKU container to remain suitable for administration to a patient after said absence, or said presence and size of particles in the liquid pharmaceutical product has been determined.

[0051] An example system 5 of some embodiments is schematically illustrated in FIG. 1A. The system may comprise a laser 10. The laser can be in optical communication with a beam expander 15. The beam expander 15 can be in optical communication with a cylindrical lens 20. The cylindrical lens can be optical communication with a solid housing that conforms to a SKU container suitable for administration to a patient, the SKU container comprising a cylindrical vessel configured to contain a liquid pharmaceutical product 25. The solid housing can comprise an inner surface that conforms to the convex curved surface of the cylindrical vessel, and an outer surface that is flat or substantially flat. A first difference, between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, may be less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product. The system may further comprise a beam block 30 in optical communication with the laser 10, beam expander 15, cylindrical lens 20, solid housing that conforms to the cylindrical vessel 25, and solid housing 30. As such, a beam of electromagnetic radiation (e.g., visible light) emitted by the laser 10 may pass through the beam expander 15, cylindrical lens 20, so that a sheet of electromagnetic radiation illuminates the solid housing that conforms to the cylindrical vessel 25 and the contents thereof. The illumination may produce side scatter, for example in the presence of particles in liquid formulation in the cylindrical vessel. At least a portion of the beam of electromagnetic radiation may reach the beam block 30. The system 5 may further comprise an objective 35, a tube lens 40, and a camera 45, arranged so that light emitted by the solid housing that conforms to the cylindrical vessel 25 passes through the objective 35, and tube lens 40, and is detected by the camera 45. In particular, side scatter from the illuminated solid housing and cylindrical vessel in the in liquid formulation in the cylindrical vessel 25 (which has been illuminated by the laser 10) may be detected by the camera 45. In some embodiments, the system further comprises a processor 50 configured to determine a presence or absence, and if present a concentration and size, of particles in the liquid pharmaceutical product in the cylindrical vessel, 25. The determining may utilize on Mie scattering theory. For some of the systems 5, the processor 50 may be configured to determine the size of the particles based on side-scattering light intensity, and not subvisible particle morphology. Following the determining an absence, or presence and size of particles in a liquid pharmaceutical product by a system 5 as described herein, the liquid pharmaceutical product in the SKU container may remain suitable for administration to a patient.

[0052] By way of example, in some of the systems 5, the determination of the size of the particles by the processor 50 comprises obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation and template mapping the input image to a template. The determination by the processor 50 may further comprise downsizing the input image by a factor, such as about 10 (for example, 15, 12, 10, 9, 8, 7, or 5, including ranges between any two of the listed values, such as 15-5, 15-10, 12-10, 12-8, 10-8, or 10-5), in which the template is also downsized by the factor. The determination may further comprise Gaussian blurring the downsized input image and downsized template. The determination may further comprise cross-correlating between the Gaussian blurred and downsized input image and template image.

[0053] In some of the systems 5, the processor 50 is configured to categorize the detected subvisible particles according to particle diameter bins. For example, the particle diameter bins may comprise bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

[0054] In some of the systems 5, the solid housing that conforms to the cylindrical vessel 25 may have a refractive index of about 1.1 to about 1.7, such as about 1.2 to about 1.6, or about 1.4. In some of the systems 5, the solid housing that conforms to the cylindrical vessel 25 comprises or consists of polydimethylsiloxane (PDMS) elastomer. In some of the systems 5, the solid housing that conforms to the cylindrical vessel 25 comprises two or more facets that are each flat or substantially flat. The flat or substantially flat facets may comprise the outer surface of the solid housing 25. The inner surface of the solid housing 25 may be adapted to conform the a cylindrical vessel. The cylindrical vessel may comprise or consist of a shelf keeping unit (SKU) container.

[0055] Following the determining of an absence, or presence and size of particles in a liquid pharmaceutical product by a system 5 as described herein, the liquid pharmaceutical product in the SKU container may remain suitable for administration to a patient. For example, the liquid pharmaceutical product may remain sealed in the SKU container. For example, the SKU container may remain intact. For example, the liquid pharmaceutical product remaining sterile.

[0056] Following the determining of an absence, or presence and size of particles in a liquid pharmaceutical product by a system 5 as described herein, in addition to remaining suitable for administration to a patient, the liquid pharmaceutical product in the SKU container further remains suitable for continued storage under specified conditions, such as stability, temperature cycling, mechanical stresses, and / or light stress.

[0057] Methods for determining an absence, or presence and size of particles in a liquid pharmaceutical product Described herein are methods for determining an absence, or presence and size of particles in a liquid pharmaceutical product. FIG. 6 is a flow diagram illustrating such methods 100. The method may comprise providing a liquid pharmaceutical product in a SKU container suitable for administration to a patient. The SKU container may comprise a cylindrical vessel in which the pharmaceutical product is disposed therein 110. The method may comprise illuminating the cylindrical vessel with a sheet of electromagnetic radiation, thereby producing side scatter light 120. The method may comprise determining a presence or absence, and if present, a concentration and size, of a particle in the liquid pharmaceutical product in the cylindrical vessel. The determining may utilizes Mie scattering theory 130. The analyzed liquid pharmaceutical product in the SKU container remain suitable for administration to a patient after determining the absence, or the presence and size of particles in the liquid pharmaceutical product 140.

[0058] For some methods 100, the illuminating illuminates the cylindrical vessel disposed in a solid housing that conforms to the cylindrical vessel 145. The solid housing vessel comprises (i) an inner surface that conforms to the convex curved surface of the cylindrical vessel, and (ii) an outer surface comprising a facet that is flat or substantially flat. A first difference between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product. Optionally, the method further comprises disposing the cylindrical vessel in the solid housing prior to the illuminating.

[0059] For any of the methods described herein, the size of the particle may be determined 130 based on side-scattering light intensity, and not subvisible particle morphology.

[0060] For any of the methods described herein, the determining 130 may comprises obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation, and template mapping the input image to a template. For some methods, the determining 130 may further comprise downsizing the input image by a factor, such as about 10, wherein the template is also downsized by the factor, Gaussian blurring the downsized input image and downsized template, and cross-correlating between the Gaussian blurred and downsized input image and template image. For example the factor may be 10, or 15, 12, 9, 8, 7, or 5, including ranges between any two of the listed values (such as 15-5, 15-10, 12-10, 12-8, 10-8, or 10-5). For some methods, the template image is downsized prior to obtaining the input image.

[0061] For any of the methods described herein, the method may comprise using astigmatism as an estimator of the particle's axial position and determining the incident light intensity for that particle. For any of the methods described herein, the method may further comprise categorizing detected subvisible particles according to particle diameter bins. By way of example, such particle diameter bins may comprise bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

[0062] For any of the methods described herein, the determining 130 is repeated for additional particles. For example, the determining maybe repeated at least 1, 2, 5, 10, 100, 1000, 10,000, 100,000, or 1,000,000,000 times, including ranges between any two of the listed values for example, 1-100, 1-1000, 1-100,000, 1-1,000,000, 10-100, 10-1000, 10-100,000, 10-1,000,000, 100-1000, 100- 100,000, 100-1,000,000, or 10,000-1,000,000.

[0063] For any of the methods described herein, the solid housing may have a refractive index of about 1.1 to about 1.7, such as about 1.2 to about 1.6, or about 1.4. For any of the methods described herein, the solid housing may comprise or consist of polydimethylsiloxane (PDMS) elastomer. For any of the methods described herein, the solid housing may comprise two or more facets that are each flat or substantially flat.

[0064] For any of the methods described herein, the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient 140 may comprise: (i) the liquid pharmaceutical product remaining sealed in the SKU container, (ii) the SKU container remaining intact, (iii) the liquid pharmaceutical product remaining sterile, or a combination of two or more of (i), (ii), and (iii).

[0065] For any of the methods described herein, in addition to remaining suitable for administration to a patient 140, the liquid pharmaceutical product in the SKU container may further remain suitable for continued storage under specified conditions, such as stability, temperature cycling, mechanical stresses, and / or light stress.

[0066] Examples, alternative embodiments, variations, and applications

[0067] The non-destructive and non-invasive nature of the systems and methods described herein position them for various applications. These include continuous monitoring of a single sample over time, a task that necessitates the sample's preservation during testing, rendering existing invasive methods unsuitable. In contrast, the non-destructive systems and methods described herein are well- suited for this particular application. Additionally, systems and methods described herein offer a cost- effective solution by reducing waste of SVP testing and obviates the requirement for preparatory steps such as sample withdrawal and liquid filtration. As a result, the systems and methods are exceptionally well-suited for conducting initial tests on a large group of samples. Direct characterization of subvisible particles in pharmaceutical drug products with non-invasive Mie-scattering-based light sheet technology

[0068] The characteristics of subvisible particles (SVPs) are critical quality attributes of pharmaceutical injectables and ophthalmic solutions. However, the current compendial SVP testing methods, namely the light obstruction method and the membrane microscope method, are destructive and wasteful of the target samples. In this study, we present the development of a non- invasive particle analysis system for SVP testing that is compatible with typical drug product (DP) containers, targeting particles between 2 to 100 pm. Our system reduces cylindrical container associated aberrations through the use of custom holders and captures the side-scattered light from the intact sample vial in a light sheet illumination geometry. Particle sizes are determined using Mie scattering theory and concentration calculated from the scattering volume. To evaluate its functionality and feasibility as a non-destructive SVP analyzer, we evaluated the system using a series of polystyrene bead suspensions in ISO 2R and 6R vials. Additionally, the Applicants evaluated the relationship between the sampling volume and the accuracy of the calculated particle concentration. The Applicants found our particle analyzer can sort SVPs into four size-based bins commonly used in SVP characterization, and the analyzer can reliably measure SVPs in the concentration range of 4.6e2 to 5.0e5 particle / mL (within a margin of ± 15% error with a 90% confidence interval).

[0069] 1. Introduction

[0070] The characteristics of subvisible particles (SVPs) in the 1-100 pm range[l]-[4] are critical quality attributes in pharmaceutical industry. Common sources of SVPs include random-sourced particles, contaminants, protein aggregates, surfactant degradants, and silicone oil droplets[5]-[9]. It has been reported that the presence of certain types of SVPs in parental DPs can trigger immunogenicity thus causing safety concerns[4],

[0010] —

[0012] . According to the standards set by United States Pharmacopeial Convention (USP) in chapter <787>

[0013] , <788>

[0014] and <1788>

[0015] standards, and corresponding EP and JP monographs, SVP testing is required for all final therapeutic protein products.

[0071] Light obstruction (LO) method[4], [9],

[0016] —

[0019] is one of the compendial SVP test methods. A typical light obstruction system has a light source facing a detector. The fluid containing particles flows between the light source and the detector. When a particle passes through the light path, it obstructs part of the light and causes a drop in the detector signal. The particle size is then computed from the magnitude of the signal drop. The membrane microscope particle test is the other compendial method for SVP test

[0016] ,

[0017] ,

[0019] , It requires collecting, rinsing, and drying particles >10 pm on a micro- porous membrane filter. The prepared sample is typically sized and counted under lOOx magnification. The recent USP <1788>

[0015] includes flow imaging[9],

[0016] -

[0024] as a complementary test to LO particle test. Instead of a photo detector that sensing the light intensity, a flow imaging system employs a camera to capture images of the particles as they pass through the light path. Therefore, the flow imaging method can provide additional information such as particle morphologies, which can benefit particle classification.

[0072] These compendial methods are destructive and wasteful of the target samples. They require the liquid testing sample be withdrawn from the original DP containers. The LO method and the flow imaging method involve flowing the target fluid through the testing systems and into waste receptacle. The membrane microscope requires the particles of interest to be filtered out from the liquid sample for observation. As a result, the DP unit(s) and the liquid testing sample itself are completely destroyed as part of the method sample preparation and testing procedure. This results in a significant amount of waste. Applications such as product stability trending are particularly challenging due to in-batch vial to vial variability in addition to waste. Therefore, a non-invasive SVP testing method would be a much more desirable solution for improved data quality and reduced resource burden.

[0073] In this study, the Applicants report the development of a non-invasive Mie-scattering-based light sheet (MSLS) liquid particle analyzer that is capable of directly analyzing SVPs in parenteral DPs. The procedure is non-invasive and non-destructive, and after the analysis the intact DP units (e.g. vials or syringes) can be reused for other applications. To achieve this, the Applicants developed housings for ISO 2R and 6R vials to partially compensate for the aberration caused by the cylindrical vials. These housings can be put on and taken off the sample vials for testing with ease. The MSLS analyzer utilizes a light sheet for illumination and collects the side scattered light from the particles. The particle sizes are then determined based on Mie scattering theory. The Applicants demonstrated the functionality of our MSLS analyzer prototype with a series of polystyrene particle suspension samples. Finally, the Applicants determined the minimum reportable concentration to be 3.8 particle / mL and the concentration range within which the MSLS analyzer could provide a reasonable estimation to be 4.6e2 - 5.0e5 particles / mL with ± 15% error margin at a 90% confidence interval). The MSLS analyzer can sort the particles into four commonly used size bins of 2 to 5 pm, 5 to 10 pm, 10 to 25 pm and above 25 pm.

[0074] 2. Principle and method

[0075] 2.1 System setup and general workflow

[0076] The Applicants' MSLS analyzer prototype, comprising a system in accordance with some embodiments herein, essentially functioned as a light sheet microscope (see Fig. 1(a) for setup schematics). A Gaussian laser beam (Spectra Physics, 532 nm) was optically transformed by a cylindrical lens (Thorlabs U1558RM, f = 300.0 mm) into the illumination light sheet. The sample under test was placed on a three-axis scanning stage inside the sample housing which was designed to compensate for the astigmatism introduced by the sample's cylindrical geometry. The side-scattered light from the particles within the sample was collected through a long working distance objective lens (Olympus LMPLFLN10X) and finally detected by an sCMOS camera (PCO edge 5.5). By using a tube lens (Thorlabs LA1433-A), the Applicants achieved a system magnification of 8.3. The exposure time was set at 20 ms for image capturing.

[0077] During light sheet image acquisition, the sample was 3D-scanned and a collection of light sheet images representing multiple fields-of-view of the liquid sample was captured. FIG. IB is an example of a captured light sheet image. The sample imaged was a water suspension with 3-pm polystyrene beads. Particle detection was performed on the acquired images to identify all the particles that appeared during the capturing process. For each detected particle, its side-scattered light intensity was extracted from the corresponding pixel values, and its size was then determined by referencing a pre-calculated size-scattering intensity curve. By combining the results of all appeared particles and considering the total imaging volume, a final calculation of the particle size-concentration statistics within the sample could be generated.

[0078] 2.2 Sample housing for astigmatism compensation

[0079] The cylindrical geometry of typical DP container (e.g. vials, syringes) produces severe astigmatism which presents a major obstacle to successful non-invasive imaging inspection. Here we created a square sample housing, to be placed around the DP container, to mitigate the astigmatism. The sample housings were made of Polydimethylsiloxane (PDMS) elastomer (SLYGARD™ 184) and has a refractive index (Rl) of 1.43. On the one hand, PDMS was easy to mold to generate flat surfaces. On the other hand, compared with air - liquid combination, PDMS - liquid combination has smaller Rl gap, thus results in weaker astigmatism. FIG. 2A shows the two types of sample housing we created for ISO 6R vials (FIG. 2A at (a2)) and ISO 2R vials (FIG. 2A at(a4)). The detailed description of the sample housing production procedure was included in the Supplementary document.

[0080] FIGs. 2B-D illustrate the effectiveness of the astigmatism-compensating sample housing by simulating the optical system and performing ray tracing on RayLab. The simulated system was simplified as follows: a point source was covered by a half cylinder, the light emitted from the light source was collected by a lens and detected by a screen. FIGs. 2B-D showed the patterns collected by the screen at several axial position near the focal plane (along optical axis direction) with and without sample housing. It can be clearly observed that the sample housing reduced the difference between the focal lengths of tangential focal plane and sagittal focal plane. By applying the sample housing, the astigmatism introduced by the cylindrical DP container was mitigated to an extent that allowed subsequent particle detection to be performed.

[0081] We would like to specifically clarify that the MSLS analyzer remained an aberrated imaging system even with the use of the astigmatism-compensating sample housing. The side-scattered light from a particle formed a wide-spread, highly distorted "imprint" on the camera sensor whose shape was dominated by the system aberration instead of the morphology of the particle itself. As can be seen in FIG. IB , a 3-pm particle's imprint had a size of ~150 pm, far exceeding the particle's actual size. However, this astigmatism property of the MSLS analyzer did not pose obstruction to the particle sizing task, as the MSLS analyzer extracted the side-scattering light intensity of the captured particles rather than relied on their imprints' morphology information. In addition, the side-scattered intensity of a particle was not affected by the presence of aberration as long as the side-scattered light was effectively collected by the objective lens. Furthermore, the astigmatism property of the MSLS analyzer benefited the particle sizing and counting task in two ways: 1) it made particles of different sizes produce similar imprints. Thus, the particle detection for each captured frame could be achieved in a conventional template matching way robustly. 2) The astigmatism could serve as an estimator of a particle's axial position and therefore helped with determining the accurate incident light intensity for that particle. Further details about particle detection, sizing and counting are elaborated in subsequent sections.

[0082] FIGs. 2A-D demonstrate the sample housings compensating astigmatism. FIG. 2A at references (al)- (a4) depicts vials with and without sample housings. The patterns behind the vials were less distorted after putting on sample housings. FIG. 2B at references (bl)-(b4) depict diagrams at the tangential focal planes of (bl) ISO 6R vial without sample housing, (b2) ISO 6R vial with sample housing, (b3) ISO 2R vial without sample housing and (b4) ISO 2R vial with sample housing. FIG. 2C at references (cl)~ (c4) depicts spot diagrams at positions where the spots were with aspect ratio of 1 for (cl) ISO 6R vial without sample housing, (c2) ISO 6R vial with sample housing, (c3) ISO 2R vial without sample housing and (c4) ISO 2R vial with sample housing. FIG. 2D at references (dl)-(d4) depict spot diagrams at the sagittal focal planes of (dl) ISO 6R vial without sample housing, (d2) ISO 6R vial with sample housing, (d3) ISO 2R vial without sample housing and (d4) ISO 2R vial with sample housing. Unit: mm.

[0083] 2.3 Particle detection by template matching method

[0084] The applicants chose template matching

[0025] by means of cross correlation as our approach for our particle detection task. The particle imprints in a captured image could be broadly regarded as a template imprint being translated and duplicated multiple times without size scaling or rotation. For the reported MSLS analyzer, the templates (for both ISO 2R vials and 6R vials) were manually cropped from the corresponding light sheet image sets of samples containing 3-pm polystyrene bead only.

[0085] FIG. 3 illustrates a method for determining an absence, or presence and size of particles in a liquid pharmaceutical product in accordance with some embodiments herein. (1) Down-sizing and Gaussian blurring both the template and the input image. (2) Normalized cross-correlation between the template and the input image (both are lOx down-sized thumbnails). (3) Peak finding. (4) Placing bounding boxes around detected particle imprints. (5) Cropping out each individual particle imprints. Scale bar: 50 pm.

[0086] FIG. 3 illustrates how the particle detection was performed. First, the applicants named the image they expected to apply particle detection to as the input image. Two steps of preprocessing ((1) in FIG. 3) were performed before applying the normalized cross-correlation between the template and the input image. 1) Both the template and the input image were down-sized by a factor of 10 (for both width and height) for higher processing speed. 2) Both the down-sized template and input image were Gaussian blurred to eliminate multiple peaks for a single match. Normalized cross-correlation (@ in FIG. 3) was then performed between preprocessed template and input image. An example of correlation map is shown in Fig. 3 where a peak indicated that a particle imprint was detected. The Applicants first localized the valid peaks in the lOx down-sized thumbnail source image ((5) in FIG. 3) and then remapped the peak positions to the original source image. Then bounding boxes centered on the peak positions, with the size of 1.4x that of the template, were placed to box out the found particle imprints in the original input image ((4) and (5) FIG. 3). Based on the bounding boxes, individual particle imprints were cropped out for the subsequent particle sizing process.

[0087] 2.4 Mie-scattering based particle sizing and counting

[0088] FIG. 4 illustrates determining the size of particle in embodiments of methods and systems describe herein. Reference 4(a) refers to a workflow for determining the particle size from the particle imprint. FIG. 4 at Reference 4(a) illustrates the process of particle sizing for a given particle imprint. The found particle imprints underwent astigmatism-based localization and Mie-scattering based size calculation. And the results of all the particle imprints formed the final particle statistics of the sample analyzed. Reference 4(b) illustrates the light sheet generated by the MSLS analyzer and the particle imprints at varied axis positions (-60, 0 and 60 pm). The intensity profile is along the dash line and its corresponding Gaussian fit are presented. The star mark indicates the axial location of the particle. Scale bar: 100 pm. Reference 4(c) illustrates the Mie scattering model scheme and the derived scattering reading curve. The star mark indicates the scattering reading of the certain particle imprint in this figure.

[0089] 2.4.1 Mie-scattering model

[0090] The particle sizing method of some embodiments was based on Mie scattering theory

[0026] . The intensity of the side scattered light was an indicator of the particle size. To connect the side scattering intensity with the pixel values of a particle imprint, we introduced a parameter named scattering reading (SC) which was defined as the sum of all the pixel values within its corresponding bounding box, as illustrated in FIG. 4 at Reference 4(a). The particle size -scattering reading curve was calculated based on a simplified Mie scattering model demonstrated in Fig. 4 at Reference 4(c). We approximated the scenario as a spherical particle scattering the incident plane wave light. By considering a specific solid angle range within which the scattered light could be received by the objective lens, we calculated the scattering cross section of a particle. Given the incident light intensity and the camera specifications, including exposure time, quantum efficiency and conversion factor, the scattering reading for a particle with certain size was calculated. The detailed derivation of the particle size - scattering reading curve was explained in the Supplementary document.

[0091] 2.4.2 Illuminating light sheet cross section and sampling volume of the MSLS analyzer

[0092] From the scattering model, accurate particle size determination relied on accurate measurement of the incident light sheet itself. Therefore, the Applicants examined the light sheet directly using an observation camera (the imaging source DMK23UP031). The cross-section of the light sheet was shown in FIG. 4B. The full width at half maximum of the light sheet was measured to be 58.6 pm. The normalized Gaussian fitting of the light sheet profile was expressed as (unit: pm): z - 0.15 , f =exp (“(- n)’

[0093] Combining the light sheet thickness, the pixel count and size of our camera and the magnification of the MSLS analyzer, the sampling volume of a single frame was determined to be 3.7e-4 mL. During one measurement, 700 frames from different field of views were captured, resulting in the total sampling volume of 0.26 mL.

[0094] It was clear that particles at different axial locations did not share the same incident light intensity. However, the particle size - scattering reading curve was calculated based on a consistent incident light intensity value (the peak intensity of the light sheet). Therefore, the size of a particle could be underestimated if it is off the center of the light sheet. There are two possible approaches for correcting such off-light-sheet-center error: 1) Perform particle tracking across different frames and record the corresponding scattering readings. A particle will generate maximum scattering reading when it is at the light sheet center. Thus, querying the scattering reading curve with a particle's maximum scattering reading should result in a more accurate estimation of the particle size. 2) Localize the particle axially and then applying a scale factor to correct for the particle off-light-sheet- center error. The particle tracking method was intuitively straight-forward but may not be able to handle the situation when a particle never passes the center of the light sheet. Conversely, the particle localization method did not depend on the prerequisite that the particle must pass the light sheet center. Moreover, considering the residual astigmatism in our reported system, particle localization could be achieved without introducing any additional modulation into the imaging system. Therefor the particle localization method was chosen as our approach, and the procedural details are elaborated in the following section.

[0095] 2.4.3 Astigmatism-based particle localization and particle sizing

[0096] Due to the cylindrical nature of the vials and the imperfect Rl matching between the PDMS sample housings (Rl: 1.43) and the contents of the DP containers (Rl: 1.33 ~ 1.37), there was a residual amount of astigmatism in the imaging system. This was serendipitously helpful as it caused the imprint of a particle to elongate in different directions (either horizontally or vertically) to varying extends at different axial locations

[0027] -

[0032] . We used this distortion as an axial particle location estimator.

[0097] In practice the aspect ratio of a particle imprint was defined as the indicator to be observed, and its variation with the axial position of the particle was recorded as a further reference for localization process. The Applicants determined the relation between the aspect ratio of a particle imprint and the axial position of the particle through experiment. As mentioned previously, the particle imprints were aberration dominant and particle size insensitive. As such, the Applicants can calibrate the axial particle location estimator by using only 3 pm polystyrene beads (Polybead, 17134-15, coefficient of variance: 5%) without loss of generality. The focal plane of objective was scanned from -100 to 100 pm with step size of 10 pm, while the light sheet and the sample remained stationary. For each captured image, autocorrelation was performed, and the aspect ratio of the main autocorrelation peak was calculated. In the situation where the particles to be imaged were of comparable size, the captured image can be expected to contain the imprints of particles at different axial positions, the particles at the light sheet center should always produce the strongest signals on the camera sensor because they were illuminated by the most intense light. Thus, the main peak of the autocorrelation was dominant by the particles at the light sheet center. As such, one could obtain the aspect ratio of the in-center particle imprints by analyzing the aspect ratio of the main peak of the autocorrelation of the captured image. The Applicants performed linear fitting between z positions and the imprints of the particles to determine the slope ( / 3). With the fitted slope ( / 3) and the templates representing the in-center particle imprints, the off-center distance (Az) of a particle of interest could be determined by comparing its aspect ratio (ARp) with the template's aspect ratio (ARt)

[0098] Az = (} ■ (ARp- ARt)

[0099] Both ARpand ARtwere calculated from the corresponding autocorrelations of the particle of interest and the template. According to our experiment, we found the slope ( / 3) for large vial was -16 and the slope ( / 3) for small vial was -21, details were provided in the supplementary document.

[0100] The scale factor C for correcting the off-center error was then determined by finding the intensity decrease at axial position d compared to the maximum value from the light sheet's cross-section profile f:

[0101] C = l / f(Az~)

[0102] With the corrected scattering reading, the particle size was able to be determined from the particle size - scattering reading curve and then classified into the following categories: below 5 pm, 5 to 10 pm, 10 to 25 pm and above 25 pm.

[0103] 3. Results

[0104] The Applicants prepared a series of samples to demonstrate the functionality of our MSLS particle counter. For each type of particles, the particle statistics for each sample were listed in Table 1. Samples were prepared in both ISO 2R vials and 6R vials. The particle ground truth statistics for each sample was verified by hemocytometer. The measurements were repeated three times for each sample. The results were showed in FIGs. 5A-B. For the control samples without polystyrene beads, the MSLS analyzer produced near-zero results for all size classes. For the polystyrene bead samples, the MSLS particle analyzer produced count values close to the ground truth, but with different error bar widths for different orders of magnitude of particle concentrations.

[0105] The relation between the results and the sampling volume is further discussed, as follows. The minimum concentration value that MSLS analyzer could provide was 3.8 particle / mL - effectively equal to one particle over the total sampling volume of 0.26 mL. One can also analyze the relation between the total imaging volume and the target particle concentration from a statistical inference perspective. The number of the particles captured in a measurement should follow Poisson distribution with a mean equal to the actual concentration multiplied by the imaging volume. Based on this fact, the Applicants were able to determine that at a concentration of 463 particles / mL or higher, we can expect our results to be within a margin of ± 15% error with a 90% confidence interval, or better. Detailed derivation was reported in the supplementary document.

[0106] FIG. 5C showed a typical error that the MSLS analyzer encountered during the measurements when two particle imprints became close or even overlapped with each other. In such cases, the particle size was overestimated because of the contribution of extra scattered light from other particles. When particle concentration of a sample would become high enough that the particle imprints overlap frequently, the MSLS analyzer would fail to provide accurate particle statistics (size and concentration). The Applicants performed the simulation described in the supplementary document to determine this upper concentration bound of our MSLS analyzer. The Applicants set the breakdown proportion of overlapped imprints to be 10% and the corresponding upper concentration limit was found to be 5.00e5 particle / mL.

[0107] Table 1: Particle statistics of prepared samples

[0108] Unit: particle / mL

[0109] 4. Discussion

[0110] The Applicants developed the MSLS analyzer to characterize subvisible particles in pharmaceutical DP containers non-destructively. The system used light sheet microscopy and Mie scattering model to perform particle sizing and counting directly for samples in representative DP containers of ISO 2R vials and ISO 6R vials. Square sample housings made of PDMS were created to partially compensate for the severe astigmatism inherent to cylindrical containers. As the system was still aberration dominated, particle detection was achieved by template matching. For every detected particle imprint, astigmatism-based particle localization was performed to determine the corresponding incident light intensity. This information was then used to scale the particle's scattering reading accordingly such that the pre-calculated particle size - scattering reading curve could be used for querying the particle size. By combining the results of all the particles within the imaging volume, an estimation of the particle concentration statistics for a sample was generated.

[0111] The Applicants wish to clarify that the MSLS analyzer could estimate the particle size range but could not measure the exact particle size. The limitation arises from three aspects. 1) The estimation relied on the refractive index of the media and the target particles. For unknown particles, the estimated size can be expected to have deviations as their refractive index would not be known without prior knowledge or direct measurement. 2) The scattering model treated all particles as spheres. 3) The scattering reading values exhibited fluctuations as the particle size increased, as observed in FIG. 5. Such property resulted in situations where a single scattering reading points to multiple sizes within an acceptable range. These considerations will be appreciated when implementing the methods and systems described herein.

[0112] A significant advantage of the methods and systems described herein (comprising MSLS analyzers and / or analysis) are their complete non-invasiveness. The only required manipulation of the sample was to place it inside the sample housing. Furthermore, the sample housings described herein are reusable and easy to make. Without being limited by theory, the control of the astigmatism was the main contributor in enabling the non-invasiveness. On the one hand, the Applicants used the sample housing to mitigate the severe astigmatism to an extend that the subsequent processing could be performed. On the other hand, the residual astigmatism played a crucial role in particle axial localization and accurate size estimation.

[0113] The non-invasiveness of the MSLS analyzer made it well-suited for applications such as monitoring the variation of a single sample over time and conducting initial testing for a large group of samples. Further improvements to the MSLS analyzer could involve replacing mechanical sample scanning by stages with light sheet scanning for higher measuring speed, as well as exploring additional features besides the scattering intensity that could serve as potential indicators for particle characteristics such as size, shape, or chemical composition, and bulk solution properties such as color, turbidity, and viscosity.

[0114] References

[0115] The following references are incorporated herein by reference in their entireties:

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[0145] GENERAL

[0146] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0147] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted.

[0148] Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range and each endpoint, unless otherwise indicated herein, and each separate value and endpoint is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0149] Preferred embodiments of this disclosure are described herein, including the best mode known to the inventors for carrying out the disclosure. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. Combinations of the elements described herein, in suitable variations thereof, are encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

What is claimed is:

1. A method for determining an absence, or presence and size of particles in a liquid pharmaceutical product, the method comprising: providing the liquid pharmaceutical product in a shelf keeping unit (SKU) container suitable for administration to a patient, said SKU container comprising a cylindrical vessel in which the pharmaceutical product is disposed therein; illuminating the cylindrical vessel with a sheet of electromagnetic radiation, thereby producing side scatter light; and determining a presence or absence, and if present, a concentration and size, of a particle in the liquid pharmaceutical product in the cylindrical vessel, wherein said determining utilizes on Mie scattering theory, wherein analyzed liquid pharmaceutical product in the SKU container remains suitable for administration to a patient after said determining the absence, or the presence and size of particles in the liquid pharmaceutical product.

2. The method of claim 1, wherein said illuminating illuminates the cylindrical vessel disposed in a solid housing that conforms to the cylindrical vessel, said solid housing comprising: an inner surface that conforms to the convex curved surface of the cylindrical vessel; and an outer surface comprising a facet that is flat or substantially flat, wherein a first difference between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product, optionally wherein the method further comprises disposing the cylindrical vessel in the solid housing prior to the illuminating.

3. The method of any one of the preceding claims, wherein the size of the particle is determined based on side-scattering light intensity, and not subvisible particle morphology.

4. The method of any one of the preceding claims, wherein said determining comprises: obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation; and template mapping the input image to a template.

5. The method of claim 4, further comprising: downsizing the input image by a factor, such as about 10, wherein the template is also downsized by the factor;Gaussian blurring the downsized input image and downsized template; and cross-correlating between the Gaussian blurred and downsized input image and template image.

6. The method of claim 5, wherein the template image is downsized prior to obtaining the input image.

7. The method of any one of the preceding claims, comprising using astigmatism as an estimator of the particle's axial position and determining the incident light intensity for that particle.

8. The method of any one of the preceding claims, further comprising categorizing detected subvisible particles according to particle diameter bins, such as bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

9. The method of any one of the preceding claims, wherein the determining is repeated for additional particles.

10. A system for determining an absence, or presence and size of particles in a liquid pharmaceutical product, the system comprising: a Mie-scattering-based light sheet (MSLS) liquid particle analyzer comprising an illumination source and a detector; and a solid housing that conforms to a cylindrical vessel configured to contain a liquid pharmaceutical product, said solid housing comprising: an inner surface that conforms to the convex curved surface of the cylindrical vessel; and an outer surface that is flat or substantially flat, wherein a first difference, between a refractive index of the solid housing and a refractive index of the liquid pharmaceutical product, is less than a second difference between a refractive index of ambient air and a refractive index of the liquid pharmaceutical product; anda processor configured to determine a presence or absence, and if present a concentration and size, of particles in the liquid pharmaceutical product in the cylindrical vessel, wherein said determining utilizes on Mie scattering theory, wherein the illumination source is configured to illuminate the solid housing configured to contain a SKU container comprising a cylindrical vessel containing a liquid pharmaceutical product, wherein the detector is configured to receive side scatter light from the illuminated solid housing, and wherein the system is configured for the liquid pharmaceutical product in the SKU container to remain suitable for administration to a patient after said absence, or said presence and size of particles in the liquid pharmaceutical product has been determined.

11. The system of claim 10, wherein the processor is configured to determine the size of the particles based on side-scattering light intensity, and not subvisible particle morphology.

12. The system of any one of claims 10-11, wherein the determination of the size of the particles by the processor comprises: obtaining an input image of the particle illuminated by the sheet of electromagnetic radiation; and template mapping the input image to a template.

13. The system of claim 12, wherein the determination by the processor further comprises downsizing the input image by a factor, such as about 10, wherein the template is also downsized by the factor;Gaussian blurring the downsized input image and downsized template; and cross-correlating between the Gaussian blurred and downsized input image and template image.

14. The system of any one of claims 10-13, wherein the processor is configured to categorize the detected subvisible particles according to particle diameter bins, such as bins of 2 pm to 5 pm, 5 pm to 10 pm, 10 pm to 25 pm, and above 25 pm.

15. The method of any one of claims 2-9 or the system of any one of claims 10-14, wherein the solid housing has a refractive index of about 1.1 to about 1.7, such as about 1.2 to about 1.6, or about 1.4.

16. The method of any one of claims 2-9 or 15, or the system of any one of claims 10-15, wherein the solid housing comprises or consists of polydimethylsiloxane (PDMS) elastomer.

17. The method of any one of claims 2-9 or 15-16, or the system of any one of claims 10- 16, wherein the solid housing comprises two or more facets that are each flat or substantially flat.

18. The method or system of any one of the preceding claims wherein the particle is or particles are a subvisible particle.

19. The method or system of any one of the preceding claims wherein the particle has or particles have an average diameter of about 1 pm to 100 pm, or about 2 pm to 100 pm.

20. The method or system of any one of the preceding claims wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the liquid pharmaceutical product remaining sealed in the SKU container.

21. The method or system of any one of the preceding claims wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the SKU container remaining intact.

22. The method or system of any one of the preceding claims wherein the liquid pharmaceutical product in the SKU container remaining suitable for administration to a patient comprises the liquid pharmaceutical product remaining sterile.

23. The method or system of any one of the preceding claims, wherein in addition to remaining suitable for administration to a patient, the liquid pharmaceutical product in the SKU container further remains suitable for continued storage under specified conditions, such as stability, temperature cycling, mechanical stresses, and / or light stress.

24. The method or system of any one of the preceding claims wherein the SKU container comprises a vial, syringe, or autoinjector.

25. The method or system of any one of the preceding claims wherein the liquid pharmaceutical product comprises a therapeutic protein, such as an antigen binding protein or a fusion protein.

26. The method or system of claim 25, wherein the antigen binding protein comprises or consists of a monoclonal antibody or binding fragment thereof.

27. The method or system of any one of the preceding claims wherein the liquid pharmaceutical product comprises a liquid drug product or a reconstituted lyophilized drug product.

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