Low acid sealing fluid for sealing capsules

Abstract

The present application discloses a sealing fluid comprising an acid, an alcohol and optionally water, the acid is lactic acid or acetic acid, the alcohol is isopropanol or ethanol, the sealing fluid is a liquid composition for sealing telescopically joined hard capsules with coaxial partly overlapping body parts.

Description

[0001] PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0002] LOW ACID SEALING FLUID FOR SEALING CAPSULES

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 700,862, filed September 30, 2024, which is incorporated herein by reference in its entirety.

[0005] FIELD

[0006] The present application discloses a sealing fluid comprising an acid, an alcohol and optionally water, the acid is lactic acid or acetic acid, the alcohol is isopropanol or ethanol, the sealing fluid is a liquid composition for sealing telescopically joined hard capsules with coaxial partly overlapping body parts.

[0007] BACKGROUND

[0008] Capsules are well known dosage forms for pharmaceuticals, nutraceuticals, dietary supplement ingredients and the like. A hard capsule normally consists of a shell filled with one or more substances. A hard capsule shell consists of two parts, a cap and a body, both have cylindrical shape with an open end and a close end; the outer diameter of the cylindrical open end of the body fits telescopically into the inner diameter of the cylindrical open end of the cap. Once the capsule, that is the body, has been filled with the content of the capsule, the capsule is closed, for closing the capsule the open end of the body is telescopically inserted into the open end of the cap.

[0009] INTRODUCTION

[0010] Hard capsules are generally manufactured by using a dip molding process, a mold pin is dipped into a melt, which is a liquid film forming composition comprising a dissolved film forming polymer. After extraction a film forms on the mold pin. The film is stripped from the mold pin; the dip molding is done separately to manufacture the cap and the body. So, in the closed capsule the cylindrical open end of the cap partly overlaps with the cylindrical open end of the body, that is part of the inner cylindrical surface of the cap is in contact with part of the outer cylindrical surface of the body. Between these overlapping surfaces of the cap and the body leakage may occur, since for various reasons the match of the inner diameter of the cap and the outer diameter of the body cannot be so exact and tight that any leakage is prevented, for example when the body is inserted into the cap when PCT / US25 / 48156 26 September 2025 (26.09.2025) closing the respective air volume in the cap needs to escape, other wise an overpressure may build up which may prevent a complete closing or even destroy the capsule; also the forces which need to be applied for sliding the cap over the body must not bee to great in order to avoid damage of the cap or the body when closing. So, there is always some tolerance between the cap and the body resulting in a slit between the overlapping parts of the cap and the body.

[0011] Once the capsule is closed, the beginning of this slit between the rim of the cap and the surface of the body is visible and approachable.

[0012] In some cases, it is desired to avoid leakage of the content from the capsule, for example when the capsule is filled with a liquid substance. For this purpose, the capsule is sealed, that is the slit between the cap and the body is closed be sealing. This sealing can also be viewed as a gluing or a bonding of the cap and the body to each other by means of a sealing fluid. When sealing the capsule the sealing fluid is applied onto the beginning of this slit between the rim of the cap and the surface of the body. By capillary action the sealing fluid is then spread and distributed into the inside of the slit. Capsule shells may be made of a variety of film forming polymers such as gelatin, HPMC, pullulan or starch. In case of HPMC there are two principally different methods for forming the film on the mold pin in the dip molding process: conventional gelation of HPMC at temperatures below the gelling temperature of a melt of HPMC requires in the melt the presence of a gelling system such as gellan; whereas thermal gelation occurs at temperatures above the gelation temperature of a melt of HPMC and does not require the presence of an additional gelling system in the melt.

[0013] WO 2022 / 128905 Al discloses a sealing fluid which contains at least 32.5 wt% of an acid, which is lactic acid or acetic acid, and at least 17.5 wt% of an alcohol, isopropanol or ethanol.

[0014] The sealing fluid disclosed in WO 2022 / 128905 Al imparts a distinctly sour taste on the capsules sealed therewith.

[0015] The problem to be solved was to provide a sealing fluid which is usable in automated sealing machines for automatized sealing of capsules, so large scale bulk production to reduce manufacturing time and costs and to reduce waste due to imperfection of the product should be possible. The sealing fluid should enable sealing of capsules immediately after PCT / US25 / 48156 26 September 2025 (26.09.2025) filling of the capsules at a rate compatible with conventional capsule filling lines. Also, no problems such as clogging should occur.

[0016] The sealing fluid should provide for an effective seal of the filled capsules to avoid leakage of any content, so a low leakage rate is desired. The sealing fluid should not have a detrimental effect on shape, dimension, or stability of the capsule. The sealing fluid should be applicable to all kinds of capsule, especially to capsules with a combination of HPMC as film forming polymer and gellan as gelling system, that is to capsule shells made of HPMC and gellan as main or even sole components of the capsule shell. Furthermore the capsules sealed with the sealing fluid should have less sour taste compared to capsules sealed with the sealing fluid disclosed in WO 2022 / 128905 Al. The integrity and quality of the sealing disclosed in WO 2022 / 128905 Al is affected by the acid in an amount of at least 32.5 wt%. Reducing this amount of acid in order to reduce the sour taste will jeopardize the integrity and quality of the sealing.

[0017] The problem is solved with a sealing composition comprising an acid, preferably lactic acid, in an amount of not more than 30 wt%, and an alcohol, preferably isopropanol, in an amount of at least 50 wt%, and optionally water.

[0018] Abbreviations and definitions used in this specification

[0019] HPMC hydroxypropyl methylcellulose, also called hypromellose or Cellulose, 2- hydroxypropyl methyl ether or cellulose hydroxypropyl methyl ether, CAS 9004-65-3

[0020] SUMMARY

[0021] Subject of the disclosure is a sealing fluid for sealing hard capsules comprising an acid and an alcohol; the acid is lactic acid, acetic acid or a combination thereof; the alcohol is isopropanol, ethanol or a combination thereof; wherein the amount of the acid is not more than 30 wt%; the amount of the alcohol is at least 50 wt%; the wt% being based on the weight of the sealing fluid. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0022] DETAILED DESCRIPTION

[0023] Preferably, the amount of the alcohol is at least 51 wt%, at least 52 wt%, at least 53 wt%, at least 54 wt%, at least 55 wt%, at least 56 wt%, at least 57 wt%, at least 58 wt%, at least 58.5 wt%, at least 59 wt%, at least 59.5 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the alcohol is not more than 80 wt%, not more 75 wt%, not more 70 wt%, not more than 65 wt%, nor more than 62.5 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid; any of the lower limits may be combined with any of the upper limits of the possible amounts of the alcohol.

[0024] Possible ranges for the lower limits and the upper limits of the possible amounts of the alcohol are: from 50 to 80 wt%, from 50 to 75 wt%, from 50 to 70 wt%, from 50 to 65 wt%, from 50 to

[0025] 62.5 wt%; from 51 to 80 wt%, from 51 to 75 wt%, from 51 to 70 wt%, from 51 to 65 wt%, from 51 to

[0026] 62.5 wt%; from 52 to 80 wt%, from 52 to 75 wt%, from 52 to 70 wt%, from 52 to 65 wt%, from 52 to

[0027] 62.5 wt%; from 53 to 80 wt%, from 53 to 75 wt%, from 53 to 70 wt%, from 53 to 65 wt%, from 53 to

[0028] 62.5 wt%; from 54 to 80 wt%, from 54 to 75 wt%, from 54 to 70 wt%, from 54 to 65 wt%, from 54 to

[0029] 62.5 wt%; from 55 to 80 wt%, from 55 to 75 wt%, from 55 to 70 wt%, from 55 to 65 wt%, from 55 to

[0030] 62.5 wt%; from 56 to 80 wt%, from 56 to 75 wt%, from 56 to 70 wt%, from 56 to 65 wt%, from 56 to

[0031] 62.5 wt%; from 57 to 80 wt%, from 57 to 75 wt%, from 57 to 70 wt%, from 57 to 65 wt%, from 57 to

[0032] 62.5 wt%; from 58 to 80 wt%, from 58 to 75 wt%, from 58 to 70 wt%, from 58 to 65 wt%, from 58 to

[0033] 62.5 wt%; from 58.5 to 80 wt%, from 58.5 to 75 wt%, from 58.5 to 70 wt%, from 58.5 to 65 wt%, from

[0034] 58.5 to 62.5 wt%; PCT / US25 / 48156 26 September 2025 (26.09.2025) from 59 to 80 wt%, from 59 to 75 wt%, from 59 to 70 wt%, from 59 to 65 wt%, from 59 to

[0035] 62.5 wt%; from 59.5 to 80 wt%, from 59.5 to 75 wt%, from 59.5 to 70 wt%, from 59.5 to 65 wt%, from

[0036] 59.5 to 62.5 wt%; the wt% being based on the weight of the sealing fluid.

[0037] Preferably, the amount of the acid is not more than 27.5 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the acid is at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid.

[0038] Any of the lower limits may be combined with any of the upper limits of the possible amounts of the acid.

[0039] Preferably, the amount of acid is from 10 to 27.5 wt%, from 12.5 to 27.5 wt%, from 15 to 27.5 wt%, from 17:5 to 27.5 wt%, from 18 to 27.5 wt%, from 19 to 27.5 wt%, with a narrower range preferred over a broader range; more preferably, the amount of acid is from 10 to 25 wt%, from 12.5 to 25 wt%, from 15 to 25 wt%, from 17.5 to 25 wt%, from 18 to 25 wt%, from 19 to 25 wt%, with a narrower range preferred over a broader range; even more preferably, the amount of acid is from 10 to 22.5 wt%, from 12.5 to 22.5 wt%, from 15 to 22.5 wt%, from 17:5 to 22.5 wt%, from 18 to 22.5 wt%, from 19 to 22.5 wt%, with a narrower range preferred over a broader range; especially, the amount of acid is from 10 to 22 wt%, from 12.5 to 22 wt%, from 15 to 22 wt%, from 17.5 to 22 wt%, from 18 to 22 wt%, from 19 to 22 wt%, with a narrower range preferred over a broader range; more especially, the amount of acid is from 10 to 21 wt%, from 12.5 to 21 wt%, from 15 to 21 wt%, from 17.5 to 21 wt%, from 18 to 21 wt%, from 19 to 21 wt%, with a narrower range preferred over a broader range; the wt% being based on the weight of the sealing fluid.

[0040] Any of the ranges of the possible amounts of the alcohol mentioned herein can be combined with any of the ranges of the possible amounts of the acid mentioned herein. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0041] Preferably, the acid is lactic acid; more preferably, the acid is lactic acid and the alcohol is isopropanol.

[0042] Preferably, the sealing fluid comprises water; more preferably, the amount of the water is at least 5 wt%, at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the water is not more than 30 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid.

[0043] Any of the lower limits may be combined with any of the upper limits of the possible amounts of water.

[0044] Preferably, the amount of water is from 5 to 30 wt%, from 10 to 30 wt%, from 12.5 to 30 wt%, from 15 to 30 wt%, from 17.5 to 30 wt%, from 18 to 30 wt%, from 19 to 30 wt%, with a narrower range preferred over a broader range; more preferably, the amount of water is from 5 to 25 wt%, from 10 to 25 wt%, from 12.5 to 25 wt%, from 15 to 25 wt%, from 17.5 to 25 wt%, from 18 to 25 wt%, from 19 to 25 wt%, with a narrower range preferred over a broader range; even more preferably, the amount of water is from 5 to 22.5 wt%, from 10 to 22.5 wt%, from 12.5 to 22.5 wt%, from 15 to 22.5 wt%, from 17.5 to 22.5 wt%, from 18 to 22.5 wt%, from 19 to 22.5 wt%, with a narrower range preferred over a broader range; especially, the amount of water is from 5 to 22 wt%, from 10 to 22 wt%, from 12.5 to 22 wt%, from 15 to 22 wt%, from 17.5 to 22 wt%, from 18 to 22 wt%, from 19 to 22 wt%, with a narrower range preferred over a broader range; more especially, the amount of water is from 5 to 21 wt%, from 10 to 21 wt%, from 12.5 to 21 wt%, from 15 to 21 wt%, from 17.5 to 21 wt%, from 18 to 21 wt%, from 19 to 21 wt%, with a narrower range preferred over a broader range; the wt% being based on the weight of the sealing fluid.

[0045] The sealing fluid can comprise the acid lactic acid, the alcohol isopropanol, ethanol or a combination thereof and optionally water, with the amounts of lactic acid, of alcohol and of the optional water as disclosed herein, also with all their aspects and combinations. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0046] The sealing fluid can comprise other ingredients, such as further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the sum of the amounts of the acid, the alcohol and water are at least 90 wt%, at least 92.5 wt%, at least 95 wt%, at least 97.5 wt%, at least 98 wt%, at least 99 wt%, with a higher sum of the amounts being preferred over a lower sum of the amounts, with the wt% being based on the weight of the sealing fluid.

[0047] In one aspect, the sealing fluid consists of the acid, the alcohol and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the acid is lactic acid; more preferably, the acid is lactic acid and the alcohol is isopropanol; with the amounts of acid and of alcohol as disclosed herein, also with all their aspects and combinations, preferably, the amount of acid is from 17.5 to 22.5 wt%, and the amount of alcohol is from 50 to 75 wt%, from 51 to 75 wt%, from 52 to 75 wt%, from 53 to 75 wt%, from 54 to 75 wt%, from 55 to 75 wt%, from 56 to 75 wt%, from 57 to 75 wt%, from 58 to 75 wt%, from 58.5 to 75 wt%, from 59 to 70 wt%, from 59 to 65 wt%, with a narrower range preferred over a broader range; with the wt% being based on the weight of the sealing fluid.

[0048] In an aspect, the sealing fluid consists of the acid lactic acid, the alcohol isopropanol, ethanol or a combination thereof, preferably isopropanol, and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the amount of lactic acid is from 17.5 to 22.5 wt%, and the amount of alcohol is from 50 to 75 wt%, from 51 to 75 wt%, from 52 to 75 wt%, from 53 to 75 wt%, from 54 to 75 wt%, from 55 to 75 wt%, from 56 to 75 wt%, from 57 to 75 wt%, from 58 to 75 wt%, from 58.5 to 75 wt%, from 59 to 70 wt%, from 59 to 65 wt%, with a narrower range preferred over a broader range; with the wt% being based on the weight of the sealing fluid. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0049] Any water is preferably demineralized water.

[0050] Any viscosity mentioned herein is determined with a rotational viscometer with a cylindrical spindle and is measured at 22 °C.

[0051] Preferably, the sealing fluid has a viscosity of 500 cps or below, 450 cps or below, 400 cps or below, 350 cps or below, 300 cps or below, 250 cps or below, of 200 cps or below, of 150 cps or below, of 125 cps or below, of 100 cps or below, of 75 cps or below, of 60 cps or below, of 50 cps or below, of 45 cps or below, of 40 cps or below, of 35 cps or below, of 30 cps or below, of 25 cps or below, of 20 cps or below, of 15 cps or below, with a lower limit preferred over a higher limit.

[0052] Preferably, the sealing fluid does not contain any substance that increases by its addition the viscosity of the sealing fluid.

[0053] Preferably, the sealing fluid does not contain HPMC, and / or the sealing fluid does not contain cellulose derivatives, and / or the sealing fluid does not contain gelatin, and / or the sealing fluid does not contain pullulan, and / or the sealing fluid does not contain starch, and / or the sealing fluid does not contain modified starch, and / or the sealing fluid does not contain any polymer which is conventionally used as film forming polymer in the preparation of capsules, such as gelatin, pullulan, starch, modified starch, or cellulose derivatives, such as HPMC, so and / or the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and HPMC, and / or; the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and cellulose derivatives; preferably, the sealing fluid does not contain any polymer, and / or the sealing fluid does not contain any gelling agent, and / or the sealing fluid does not contain any gelling aid, and / or the sealing fluid does not contain any gelation system comprising a gelation agent and optionally a gelling aid. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0054] Further subject of the disclosure is a method for preparation of the sealing fluid, wherein the acid, the alcohol and optionally any water and any optional other ingredient, such as any further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners, are mixed together; with the sealing fluid, the acid and the alcohol as defined herein, also with all their aspects.

[0055] The mixing of the acid, the alcohol and water and of any optional other ingredient, such as and further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners, can be done in any order.

[0056] Further subject of the disclosure is a method for sealing a hard capsule, the hard capsule comprises a hard capsule shell and the content contained in the hard capsule shell, the hard capsule shell of the capsule consists of a cap and a body with the body being telescopically inserted in the cap providing a slit between the overlapping parts of the cap and the body; wherein the sealing is done by applying the sealing fluid onto said slit; with the sealing fluid as defined herein, also with all its aspects. By the method for sealing a hard capsule a sealed hard capsule is provided. Preferably, the application of the sealing fluid onto said slit is done by spraying the sealing fluid onto the slit.

[0057] The hard capsule shell is filled and closed providing the capsule before the sealing. When closing the capsule the cap and the body are telescopically joined. This joining can be done for example by inserting the body into the cap, that is the body slides into the cap, or the other way around, the cap slides over the body. The cap and the body partly overlap in the closed capsule. Thereby a slit is formed between the overlapping parts of the cap and the body. When sealing the capsule the sealing fluid is applied onto the slit, that is onto the beginning of this slit which is approachable from the outside of the capsule. The beginning of the slit is located between the rim of the cap and the surface of the body.

[0058] The sealing fluid can be applied uniformly around the whole surface of the capsule, thereby also onto the slit, or the sealing fluid may be applied predominantly or only onto the slit. The sealing fluid may be applied onto the slit over the whole length of the slit or only to PCT / US25 / 48156 26 September 2025 (26.09.2025) a part or to parts of the length of the slit. Preferably it is applied over the whole length of the slit.

[0059] The sealing fluid can be applied by spraying onto the slit or onto the capsule and thereby also onto the slit.

[0060] The sealing fluid can have ambient temperature or a temperature below ambient temperature when it is applied onto the capsule, that is onto the slit.

[0061] After the application of the sealing fluid onto the slit the capsule may be dried. This drying may for example be done to remove any excess of the sealing fluid. It may also be done to ensure that the part of the surfaces of the overlapping parts of the cap and the body, which face each other, that is the part of the surfaces of the cap and the body that form the slit, securely bond to each other.

[0062] Further subject of the disclosure is a sealed hard capsule obtainable by the method for sealing a hard capsule, with the method as defined herein, also with all its aspects.

[0063] Further subject of the disclosure is a sealed hard capsule obtained by the method for sealing a hard capsule, with the method as defined herein, also with all its aspects.

[0064] Capsules suitable for the method for sealing a hard capsule of the present disclosure may have a shell made out of known film forming polymers such as gelatin, cellulose derivatives, such as HPMC, pullulan, starch or modified starch. The capsule shell may comprise further components such as a gelling system, the gelling system can be a gelling agent together with a gelling aid, or a gelling agent alone, a typical gelling agent is gellan, a typical gelling aid is KC1. In one aspect, the method for sealing a hard capsule of the present disclosure is a method for sealing hard capsules wherein the film forming polymer of the capsule shell is gelatin, cellulose derivatives, such as HPMC, pullulan, starch or modified starch, in an aspect the film forming polymer is HPMC, in an aspect the film forming polymer is HPMC and the capsule shell contains gellan as gelling agent. The amount of gellan in the capsule shell may be from 0.01 to 10 wt%, preferably 0.01 to 7 wt%, more preferably 0.1 to 7 wt%, even more preferably from 1 to 7 wt%, especially from 3 to 6 wt%, more especially from 4 to 6 wt%, the wt% being based on the weight of HPMC. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0065] Any capsule mentioned herein which is sealed or sealable with the sealing fluid disclosed herein, is a hard capsule.

[0066] OVERVIEW OF SEVERAL ASPECTS

[0067] Aspects of the disclosure are provided below in the following clauses:

[0068] 1. A sealing fluid for sealing hard capsules comprising an acid and an alcohol; the acid is lactic acid, acetic acid or a combination thereof; the alcohol is isopropanol, ethanol or a combination thereof; wherein the amount of the acid is not more than 30 wt%; the amount of the alcohol is at least 50 wt%; the wt% being based on the weight of the sealing fluid.

[0069] 2. The sealing fluid according to clause 1, wherein the amount of the alcohol is at least 51 wt%, at least 52 wt%, at least 53 wt%, at least 54 wt%, at least 55 wt%, at least 56 wt%, at least 57 wt%, at least 58 wt%, at least 58.5 wt%, at least 59 wt%, at least 59.5 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid, and / or the amount of the alcohol is not more than 80 wt%, not more 75 wt%, not more 70 wt%, not more than 65 wt%, nor more than 62.5 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid.

[0070] 3. The sealing fluid according to clauses 1 or 2, wherein the amount of the acid is not more than 27.5 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the acid is at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid.

[0071] 4. The sealing fluid according to one or more of clauses 1 to 3, wherein PCT / US25 / 48156 26 September 2025 (26.09.2025) the acid is lactic acid; preferably, the acid is lactic acid and the alcohol is isopropanol.

[0072] 5. The sealing fluid according to one or more of clauses 1 to 4, wherein the sealing fluid comprises water; preferably, the amount of the water is at least 5 wt%, at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the water is not more than 30 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid.

[0073] 6. The sealing fluid according to one or more of clauses 1 to 5, wherein the sealing fluid comprises further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the sum of the amounts of the acid, the alcohol and water are at least 90 wt%, at least 92.5 wt%, at least 95 wt%, at least 97.5 wt%, at least 98 wt%, at least 99 wt%, with a higher sum of the amounts being preferred over a lower sum of the amounts, with the wt% being based on the weight of the sealing fluid.

[0074] 7. The sealing fluid according to one or more of clauses 1 to 6, wherein the sealing fluid consists of the acid, the alcohol and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the acid is lactic acid; more preferably, the acid is lactic acid and the alcohol is isopropanol.

[0075] 8. The sealing fluid according to one or more of clauses 1 to 7, wherein the sealing fluid consists of the acid lactic acid, the alcohol isopropanol, ethanol or a combination thereof, preferably isopropanol, and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; PCT / US25 / 48156 26 September 2025 (26.09.2025) preferably, the amount of lactic acid is from 17.5 to 22.5 wt%, and the amount of alcohol is from 50 to 75 wt%, from 51 to 75 wt%, from 52 to 75 wt%, from 53 to 75 wt%, from 54 to 75 wt%, from 55 to 75 wt%, from 56 to 75 wt%, from 57 to 75 wt%, from 58 to 75 wt%, from 58.5 to 75 wt%, from 59 to 70 wt%, from 59 to 65 wt%, with a narrower range preferred over a broader range; with the wt% being based on the weight of the sealing fluid.

[0076] 9. The sealing fluid according to one or more of clauses 1 to 8, wherein the sealing fluid does not contain HPMC, and / or the sealing fluid does not contain cellulose derivatives, and / or the sealing fluid does not contain gelatin, and / or the sealing fluid does not contain pullulan, and / or the sealing fluid does not contain starch, and / or the sealing fluid does not contain modified starch, and / or the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and HPMC; the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and cellulose derivatives; preferably, the sealing fluid does not contain any polymer, and / or the sealing fluid does not contain any gelling agent, and / or the sealing fluid does not contain any gelling aid, and / or the sealing fluid does not contain any gelation system comprising a gelation agent and optionally a gelling aid.

[0077] 10. A method for preparation of the sealing fluid, wherein the acid, the alcohol and optionally any water and any optional further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners, are mixed together.

[0078] 11. A method for sealing a hard capsule, the hard capsule comprises a hard capsule shell and the content contained in the hard capsule shell, the hard capsule shell of the capsule consists of a cap and a body with the body being telescopically inserted in the cap providing a slit between the overlapping parts of the cap and the body; wherein the sealing is done by applying the sealing fluid onto said slit; PCT / US25 / 48156 26 September 2025 (26.09.2025) with the sealing fluid as defined in one or more of clauses 1 to 9; preferably, the application of the sealing fluid onto said slit is done by spraying the sealing fluid onto the slit.

[0079] 12. A sealed hard capsule obtainable by the method for sealing a hard capsule according to clauses 11.

[0080] EXAMPLES

[0081] Materials and abbreviations capsules in the examples DRcaps ® Capsules of Capsugel, now a Lonza company, Lonza Ltd, Basel, Switzerland, were used, DRcaps Capsules have HPMC as the film forming polymer and gellan gum as gelling agent. cps viscosity in centipoise, measured at 22 °C, determined with a rotational viscometer with a cylindrical spindle

[0082] One centipoise is one millipascal- second (mPa*s); also the abbreviations cp and and cPs are sometimes seens for cps.

[0083] EtOH ethanol

[0084] Ex example

[0085] IPA Isopropyl alcohol, isopropanol lactic acid (S)-Lactic acid

[0086] RH relative humidity w, wt% weight, weight percent

[0087] Examples

[0088] (A) Sealing fluid

[0089] A sealing fluid solution consisting of

[0090] • lactic acid,

[0091] • IPA,

[0092] • water, and optionally

[0093] • EtOH, the wt% being based on the weight of the sealing fluid solution, was prepared by mixing the components. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0094] Preferably, demineralized water is used as water, which was the case in all examples disclosed herein. The sealing fluid was used at ambient temperature to seal capsules.

[0095] (B) General description of the sealing and the Leak Rate Detection

[0096] Capsules of size 00 were used in the examples.

[0097] Capsules bodies were filled in vertical orientation, that is with the opening of the body facing upwards, with a test liquid of a predetermined viscosity, each capsule body was filled with the same amount of test liquid, and while keeping the capsule in vertical orientation the capsules bodies were telescopically closed with a respective capsule cap and the closed capsules were sprayed with the sealing fluid. The amount of sealing fluid sprayed per capsule was 25 mg.

[0098] Any viscosity herein was determined at 22 °C with a rotational viscometer with a cylindrical spindle and is stated in the unit centipoise, cps.

[0099] The spray of the sealing fluid was directed to the slit provided by the overlap between the telescopically joined cap and body. The sealing fluid fuses the cap with the body in the area of the slit to make a single piece capsule.

[0100] After spraying the sprayed capsules were spread on the white filter paper on a tray. No additional drying was done. The capsules were left lying on the white paper for 4 hours at room temperature and ambient pressure, and then the tray was placed in a vacuum of 250 mbar for 20 minutes.

[0101] After the exposure to vacuum the capsules on the white filter paper and the white filter paper were visually inspected: Leaking capsules will show by a stain, which appears as a spot, a wettened area on the filter paper. The stains were counted. The leaking capsules were manually separated from the non-leaking capsules.

[0102] Leak Rate is given as % of leaking capsules based on the number of capsules tested for leaking.

[0103] In case of lab scale operation, leak rates of 0.5% or below are acceptable. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0104] In case of pilot plant scale I production scale operation, leak rates of 0.1% or below are acceptable.

[0105] Batch size is the number of capsules that were tested with one sealing fluid

[0106] 5 composition; all capsules of one batch were sprayed with the same sealing fluid and all were visually inspected and the number of leakers determined by counting.

[0107] (C) Tests

[0108] Table 1 shows the parameters and the results, wt% are based on the weight of sealing fluid.

[0109] 10

[0110] The Comparative Example (CompEx) was done with the sealing fluid disclosed in WO 2022 / 128905 Al, Example (A), sealing fluid (Al): 40 wt% lactic acid 100%, 40 wt% isopropanol 100% and 20 wt% water (40 : 40 : 20) with a viscosity of ca. 7 cps at 22 °C.

[0111] 15

[0112] The sealing fluid of Examples 1, 2 and 3 (20 wt% lactic acid 100%, 60 wt% isopropanol 100% and 20 wt% water (20 : 60 : 20)) has a viscosity of < 10 cps at 22 °C. PCT / US25 / 48156 26 September 2025 (26.09.2025)

[0113] The fill weight of the capsules with test liquid was:

[0114] • for the runs with the test liquid of 150 cps: 650 mg.

[0115] • for the runs with the test liquid of 54 cps: 600 mg

[0116] 5

[0117] The dimension, shape and stability of the capsules were not affected by the sealing.

[0118] No problems such as clogging of the sealing machine was observed.

[0119] 10 Samples of capsules of Example 2 were placed into stability chambers at 25 °C and 60% relative humidity (RH), at 40 °C and 75% RH, and at 20 °C and 50 RH, with no signs of quality issue after 6 weeks.

[0120] The sealed capsules of the CompEx had distinctly sour taste, capsules of the inventive examples had little or no sour taste.

[0121] It was surprising that the capsules sealing fluid would actually seal the capsules with a reduced acid content.

[0122] 20

Claims

PCT / US25 / 48156 26 September 2025 (26.09.2025)CLAIMS1. A sealing fluid for sealing hard capsules comprising an acid and an alcohol; the acid is lactic acid, acetic acid or a combination thereof; the alcohol is isopropanol, ethanol or a combination thereof; wherein the amount of the acid is not more than 30 wt%; the amount of the alcohol is at least 50 wt%; the wt% being based on the weight of the sealing fluid.

2. The sealing fluid according to claim 1, wherein the amount of the alcohol is at least 51 wt%, at least 52 wt%, at least 53 wt%, at least 54 wt%, at least 55 wt%, at least 56 wt%, at least 57 wt%, at least 58 wt%, at least 58.5 wt%, at least 59 wt%, at least 59.5 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid, and / or the amount of the alcohol is not more than 80 wt%, not more 75 wt%, not more 70 wt%, not more than 65 wt%, nor more than 62.5 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid.

3. The sealing fluid according to claim 1, wherein the amount of the acid is not more than 27.5 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the acid is at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid.

4. The sealing fluid according to claim 1, wherein the acid is lactic acid; preferably, the acid is lactic acid and the alcohol is isopropanol.

5. The sealing fluid according to claim 1, wherein the sealing fluid comprises water;PCT / US25 / 48156 26 September 2025 (26.09.2025) preferably, the amount of the water is at least 5 wt%, at least 10 wt%, at least 12.5 wt%, at least 15 wt%, at least 17.5 wt%, at least 18 wt%, at least 19 wt%, with a higher limit preferred over a lower limit, the wt% being based on the weight of the sealing fluid; and / or the amount of the water is not more than 30 wt%, not more than 25 wt%, not more than 22.5 wt%, not more than 22 wt%, not more than 21 wt%, with a lower limit preferred over a higher limit, the wt% being based on the weight of the sealing fluid.

6. The sealing fluid according to claim 1, wherein the sealing fluid comprises further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the sum of the amounts of the acid, the alcohol and water are at least 90 wt%, at least 92.5 wt%, at least 95 wt%, at least 97.5 wt%, at least 98 wt%, at least 99 wt%, with a higher sum of the amounts being preferred over a lower sum of the amounts, with the wt% being based on the weight of the sealing fluid.

7. The sealing fluid according to claim 1, wherein the sealing fluid consists of the acid, the alcohol and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the acid is lactic acid; more preferably, the acid is lactic acid and the alcohol is isopropanol.

8. The sealing fluid according to claim 1, wherein the sealing fluid consists of the acid lactic acid, the alcohol isopropanol, ethanol or a combination thereof, preferably isopropanol, and water and optionally of further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners; preferably, the amount of lactic acid is from 17.5 to 22.5 wt%, and the amount of alcohol is from 50 to 75 wt%, from 51 to 75 wt%, from 52 to 75 wt%, from 53 to 75 wt%, from 54 to 75 wt%, from 55 to 75 wt%, from 56 to 75 wt%, from 57 to 75 wt%, from 58 to 75 wt%, from 58.5 to 75 wt%, from 59 to 70 wt%, from 59 to 65 wt%, with a narrower range preferred over a broader range;PCT / US25 / 48156 26 September 2025 (26.09.2025) with the wt% being based on the weight of the sealing fluid.

9. The sealing fluid according to claim 1, wherein the sealing fluid does not contain HPMC, and / or the sealing fluid does not contain cellulose derivatives, and / or the sealing fluid does not contain gelatin, and / or the sealing fluid does not contain pullulan, and / or the sealing fluid does not contain starch, and / or the sealing fluid does not contain modified starch, and / or the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and HPMC; the sealing fluid does not contain any polymer selected from the list gelatin, pullulan, starch, modified starch, and cellulose derivatives; preferably, the sealing fluid does not contain any polymer, and / or the sealing fluid does not contain any gelling agent, and / or the sealing fluid does not contain any gelling aid, and / or the sealing fluid does not contain any gelation system comprising a gelation agent and optionally a gelling aid.

10. A method for preparation of the sealing fluid, wherein the acid, the alcohol and optionally any water and any optional further ingredients selected from the group of coloring agents, flavors, taste modifiers, and sweeteners, are mixed together.

11. A method for sealing a hard capsule, the hard capsule comprises a hard capsule shell and the content contained in the hard capsule shell, the hard capsule shell of the capsule consists of a cap and a body with the body being telescopically inserted in the cap providing a slit between the overlapping parts of the cap and the body; wherein the sealing is done by applying the sealing fluid onto said slit; with the sealing fluid as defined in claim 1; preferably, the application of the sealing fluid onto said slit is done by spraying the sealing fluid onto the slit.PCT / US25 / 48156 26 September 2025 (26.09.2025)12. A sealed hard capsule obtainable by the method for sealing a hard capsule according to claim 11.5

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