Paracetamol Suspension Particle Sizing for Browning Control

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Solution Overview

Problem

Existing paracetamol liquid suspensions face challenges with sedimentation and browning over time, particularly due to large particle sizes, which can lead to discoloration and the need for dyes to mask these changes, posing issues for patient acceptance and product stability.

Innovation Solution

Formulating paracetamol liquid suspensions with particles having a d50 of less than or equal to 10µm and a d90 of less than or equal to 35µm, ensuring the suspensions are substantially dye-free and optionally free of invert and reducing sugars, thereby reducing sedimentation and browning over prolonged periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If paracetamol particles with larger average size are used in liquid suspension, then manufacturing cost and ease of formulation are improved, but sedimentation rate increases and browning discoloration occurs during storage

Engineering Contradiction:
Improveease of formulationVSAvoidstorage stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by reducing the particle size of paracetamol from conventional larger sizes to a specific range (d50 ≤ 10μm, d90 ≤ 35μm). This parameter modification resolves the contradiction by preventing sedimentation and browning during storage while maintaining ease of formulation through controlled particle size distribution.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies segmentation by dividing paracetamol into fine particles with a controlled size distribution (d50 ≤ 10μm, d90 ≤ 35μm). This segmentation prevents the particles from settling and undergoing browning reactions, thereby improving storage stability while maintaining formulation simplicity.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If paracetamol particles with larger average size are used in liquid suspension, then formulation simplicity is improved, but browning discoloration increases during prolonged storage

Engineering Contradiction:
Improveformulation simplicityVSAvoidbrowning discoloration
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the particle size parameter of paracetamol to d50 ≤ 10μm and d90 ≤ 35μm. This parameter change eliminates browning discoloration during storage while keeping the formulation simple and free from additional masking agents.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of fine particle sedimentation into a benefit by carefully controlling the particle size distribution. The fine particles remain suspended without settling, and the formulation becomes dye-free while maintaining simplicity.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Illumination intensity

If dyes are added to mask discoloration in paracetamol suspension, then appearance is improved, but product complexity and potential patient allergies increase

Engineering Contradiction:
ImproveappearanceVSAvoidproduct complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates dyes from the formulation by preventing discoloration at its source through fine particle size control (d50 ≤ 10μm, d90 ≤ 35μm). This removal of dyes simplifies the product and eliminates allergy concerns while maintaining acceptable appearance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of discoloration into a benefit by using fine particle size to prevent the discoloration mechanism itself, making dye addition unnecessary and simplifying the overall product formulation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The formulation achieves a storage-stable, organoleptically pleasing suspension with reduced sedimentation and browning, maintaining a commercially acceptable appearance without the need for dyes, even after 12-36 months.

Implementation Method 1

One challenge associated with liquid suspensions is sedimentation, that is the tendency for particles in suspension to settle out of the fluid. Among all the ingredients of a suspension, the suspended phase (i.e., containing API particles, in this case, paracetamol particles) is one of the most critical components since it might tend to sediment over time and under specific conditions.

Methodology Applied
Scientific EffectSedimentation: Sedimentation

Implementation Method 2

Stokes' law is often used to express the sedimentation rate: Where dS/dt is the sedimentation rate, d is the diameter of the particles, ρP is the density of the particles, ρM is the density of the medium, g is the gravitational constant and η is the viscosity of the medium. According to Stokes' law, the sedimentation rate of a suspension decreases with decreasing the particle diameter

Methodology Applied
Scientific EffectStokes' law:

Data Source

PatentEP3843703B1Paracetamol liquid suspensions
Publication Date: 2025.11.05 HALEON CH SARL
  • EP3843703B1 patent drawingFigure 1(a)~1(e)
  • EP3843703B1 patent drawingFigure 2
  • EP3843703B1 patent drawingFigure 3

AI summary

The present invention relates to pharmaceutical liquid suspensions suitable for oral administration. More specifically, the present invention relates to pharmaceutical liquid suspensions containing paracetamol wherein the suspensions are formulated with paracetamol particles having a d50 of less than or equal to 10µm and a d90 of less than or equal to 35µm such that browning discoloration is reduced during prolonged storage.