Описание: VISCOSITY / RHEOLOGY / SPREADABILITY
Executive Summary / Scope
Chapter focuses on the following aspects of rheological properties of topical semi-solid formulations:
- Analytical instrumentation and techniques to determine rheological properties.
- Factors affecting rheological properties:
o Formulation physical/chemical parameters (i.e., pH, concentration of excipients, excipient combinations, etc.)
o Primary container closures o Manufacturing/process equipment
- Review of current literature and recommendation on best practices for 1) characterizing the rheological aspects of topical semi-solid formulations during development phase and 2) rotational viscosity methods to ensure product consistency for commercial stage products.
2. Background 2.1. Definitions
2.1.1. Rheology, viscosity, thixotropy, rheopexy, viscoelastic behavior 2.2. Why is rheology important for topical semi-solid formulations?
2.2.1. Newtonian systems vs non-Newtonian systems
2.2.2. Raw materials
2.2.3. Formulations
2.2.4. Effect of Processing parameters
2.2.5. Quality Control
2.3. Rheological Test Methods
2.3.1. Continuous shear vs Oscillatory shear
2.4. Instrumentation 2.4.1. Viscometry: Single point vs Multiple point instruments
2.4.2. Rheometry: Controlled stress vs Oscillatory Rheometers
3. Review of current state and outline best practice
3.1. USP chapters 911,912 and 1911 and 1912
3.2. Rheology of different dosage forms 3.2.1. Creams
3.2.2. Ointments 3.2.3. Lotions
3.2.4. Gels 3.2.5. Others (foams, SLN dispersions etc.)
3.3. White papers from instrument manufacturers
3.3.1. Application specific analysis of rheology
3.3.1.1. Effect of temperature on viscosity
3.3.1.2. Effect of shear rate on moduli
3.3.1.3. Determination of yield stress
3.4. Correlation of processing conditions to the rheological data 3.4.1. Speed of mixing
3.4.2. Processing temperature
3.4.3. Others (use of vacuum, presence of nitrogen, mixing type - homogenizers, dispersers, propellers, spindle mixers etc.)
4. Recommendation for next steps
4.1. Identify gaps 4.1.1. Temperature dependent studies
4.1.1.1. What is there to gain by evaluating the rheology of a semi-solid product at temperatures other than its recommended storage condition. 4.1.2. How is viscosity data being used
4.1.2.1. What other variables of product development can viscosity/rheology be evaluated for other than physical stability.
ROLE OF EXCIPIENTS ON THE Q3 (MICROSTRUCTU
