Pharmaceutical Suspension and Emulsion Evaluation Quiz

Evaluation and Stability of Pharmaceutical Suspensions

• Viscosity measurement is crucial in evaluating suspension stability, with pre- and post-mixing viscosity compared to standard values for corrective action.
• Particle size determination is performed using optical microscopy and Coulter counter apparatus, with the Coulter counter instrument measuring impedance between electrodes to count particles.
• Brownian movement of particles prevents sedimentation, depending on particle size, density of dispersed phase, and viscosity of the disperse medium.
• Sedimentation in pharmaceutical suspensions is the settling of particles or floccules under gravitational force, with velocity expressed by Stoke’s equation.
• Limitations of Stokes law for sedimentation include assumptions of diluted suspensions, spherical particles, and the absence of interference.
• Stokes law is useful in preventing sedimentation by considering factors like particle size, viscosity of the medium, and density of the medium.
• Sedimentation volume (F) is a ratio of the ultimate volume of sediment to the original volume of suspension before settling, providing a qualitative account of flocculation.
• Inducing flocculation can be achieved through the use of flocculating agents, such as electrolytes and detergents.
• Viscosity measurement is crucial in evaluating suspension stability, with pre- and post-mixing viscosity compared to standard values for corrective action.
• Particle size determination is performed using optical microscopy and Coulter counter apparatus, with the Coulter counter instrument measuring impedance between electrodes to count particles.
• Brownian movement of particles prevents sedimentation, depending on particle size, density of dispersed phase, and viscosity of the disperse medium.
• Sedimentation in pharmaceutical suspensions is the settling of particles or floccules under gravitational force, with velocity expressed by Stoke’s equation.

Emulsion Instability and Factors Affecting Physical Stability

• Uniform globule size distribution maximizes stability and is affected by viscosity, phase volume ratio, and density of phases.
• Microscopic examination is used to analyze globule size distribution for evaluating physical stability.
• Ostwald ripening, or disproportionation, occurs due to finite solubility of liquid phases and leads to a shift in droplet size distribution to larger values over time.
• Coalescence results in irreversible damage to emulsions, causing fusion of globules and a reduction in their number and increased size.
• Factors causing coalescence include insufficient emulsifying agent, altered partitioning, incompatibilities, temperature changes, and presence of microorganisms.
• Addition of opposite type emulsifying agents or anionic and cationic emulsifying agents in the same emulsion can lead to emulsion cracking.
• Decomposition or precipitation of emulsifying agents, addition of common solvent, and microbial action can also cause emulsion cracking.
• Excess dispersed phase concentration exceeding 74% can lead to emulsion cracking, as can keeping the creaming condition for a longer duration.
• Phase inversion occurs due to the addition of substances altering emulsifying agent solubility or alterations in phase volume ratio.
• Chemical instability types include oxidation, microbial contamination, and adverse storage conditions.
• Oxidation of oils and fats in emulsions can be controlled by antimicrobial agents and antioxidants.
• Adverse storage conditions, such as temperature fluctuations and freezing of the aqueous phase, can also lead to emulsion instability.