Lab 2 Suspensions

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Lab 2 Suspensions

For enquiries please email both: Simisola @ Kundai @

For enquiries please email both: Simisola @ Kundai @

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What is it?

Two- phase system with uniform dispersion. Dispersed phase Continuous phase .


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Why formulate a suspension?

Drug molecules with low solubility. To mask the taste of an unpleasant tasting drug (in it’s soluble form). Faster dissolution rate compared to solid dosage forms. Stability of drugs – mixed prior to use and given a short expiry date (e.g. mix antibiotics in pharmacy for patients). Prolonged effect if given in the insoluble form e.g. intramuscular injections. Prolonged effect topically as solid remains on the skin for longer.

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Properties of a good suspension

Easy to re-disperse by shaking when sediment forms. Pourable . Insoluble particles stay in suspension long enough → accurate dose can be measured. Particles size: Small, uniform and free from grittiness .

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Formulation additives

Suspending agents To reduce sedimentation. Over time particles settle on the bottom and may be difficult to re-disperse . ( If ↑ η (viscosity) continuous phase or ↓ particle size ) Flocculating agent To prevent caking of suspended particles. Deflocculated suspension is difficult to re-disperse . Flocculated reduce pourability . Wetting agent To improve the flow of the liquid vehicle across the particle surface, which in turn improves the homogeneity of distribution of the drug particles throughout the formulation. Air trapped on particles → float on suspension are not dispersed

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Formulation 1: Paediatric Chalk Mixture BP Formulation 2: Kaolin and Morphine Mixture BP Formulation 3: Calamine Lotion.

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Remember …

Learn how to write a label. Learn abbreviations (prn,bd,tds,mitte ). Expiry is 2 weeks from date of manufacture unless stated otherwise Method is ALWAYS in past tense . Get the required amount of chemical, don’t be wasteful. Relationship b/w SG and density: SG of water = 1. If SG of substance is more than 1, it is more dense than water and the opposite is true.