Mahmud's Portfolio - Excipients

Pharmaceutical excipients

Learning objectives: Learn about the excipients used in pharmaceutical formulations, their classification and uses

Pharmaceutical excipients

Pharmaceutical excipients are inactive substances formulated alongside the active pharmaceutical ingredient (API) of a medication. They aid the manufacturing process, protect or enhance stability, improve bioavailability, and ensure patient acceptability. Excipients make up the bulk of most drug products, transforming pure chemicals into safe, stable, and easily swallowable doses. [USP short video]

Key roles of excipients:

Manufacturing aid: Help powders flow smoothly and prevent ingredients from sticking to factory machines.

Stability: Protect the active drug from moisture, light, heat, and oxygen to extend shelf life.

Delivery and absorption: Control how and where a drug dissolves and enters the body.

Patient acceptability: Add pleasant tastes, colors, or textures to make medicines easier to take.

Common types and examples

Diluents / Fillers: Add bulk to small active doses to make pills a usable size (e.g., lactose, microcrystalline cellulose).

Binders: Act as glue to hold compressed tablet ingredients together (e.g., starch, povidone).

Disintegrants: Help tablets break apart quickly in the gut (e.g., croscarmellose sodium).

Lubricants: Keep ingredients from sticking to compression equipment during manufacturing (e.g., magnesium stearate).

Preservatives: Stop bacteria and fungus from growing in liquid medicines (e.g., parabens, benzyl alcohol).

Coatings: Mask bad tastes and protect pills from stomach acid or moisture (e.g., various cellulose polymers).

Preservatives used in ophthalmic preparations

Preservative Name Standard Ophthalmic Concentration

Chlorocresol (Na edetate 0.1%) 0.05% – 0.1%

Chlorhexidine 0.005% – 0.01%

Chlorobutanol 0.5%

Benzalkonium Chloride 0.004% – 0.02%

Cetrimide 0.005% – 0.01%

Phenyl mercuric (usually Nitrate or Acetate) 0.001% – 0.004%

Sodium Benzoate 0.1% – 0.2%