Formulation

This refers to the way in which a tablet, capsule, suspension or other form of medication is put together in order to achieve the desired properties that impact pharmacokinetic behaviour of the drug. For example, sustained release preparations release drug very slowly so that there is no sharp peak of drug in the plasma; this slows concentration-dependent elimination and generates much smaller fluctuations between peak and trough levels during a repeated administration regimen. In designing formulations, pharmacists and chemists consider factors such as GI transit time and the local pH environment in various portions of the GI tract, if the formulation is for PO administration.

Formulations prepared for administration by different routes may employ different salts of drug compounds. As such, it should be recognised that a stated mass of drug in a single tablet, capsule, or other unit of administration, may refer to the mass of the salt, rather than to the mass of the drug itself. This should be accounted for when the same dose of a different salt of the drug is to be administered.