Passage IV
Biopharmaceutics is the study of the factors influencing the bioavailability of a drug in man and animals
and the use of this information to optimize pharmacological and therapeutic activity of drug products.
Examples of some these factors include: chemical nature of a drug (weak acid or weak base), inert
excipients used in the formulation of a dosage form (e.g. diluents, binding agents, disintegrating agents,
coloring agents, etc.), method of manufacture (dry granulation and/ or wet granulation), physicochemical
properties of drugs (pKa, particle size and size distribution, partition coefficient, polymorphism, etc.).
Generally, the goal of biopharmaceutical studies is to develop a dosage form that will provide consistent
bioavailability at a desirable rate. The importance of a consistent bioavailability can be very well
appreciated if a drug has a narrow therapeutic range (e.g. digoxin) where small variations in blood
concentrations may result in toxic or sub-therapeutic concentrations.