Skip to content

Tag Archives: Passive Diffusion

Pharmacokinetics – Distribution Series II – Rate of Drug Distribution


Figure 4.1 shows the plasma concentration and the typical tissue concentration profile after the administration of a drug by intravenous injection. It can be seen that during the distribution phase, the tissue concentration increases as the drug distributes to the tissue. Eventually, a type of equilibrium is reached, and following this, in the postdistribution phase, […]

Drug Absorption in the Gastrointestinal Tract


Rate-Limiting Steps in Drug Absorption Disintegration of the drug product and subsequent release of the drug (rate-limiting step) Dissolution of the drug in an aqueous environment (rate-limiting step) Absorption across the cell membranes into the systemic circulation (rate-limiting step) Physiochemical Factors that Affect Drug Absorption Drug disintegration (rate-limiting step) Drug dissolution (rate-limiting step) Drug across the cell […]

Biopharmaceutics – Drug Absorption – Part One – Passage of Drugs Across Cell Membranes


Key Ways For Drugs Across Cell Membranes Passive Diffusion Facilitated Diffusion Active Transport Passive Diffusion Passive diffusion is the major absorption process for most drugs. Theoretically, a lipophilic drug may pass through the cell or go around it. If the drug has a low molecular weight and is lipophilic, the lipid cell membrane is not […]