Absorption Of Drugs
Absorption : Absorption is the process by which drug molecules cross biological membranes. It is usually associated with oral drugs and their absorption through the GIT. It also occurs by subcutaneous, intra muscular and transdermal routes of administration of drugs. However, the absorptive process does not occur during direct injection of drug by intravenous or intra arterial injection. Biological Membrane: Biological membranes consist of a lipid bilayer separating different compartments, with protein molecules acting as enzymes, channels or carrier proteins. Drugs have to cross the biological membranes to get absorbed. Processes Determining Absorption: Absorption, distribution and excretion of drugs overlap in the processes determining them. These processes include: 1. Passive Transport a. Simple diffusion b. Filtration/ Aqueous diffusion c. Bulk flow 2. Active Transport a. Primary active transport b. Secondary active transport c. Pinocytosis ...