Speakers - 2026

Title: Biotransformation of pharmaceutical drugs

Abstract

Biotransformation is vital to survival because it transforms absorbed nutrients (food, oxygen, etc.) into substances required for normal body functions. For some pharmaceuticals, it is a metabolite that is therapeutic and not the absorbed drug. For example, phenoxybenzamine, a drug given to relieve hypertension caused by pheochromocytoma, a kind of tumor, is biotransformed into a metabolite, which is the active agent. Biotransformation also serves as an important defense mechanism since toxic xenobiotics and body wastes are converted into less harmful substances and substances that can be excreted from the body. Toxicants that are lipophilic, non-polar, and of low molecular weight are readily absorbed through the cell membranes of the skin, GI tract, and lung. These same chemical and physical properties control the distribution of a chemical throughout the body and its penetration into tissue cells. Lipophilic toxicants are hard for the body to eliminate and can accumulate to hazardous levels. However, most lipophilic toxicants can be transformed into hydrophilic metabolites that are less likely to pass through membranes of critical cells. Hydrophilic chemicals are easier for the body to eliminate than lipophilic substances. Biotransformation is thus a key body defense mechanism.