Which term describes the process of chemical modification of drugs in the body?

• A. Mechanism of action
• B. Medication absorption
• C. Solute
• D. Biotransformation

Answer: (D)

Biotransformation is the body's chemical modification of drugs, primarily in the liver through enzymes such as the cytochrome P450 system. It converts lipophilic drugs into more polar metabolites that are easier to eliminate in urine or bile. This involves two main phases: Phase I reactions (oxidation, reduction, hydrolysis) that create or reveal functional groups, and Phase II reactions (conjugation like glucuronidation or sulfation) that add polar segments to increase solubility. This process influences how long a drug acts, its potential toxicity, and whether a drug is active or needs activation as a prodrug. It also explains why drug interactions can occur when one substance alters metabolic enzymes. In contrast, another concept describes how a drug produces its effect, while another refers to how a drug enters the bloodstream, and another is just a general term for a dissolved substance.