Lääkitysaineenvaihdunta

Lääkitysaineenvaihdunta, often referred to as drug metabolism, describes the biochemical processes by which a living organism modifies a drug or poison. This process typically involves enzymes that catalyze chemical reactions, converting the drug into a more water-soluble compound that can be more easily excreted from the body. This conversion is crucial for drug elimination and often renders the drug inactive, although sometimes metabolites can retain or even gain pharmacological activity.

The primary site of drug metabolism in mammals is the liver, due to the high concentration of metabolizing enzymes there, particularly within the hepatic endoplasmic reticulum. Other tissues, such as the lungs, kidneys, intestines, and skin, also contribute to drug metabolism. The process is generally divided into two phases. Phase I reactions, often called functionalization reactions, introduce or expose polar functional groups on the drug molecule, typically through oxidation, reduction, or hydrolysis. Cytochrome P450 enzymes are key players in many Phase I reactions. Phase II reactions, or conjugation reactions, involve the attachment of an endogenous molecule, such as glucuronic acid, sulfate, or glutathione, to the drug or its Phase I metabolite. This further increases water solubility and facilitates excretion.

Factors such as age, genetics, disease states, and interactions with other drugs can significantly influence the rate and pathway of drug metabolism, leading to variations in drug efficacy and toxicity among individuals. Understanding lääkitysaineenvaihdunta is fundamental in pharmacology and clinical medicine for optimizing drug therapy, predicting drug interactions, and developing new medications.