Active metabolite

Active Metabolite

An active metabolite is a biologically active compound that is the product of metabolism. It is formed from the parent compound, or prodrug, through the process of biotransformation. Active metabolites can have similar, more potent, or entirely different pharmacological effects compared to the parent compound.

Metabolism and Biotransformation

Metabolism is a complex process that occurs in living organisms to maintain life. It involves a series of chemical reactions that break down nutrients and convert them into energy and new molecules. Biotransformation is a part of metabolism that transforms xenobiotics, such as drugs, into more soluble compounds for excretion.

The process of biotransformation involves two phases: Phase I and Phase II. In Phase I, the parent compound undergoes oxidation, reduction, or hydrolysis to form a more polar metabolite. In Phase II, the metabolite is further modified through conjugation reactions to increase its solubility.

Pharmacological Effects of Active Metabolites

Active metabolites can have a range of pharmacological effects. Some active metabolites have similar effects to the parent compound, but others can have more potent or entirely different effects. The pharmacological activity of an active metabolite depends on its chemical structure and the site of action in the body.

For example, the active metabolite of the drug diazepam, known as nordazepam, has similar sedative and anxiolytic effects to the parent compound. On the other hand, the active metabolite of the drug codeine, known as morphine, has more potent analgesic effects.

Clinical Significance

The formation of active metabolites has significant implications in clinical pharmacology and therapeutics. It can influence the efficacy and safety of drugs. For instance, the active metabolite of the drug clopidogrel, a widely used antiplatelet agent, is responsible for its therapeutic effect. However, the formation of this active metabolite varies among individuals due to genetic polymorphisms, leading to variability in drug response.

Moreover, some active metabolites can cause adverse effects. For example, the active metabolite of the drug acetaminophen, known as NAPQI, can cause liver toxicity at high doses.

See Also

• Prodrug
• Pharmacokinetics
• Pharmacodynamics
• Drug metabolism