Journal of Pharmaceutics & Drug Delivery ResearchISSN: 2325-9604

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Commentary, J Pharm Drug Deliv Res Vol: 12 Issue: 1

Significance of Drug Metabolism

Eunyoung Han*

Department of Precision Medicine, University of Campania, Naples, Italy

*Corresponding Author: Eunyoung Han
Department of Precision Medicine, University of Campania, Naples, Italy

Received date: 03 January, 2023, Manuscript No. JPDDR-23-89401;

Editor assigned date: 05 January, 2023, PreQC No. JPDDR-23-89401 (PQ);

Reviewed date: 19 January, 2023, QC No. JPDDR-23-89401;

Revised date: 26 January, 2023, Manuscript No. JPDDR-23-89401 (R);

Published date: 31 January, 2023, DOI: 10. 4172/2325-9604.1000207

Citation: Han E (2023) Significance of Drug Metabolism. J Pharm Drug Deliv Res. 12:1


Drug metabolism refers to the chemical reactions that occur in the body to transform drugs into substances that can be eliminated through urine or faces. Understanding drug metabolism is crucial in pharmacology and toxicology as it affects the efficacy and safety of drugs.

The liver is the primary site of drug metabolism, although other organs such as the kidneys, lungs, and intestines also play a role. The liver is composed of hepatocytes, which contain various enzymes responsible for drug metabolism.

The process of drug metabolism can be divided into two phases: Phase I and phase II. In phase I, enzymes such as cytochrome P450 (CYP) and Flavin Mono Oxygenase (FMO) catalyze oxidation, reduction, or hydrolysis reactions to convert drugs into more polar metabolites. These metabolites are usually less active than the parent drug and can be excreted more easily from the body. However, some phase I metabolites may be toxic or reactive and cause adverse effects.

In phase II, enzymes such as Glucuronosyltransferases (UGTs) and Sulfotransferases (SULTs) catalyze conjugation reactions to further increase the polarity of the metabolites. Conjugation involves the addition of small molecules such as glucuronic acid, sulphate or amino acids to the metabolites. Conjugated metabolites are even more watersoluble than phase I metabolites and can be readily excreted from the body.

The interplay between phase I and phase II reactions is essential for drug metabolism. Drugs that are extensively metabolized in phase I but have limited conjugation in phase II may accumulate in the body and cause toxicity. On the other hand, drugs that are predominantly metabolized in phase II may have low efficacy as they are rapidly excreted from the body.

Genetic polymorphisms in drug-metabolizing enzymes can significantly affect drug metabolism. Polymorphisms are variations in the DNA sequence that affect the structure or function of the enzyme. For example, some individuals may have a genetic variation in the CYP2D6 enzyme that affects its activity. This can result in poor metabolism of drugs that are substrates of CYP2D6, leading to drug toxicity or lack of efficacy.

Drug Metabolism

Drug interactions can also impact drug metabolism. Some drugs can inhibit or induce the activity of drug-metabolizing enzymes, leading to altered metabolism of co-administered drugs. For example, the antibiotic erythromycin is a potent inhibitor of CYP3A4, which is responsible for the metabolism of many drugs, including the immunosuppressant cyclosporine. Co-administration of erythromycin can lead to increased plasma concentrations of cyclosporine, which can cause toxicity.

Another important factor that affects drug metabolism is age. In neonates and infants, drug metabolism is generally slower than in adults due to the immaturity of drug-metabolizing enzymes. In the elderly, drug metabolism may also be slower due to decreased hepatic function and a reduced number of drug-metabolizing enzymes.

The route of drug administration can also affect drug metabolism. Drugs that are administered intravenously bypass the first-pass metabolism in the liver and may have a higher bioavailability than orally administered drugs. On the other hand, orally administered drugs must first undergo absorption in the gut and then be transported to the liver via the portal vein. During this process, some drugs may undergo significant first-pass metabolism in the liver, resulting in lower bioavailability.

Drug metabolism is a complex process that involves multiple enzymes, genetic polymorphisms, drug interactions, age, and route of administration the factors that affect drug metabolism.

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