Drug interaction is a situation in which two or more separate drugs have been absorbed into the body and their effects are affected by each other, i.e. the effects are increased or decreased, or they produce a new effect that neither produces on its own.

Differing types of interactions include:

• Enzyme induction - drug A induces the body to produce more of an enzyme which metabolises drug B thus reducing the effective concentration of the drug B leading to loss of effectiveness of drug B. Drug A effectiveness is not altered
• Enzyme inhibition - drug A inhibits the production of the enzyme metabolising drug B, thus an elevation of drug B occurs possibly leading to an overdose.

References

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U. N. Harle, N. J. Gaikwad. Emerging Challenge of Herb-Drug Interaction. Indian Journal of Pharmaceutical Education Vol. 39, Number 02, 2005 ^*

External links

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• Drug Interactions: What You Should Know. U.S. Food and Drug Administration, Center for Drug Evaluation and Research ^*
• Cytochome P450 table maintained by the Indiana University School of Medicine
• Free Drug Interaction Checker

Pharmacology