Drug Interactions

New drugs are formulated and introduced into the market every year. Any given patient is being treated with a multitude of drugs. The reasons for this are many; longer life spans, clustering of diseases in a patient, mushrooming of sub-specialities and the incessant promotional campaigns by pharmaceutical companies.

All of this exposes patients to deleterious side effects of polypharmacy. Also, many of the commonly used drugs have clinically important interactions when used together. These interactions can decrease or enhance the efficacy of either of the two interacting drugs and predispose the patient to lower therapeutic efficacy or drug toxicity, respectively.

An attempt is being made to generate awareness among physicians about important drug interactions. It is not possible to enumerate all such interactions; however, interactions of the commonly prescribed drugs viz. anti-diabetics, anti-hypertensives, cardiovascular drugs, anti-tubercular, anti-epileptic, warfarin, newer oral anticoagulants, and anti-infectives have been presented in tabular form.

The detailed mechanisms of these interactions have not been discussed as we want this chapter to be a desktop, ready-reckoner for the busy physician to be used in the clinic. A summary of the very important and must-remember drug interactions is given in the end.