Drug interactions

Abstract

Drug interactions, resulting from multiple drug therapies, can be attributed to (i) physicochemical factors, e.g., incompatibility of pharmaceutical preparations, (ii) pharmacokinetic factors, e.g., interference of absorption, distribution, metabolism and excretion, or due to (iii) pharmacodynamic factors, e.g., interference at the target site or the associated signaling mechanism. Drug interactions may also occur between drugs and other xenobiotics such as food constituents, environmental pollutants and herbal products. These drug interactions produce dichotomous clinical outcomes: One that is beneficial, and one that is harmful. In many acute conditions where patients have already ended up with some compromised organ functions, both pharmacokinetic and pharmacodynamic factors can exacerbate the drug interaction problem and potentially result in toxicity. Pharmaceutical incompatibility of drug injection solutions is another potential cause of adverse drug interactions which should not be overlooked. A lack of knowledge on the various drug interactions is a major contributing factor to adverse drug reactions or therapeutic failures.