Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!

Drug interactions occur when one drug modifies the actions of another drug in the body. Drug interactions can result from pharmacokinetic alterations, pharmacodynamic changes, or a combination of both. Interactions between drugs in vitro (eg, precipitation when mixed in solutions for intravenous administration) are usually classified as drug incompatibilities, not drug interactions.

Although hundreds of drug interactions have been documented, relatively few are of enough clinical significance to constitute a contraindication to simultaneous use or to require a change in dosage. Some of these are listed in Table 61–1. In patients taking many drugs, however, the likelihood of significant drug interactions is increased. Elderly patients have a high incidence of drug interactions because they often have age-related changes in drug clearance and commonly take multiple medications.

Table 61–1 Some Important Drug Interactions.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.