Drug-drug interactions: new trends

Abstract

The modification of the action of one drug by the other had been noticed for a long time. For example, in 19995, Williams (1) discovered that there was an enhanced metabolism of oestrogens caused by phenabarbital and rifampicin (all of which are now known to be inducers of drug metabolism). Chloroquine was found to interact with Ampicillin and decreased peak plasma concentration of the former from 29 to 19 %. This effect was considered significant in reducing the bioavailability of Ampicillin (2).

Such interactions were discovered coincidentally and the most important drug-drug interactions are those reported from cimeditine (Tagamet). Cimetidine is a h1 receptor antagonist widely used in peptic ulcer disease. Other mwmbers of cimetidine family especially ranitidine, also cause some significant drug inmteractions.

Recent findings (3) have shown that the mechanism by which cimetidine caused drug interactions might not be the well- known inhibition of the microenzymes P450 complex, rather through a direct action on the gut muscle which directly slow down its movement and decreased gastric emptying process (4). 

Other findings were also considered especially the ones produced by anticholigergics like propentheline. These have involved many compounds and in clinical practice have greater implications of drug-drug interactions.