H2-Receptor Antagonist Interaction with Cefixime

Cefixime is a third generation orally active cephalosporin with a broad spectrum of antibacterial activity, especially against Entrobacteriaceae in vitro It has increased resistance against many plasmid and chromosomally mediated ^-lactamases. Hj-recepor antagonists are drugs used to block the action of histamine on parietal cells in the stomach, decreasing acid production by these cells. All cephalosporins cause gastric upsets even in normal subjects and H2-receptor antagonists may be co-administered in patients having cephalosporin therapy and complaining about gastric irritations, specially the peptic ulcer patients, who are the real victims of this simultaneous drug therapy. The behavior of three most commonly used Hj-receptor antagonists, cimetidine, ranitidine and famotidine in presence of cefixime has been studied, using standard dissolution apparatus, in simulated gastric juice and in buffer of pH 7.4 simulating blood pH, at different temperatures (37° 60°C) simulating body temperature as well as accelerated temperature study. The stability of cefixime in presence of interacting drugs has also been studied. These studies revealed that simultaneous use of this drug depressed the availability of the cimetidine, ranitidine and famotidine. These results clearly indicate a warning against multiple drug therapy, extreme care should be taken in this respect.