Hetacillin

Hetacillin is a semisynthetic penicillin prodrug which itself has no antibacterial activity, but is converted in the body to ampicillin and has actions and uses similar to those of ampicillin. Hetacillin is prepared by reacting ampicillin with acetone. Ampicillin rapidly decomposes because of the intramolecular attack of the side chain amino group on the lactam ring. In vitro studies have shown that hetacillin is resistant to beta lactamase activity. However, this effect is transient, as the hydrolysis product, ampicillin, is readily inactivated by beta lactamase. Hetacillin locks up the offending amino group and prevents the decomposition of Hetacillin. Once hydrolyzed to ampicillin (and acetone), ampicillin binds to the penicillin binding proteins found in susceptible bacteria. This inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins.