Ciclacillin

Ciclacillin (INN) or cyclacillin (USAN), trade names Cyclapen, Cyclapen-W, Vastcillin, and others, is an aminopenicillin antibiotic. Its spectrum of activity is similar to that of ampicillin, although it is less susceptible to beta-lactamases than ampicillin and has much higher bioavailability. A large randomized, double-blind clinical trial published in 1978 also showed that ciclacillin is associated with significantly fewer and milder adverse effects than ampicillin; later studies seemed to confirm this improved tolerability, at least in children.