Amoxycillin: A review of its antibacterial and pharmacokinietic properties and therapeutic use.

Amoxycillin2 is an acid stable semisynthetic penicillin closely related to ampicillin. Unlike pivampicillin and hetacillin, amoxycillin is not converted to ampicillin in the body. The antibacterial spectrum and level of activity of amoxycillin is essentially the same as for ampicillin, and there is complete cross-resistance between the two drugs. After oral administration, amoxycillin is better absorbed than ampicillin. Mean peak serum levels of amoxycillin are generally twice those of ampicillin after an equal dose. The better absorption and penetration into certain body tissues and fluids of amoxycillin and its greater activity against experimental infections in mice, suggest that it might be preferred to ampicillin in the treatment of some infections, but any clear superiority over ampicillin in clinical practice has yet to be demonstrated. However, these properties have enabled amoxycillin to be given at half the dose of ampicillin without loss of therapeutic efficacy, and the princpal side-effects of skin rashes and diarrhoea have tended to be less frequent with amoxycillin than with ampicillin. Other side-effects are essentially similar in nature to those reported with ampicillin.