Amoxycillin is better than ampicillin due to:

Amoxicillin It is a close congener of ampicillin (but not a prodrug); similar to it in all respects except: * Oral absorption is better; food does not interfere with absorption; higher and more sustained blood levels are produced. * Incidence of diarrhoea is lower. * It is less active against Shigella and H. influenzae. Many physicians now prefer it over ampicillin for bronchitis, urinary infections, SABE and gonorrhoea. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:701