Abstract

Gastric acid partially destroys benzylpenicillin (penicillin G) and only a small and inconsistent fraction of an oral dose is absorbed. To be certain of its effect the drug must be injected. A number of acid-stable penicillins with the antibacterial range of benzylpenicillin but quite well absorbed from the gut are now available, phenoxymethylpenicillin (penicillin V) for example. In vitro phenoxymethylpenicillin is a little less effective than benzylpenicillin against streptococci¹ and considerably less effective against H. influenzae and gonococci. In addition, a higher proportion of phenoxymethylpenicillin than of benzylpenicillin is bound to plasma protein.² Though controlled trials show that oral benzylpenicillin is as effective as oral phenoxymethylpencillin for most patients with susceptible infections treated outside hospital,^3–6 our consultants prefer phenoxymethylpenicillin because absorption is less variable.