ABSTRACT
With the discovery of the penicillin nucleus, 6-APA, it became possible to synthesize new penicillins by the introduction of side chains (Batchelor et al., 1959). Based on this, four acid-stable phenoxypenicillins were developed that were suitable for oral administration, although only phenoxymethylpenicillin (Pen V) is now available for clinical use. Pen V was introduced in 1953 (Spitzy, 1953) and has become synonymous with oral penicillin. Penicillin V, like Pen G, is a natural penicillin produced biosynthetically. It is obtained when the precursor, phenoxyacetic acid, is added to the fermentation medium, whereas addition of phenylacetic acid results in production of penicillin G. The chemical structure of Pen V is shown in Figure 4.1.
