Penicillins

Abstract

The penicillins are part of the larger antibiotic group, the beta-lactams, which includes the cephalosporins. However none of the latter are used in aquaculture and for practical purposes the penicillins form a distinct group. They are weak acids and are chemically rather unstable, being decomposed by heat, light, oxidizing and reducing agents. They are rendered microbiologically inactive by heavy metals. They are sensitive to alkaline solutions although their crystalline sodium and potassium salts are reasonably stable in cool, dark conditions. Most penicillins are sensitive to acids but a few are stable and therefore active by mouth.