Intraocular penetration of cephaloridine.

Cephaloridine ('Ceporin') is a semisynthetic compound, 7[(2-thienyl)-acetamide]-5(i-pyridylmethyl)-5-cephem-4-carboxylic acid betaine, derived from cephalosporin C. This is an antibiotic produced by Cephalosporium acremonium, a fungus isolated from a sewage outfall off the Sardinian coast (Brotzu, I948). The cephalosporins are closely related chemically to the penicillins in that they contain a f3-lactam ring. This is the part of the molecule which almost certainly combines irreversibly with the binding sites on sensitive bacteria. Whereas penicillins contain a fivemembered thiazolidine ring, the cephalosporins have a six-membered dihydrothiazine ring (Fig. i).