Structures and Classification of Cephalosporin Drugs

Despite the chemical similarity of the cephalosporins and penicillins, differences in chemical reactivity and stability exist. This is most obvious when conditions to prepare the penicilloyl determinant are applied to the cephalosporins. 

In early studies on cephalosporin C in E. P. Abraham s laboratory in Oxford, acid hydrolysis yielded no penicillamine and alkali treatment led to fragmentation of the molecule. Aminolysis of cephalosporins in the presence of polylysine or protein gave results (including the appearance of 

The work outlined above, and the interpretation of the chemical findings, indicates that as far as any resultant determinants are concerned, aminolysis results in structures in which only the R1 side chain, the attached amide, and remnants of the p-lactam ring remain from the original cephalosporin molecule. The resultant penaldate- and any penamaldate-like structures finked to carrier protein therefore represent hapten-carrier complexes that may interact with side chain (Rl)-specific IgE antibodies in allergic responses to therapeutic dosage of cephalosporin drugs. 

1 Studies Implicating the R1 Side Chain in Clinical Hypersensitivity 

From Harle DG, Baldo BA. Drugs as allergens An immunoassay for detecting IgE antibodies to cephalosporins . Int Arch Allergy Appl Immunol. 1990 92 439. Reprinted with permission from S. Kaiger AG, Basel IgE in serum from patient with anaphylaxis to cephalothin 

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