Incidence of Penicillin Hypersensitivity and Clinical Aspects

The incidence of hypersensitivity reactions to penicillins is about 1-2 % but, importantly, up to about 10 % of patients taking a penicillin report. 

Penicillins can cause all four types of hypersensitivity responses provoking type I IgE-mediated reactions such as urticaria, angioedema, asthma, and anaphylaxis type n antibody-mediated hemolytic anemia and thrombocytopenia type III immune complex-mediated serum sickness-like reactions and vasculitis and type IV T cell-mediated contact dermatitis, rashes, and other skin eruptions (refer to Chaps. 2 and 3). Table 5.1 lists clinical adverse reactions, together with their immune 

All penicillins contain a p-lactam ring fused to a thiazolidine ring and individual penicillins are distinguished by the nature of the side chain R group (Fig. 5.3). The structures of the most clinically important and frequently used penicillins are shown in Fig. 5.4. 

John Farrell, Catherine S Lane, Andrew V Stachulski, NeU S French, Dean J Naisbitt, Munir Pirmohamed, B. Kevin Park. Direct evidence for the formation of diastereoisomeric benzylpenicUloyl haptens from benzylpenidllin and benzylpenicillenic acid in patients. J Pharmacol Exp Then 2011 338 841-9. Reprinted with permission from Americtm Society for Pharmacology and Experimental Therapeutics 

Structures of the degradation products of the penicilloyl determinant, viz., penamaldyl and penaldyl determinants and peniciUamine, are shown in Fig. 5.6. 

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