Oral Desensitization for Penicillin Sensitivity

To the Editor.— In the recent report of a successful parenteral desensitization of a pregnant, penicillin-allergic woman with syphilis, Ziaya and colleagues¹ proposed that parenteral desensitization is preferable to the more widely studied oral desensitization method.^2-4 Fatal and near-fatal anaphylactic reactions during parenteral desensitization are well documented² and should have been considered more carefully.

Four important considerations suggest that oral desensitization is safer. First, deaths from orally administered penicillins are exceedingly rare.² In one large study, all of 72 fatal anaphylactic reactions to penicillin were induced by parenteral therapy,⁵ despite the more prevalent use of oral therapy. Second, the drug polymers and penicillin-mold protein conjugates that contaminate therapeutic materials, thought to be important elicitors of anaphylaxis,⁶ would not be expected to be absorbed after oral administration. Third, blood levels gradually rise after oral administration, favoring univalent (harmless) conjugation, in contrast to the locally very