I have a PCN allergic patient w/ nuerosyphilis who has been desensitized to PCN and needs Bicillin LA weekly x 3. Can I reasonably presume that he will maintain his desensitized state in the 7 day interval between bicillin administration? Should I advise a shorter interval between doses or repeat desensitization before each bicillin dose?


Thank you for your inquiry.

Unfortunately I cannot answer your inquiry definitively. I could find no reference in the literature which substantiates the ability of Bicillin to maintain a desensitized state to penicillin. However, as you mentioned, this would be theoretically possible. What you might consider doing is retesting to penicillin prior to the next dose of Bicillin, and if the tests are negative, administering the drug without going through a desensitization procedure would be reasonable. If the tests are positive, then I would assume it would be necessary to perform another desensitization.

Thank you again for your inquiry and we hope this response is helpful to you.

Phil Lieberman, M.D.

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