In preparing to resume penicillin skin testing, I am aware of the suggested protocol of using Prepen and Penn G initially as prick testing, and then if negative intradermal testing at full strength. If the patient has a convincing history of anaphylaxis, is it advisable to dilute the Prepen and test in ascending dilutions to full strength? Would full strength pricks be done prior to diluted intradermals?


Thank you for your inquiry.

It has always been my personal practice to follow the directions that are in the package insert for Pre-Pen. This is to perform a prick test first, and if negative, follow with an intradermal test. Both tests are done with the full strength material. I have not found it necessary to use more dilute solutions. However, as you are aware, patients can develop systemic allergic reactions due to penicillin skin testing, and if you feel that a particular patient is at risk for such, there would of course be nothing wrong with performing serial dilution skin testing starting with a more dilute solution such as in hymenoptera skin testing. This would entirely be left up to your clinical appraisal.

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

Phil Lieberman, M.D.

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