Thank you for your inquiry.
Unfortunately, the answer to your question can only be given in a speculative manner. The reason for this is, at least to the best of my knowledge and according to a literature search, there has been no published protocol for desensitization to methadone, and I could not find a bona fide case of urticaria or anaphylaxis to this drug. Therefore any protocol would be “breaking new ground,” at least according to the literature I could find, and my lack of personal experience with allergy to this drug.
Nonetheless, since methadone is available in liquid form, I see no reason why you could not attempt a desensitization regimen using the same principles employed for desensitization to other agents.
I would begin with a dose of either 1/100th to 1/1,000th of the desirable dose, and administer the drug orally in doubling doses, given every 30 minutes. Unless the patient had experienced an episode of anaphylaxis to the previous administration of an opioid, I think that this could be done in an outpatient setting. It may take more than one day to complete, and the patient should be kept on the last dose administered during any break in the procedure.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.