Q:

5/23/2013
My patient is a 48 year old F with breast cancer who started tamoxifen and 3 days later broke out in an itchy red rash all over her body and throat tingling. She was seen in the ER told to stop tamoxifen and treated with prednisone, hydroxyzine, pepcid and benadryl. Rash resolved within 3 days. Her oncologist plans to treat her with toramifine which is also a selective estrogen receptor modulator. She is currently taking Benadryl 25mg qHS for persistent itching. I have reviewed your recommendations from a similar entry dated 12/21/11 and have a few additional questions.

1. Is provocative dosing necessary for toramifine?
2. If so, would you start with 1/1000 or 1/100? How would you increase over a 1-2 week period?
3. Would you premedicate prior to the first dose?

As always, thank you for your input.

A:

Thank you for your inquiry.

Based on the fact that toremifene is structurally similar to tamoxifen, one should approach the administration of toremifene in a patient who has had a reaction to tamoxifen carefully. I would therefore suggest that should toremifene be the only alternative drug for your patient, a provocative dosage regimen be employed.

Unfortunately, to my knowledge, and based on a literature search, there are no published protocols for provocative dosing to toremifene (or for that matter, for tamoxifen) and therefore one is left with designing a protocol using a procedure analogous to those that have been employed for other drugs. Also, since toremifene is only available in a 60 mg pill, establishing appropriate dilutions might be difficult, but I would start with a dose 1/1,000th of the desired dose (usually 60 mg daily), and proceed with doubling doses over a two week period until which time the desired dose is reached. Of course, you should take into consideration the cumulative dose administered during this procedure. The frequency of dosing would have to be calculated based upon this rough format.

As you can see, this is not a convenient procedure, and if any other non-structurally related drug could substitute, it would be desirable. This of course would have to be the decision of the oncologist.

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

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology