Q:

12/10/2012
Do you have a desensitization protocol for low dose methotrexate that you can share? I have looked in the literature and can only find protocols for high dose chemotherapeutic dosages and I need one for a patient with rheumatoid arthritis. Thank you.

A:

Thank you for your inquiry.

Unfortunately I am not aware of, and could not find, a desensitization protocol to commonly applied doses used to treat patients with rheumatoid arthritis. However, as you mentioned, there are quite a number of desensitization protocols to methotrexate used in doses for treatment of cancer. One can actually adopt the same principles to a desensitization protocol used for the lower doses designed to treat rheumatoid arthritis. You should be able to accomplish this since this drug is available, as you know, in a liquid for intravenous use.

My suggestion is to start with 1:1,000 to 1:10,000 of the desired amount and progress slowly thereafter with doses administered every hour until the therapeutic dose is reached (using the same principles as one would apply in doing a penicillin desensitization). The venue to be used would be dependent upon your clinical judgment based upon the severity of the preceding reaction.

When you reached a dose of 1 mg, you could switch to the tablet, which is available in a 2.5 mg strength.

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