Topical Mustargen
Information for the Physician
Topical nitrogen mustard (Mustargen, mechlorethamine) can be used either mixed in Aquaphor ointment by a trained pharmacist or compounded in water by patients at home prior to application. The water preparation of Mustargen is unstable and needs to be used immediately, whereas the ointment preparation of Mustargen is stable for a few months. We prefer Mustargen compounded in the ointment base because of the lower incidence of contact dermatitis, stability of the formulation, and additional moisturizing benefit.
Topical nitrogen mustard can be compounded at various strengths. Standard dosing we use at Stanford includes, 10mg%, 20mg%, 30mg%, or 40mg%; however, there are certainly situation where we would use a lower or higher concentration. The amount dispensed will depend on the amount your patient requires. 400 grams is usually our upper limit because a patient can apply Mustargen once a day to the entire body for a month with 400 grams.
Topical Nitrogen mustard is dispensed in mg% concentrations. To give an example of how to write a proper prescription for Mustargen , we have provided the following cases:
Example 1: 50 year old woman with Stage IB Mycosis Fungoides involving approximately 30% of her body surface area returned to our clinic for follow-up. She has been applying 10mg% Mustargen once daily from her neck to her feet with a good clinical response and no side effects to report. At this visit, we recommended increasing the Mustargen to 20mg% to be applied once daily from her neck to her feet. Our prescription would be written as:
Mustargen ointment 20mg%. Please mix 80 mg of Mustargen with 400 grams of Aquaphor ointment. Quantity: 400 grams.
Example 2: 70 year old male with Stage IA Mycosis Fungoides involving the bilateral buttock. The remainder of the skin examination is within normal limits. The patient has not received any therapy yet. We would like to start topical Mustargen at 10mg% to be applied to the bathing trunk area once a day. We estimate he will require 200 grams every 4-6 weeks. Our prescription would be written as:
Mustargen ointment 10mg%. Please mix 20 mg of Mustargen with 200 grams of Aquaphor ointment. Quantity: 200 grams.
We illustrate this point because the mg% dosing may cause confusion, which could lead to sub-therapeutic concentrations or excess concentrations dispensed to the patient.
We recommend to the patient, application of a small amount of Mustargen to a selected test-patch on your skin, once a day, for 7-10 days to rule out the possibility of a contact dermatitis. The test-patch can be a palm-sized patch on your arm, leg, or trunk.
If there is no significant irritation, new rash, or increased redness or itching, we recommend application of the Mustargen to all areas as planned.
We like to emphasis to the patient a very thin film of Mustargen to the skin is sufficient. Application of copious amounts to the skin has no additional benefits.
The Mustargen is maximally absorbed usually within the first hour after application, but we usually ask the patient to leave the medication on for at least four hours.
The use of additional moisturizing lotions, creams, or ointments throughout the day is always recommended. (This is especially important if you are using the water preparation, since the skin will likely be more xerotic.)
Please do not hesitate to call us if you have any questions.
Local pharmacies with compounding services close to Stanford:
Safeway Los Altos Compounding Pharmacy
225 2nd Street
Los Altos, CA 94022
Phone: (650) 948-1212 / (650) 949-8662
Fax: (650) 949-2269
Avella Specialty Pharmacy - Greater Sacramento Area
Phone: (877) 546-5779
Fax: (877) 546-5780
