Nitrogen Mustard (mechlorethamine)
Brand name: Mustargen® and Valchlor™
Mechlorethamine, also known as nitrogen mustard (NM), is an anti-cancer drug that inhibits DNA replication. Originally developed as an intravenous cancer chemotherapy, its topical application to the skin has been shown to be an effective treatment of early stage (Stage I-A, I-B, and II-A) cutaneous T-cell lymphoma (CTCL).
Topical NM can be a compound mixed by specialty pharmacists. Originally it was formulated in water but is available today in a compounded ointment base. A gel form of mechlorethamine (Valchlor™) has become available for treatment of cutaneous lymphoma. Using either form, compounded ointment or gel, individual skin lesions are typically treated; however, NM can be applied to involved and uninvolved areas of the skin when appropriate.
NM should be applied to a dry skin surface area at a time when it can remain on the skin for at least four hours. It need not be washed off after application. Hands should be washed after application to avoid trapping in finger web spaces and transferring the compound to other individuals.
The most frequent complication of topical NM therapy is the development of an irritant reaction (itching or stinging) which usually subsides with a dose or application frequency adjustment. Approximately ten percent of individuals may develop an allergic reaction which usually occurs within three to six weeks after initiation of treatment. Symptoms include reddening, burning, stinging, or itching. In severe cases, the skin may develop blisters, like a poison ivy reaction. Less frequently encountered toxicities of NM therapy include potential for bone marrow suppression and secondary skin cancers.
Patients with CTCL who demonstrate clinical clearing of patch and plaque lesions for the duration of NM therapy for 6-12 months may taper the frequency of treatments over time to a less cumbersome schedule.
Topical nitrogen mustard may be combined with topical steroids and/or systemic agents in some cases of advanced stage disease.