Other commonly used names are chlormethine; ntirogen mustard.

• Antineoplastic, topical

Mechlorethamine (me-klor-ETH-a-meen) belongs to the group of medicines called alkylating agents. It is used to treat certain skin conditions that could turn to cancer if left untreated.

Mechlorethamine interferes with the growth of problem cells, which are eventually destroyed. However, there is also a chance that mechlorethamine can cause some kinds of skin cancer, especially after it has been used for several years.

Before you begin treatment with mechlorethamine, you and your doctor should talk about the good this medicine will do as well as the risks of using it.

Mechlorethamine is available only with your doctor's prescription, in the following dosage forms:

Topical
• Ointment (U.S. and Canada)
• Topical solution (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For mechlorethamine applied to the skin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to mechlorethamine.

Pregnancy—Although mechlorethamine applied to the skin has not been shown to cause problems in humans, some of it may be absorbed through the skin.

Breast-feeding—Although mechlorethamine applied to the skin has not been shown to cause problems in nursing babies, some of it may be absorbed through the skin. Because this medicine can cause serious side effects, breast-feeding is generally not recommended while you are using it.

Children—There is no specific information about use of mechlorethamine on the skin in children.

Older adults—Many medicines have not been tested in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information about the use of mechlorethamine on the skin in the elderly.

Mechlorethamine may be used either as a solution or as an ointment. If you are using the solution, it must be mixed just before you use it since it breaks down quickly. Mix the solution carefully according to your doctor's or pharmacist's directions.

When preparing the solution, remember:

• Do not use the mechlorethamine if the solution is discolored or if droplets of water appear in the vial.
• Avoid inhaling the powder or any vapors. If some of the powder or solution accidentally gets on your skin, immediately wash that area of skin. Use a large amount of water and continue to wash for at least 15 minutes. If eye contact occurs, use an eyewash recommended by your doctor. Keep this eyewash on hand. Follow carefully any other instructions your doctor may have given you.
• All equipment used must be specially cleaned, even if it is to be thrown away. Follow carefully your doctor's instructions for doing this, using the special solution recommended.

Take a shower and rinse carefully just before you apply mechlorethamine solution or ointment, unless otherwise directed by your doctor. Make sure your skin is completely dry before applying the ointment. Do not shower again until the next treatment.

Apply the solution or ointment all over the body, until the entire amount for a dose is used up. Wear rubber or plastic gloves if you are using your hands. To apply the solution, a 2-inch-wide soft brush or gauze may be used instead. Let the solution dry.

Mechlorethamine should be applied more lightly to the groin, armpits, inside the bends of the elbows, and behind the knees. These areas are more likely to get irritated.

Avoid contact with the eyes, nose, or mouth, unless otherwise directed by your doctor.

Mechlorethamine is usually applied once a day. However, follow your doctor's instructions. Continue to use the medicine as long as you are told to. This may be months or years. However, do not use this medicine more often or for a longer time than ordered. To do so may increase the chance of unwanted effects.

Dosing—

The dose of mechlorethamine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of mechlorethamine. If your dose is different, do not change it unless your doctor tells you to do so.

• For topical dosage forms (ointment or solution):
  • For mycosis fungoides:
    • Adults—Apply to the entire skin surface once a day. Several months after this medicine has helped your problem, your doctor may decrease the treatments to several times a week.
    • Children—Dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, go back to your regular dosing schedule and check with your doctor. Do not change the amount you are using unless directed to do so by your doctor.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light. This applies to either the ointment or the vials of mechlorethamine used to make the solution. The solution should not be stored but instead should be freshly made just before it is used.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits to make sure that mechlorethamine is working properly and to check for unwanted effects.

Along with its needed effects, a medicine may cause some unwanted effects. When mechlorethamine is applied to the skin, it does not usually cause the same effects as when it is given by injection. However, stop using this medicine and check with your doctor immediately if the following side effects occur:

• Hives;  shortness of breath (sudden) ;  skin rash or itching;  sore, reddened skin 

Check with your doctor also if you develop dry skin. There may be a lotion or ointment that you can use to help this. However, do not use anything else on your skin unless directed by your doctor.

Your skin color may darken after you have used this medicine for a while. The effect will go away after you have stopped using the medicine.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.