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Mechlorethamine (Topical)

Medically reviewed by Last updated on Aug 7, 2020.


(me klor ETH a meen)

Index Terms

  • HN2
  • Mechlorethamine HCl (Topical)
  • Mechlorethamine HCl Gel
  • Mechlorethamine Topical Gel
  • Topical Nitrogen Mustard

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Gel, External:

Valchlor: 0.016% (60 g) [contains edetate disodium, isopropyl alcohol, menthol, propylene glycol]

Brand Names: U.S.

  • Valchlor

Pharmacologic Category

  • Antineoplastic Agent, Alkylating Agent
  • Antineoplastic Agent, Alkylating Agent (Nitrogen Mustard)


Mechlorethamine is a nitrogen mustard alkylating agent which forms inter- and intra-strand DNA cross-links, resulting in inhibition of DNA synthesis. Topical application allows for skin-directed treatment while minimizing systemic nitrogen mustard exposure (Lessin 2013).


Topical: None detected (Lessin 2013)


Topical: No detectable systemic exposure in a clinical study (Lessin 2013)

Use: Labeled Indications

Cutaneous T-cell lymphoma: Topical treatment of stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma in patients who have received prior skin-directed therapy


Known severe hypersensitivity to mechlorethamine or any component of the formulation

Dosing: Adult

Cutaneous T-cell lymphoma (mycosis fungoides-type): Topical: Apply a thin film once daily to affected areas of skin. In the clinical study, treatment was continued for 1 year and concurrent use of topical or systemic corticosteroids was not allowed (Lessin 2013).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Adjustment for Toxicity

Skin ulceration (any grade), blistering, or dermatitis (moderately severe-to-severe): Withhold treatment; upon improvement, may reinitiate treatment with a reduced frequency of once every 3 days; if every 3-day application is tolerated for at least 1 week, may increase to every other day for at least 1 week, then (if tolerated) may increase to once daily.


Apply a thin film topically to affected area. Apply immediately (or within 30 minutes) after removal from refrigerator; return to refrigerator promptly after each use. Apply to completely dry skin at least 4 hours before or 30 minutes after showering/washing. Allow treated area(s) to dry for 5 to 10 minutes after application before covering with clothing. May apply emollients (moisturizers) to treated area 2 hours before or 2 hours after mechlorethamine application. Do not use occlusive dressings over treatment areas. Avoid fire, flame, and smoking until mechlorethamine has dried.

Caregivers should wear nitrile gloves when applying to patients. Wash hands thoroughly with soap and water after handling/application. If accidental skin exposure occurs, wash thoroughly for at least 15 minutes with soap and water; remove any contaminated clothing.


Prior to dispensing, store in freezer at -25°C to -15°C (-13°F to 5°F). After dispensing, refrigerate at 2°C to 8°C (36°F to 46°F); apply immediately (or within 30 minutes) after removal from refrigerator; return to refrigerator promptly after each use.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.


Dermatologic: Dermatitis (56%; moderately severe or severe: 23%), pruritus (20%), bacterial skin infection (11%)

Hematologic & oncologic: Hematologic abnormality (decreased hemoglobin, neutrophils, or platelets; 13%)

1% to 10%:

Dermatologic: Dermal ulcer (6%), skin hyperpigmentation (5%)

Hematologic & oncologic: Malignant neoplasm (nonmelanoma skin cancer; 2%)

Postmarketing and/or case reports: Anaphylaxis, hypersensitivity reaction


Concerns related to adverse effects:

• Accidental exposure: Eye exposure may result in pain, burning, inflammation, photophobia, and blurred vision. Blindness and severe anterior eye injury (irreversible) may occur. If exposure to eye(s) occurs, promptly irrigate for at least 15 minutes with copious amounts of water, normal saline, or balanced salt ophthalmic irrigating solution; obtain immediate medical care, including ophthalmology consultation. Exposure to mucous membranes may cause pain, redness, and ulceration; may be severe. If mucosal contact occurs, irrigate promptly for at least 15 minutes with copious amounts of water and obtain medical consultation.

• Dermatitis: Dermatitis commonly occurs; may be moderately severe or severe. Monitor for redness, swelling, itching, blistering, ulceration, and secondary skin infections. Facial, genitalia, anus and intertriginous skin areas are at increased risk for dermatitis. Dermatitis may require dosage reduction.

• Hypersensitivity: Hypersensitivity reactions (including anaphylaxis) have occurred with topical mechlorethamine application.

• Secondary exposure: Avoid direct contact with mechlorethamine (other than intended treatment areas for the patient). Secondary exposure risks include dermatitis, mucosal injury, and secondary malignancies. To prevent secondary exposure, follow recommended application procedures.

• Secondary malignancy: In a clinical study, non-melanoma skin cancers developed during or within 1 year following treatment. Some instances occurred in patients who had received previous treatments that were associated with non-melanoma skin cancer. Monitor for non-melanoma skin cancers during and following treatment; may occur anywhere on the skin, including untreated areas.

Other warnings/precautions:

• Flammable gel: Mechlorethamine gel contains alcohol and is flammable; follow recommended application procedures and avoid fire, flame, and smoking until mechlorethamine has dried.

Monitoring Parameters

Monitor for dermatologic toxicity (skin ulcers, blistering, dermatitis, secondary skin infections), and signs/symptoms of nonmelanoma skin cancer or hypersensitivity reactions.

Reproductive Considerations

Females of reproductive potential are advised not to become pregnant during topical mechlorethamine treatment. Females of reproductive potential and males with female partners of reproductive potential should use a barrier method of contraception during therapy.

Pregnancy Considerations

Based on the mechanism of action, case reports in humans, and data from animal reproduction studies, in utero exposure to topical mechlorethamine may cause fetal harm. There are case reports of major birth defects following maternal administration of systemic mechlorethamine.

Patient Education

What is this drug used for?

• It is used to treat a type of lymphoma that affects the skin.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Itching

• Skin discoloration

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Skin sores

• Blisters

• Redness

• Swelling

• Skin infection

• Skin ulcers

• Mole changes

• Skin growths

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.