- What is methoxsalen? How does it work (mechanism of action)?
- What are the uses for methoxsalen?
- What are the side effects of methoxsalen?
- What is the dosage for methoxsalen?
- Which drugs or supplements interact with methoxsalen?
- Is methoxsalen safe to take if you are pregnant or breastfeeding?
- What else should you know about methoxsalen-oral?
What is methoxsalen? How does it work (mechanism of action)?
- Methoxsalen is a naturally occurring photoactive chemical found in the seeds of the Ammi majus (Umbelliferae) plant and in the roots of Heraclem candicans. It belongs to a group of compounds known as psoralens, or furocoumarins. It is used for treating psoriasis, idiopathic vitiligo (leucoderma) and cutaneous (skin) manifestations of T-cell lymphoma. The exact mechanism of action of methoxsalen is not known.
- Methoxsalen has several biological actions that may be responsible for its medical effects. Ultraviolet radiation of 320-400 nm wavelength (UVA) is beneficial for treating psoriasis, vitiligo, and skin manifestations of T-cell lymphoma. Methoxsalen is a photosensitizer that increases the reaction of the skin to UVA. Methoxsalen also combines with DNA in skin cells. Upon administration, methoxsalen reaches the skin via blood. When UVA penetrates the skin, cellular damage occurs, leading to inflammation. The damaged skin heals after several days to weeks.
- Some experts suggest that methoxsalen improves vitiligo by stimulating melanocytes (melanin forming skin cells) to move up the hair follicle and to repopulate the epidermis. Psoriasis causes an over production of skin cells. Methoxsalen may benefit psoriasis by decreasing skin cell production by damaging DNA.
- The FDA approved methoxsalen capsules in December 1954.
- 8-MOP, Oxsoralen Ultra are the brand names for methoxsalen.
- Methoxsalen is available in generic form.
- You need a prescription to obtain methoxsalen.
What are the uses for methoxsalen?
- Oral methoxsalen combined with UVA (ultraviolet A) radiation is used as photochemotherapy for the treatment of severe, disabling psoriasis that is difficult to treat and is unresponsive to other treatments.
- It also is used for treating idiopathic vitiligo (leucoderma) and cutaneous (skin) manifestations of T-cell lymphoma.
What are the side effects of methoxsalen?
Common side effects include:
Other side effects include:
- Leg cramps
- Low blood pressure
- Stomach upset
Possible serious side effects include:
What is the dosage for methoxsalen?
- Patients must not sunbathe 24 hours before methoxsalen administration and UV exposure because a sunburn may prevent an accurate evaluation of the response to treatment.
- UVA-absorbing wrap-around sunglasses designed to prevent entry of radiation to the eyes should be worn during the day for 24 hours after methoxsalen administration.
- Patients must avoid sun exposure, including through-the window or through cloud cover, for at least 8 hours after methoxsalen administration. Hat and gloves, and/or sunscreens with SPF equal to or greater than 15 should be used if sun exposure cannot be avoided. Sunscreens should be applied to all areas of the body exposed to the sun (including lips). However, sunscreens should not be applied to areas affected by psoriasis until after treatment in the UVA chamber.
- The recommended oral dose for treating psoriasis is 10 to 70 mg every other day with milk or food 2 hours before UVA exposure. The dose is based on weight.
Cutaneous T-Cell Lymphoma
- The recommended initial oral dose for treating cutaneous T-Cell lymphoma is 0.6 mg/kg. Ann additional 10 mg should be taken if the blood concentration of methoxsalen is less than 50 ng/ml.
- The recommended oral dose for treating vitiligo is 20 mg every other day with milk or food 2 to 4 hr before UVA exposure. The dose must not exceed 0.6 mg/kg since larger doses may result in serious skin burns.
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Which drugs or supplements interact with methoxsalen?
- Use of drugs that cause sun sensitivity will increase the risk of severe skin burns when using methoxsalen. Examples of such drugs include coal tar or coal tar derivatives, doxycycline (Vibramycin), tetracycline, demeclocycline, methylene blue (Provayblue), griseofulvin (Gris-PEG), thiazide diuretics, fluoroquinolone antibiotics, and several other drugs.
IMAGESBrowse our medical image collection of allergic skin disorders such as psoriasis and dermatitis and more caused by allergies See Images
Is methoxsalen safe to take if you are pregnant or breastfeeding?
What else should you know about methoxsalen-oral?
What preparations of methoxsalen-oral are available?
Capsule: 10 mg
How should I keep methoxsalen-oral stored?
Methoxsalen should be stored at 15 C to 30 C (59 F to 86 F).
Methoxsalen (8-MOP, Oxsoralen Ultra) is an oral prescription drug used to treat severe, disabling psoriasis that has been unresponsive to other treatments. Methoxsalen also is prescribed to treat idiopathic vitiligo and skin manifestations of T-cell lymphoma. Side effects, drug interactions, warnings, and pregnancy and breastfeeding information should be reviewed prior to taking any medication.
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Related Disease Conditions
Non-Hodgkin's lymphoma is cancer of the lymphatic system, a vital part of the body's immune system. Symptoms and signs include swollen lymph nodes, fever, night sweats, coughing, weakness, chest pain, unexplained weight loss, and abdominal pain. Treatment depends on which type of non-Hodgkin's lymphoma one has, the stage of the cancer, one's age, how fast the cancer is growing, and whether one has other health problems.
Psoriasis is a long-term skin condition that may cause large plaques of red, raised skin, flakes of dry skin, and skin scales. There are several types of psoriasis, including psoriasis vulgaris, guttate psoriasis, inverse psoriasis, and pustular psoriasis. Symptoms vary depending on the type of psoriasis the patient has. Treatment of psoriasis may include creams, lotions, oral medications, injections and infusions of biologics, and light therapy. There is no cure for psoriasis.
Vitiligo is a condition in which the skin turns white due to the loss of pigment from the melanocytes, cells that produce the pigment melanin that gives the skin color.
Scalp Psoriasis (Psoriasis of the Scalp)
Scalp psoriasis causes red, raised, scaly patches that may extend from the scalp to the forehead and the back of the neck and ears. Symptoms and signs include itching, hair loss, flaking, silvery scales, and red plaques. Treatment includes topical medicated shampoos, creams, gels, oils, ointments, and soaps, medications, and light therapy.
Is Psoriasis Contagious?
Psoriasis is an incurable skin disease that causes reddish patches of skin topped with a thick layer of dry silvery scales. Psoriasis cannot spread and is not contagious.
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