Oxsoralen-Ultra (methoxsalen)

Methoxsalen therapy must be accompanied by some form of UVA irradiation. Use of sunlight or conventional artificial UV light sources (e.g., hot or cold quartz lamps, fluorescent sunlamps, blacklights) is preferred by some clinicians but others prefer to use light from sources that provide high-intensity UVA light. Following topical methoxsalen application, conventional UV light sources are used by most clinicians; sunlight is used rarely.

Initial UV light exposure times should be based on the minimum phototoxic dose (MPD) for the specific light source being used. MPD can be determined by irradiating several skin areas 2 cm in diameter with varying light exposure times and determining the exposure time that produces erythema at 72 hours. When sunlight is used as the UV light source, initial sunlight exposure following methoxsalen administration should not exceed 15, 20, or 25 minutes for patients with light, medium, or dark skin colors, respectively; subsequent exposure may be increased 5 minutes each day, depending on the degree of erythema and tenderness. Exposure time should be reduced for noontime sun and for high-altitude or low-latitude (0-20degrees) exposure. Following topical application of methoxsalen, initial exposure to sunlight should not exceed 1 minute; subsequent exposure time may be increased cautiously depending on erythemic response. If a conventional artificial light source is used, exposure time should usually be 50% of that producing erythema after sunlight exposure or should be adjusted according to the MPD and the directions of the manufacturer of the device. Clinicians should consult published protocols and specialized references for information on the use of high-intensity UVA light sources.

To prevent serious burns following administration of methoxsalen, patients should be carefully instructed not to exceed the recommended dosage and UV light exposure time; the appropriate precautions associated with psoralen therapy and protective measures must be employed. (See Cautions: Precautions and Contraindications.)

Methoxsalen conventional and liquid-filled capsules should not be used interchangeably in the treatment of psoriasis. The liquid-filled capsules are absorbed more rapidly and extensively, have earlier peak photosensitivity times, and have substantially lower minimum phototoxic doses (MPD) than the conventional capsules. Dosages of these preparations are not interchangeable. Patients must be treated in accordance with the dosimetry specifically recommended for the dosage form employed. Before using PUVA therapy with the liquid-filled capsules, the MPD and peak photosensitivity time after drug administration should be evaluated in each patient.

Methoxsalen is usually administered orally. Oral methoxsalen may be administered as a single dose with milk or after a meal, or in 2 divided doses approximately 30 minutes apart, to minimize adverse GI effects.

Methoxsalen may also be applied topically in the form of a 1% lotion; occasionally, the lotion may need to be diluted 10- or 100-fold to avoid excessive reactions. Methoxsalen lotion should be applied only to small, well-defined, vitiliginous lesions (less than 10 cm2) by a physician. Methoxsalen lotion should not be dispensed to a patient for home use. The hands and fingers of the individual applying the lotion should be protected by gloves or finger cots to avoid photosensitization and possible burns. The lotion may be applied with a cotton swab, allowed to dry for 1-2 minutes, then reapplied. The borders of the vitiliginous lesion being treated should be protected with petrolatum and a sunscreen to prevent hyperpigmentation.

No dosing information is available for this tab.

No dosing information is available for this tab.

There is no enhanced messaging for this drug.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

There is no enhanced messaging for this drug.

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

There are no moderate contraindications for this drug.

There is no enhanced messaging for this drug.

There are no severe adverse reactions for this drug.

There are no less severe adverse reactions for this drug.

No enhanced messaging available.

No enhanced messaging available.

Animal reproduction studies have not been performed with oral or topical methoxsalen. It is not known whether methoxsalen can cause fetal harm when administered orally or topically to pregnant women. Methoxsalen should be used during pregnancy only when clearly needed.

Since it is not known whether methoxsalen is distributed into milk, the drug should be used with caution in nursing women.

No enhanced messaging available.