8-MOP, Oxsoralen, Uvadex
Classifications: psoralen; pigmenting agent; Therapeutic:pigmenting agent
Pregnancy Category: C
10 mg capsules, 20 mcg/mL solution; 1% lotion
Plant derivative with strong photosensitizing effects: used with ultraviolet-A light (UVA) in therapeutic regimens called
PUVA (P-psoralen). After photoactivation by long wavelength, UVA, methoxsalen combines with epidermal cell DNA causing photodamage
Photodamage inhibits rapid and uncontrolled epidermal cell turnover characteristic of psoriasis. Results in an inflammatory
reaction with erythema. Strongly melanogenic.
With controlled exposure to UVA to repigment vitiliginous skin and for symptomatic treatment of severe disabling psoriasis
that is refractory to other forms of therapy.
(PUVA therapy) mycosis fungoides.
Sunburn, sensitivity (or its history) to psoralens, diseases associated with photosensitivity (e.g., SLE, albinism, melanoma
or its history); invasive squamous cell cancer; cataract; aphakia; previous exposure to arsenic or ionizing radiation; pregnancy
(category C), lactation. Safety (oral) in children is not established.
Hepatic insufficiency; GI disease; chronic infection; treatment with known photosensitizing agents; immunosuppressed patient;
cardiovascular disease; lactation. Safety (lotion) in children <12 y is not established.
Route & Dosage
Adult: Topical Apply lotion 12 h before exposure to UV light once/wk
Adult: PO Give 1.52 h before exposure to UV light 23 times/wk: <30 kg, 10 mg; 3050 kg, 20 mg; 5165 kg, 30 mg; 6680 kg, 40 mg; 8190 kg, 50 mg; 91115 kg, 60 mg; >115 kg, 70 mg
- Note: Methoxsalen therapy with UV light (PUVa therapy) should be done under the complete control of a physician with special competence
and experience in photochemotherapy.
- Give with milk or food to prevent GI distress.
- Maintain consistent time relationship between fooddrug ingestion. Food digestion and absorption appear to affect drug
- Only small (<10 cm2), well-defined areas are treated with lotion. Systemic treatment is used for large areas.
- Apply lotion with cotton swabs, allow to dry 12 min, then reapply. Protect borders of the lesion with petrolatum and
sunscreen lotion to prevent hyperpigmentation.
- Use finger cots or gloves to apply lotion and prevent photosensitization and burned skin.
- Apply sunscreen lotion to the skin for about one third of the initial exposure time during PUVA therapy until there is sufficient
tanning. Do not apply to psoriatic areas before treatment.
- Store lotion and capsules at 15°30° C (59°86° F) in light-resistant containers unless otherwise
directed by manufacturer.
Adverse Effects (≥1%)CNS:
Nervousness, dizziness, headache, mental depression
or excitation, vertigo, insomnia
. Special Senses: Cataract
formation, ocular damage. GI:
and other GI disturbances, toxic hepatitis. Skin:
Phototoxic effects: severe edema and erythema
painful blisters; burning
, peeling, thinning, freckling, and accelerated aging of skin; hyper- or hypopigmentation; severe skin pain (lasting 12
mo), photoallergic contact dermatitis (with topical use), exacerbation of latent photosensitive dermatoses, malignant melanoma
(rare). Body as a Whole:
Transient loss of muscular coordination, edema, leg cramps, systemic immune effects, drug fever.
InteractionsDrug: Anthralin, coal tar, griseofulvin, phenothiazines
, nalidixic acid, sulfonamides
, bacteriostatic soaps
compound photosensitizing effects. Food:
Food will increase peak and extent of absorption.
Variably from GI tract. Peak:
2 h. Duration:
810 h. Distribution:
Preferentially taken up by epidermal cells; distributes into lens of eye. Elimination:
8090% in urine within 8 h. Half-Life:
Assessment & Drug Effects
- Schedule a pretreatment ophthalmologic exam to rule out cataracts; repeat periodically during treatment and at yearly intervals
- Lab tests: Monitor CBC, kidney and liver function, and antinuclear antibody tests during oral therapy.
- Fair-skinned patients appear to be at greatest risk for phototoxicity from PUVA therapy (see ADVERSe EFFECTS).
- Be aware that repigmentation is more rapid on fleshy areas (i.e., face, abdomen, buttocks) than on hands or feet.
Patient & Family Education
- Expect that effective repigmentation may require 69 mo of treatment; periodic treatment usually is necessary to retain
pigmentation. If, after 3 mo of treatment, there is no apparent response, drug is discontinued.
- Avoid additional exposure to UV light (direct or indirect) for at least 8 h after oral drug ingestion and UVA exposure.
- Understand intended treatment schedule: After topical application, the initial sunlight exposure is limited to 1 min, with
subsequent gradual and incremental exposures by prescription.
- Avoid additional UV light for 2448 h after topical application and UVA exposure.
- Wear sunscreen lotion (with SPF 15 or higher) and protective clothing (hat, gloves) to cover all exposed areas including
lips, to prevent burning or blistering if sunlight cannot be avoided after the treatment.
- Do not sunbathe for at least 48 h after PUVA treatment. Sunburn and photochemotherapy are additive in the production of
burning and erythema.
- Wear wraparound sunglasses with UVA-absorbing properties both indoors and outdoors during daylight hours for 24 h. Do not
substitute prescription sunglasses or photosensitive darkening glasses; they may actually increase danger of cataract formation.
- Alert physician to appearance of new psoriatic areas, flares, or regressed cleared skin areas during treatment and maintenance