Methoxsalen
The most commonly reported side effect of methoxsalen alone is nausea, which
occurs with approximately 10% of all patients. This effect may be minimized
or avoided by instructing the patient to take methoxsalen with milk or food,
or to divide the dose into two portions, taken approximately one-half hour apart.
Other effects include nervousness, insomnia, and psychological depression.
Combined methoxsalen/uva therapy
- Pruritus: This adverse reaction occurs with approximately 10% of
all patients. In most cases, pruritus can be alleviated with frequent application
of bland emollients or other topical agents; severe pruritus may require systemic
treatment. If pruritus is unresponsive to these measures, shield pruritic
areas from further UVA exposure until the condition resolves. If intractable
pruritus is generalized, UVA treatment should be discontinued until the pruritus
disappears.
- Erythema: Mild, transient erythema at 24–48 hours after PUVA therapy
is an expected reaction and indicates that a therapeutic interaction between
methoxsalen and UVA occurred. Any area showing moderate erythema (greater
than Grade 2 — see Table 1 for grades of erythema) should be shielded during
subsequent UVA exposures until the erythema has resolved. Erythema greater
than Grade 2 which appears within 24 hours after UVA treatment may signal
a potentially severe burn. Erythema may become progressively worse over the
next 24 hours, since the peak erythemal reaction characteristically occurs
48 hours or later after methoxsalen ingestion. The patient should be protected
from further UVA exposures and sunlight, and should be monitored closely.
- Important Differences Between Puva Erythema And Sunburn: PUVA-induced
inflammation differs from sunburn or UVB phototherapy in several ways. The
in situ depth of photochemistry is deeper within the tissue because
UVA is transmitted further into the skin. The DNA lesions induced by PUVA
are very different from UV-induced thymine dimers and may lead to a DNA crosslink.
This DNA lesion may be more problematic to the cell because crosslinks are
more lethal and psoralen-DNA photoproducts may be “new” or unfamiliar
substrates for DNA repair enzymes. DNA synthesis is also suppressed longer
after PUVA. The time course of delayed erythema is different with PUVA and
may not involve the usual mediators seen in sunburn. PUVA-induced redness
may be just beginning at 24 hours, when UVB erythema has already passed its
peak. The erythema dose-response curve is also steeper for PUVA. Compared
to equally erythemogenic doses of UVB, the histologic alterations induced
by PUVA show more dermal vessel damage and longer duration of epidermal and
dermal abnormalities.
- Other Adverse Reactions: Those reported include edema, dizziness,
headache, malaise, depression, hypopigmentation, vesiculation and bullae formation,
non-specific rash, herpes simplex, miliaria, urticaria, folliculitis, gastrointestinal
disturbances, cutaneous tenderness, leg cramps, hypotension, and extension
of psoriasis.
Copyright © 2012 by WebMD, LLC.
RxList does not provide medical advice, diagnosis or treatment. See additional information.
Updated & New