Therapeutic Agent for Vulgaris Vitiligo (Methoxsalen) is a photosensitizer primarily used in PUVA therapy (psoralen combined with long-wave ultraviolet A irradiation) for vitiligo and psoriasis. As a potent drug, its use must strictly follow the doctor's instructions, and potential severe side effects should be watched out for.
What Are the Side Effects of Therapeutic Agent for Vulgaris Vitiligo (Methoxsalen)?
Gastrointestinal Reactions
Nausea occurs in approximately 10% of patients, which can be alleviated by taking the drug with low-fat food or milk, or by dividing the dose into multiple administrations.
Gastrointestinal discomfort such as abdominal pain or dyspepsia is occasionally observed.
Skin Reactions
Phototoxic erythema: Mild erythema (an expected therapeutic response) may appear 24-48 hours after treatment; in severe cases, it may be accompanied by edema or blisters.
Pruritus: It occurs in about 10% of patients and requires treatment with emollients or topical medications.
Neurological Symptoms
These include dizziness, headache, insomnia, depression, etc. The incidence rate is relatively low, but close observation is necessary.
Others
Occasionally, hypotension, calf spasms, recurrence of herpes simplex, and other symptoms may occur.
Severe Side Effects of Therapeutic Agent for Vulgaris Vitiligo (Methoxsalen) That Require Vigilance
Risk of Skin Cancer
Long-term use may increase the risk of squamous cell carcinoma and melanoma, especially in patients who have received more than 250 cumulative PUVA treatments or have undergone a treatment course exceeding 15 years.
Eye Damage
Cataracts: Failure to wear UVA protective glasses may cause photochemical damage to the lens. Special goggles must be worn continuously within 24 hours after taking the drug.
Severe Phototoxic Reactions
Excessive ultraviolet exposure can lead to severe burns, so the irradiation dose and duration must be strictly followed.
Hepatotoxicity
Patients with hepatic insufficiency have reduced metabolic capacity, so the dose needs to be adjusted and liver enzymes should be monitored.
Precautions for Administration of Therapeutic Agent for Vulgaris Vitiligo (Methoxsalen)
Preparation Before Use
Contraindication screening: The drug is contraindicated in patients with photosensitive diseases (such as lupus erythematosus), a history of melanoma, and aphakia.
Ophthalmic examination: Ophthalmic evaluation is required before treatment and once a year.
Administration and Irradiation Specifications
Dose calculation: The dose is adjusted according to body weight (e.g., 20mg for patients weighing 30-50kg), and elderly patients start with a low dose.
Irradiation time: The initial UVA dose is determined based on skin type (0.5J/cm² for Type Ⅰ, 2.0J/cm² for Type Ⅳ), and subsequent doses are adjusted according to the patient's response.
Protective Measures
Eye protection: UVA-opaque glasses must be worn within 24 hours after taking the drug.
Skin protection: Avoid direct sunlight within 8 hours after treatment, and refrain from sunbathing within 48 hours.
Emergency Treatment
In case of overdose, induce vomiting immediately, avoid light for 24 hours, and monitor skin and eye symptoms.
