Indications 

This pharmaceutical agent is employed concomitantly with controlled ultraviolet light (UVA) exposure to manage severe cases of psoriasis, and it may find application in the treatment of other dermatological conditions such as vitiligo and cutaneous T-cell lymphoma (CTCL). Methoxsalen operates by augmenting the skin’s sensitivity to UVA light. In psoriasis therapy, this synergistic approach serves to decelerate the excessive proliferation of epidermal cells. In contrast, when employed for vitiligo treatment, this combination facilitates the expansion of pigment-producing melanocytes within the dermal layer. Note that the administration of this medication is not recommended for pediatric patients under the age of 12. 

Uses and Dosage 

Administer this medication orally with a meal or milk following your physician’s guidance, typically 2 to 4 hours before the scheduled UVA light treatment. Co-administration of methoxsalen with food serves to enhance the absorption while mitigating the likelihood of experiencing nausea. 

The prescribed dosage of methoxsalen is contingent upon your body weight, medical condition, and individual response to the treatment regimen. The intensity and duration of UVA light exposure during each treatment session are predicated on your skin type and the observed response to the therapy. Initially, it is better to undergo UVA light treatments 2 to 4 times weekly, gradually reducing frequency as your condition ameliorates. 

For 24 hours after ingesting the methoxsalen capsule, wear wrap-around sunglasses capable of blocking UVA light during daylight hours. This precautionary measure is vital to prevent the absorption of UVA rays by the eye lenses, a phenomenon that can lead to the development of cataracts. Avoid direct sunlight exposure on the skin or lips for at least 8 hours following methoxsalen ingestion, including sunlight penetrating through windows. This step is crucial in preventing overexposure to UVA rays, which may result in sunburn. In situations where avoiding sunlight is unfeasible, employ protective attire such as a hat, gloves, long-sleeved clothing, and pants, in combination with UVA-blocking sunscreen. Consult your healthcare provider or pharmacist for guidance on selecting an appropriate sunscreen. Note that sunscreen should only be applied to areas of the skin affected by psoriasis or vitiligo after the UVA light treatment. 

Side Effects 

Common Side Effects

Methoxsalen administration may entail potential side effects, including the possibility of experiencing nausea or disturbances in sleep patterns. In conjunction with UVA light treatment, there is a potential for mild skin reactions, such as itching, dryness, reddening, or darkening. Should any of these effects persist or worsen, promptly inform your healthcare provider or pharmacist. 

Should the need arise, seek guidance from your doctor or pharmacist regarding selecting appropriate products, such as moisturizers, to alleviate dry or itchy skin. 

Severe Side Effects

Keep in mind that your physician has prescribed this medication based on a careful assessment, deeming that the therapeutic benefits outweigh the associated risks of side effects. Many individuals undergoing this treatment regimen do not experience severe side effects. 

Immediate medical attention is warranted if any severe side effects manifest, including but not limited to:  

• Skin reddening, blistering, peeling, or burning 
• Skin thinning or wrinkling 
• Painful discoloration or changes in the nails 
• Unusual growths or moles 
• Skin sores 
• Ankle swelling 
• Alterations in mental or emotional well-being, such as depression or nervousness  
• Any diminishment or blurring of vision 

Cautions 

Before commencing methoxsalen treatment, disclose any known allergies to your healthcare provider or pharmacist, as well as any other allergies you may have. This medication may contain inactive constituents that could trigger allergic reactions or other adverse effects. Discuss with your pharmacist for a more comprehensive understanding of the product’s composition. 

Before initiating this medication, provide your medical history to your healthcare provider or pharmacist, particularly if you have an account of conditions that render you sensitive to light, such as lupus, specific porphyrias, xeroderma pigmentosum, or albinism. Other pertinent aspects of your medical history include a history of skin cancer (melanoma, basal cell, or squamous cell carcinomas), prior removal of the natural lens in the eye, previous exposure to coal tar/UVB treatment, radiation therapy, or arsenic treatment. Disclose any preexisting conditions, including cataracts, liver disease, heart disease, or kidney disease. 

Moreover, before undergoing any surgical procedures, inform your surgeon and dentist about all products you currently use, encompassing prescription medications, over-the-counter drugs, and herbal supplements. This comprehensive disclosure ensures that your healthcare providers can make informed decisions in the context of your medical care.