Methoxsalen Macopharma (Methoxsalen)

• Methoxsalen is employed in photochemotherapy (PUVA) to treat several dermatological conditions that respond to UVA‑activated treatment.
• Psoriasis: reduces hyperproliferative skin lesions when combined with UVA (PUVA) therapy.
• Vitiligo: promotes repigmentation of depigmented patches during PUVA therapy.
• Cutaneous T‑cell lymphoma: assists in disease control when administered as part of PUVA protocols.

• Methoxsalen intercalates between DNA base pairs and, upon activation by UVA light, forms covalent cross‑links with pyrimidine residues. These cross‑links inhibit DNA synthesis and cell proliferation, leading to reduced epidermal turnover and modulation of immune responses in the skin. The photochemical reaction is localized to the treated area, providing targeted therapeutic effects, and the induced apoptosis of hyperactive keratinocytes contributes to clinical improvement.

Methoxsalen may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea or gastrointestinal discomfort
• Headache or dizziness
• Mild erythema or sunburn‑like skin redness
• Pruritus (itching) at exposed sites
• Transient hyperpigmentation of treated skin
• Phototoxic skin reactions with excessive UVA exposure

Serious or Rare Side Effects

• Severe phototoxic burns or blistering
• Ocular toxicity, including cataract formation
• Increased risk of skin malignancies with long‑term use
• Hepatic dysfunction or elevated liver enzymes
• Severe allergic reactions such as anaphylaxis
• Persistent or worsening skin lesions

• When using Methoxsalen, several safety considerations should be observed.
• Dose adjustment: renal or hepatic impairment may require monitoring.
• Eye protection: wear UVA‑blocking glasses during and after exposure to prevent ocular toxicity.
• Phototoxicity risk: avoid excessive UVA exposure outside treatment sessions.
• Pregnancy and lactation: use only if benefits outweigh risks, as safety data are limited.
• Drug interactions: review concomitant photosensitizing agents.
• Store at ambient temperature: keep below 25 °C, protect from moisture and light in original container.

Methoxsalen can interact with other medications, necessitating careful review.

Major Interactions (Avoid)

• Photosensitizing drugs (e.g., tetracyclines, thiazides): may amplify phototoxic reactions.
• Systemic retinoids (e.g., acitretin): increase risk of severe skin toxicity.
• Anticoagulants (e.g., warfarin): may enhance photosensitivity and bleeding risk.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (e.g., ketoconazole): may alter methoxsalen metabolism.
• Antidepressants (e.g., SSRIs): potential additive photosensitivity.
• Topical corticosteroids: may mask early signs of phototoxicity.