A topical combination product used primarily in dermatology for the treatment of chronic, scaling, and inflammatory skin conditions. Coal Tar acts as an anti-inflammatory, antipruritic, and keratoplastic agent, while Salicylic Acid provides keratolytic, comedolytic, and mild anti-inflammatory effects. This combination is a cornerstone of therapy for psoriasis and seborrheic dermatitis in the Indian context, valued for its efficacy and cost-effectiveness.
Adult: Apply a thin layer to the affected area once or twice daily, or as directed by the physician. For scalp: Apply, massage gently, leave on for 5-10 minutes, then rinse thoroughly.
Note: 1. Wash and dry the affected area. 2. Apply a thin film and rub in gently. 3. Avoid contact with eyes, mucous membranes, and genital areas. 4. For scalp use, protect the forehead with petroleum jelly to prevent staining. 5. Can be used with occlusion (plastic wrap) for thick plaques under medical guidance. 6. Wash hands after application.
The combination works synergistically. Coal Tar reduces epidermal hyperproliferation and dermal inflammation by inhibiting DNA synthesis and modulating interleukin-6. It also has antipruritic and vasoconstrictive effects. Salicylic Acid facilitates the penetration of Coal Tar by breaking down intercellular keratinocyte adhesions (desmosomes) through dissolution of the intracellular cement. It also promotes shedding of scales and unblocks pores.
Pregnancy: Category C (US FDA). No well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus, especially in the third trimester (risk of bleeding and prolonged labor due to salicylate effects). Avoid large surface area application.
Driving: No effect on driving ability.
| Warfarin and other Oral Anticoagulants | Increased risk of bleeding due to potential systemic absorption of salicylic acid displacing warfarin from protein binding sites and affecting platelet function. | Major |
| Methotrexate | Increased risk of methotrexate toxicity due to displacement from plasma protein binding by salicylic acid. | Major |
| Other Topical Medications (e.g., Tretinoin, Benzoyl Peroxide, strong acids) | Increased risk of severe local irritation and dryness. | Moderate |
| Photosensitizing Drugs (e.g., Doxycycline, Fluoroquinolones) | Additive risk of photosensitivity reactions with Coal Tar. | Moderate |
| Topical Corticosteroids | Often used sequentially (not simultaneously) in a rotational regimen. No direct pharmacokinetic interaction. | Minor |