1. Clinical Overview
Calcipotriol is a synthetic vitamin D3 analogue used topically for the treatment of plaque psoriasis. It acts as a modulator of keratinocyte differentiation and proliferation, and as an immunomodulator. In the Indian context, it is a first-line topical treatment for mild to moderate psoriasis, valued for its efficacy and non-steroidal nature, which avoids the risks of skin atrophy and systemic absorption associated with potent topical corticosteroids.
| Onset | Duration | Bioavailability |
|---|---|---|
| Clinical improvement is typically observed within 1-2 weeks of starting therapy. | The therapeutic effect persists for the duration of application but requires regular use for maintenance. Effects may last for several days after discontinuation. | Systemic bioavailability from topical application is less than 1% when applied to psoriatic plaques and less than 5% when applied to normal skin, due to minimal percutaneous absorption. |
2. Mechanism of Action
Calcipotriol binds to the vitamin D receptor (VDR), a nuclear receptor expressed in keratinocytes, Langerhans cells, fibroblasts, and activated T-lymphocytes. The drug-receptor complex heterodimerizes with the retinoid X receptor (RXR) and binds to vitamin D response elements (VDREs) in the promoter regions of target genes, modulating their transcription.
3. Indications & Uses
- Mild to moderate chronic plaque psoriasis (psoriasis vulgaris)
4. Dosage & Administration
Adult Dosage: Apply a thin layer to the affected areas once or twice daily. Maximum recommended dose is 100 grams per week.
Administration: Wash hands before and after application. Apply only to psoriatic plaques, avoiding surrounding healthy skin. Do not apply on the face, flexures, or genital areas. Do not occlude with bandages unless directed by a physician. For scalp solution, part hair and apply directly to lesions on the scalp.
5. Side Effects
Common side effects may include:
- Local skin irritation, burning, stinging, or itching at application site
- Erythema (redness)
- Dry skin
- Skin peeling
- Dermatitis
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other topical Vitamin D analogues (e.g., Tacalcitol) | Additive risk of hypercalcemia and local irritation. | Major |
| Topical corticosteroids (e.g., Betamethasone) | Often used in combination for synergistic effect. However, potent corticosteroids may increase systemic absorption of calcipotriol. Fixed-dose combinations (e.g., Calcipotriol + Betamethasone dipropionate) are available and preferred for sequential therapy. | Moderate |
| Topical salicylic acid | Salicylic acid inactivates calcipotriol by altering the pH. Should not be applied concurrently. | Major |
| Systemic drugs affecting calcium (e.g., Thiazide diuretics, Calcium supplements, Vitamin D) | Increased risk of hypercalcemia. | Moderate |
| Photosensitizing drugs (e.g., Tetracyclines, Fluoroquinolones, Thiazides) | Increased risk of photosensitivity reactions. | Moderate |
7. Patient Counselling
- DO apply a thin layer only to the psoriatic plaques.
- DO wash hands thoroughly after application.
- DO use sunscreen and protective clothing on treated areas when going outdoors.
- DON'T apply on the face, underarms, groin, or other sensitive areas.
- DON'T use more than the prescribed amount or frequency (max 100g/week).
- DON'T use occlusive dressings unless advised by your doctor.
- DON'T use other topical products (especially salicylic acid) on the same area without consulting your doctor.
8. Toxicology & Storage
Overdose: Topical overdose (application >100g/week): Symptoms of hypercalcemia may develop: fatigue, lethargy, nausea, vomiting, constipation, polyuria, polydipsia, dehydration, muscle weakness, and in severe cases, cardiac arrhythmias and renal calculi. Local overdose can cause severe skin irritation, erythema, and peeling.
Storage: Store at room temperature (15-25°C). Protect from light and heat. Do not freeze. Keep the tube or bottle tightly closed. Keep out of reach and sight of children. Do not use after the expiry date printed on the pack.