What vitamin D analogs are used to treat psoriasis?

Vitamin D Analogs for Psoriasis Treatment

Calcipotriene (calcipotriol), calcitriol, tacalcitol, and maxacalcitol are the primary vitamin D analogs used to treat psoriasis, with calcipotriene being the most widely available and studied option in the United States. 1

Mechanism of Action

Vitamin D analogs work by:

• Inhibiting keratinocyte proliferation
• Enhancing keratinocyte differentiation
• Modulating immune responses in the skin
• Acting as synthetic analogs of vitamin D3 with significantly less effect on calcium metabolism than natural vitamin D 2

Available Vitamin D Analogs

1. Calcipotriene/Calcipotriol

   • Most commonly used vitamin D analog in the US
   • Available as ointment, cream, foam, and solution formulations
   • Typical concentration: 0.005% (50 μg/g)
   • Applied once or twice daily 1

2. Calcitriol

   • Naturally occurring vitamin D3 analog
   • Available as 3 μg/g ointment
   • Generally less irritating than calcipotriene 3

3. Tacalcitol

   • Particularly useful for facial psoriasis
   • Not widely available in the US 1

4. Maxacalcitol

   • Can be used for palmoplantar psoriasis
   • Not available in the US 1

Efficacy and Recommendations

• Monotherapy: The long-term use of topical vitamin D analogs (up to 52 weeks) is recommended for mild to moderate plaque psoriasis (Strength of recommendation: A) 1

• Combination Therapy: Vitamin D analogs combined with topical corticosteroids are more effective than either agent alone (Strength of recommendation: A) 1

  • Calcipotriene plus betamethasone dipropionate is particularly effective
  • Can be used for up to 52 weeks with minimal adverse effects

• Specific Areas:

  • Scalp: Calcipotriene foam and calcipotriene plus betamethasone dipropionate gel are recommended for 4-12 weeks (Strength of recommendation: A) 1
  • Face: Tacalcitol ointment or calcipotriene combined with hydrocortisone for 8 weeks (Strength of recommendation: B) 1

Dosing Regimens

Several effective regimens include:

• Vitamin D analogs twice daily on weekdays + high-potency topical corticosteroids twice daily on weekends (Strength of recommendation: B) 1
• Morning high-potency topical corticosteroids + evening topical vitamin D analogs (Strength of recommendation: B) 1
• Maximum recommended dosages to prevent hypercalcemia:
  • 50 g/week/m² for calcipotriol
  • 100 g/week/m² for calcipotriene
  • For adolescents: limit of 80 g/week for combination formulations 1

Pediatric Considerations

• Calcipotriene/calcipotriol is recommended for childhood plaque psoriasis (Strength of recommendation: B) 1
• Occlusion should be avoided when applied to large body surface areas due to risk of increased calcium absorption 1
• Monitoring of vitamin D metabolites may be considered during therapy when applied to large body surface areas 1

Important Precautions

1. Drug Interactions:

   • Avoid simultaneous use with salicylic acid as the acidic pH inactivates calcipotriene 1
   • UVA radiation can decrease the concentration of calcipotriene on the skin
   • Thick layers of calcipotriene can block UVB radiation

2. Phototherapy Considerations:

   • When using with phototherapy, apply vitamin D analogs after the phototherapy treatment 1

3. Adverse Effects:

   • Local irritation (most common)
   • Theoretical risk of hypercalcemia when used on large body surface areas
   • Generally well-tolerated with minimal systemic effects 4

Comparative Efficacy

• Vitamin D analogs are more effective than coal tar or salicylic acid but less effective than liquor carbonis detergens (LCD) 15% solution 1
• Ultrapotent or potent corticosteroids outperform calcipotriene when used for 3-8 weeks 1
• Calcipotriene combined with betamethasone dipropionate is slightly more efficacious than betamethasone monotherapy 1

Conclusion

Vitamin D analogs represent an important component in psoriasis treatment, offering effective control with favorable safety profiles. They are particularly valuable for long-term management and when used in combination with topical corticosteroids to reduce steroid-related adverse effects.