• calcipotriol;
  • methotrexate;
  • psoriasis;
  • skin;
  • vitamin D

SummaryBackground A multicentre, randomized, double-blind, vehicle-controlled, parallel-group study was carried out to study the effect of the addition of calcipotriol ointment to methotrexate (MTX) therapy in patients with psoriasis vulgaris.

Objectives To investigate whether the addition of calcipotriol to treatment with MTX has an MTX-sparing effect, and whether the combination of treatments is safe. Additionally, to compare the effect of calcipotriol or vehicle on the duration of the relapse-free interval after cessation of MTX.

Methods Patients on maintenance therapy with MTX with controlled psoriasis were selected. The study was divided into three phases: (i) an MTX-free phase with double-blind treatment with either calcipotriol ointment or vehicle; (ii) an MTX titration phase with open MTX treatment and additional double-blind treatment with either calcipotriol or vehicle until target response; and (iii) follow-up phase: in a group of 97 patients, psoriasis was assessed using the modified psoriasis severity score, patients' assessment and safety parameters were monitored as well.

Results The combined use of calcipotriol with MTX resulted in an MTX-sparing effect of 3·4 mg week−1 (phase (II) and 2·6 mg week−1 (phase I and II taken together), while still maintaining efficacy. Calcipotriol treatment increased the time to relapse of psoriasis following discontinuation of MTX: 113 days vs. 35 days. A decrease in aspartate aminotransferase and alanine aminotransferase was seen during the study of 8% (calcipotriol) and 12% (vehicle).

Conclusions The combination of calcipotriol and MTX was safe and well tolerated. The combination resulted in lower cumulative dosages of MTX compared with MTX and vehicle. Therefore the risk of side-effects is substantially decreased.