Metformin: A Valid Add-On Drug in the Treatment of Psoriatic Arthritis-Randomized Controlled Trial

The chronic inflammatory nature of psoriasis and PsA predisposes patients to cardiovascular diseases and metabolic syndrome (MetS). MetS is associated with systemic inflammation and proinflammatory cytokines.Clinical observations and experimental results argue for an anti-inflammatory and immunosuppressant property of MET.

A randomized placebo-controlled trial was conducted to evaluate the efficacy and safety of metformin as add-on therapy to MTX compared to MTX after 24 weeks in patients with PsA.

The study randomized 56 patients with a diagnosis of PsA . Patients with a history of a cardiovascular event and diabetics were excluded. Body mass index (BMI) and classic cardiovascular risk factors were recorded. Blood samples were analysed for glucose, lipid profile, ESR, hsCRP, proinflammatory cytokines; tumour necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6) and IL-17. The homeostasis model assessment model for insulin resistance (HOMA-IR) was used. The patients were randomized in a 1:1 ratio to receive 500mg/day retarded formulation of metformin (n=29) or placebo (n=29). Continuation of stable doses of MTX (25mg/week), NSAIDs, and/or corticosteroids (prednisone <10 mg/day) was permitted. Metformin drug pause on the day of MTX was given. Folic acid supplementation was given to both groups. The primary clinical endpoint was the ACR 20% (ACR20) response at 24 weeks. Secondary endpoints included reduction in PASI score, Health Assessment Questionnaire- Disability Index (HAQ-DI) and Psoriatic arthritis response criteria (PsARC) score.