Efficacy and Safety of Risedronate (Actonel), a Third Generation Bisphosphonate in Patients With Ankylosing Spondylitis: a Phase 2 Pilot Study

Inclusion criteria: •Male or non-pregnant women (only women who are post menopausal, surgically sterile or practicing a reliable method of contraception may be included) aged 20 years or more * Meeting the Modified New York diagnostic criteria for AS (Van der Linden S et al., 1984) * Symptoms of active AS for more than 6 months prior to study entry * Treated by first-line therapy (NSAIDs) for more than 6 months prior to study entry * Bath AS Disease Activity Index (BASDAI) score of 4 or greater (Garrett S et al, 1994) and * Spinal pain of 4 or greater on a 10-cm visual analogue scale despite maximum recommended or tolerated doses of NSAIDs given for a minimum of 1 month prior to study entry Exclusion criteria: •End-stage AS with diffuse involvement of the spine (complete ankylosis) * Intraarticular corticosteroid injections or IV infusion with methylprednisolone within the past 2 months prior to study entry. Patients with IA corticosteroid injections of the sacroiliac joints within the past 9 months prior to study entry. * Severe renal insufficiency: serum creatinine \> 25% above the upper limit of normal (\>177 umol/l) * Hypocalcemia * Major surgery within the past 3 months prior to study entry or planned in the ensuing 12 months * Orthopaedic surgery within the last 12 months * Severe infections or comorbidities, or active peptic ulcer disease * Patients who received bisphosphonates in the past 12 months prior to study entry or patients having known allergies to bisphosphonates. * Patients treated with anti-osteoporotic drugs (except: Calcium and Vit. D) in the past 12 months prior to study entry. * Patients unable to remain in an upright position (sitting or standing) during a minimum of 30 minutes * No written informed consent obtained or inability to collaborate to the study design.