IRCT201212206975N3 IRCT 2013-01-31 Vice chancellor for research, Tabriz University of Medical Sciences Alendronate for the prevention of osteoporosis in ankylosing spondylitis A randomized, double-blind, placebo-controlled pilot study of the efficacy of alendronate on the prevention of bone loss in patients with early ankylosing spondylitis 2013-02-19 anticipated 20 Complete https://irct.ir/trial/7434 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention, Other design features: For elimination of the possibility of any probable bias due to the knowledge of patients and assessing physicians about the type of treatment we will perform a double blind study. Alendronate and placebo will be encapsulated and for this reason patients and assessing physicians do not have any knowledge about the type of treatment. Randomization will be performed by the Randlist software and every patient will be entered in the treatment or placebo groups. 2-3 Ankylosing spondylitis. Intervention 1: Control group will receive placebo for 12 months. Intervention 2: Treatment group will receive alendronate sodium 70 mg tablet (Ostomod, Modava company) with 70mg/week (one tablet at week)dose orally for 12 months. Alendronate is a bisphosphonate which binds to the hydroxyapatite in bone and act as a inhibitor of the resorption of bone. Chemically, it is described as bisphosphonic acid monosodium salt trihydrate. It should be taken alone on an empty stomach first thing in the morning with at least 240 mL of water. After administration, the patient should not have food, drink, medications, or supplements for at least one-half hour.