EVALUATION OF THE EFFICACY AND SAFETY OF ORAL TILUDRONATE IN PAGETS-DISEASE OF BONE - A DOUBLE-BLIND, MULTIPLE-DOSAGE, PLACEBO-CONTROLLED STUDY

Objective. To assess the optimal dosage of oral tiludronate in Paget's disease of bone. Methods. We studied 149 patients with Paget's disease, in a double-blind, randomized, placebo-controlled trial. Patients were randomly assigned to 1 of 5 therapeutic groups: a daily dose of 100 mg, 200 mg, 400 mg, or 800 mg of oral tiludronate, or a placebo. Treatment was for 3 months, followed by 3 months of placebo-controlled followup. Serum alkaline phosphatase activity (SAP) and fasting urinary excretion of hydroxyproline/creatinine (OH/Cr) were measured monthly, as were biochemical parameters reflecting renal, hepatic, and hematologic functions. Analgesic efficacy was self-evaluated from a visual analog scale and a global pain index. Results. Statistical analysis revealed that beginning at a dosage of 200 mg/day, there was a direct dose-dependent effect on the reduction of SAP and OH/Cr levels. Reduction of SAP levels was clinically significant at a dosage of 400 mg (44.9 +/- 4.2 % reduction at 90 days and 49.2 +/- 4.5 % at 180 days, mean +/- SEM) and at 800 mg (53.4 +/- 5 % at 90 days and 59.3 +/- 4.6 % at 180 days). There was a significant reduction in pain in all groups, including the group taking placebo. In only those taking 800 mg/day of tiludronate was there a significant frequency of complete resolution of pain (versus placebo). Aside from mild gastrointestinal disturbances, as experienced with other oral bisphosphonates, clinical tolerance of all 5 regimens was good. Exhaustive biochemical investigations failed to reveal significant toxicity of tiludronate up to the 800-mg daily dose investigated. Conclusion. Because of its significantly better antiresorptive effects and greater analgesic properties (compared with lower dosages), combined with the excellent clinical and biochemical tolerance, the 800-mg daily dose of tiludronate appears to be optimal for the treatment of Paget's disease of bone.