Pharmacokinetic and tolerability of i.m. disodium clodronate 200 mg/lidocaine 1%, given twice monthly, in comparison with i.m. disodium clodronate 100 mg/lidocaine 1%, given weekly, in healthy postmenopausal female patients.

ABSTRACT

BACKGROUND: Clodronate is a bisphosphonate effective in the prevention and treatment of osteoporosis in postmenopausal women. Non-adherence to bisphosphonates, however, is a major issue in clinical practice. Simplifying dose regimens may increase compliance. OBJECTIVES: To assess bioequivalence between an intramuscular (i.m.) clodronate 200 mg/lidocaine 1% twice-a-month formulation and a clodronate 100 mg/lidocaine 1% weekly formulation in 32 postmenopausal women. METHODS: In this double-blind, randomized, two-way crossover study, test and reference formulations were administered in single dose, with a 2-week wash-out between administrations. The primary endpoint was clodronic acid cumulative excretion in the first 24 hours after injection (Xu0-24h). Cumulative excretion in the 72 hours post-dose (Xu0-72h) and maximum excretion rate (Ratemax) were also evaluated. Bioequivalence was assumed if the 90% confidence intervals (CIs) of the geometric means ratios of the dose-normalized parameters were within the 80.00 - 125.00% range. Local tolerability was evaluated. RESULTS: Mean Xu0-24h values were 114.03 ±23.13 mg and 55.22 ±9.73 mg for clodronate 200 mg and 100 mg. The 90% CIs for dose-normalized Xu0-24h, Xu0-72h and Ratemax ere 95 -110%, 94 -107% and 95 - 113%. Local tolerability of both treatments was good. The differences in pain intensity between formulations were not sigificantly different at most assessment times. Headache was the only treatment-related adverse event. CONCLUSIONS: Bioequivalence of the two formulations was confirmed in terms of dose-normalized rate and amount of clodronic acid excretion. This result, together with the favorable tolerability of the novel 200 mg formulation, suggests the possibility of reducing the number of i.m. administrations from once-a-week to twice-a-month.