Pharmacokinetic Interactions Between Bazedoxifene and Cholecalciferol: An Open-Label, Randomized, Crossover Study in Healthy Male Volunteers

Abstract

Purpose: The combined administration of bazedoxifene, a tissue-selective estrogen receptor modulator, and cholecalciferol can be a promising therapeutic option for postmenopausal osteoporosis patients. This study aimed to examine the pharmacokinetic interactions between these two drugs and the tolerability of their combined administration in healthy male subjects.

Patients and methods: Thirty male volunteers were randomly assigned to one of the six sequences comprised of three treatments: bazedoxifene 20 mg monotherapy, cholecalciferol 1600 IU monotherapy, and combined bazedoxifene and cholecalciferol therapy. For each treatment, a single dose of the investigational drug(s) was administered orally, and serial blood samples were collected to measure the plasma concentrations of bazedoxifene and cholecalciferol. Pharmacokinetic parameters were calculated using the non-compartmental method. The point estimate and 90% confidence interval (CI) of the geometric mean ratio (GMR) were obtained to compare the exposures of combined therapy and monotherapy. The pharmacokinetic parameters compared were the maximum plasma concentration (C_max) and the area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUC_last). The safety and tolerability of the combined therapy were assessed in terms of the frequency and severity of adverse events (AEs).

Results: For bazedoxifene, the GMR (90% CI) of the combined therapy to monotherapy was 1.044 (0.9263-1.1765) for C_max and 1.1329 (1.0232-1.2544) for AUC_last. For baseline-adjusted cholecalciferol, the GMR (90% CI) of the combined therapy to monotherapy was 0.8543 (0.8005-0.9117) for C_max and 0.8056 (0.7445-0.8717) for AUC_last. The frequency of AEs observed was not significantly different between the combined therapy and monotherapy, and their severity was mild in all cases.

Conclusion: A mild degree of pharmacokinetic interaction was observed when bazedoxifene and cholecalciferol were administered concomitantly to healthy male volunteers. This combined therapy was well tolerated at the dose levels used in the present study.

Keywords: bazedoxifene; cholecalciferol; drug-drug interaction; pharmacokinetics; tolerability.