Pharmacokinetic Drug Interaction Between Raloxifene and Cholecalciferol in Healthy Volunteers

Comparative Pharmacokinetic Profiles of a Novel Low-Dose Micronized Formulation of Raloxifene 45 mg (AD-101) and the Conventional Raloxifene 60 mg in Healthy Subjects

Raloxifene hydrochloride shows poor bioavailability (only 2%) when orally administered because of its poor aqueous solubility and its extensive first-pass metabolism. A new micronized formulation of raloxifene was developed to improve bioavailability via enhanced gastrointestinal absorption. The primary objective of this study was to evaluate the pharmacokinetic characteristics of a new micronized raloxifene formulation (AD-101) in comparison with the conventional raloxifene formulation. This study was designed as an open-label, randomized, 2-treatment-period, crossover study with a 2-week washout period. Two treatments consisted of micronized raloxifene 45 mg daily; and conventional raloxifene 60 mg daily administered in fasting conditions. Plasma raloxifene concentrations were determined by a validated method using ultra-fast liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were calculated using a noncompartmental model. In total, 49 subjects completed the study. The geometric mean ratio (micronized/conventional) of the maximum concentration and the area under the plasma concentration-time curve from time zero to the last concentration values were 1.08 (90% CI, 0.95-1.24) and 0.97 (90% CI, 0.89-1.05), respectively. The adverse event profile did not differ between the 2 formulations. The results demonstrate that micronized formulation of raloxifene 45 mg is equivalent to conventional formulation of raloxifene 60 mg when administered at the single dose in the fasted state. After single oral dosing of AD-101, there were no serious or unexpected adverse events.

Raloxifene/Vitamin D Combination Therapy vs. Raloxifene Monotherapy on Serum 25-Hydroxy-Vitamin D Level among Postmenopausal Women with Osteoporosis or Osteopenia: A Randomized Controlled Trial

Background

We compared the efficacy of a fixed dose combination of raloxifene 60 mg/vitamin D 800 IU to raloxifene 60 mg alone on vitamin D status, as indicated by change in serum 25-hydroxy-vitamin D (25[OH]D) levels.

Methods

In this 16-week, open-label, randomized, active controlled, multicenter clinical trial conducted in 4 university-affiliated hospitals in Korea, postmenopausal women aged 55 to 70 years with osteoporosis or osteopenia were randomly assigned in a 1:1 ratio to receive raloxifene 60 mg/cholecalciferol 800 IU combination therapy or raloxifene 60 mg monotherapy. Primary endpoint was change in serum 25(OH)D level from baseline to 16 weeks after the intervention.

Results

A total of 96 participants were randomly assigned to raloxifene/vitamin D combination therapy (N=49) and raloxifene monotherapy (N=47) groups. At week 16, serum 25(OH)D level increased from baseline, only in the raloxifene/vitamin D combination therapy group. Change in serum 25(OH)D level from baseline to week 16 was higher in the raloxifene/vitamin D combination therapy group (2.7±6.5 ng/mL) than in the raloxifene monotherapy (−1.7±6.2 ng/mL; P=0.0034) group. Proportions and number of adverse events (AEs) categorized by the System-Organ Class were not different between the groups. There was only one severe AE case (spondylolisthesis; raloxifene/vitamin D group), unlikely to be related to trial intervention.

Conclusions

Among postmenopausal women with osteoporosis or osteopenia, a fixed dose combination of raloxifene 60 mg/vitamin D 800 IU showed superior efficacy in elevating serum 25(OH)D levels compared with raloxifene 60 mg alone during 16 weeks of follow-up. The safety of raloxifene/vitamin D combination was comparable to raloxifene alone.

A randomized, open-label, single-dose, two-way crossover study to assess the pharmacokinetics between two tablets of fixed-dose combination formulation with raloxifene and cholecalciferol and concomitant administration of each agents in healthy male volunteers

A new fixed-dose combination (FDC) formulation of raloxifene 60 mg and cholecalciferol 800 IU was developed to improve the medication compliance and overall efficacy of raloxifene treatment in postmenopausal osteoporosis patients. The aim of this study was to compare the pharmacokinetics between two tablets of FDC formulation of raloxifene/cholecalciferol and the two products administered concomitantly at respective doses. This randomized, open-label, single-dose, two-treatment, two-way crossover study included 46 volunteers. During each treatment period, subjects received the test formulation (FDC formulation containing raloxifene and cholecalciferol) or the reference formulation (co-administration of raloxifene and cholecalciferol), with a 14-d washout period. Serial blood samples were collected periodically over 96 hours after drug intake. In total, 46 subjects completed the study. The geometric mean ratios and its 90% confidence intervals of the FDC to the single agents for the area under the concentration-time curve from zero to the last quantifiable time point and the maximum plasma concentration met the regulatory criteria for bioequivalence: 1.1364 (1.0584–1.2201) and 1.1010 (0.9945–1.2188) for raloxifene and 1.0266 (0.9591–1.0989) and 1.0354 (0.9816–1.0921) for baseline-corrected cholecalciferol, respectively. Both formulations were well tolerated. No significant differences was observed in the incidence of adverse events between the two treatments. It was concluded that two tablets of the newly developed FDC formulation of raloxifene and cholecalciferol and the corresponding two agents administered concomitantly at respective doses were bioequivalent.