Songklanakarin Journal of Science and Technology (SJST) (Jun 2013)
Pharmacokinetics of alendronate in a combined Alendronate/Vitamin D3 tablet in healthy volunteers using plasma and urine data
Abstract
Alendronate is indicated for treatment of a variety of bone metabolism disorders. In spite of quite low plasma concentrationsfollowing oral administration, pharmacokinetic study of alendronate based on plasma concentrations had normally been reported for up to 8 h. Due to much longer detectable periods in urine, a number of pharmacokinetic studies have been based upon urinary excretion data. The objective of this study was to determine pharmacokinetics of alendronate following oral administration of combined Alendronate/Vitamin D3 tablet. Blood and urine samples were collected for 10 h after oral administration of a combined Alendronate/Vitamin D3 tablet to healthy volunteers. Alendronate levels in plasma and urine samples were determined by high-performance liquid chromatography (HPLC) with fluorescence detection. The analytical method involved co-precipitation of alendronate in plasma or urine samples with calcium and followed by solid-phase extraction (SPE) process. Pharmacokinetic parameters were analyzed by the non-compartmental method using WinNonlin. Pharmacokinetics parameters, i.e. Cmax, Tmax, AUC0-10, T1/2, were 56.6±11.8 ng/mL, 1.29±0.39 h, 132.4±46.9 ng·h/mL, and 3.43±2.24 h,respectively. Amount excreted in 10 h urine and maximum excretion rate (Rmax) were 578.59±308.9 μg and 143.3±72.8 μg/h, respectively. Although these parameters were different from previously reported values, Rmax obtained at 1.29±0.76 h agreed well with Tmax observed from plasma data. Based upon urinary excretion data, enhanced absorption of alendronate after administration of a combined Alendronate/Vitamin D3 tablet is suggested.
