Bioavailability, tissue distribution and excretion studies of a potential anti-osteoporotic agent, medicarpin, in female rats using validated LC–MS/MS method.

• Medicarpin is the active anti-osteoporotic constituent of Butea monosperma. • A sensitive LC-ESI-MS/MS method was validated for quantifying of medicarpin in rat plasma, feces, urine, and tissues. • Excretion and distribution studies were carried out in rats. • These studies are useful to understand tissue accumulation and toxicological implications. Medicarpin, one of the active constituents isolated from the extract of Butea monosperma , has been shown to have various pharmacological activities including potent anti-osteoporotic properties. The aim of this study was to investigate the oral pharmacokinetics, tissue distribution and excretion of medicarpin following single oral dose administration in female rats. Oral pharmacokinetics was explored at 5 and 20 mg/kg while tissue distribution, urinary and fecal excretion were studied following 20 mg/kg oral dose. Medicarpin was quantified in rat plasma, urine, feces and tissue samples using a validated LC–MS/MS method following reverse-phase HPLC separation on RP18 column (4.6 mm × 50 mm, 5.0 μm) using methanol and 10 mM ammonium acetate (pH 4.0) as mobile phase in the ratio of 80:20 (v/v) at a flow rate of 0.8 mL/min. The oral bioavailability of medicarpin was found to be low with low systemic levels. The concentration in tissues was significantly higher than plasma. Highest tissue concentrations were found in the liver followed by bone marrow. Urinary and fecal excretion of medicarpin was < 1 %. In conclusion, medicarpin was found to be highly distributed in body tissues and minimally excreted via urine or feces. [ABSTRACT FROM AUTHOR]