Pharmacokinetics of piperine after oral administration of Sahastara remedy capsules in healthy volunteers

Background and purpose: To investigate the pharmacokinetics of piperine after single oral doses of capsules containing Sahastara (SHT) remedy dried ethanolic extracts in healthy Thai volunteers. Experimental approach: Twenty-four healthy volunteers were divided into two dosage groups. They received a single oral dose of SHT remedy extract capsules of 100 or 200 mg. Blood was collected at time intervals of 0, 0.5, 1, 2, 4, 6, 8, 12, 24, and 48 h. Acute clinical safety was monitored by complete physical examination and laboratory tests during the study period. Piperine concentration in blood and urine was determined by liquid chromatography tandem-mass spectrometry. Findings/Results: No serious adverse events were detected, only one volunteer had abdominal pain that was self-limiting. The pharmacokinetics of piperine following SHT remedy extract capsule administration demonstrated a mean peak concentration (Cmax) of piperine of 3.77 µg/mL and 6.59 µg/mL after dosing with 100 and 200 mg, respectively. Interestingly, a secondary maximum concentration of piperine was observed in this study, which might be related to enterohepatic recirculation. Negligible amounts of unchanged piperine were detected in urine. Conclusion and implication: The systemic exposure of piperine after SHT remedy ethanolic extract demonstrated dose proportionality after single oral dosing of 100-200 mg. Piperine was detectable in plasma for at least 48 h with evidence of enterohepatic recirculation. Metabolism and excretion profiles of piperine after administration of SHT remedy extract capsule need to be further explored for phytopharmaceutical product development.