Non-linear oral bioavailability and clinical pharmacokinetics of high-dose Andrographis paniculata ethanolic extract:...

Insufficient quality control and limited dissolution of Andrographis paniculata extract capsules restricts their bioavailability and hinder the clinical use for treating mild coronavirus disease 2019 (COVID-19) patients.

This study aims to investigate pharmacokinetics and safety of high-dosage A. paniculata ethanolic extract (equivalent to 180 or 360 mg/day of andrographolide), relevant dosages used for mild COVID-19 treatment.

An open-label, single-dose, and repeated-dose conducted in healthy volunteers. Subjects received capsules containing ethanolic extract equivalent to andrographolide dosage of either 60 or 120 mg per dose, taken every eight hours daily (totaling 180 or 360 mg/day). Safety was assessed through blood chemical analysis and adverse event monitoring after 7 days of ethanolic extract administration.

Pharmacokinetics of ethanolic extract indicated low plasma levels of the major diterpenoids. The maximum plasma concentration (Cmax) of andrographolide did not exhibit a dose-proportional increase, reaching 6.44 and 11.62 µg/L for single and repeated doses of 60 mg/day, respectively. Doubling the dose (120 mg/day) only resulted in slightly higher Cmax (6.97 and 15.03 µg/L for single and repeated doses, respectively). Safety evaluation revealed mild, transient adverse events, but all parameters remained within normal ranges.

This study highlights limitations in the pharmacokinetics of the ethanolic extract of A. paniculata. It indicated non-linear proportionality in the oral bioavailability of andrographolide. These findings suggest that current extraction process of ethanolic extract may hinder its effectiveness. Further research is warranted to explore alternative extraction methods or formulation developments that can enhance the bioavailability of andrographolide and its potential therapeutic effects for COVID-19 treatment.