Exploratory pharmacokinetic-pharmacodynamic characterization and safety of standardized Andrographis paniculata aqueous extract capsules in patients with mild COVID-19

Introduction Andrographis paniculata has been used in the management of COVID-19-related conditions during the SARS-CoV-2 pandemic. However, human pharmacokinetic-pharmacodynamic (PK/PD) evidence to support a rationale for safe and evidence-based dosing of standardized extracts in clinical use remains limited. This exploratory study aimed to investigate the pharmacokinetics, preliminary PK/PD relationship, and short-term safety profile of standardized A. paniculata aqueous extract capsules in patients with mild COVID-19. Methods A single-center PK/PD clinical trial with two sequential phases (single-dose followed by multiple-dose) was conducted. Patients with mild COVID-19 received standardized A. paniculata aqueous extract capsules equivalent to 30 mg of andrographolide every 8 h (90 mg/day) for 5 consecutive days, alongside standard symptomatic treatment. Results Rapid absorption and elimination with limited systemic exposure supported repeated dosing to maintain exposure over the 5-day period. PK/PD analysis demonstrated a sigmoidal, saturable exposure-response relationship. The mean area under the concentration–time curve (AUC 0-4 h ) on day 5 approached the estimated EAUC 50 (half-maximal effective exposure) derived from the Emax model. A −2.96 log 10 reduction in viral load was observed; however, without a placebo control group, it is not possible to conclusively attribute this reduction to the investigational A. paniculata aqueous extract capsules. Adverse events were mild, with no hepatotoxicity or renal toxicity observed. Conclusion These findings provide preliminary evidence regarding the pharmacokinetics, dose-exposure characteristics, and short-term tolerability of standardized A. paniculata aqueous extract capsules, supporting further investigation in patients with mild COVID-19. Larger, placebo-controlled trials are warranted to establish causality and to evaluate clinical benefits.