Safety, tolerability and pharmacokinetics of forsythin in healthy subjects: a double-blinded, placebo-controlled single-dose and multiple-dose escalation and food effect study

Background Forsythin, an active compound from Forsythiae Fructus, has the potential to treat the common cold and influenza through its antipyretic-analgesic, anti-inflammatory and antiviral effects. The safety, tolerability and pharmacokinetic (PK) profile of forsythin were evaluated in healthy Chinese subjects.Methods This phase 1a study included three parts: double-blind, randomized, placebo-controlled single-ascending-dose (SAD) (50, 100, 200, 400, 600 or 800 mg), food effect investigation (100 mg) and multiple-ascending-dose (MAD) (50, 100 or 200 mg TID for 5 days).Results Forsythin is safe and tolerable in healthy Chinese subjects. The rates of adverse events (AEs) in the forsythin cohort were similar to those in the placebo cohort. Forsythin is well-absorbed after single or multiple doses and is extensively metabolized. The primary metabolites were aglycone M1, M1 sulphate (M2) and M1 glucuronide (M7). Exposure to forsythin (100 mg) was higher after food intake by approximately 1.4-fold, whereas M2 and M7 did not change. The steady state was reached around three days in the MAD study. Forsythin, M2 and M7 accumulation on day 5 was 1, 3 and 2, respectively.Conclusions The safety and PK profiles of forsythin support further evaluation of its efficacy in individuals with the common cold or influenza.