Enhanced bioavailability and pharmacokinetics of a novel hybrid-hydrogel formulation of fisetin orally administered in healthy individuals: a randomised double-blinded comparative crossover study

Krishnakumar and colleagues at Akay Natural Ingredients (Cochin, India), in collaboration with Life Extension (Fort Lauderdale, USA), conducted the first published human pharmacokinetic study of oral fisetin. Fifteen healthy adults each received two single doses in a randomised double-blind crossover: 1000 mg of unformulated fisetin (98.2% purity, delivering 982 mg of the compound) on one day, and 1000 mg of a hydrogel-encapsulated formulation called Hybrid-FENUMAT™ (labelled FF-20, containing only 19.2% fisetin, delivering 192 mg of the compound) on another. A 10-day washout separated the two doses. Plasma was sampled over 12 hours after each and analysed by UPLC-MS/MS for fisetin and its methoxylated metabolite geraldol.

The paper reports pharmacokinetic values adjusted to account for the different fisetin content of the two 1000 mg products: FF-20 delivered 192 mg fisetin and UF approximately 982 mg. After adjustment, reported peak parent-fisetin concentrations were 238.2 ng/mL for FF-20 and 9.97 ng/mL for UF (23.9-fold difference); reported 12-hour AUC was 341.4 versus 12.67 ng·h/mL (26.9-fold difference). The 9.97 ng/mL figure should NOT be presented as an unadjusted, directly observed peak after the 982 mg UF dose. Fisetin remained quantifiable longer with FF-20 under the study conditions. No significant adverse events were reported in this 15-person single-dose trial.

This manufacturer-funded study demonstrates a larger dose-adjusted exposure with the specific hybrid-hydrogel formulation. It did not compare food conditions, test senolytic activity or establish the human plasma or tissue concentration required for clinical efficacy. Numerical comparisons with cell-culture concentrations are not validated treatment thresholds; protein binding, exposure duration, metabolism and tissue distribution differ.

The critical caveat is the funding structure. Akay Natural Ingredients, which financially supported the study, holds the patents on both FENUMAT™ and Hybrid-FENUMAT™. Four of the six authors are Akay employees. The remaining two are employees of Life Extension, which sells the FF-20 formulation commercially as Bio-Fisetin. This does not invalidate the peer-reviewed PK measurements — the UPLC-MS/MS methodology is standard and the crossover design is appropriate — but it does mean the paper is a manufacturer-sponsored pharmacokinetic comparison of the manufacturer's own product against a generic comparator, without independent replication. Readers should weight the numbers accordingly.