Preclinical pharmacokinetic and pharmacodynamic evaluation of thiazolidinone PG15: an anti‐inflammatory candidate

Objectives Novel 5‐benzilidene thiazolidinones have been synthesized and exhibited anti‐inflammatory activity. In this work one of the compounds of the thiazolidinone chemical series, (5Z,E)‐3‐2‐(4‐chlorophenyl)‐2‐oxoethyl]‐5‐(1H‐indol‐3‐ ylmethylene)‐thiazolidine‐2,4‐dione (PG15) was investigated aiming to determine the drug's anti‐inflammatory potential in pre‐clinical studies. Methods Methods used included the in‐vitro inhibition of cyclooxygenase‐1 and ‐2, in‐vivo evaluation of anti‐inflammatory activity by air pouch and peritonitis models and the pharmacokinetic profile after intravenous (3 mg/kg) and oral (3 and 6 mg/kg) dosing to rats. Key findings A two‐compartment model with a fast distribution and an elimination half‐life of 5.9 ± 3.8 h described the PG15 plasma profile after intravenous dosing. PG15 showed an erratic and rapid absorption following oral administration with peak concentrations between 0.5 and 1 h. PG15 0.1 μM inhibited more than 30% and 13% of purified cyclooxygenase‐1 and ‐2 activity in vitro, respectively. A lack of dose dependency was observed for the anti‐inflammatory effect in the dose range investigated (0.8–50 mg/kg), with a maximum of 67.2 ± 4.6% inhibition of leucocyte migration in the carrageenan‐induced air pouch model obtained with the 3 mg/kg dose, similar to that observed for indometacin 10 mg/kg. Conclusions The erratic absorption of PG15 observed after oral dosing could explain the lack of anti‐inflammatory dose dependency.