PHARMACOKINETIC EVALUATION OF GENTISIC ACID IN RATS: ORAL VERSUS INTRAVENOUS ADMINISTRATION

Gentisic acid (2, 5-dihydroxybenzoic acid) is a diphenolic compound, present abundantly in natural sources. It possesses several pharmacological activities such as nephroprotective, hepatoprotective, neuroprotective, etc. However, the available literature on oral absorption of gentisic acid is scarce. Thus, the aim of the present study was to determine the pharmacokinetic parameters and bioavailability of gentisic acid. A single dose in-vivo pharmacokinetic study was conducted in rats. Gentisic acid was administered at 50 mg/kg, either orally or by intravenous route. Blood samples were withdrawn at designated time intervals (0.083, 0.25, 0.5, 1, 2, 4, 8, 12, and 24 h post-dose), and plasma was separated. A method for the evaluation of gentisic acid in the plasma was developed and validated. The plasma levels of gentisic acid were determined by HPLC using the validated method. The C_max for oral administration was 312 µg/mL, and T_max was at 0.083 h. The plasma exposure AUC_last values for oral and i.v route of administration were comparable (Oral: 765 h*µg/mL; I.V.: 770 h*µg/mL), indicating similar bioavailability. The relative bioavailability for oral dose was found to be 99.35%. The results suggest that gentisic acid is absorbed through the oral route of administration and shows bioavailability comparable to intravenous administration.