HPLC determination of indapamide and relative bioavailability in unfreezed human blood

Objective:To develop an HPLC-UV method for the determination of indapamide in unfreezing blood and evaluate the bioequivalence of indapamide tablets.Methods:Sample preparation based on liquid-liquid ex- traction.The compounds were separated on a Diamonsil C_(18)column(4.6 mm×200 mm,5 μm)with acetonitrile- 0.1% triethylamine(pH 4.0)(38:62,v/v)as mobile phase at a flow rate of 1.0 mL·min~(-1),and detected at 240 nm.In a randomized crossover design 18 heahhy male volunteers were given 5 mg indapamide tablets T(test drug) or tablets R(reference drug).The blood samples were obtained and determined by the newly-developed HPLC- UV method and the pharmacokinetics and bioavailability were studied.Results:The calibration curve of indapamide was linear over the range of 3.1-500 μg·L~(-1)with the limit of quantity 3.1 μg·L~(-1),the methodology recoveries were in the range of 95.6%-102.6%.Inter-day and intra-day RSDs were less than 14.2% and 9.9%,respec- tively.Pharmacokinetic parameters of indapamide after a single dose of tablets T and R were as following:C_(max)were (250.9±84.1)μg·L~(-1)and(245.4+78.8)μg·L~(-1),T_(max)were(2.4±0.5)h and(2.4±0.5)h,AUC_(0-72) were(4417.4±976.3)μg·L~(-1)and(4372.7±942.0)μg·h·L~(-1),T_(1/2)were(21.9±8.6)h and(21.4 ±5.5)h.Conclusions:The method is selective,sensitive and rapid for indapamide determination.The results of a- nalysis of variance and two one-side t-test analysis show that no significant differences between the pharmacoki- netic parameters of the two formulations and bioequivalence are observed.