Enantioselective UFLC Determination of Hydroxyzine Enantiomers and Application to a Pharmacokinetic Study in Rabbits.

Hydroxyzine is the first generation H1 receptor antagonist drug that is now marketed as a racemic mixture. The paper describes a validated enantioselective liquid chromatography method for the resolution of hydroxyzine enantiomers and cyclizine (internal standard) from 200 µL of rabbit plasma by liquid-liquid extraction technique using n-hexane and isopropanol. Hydroxyzine enantiomers were resolved at 10.2 and 11.1 min with good baseline resolution (Rs = 1.9) on a Lux amylose-2 chiral column (250 mm × 4.0 mm, 5 microns) at ambient room temperature. The mobile phase consisted of n-hexane-ethanol-diethylamine (90:10:0.1 v/v/v) pumped at 0.9 mL/min. The eluted enantiomers were detected at 254 nm. The linear calibration curve was constructed in the range 20-1000 ng/mL for both the (S)- and (R)-enantiomers. The intra- and inter-day precision were 0.16-2.6% and 0.2-1.92% for (S)-hydroxyzine and (R)-hydroxyzine, respectively. The method was successfully applied to determine the kinetic parameters of (S)- and (R)-hydroxyzine enantiomers in rabbits. The results illustrate that the disposition of hydroxyzine enantiomers is not stereoselective in rabbits.

Optimized and Validated RP-UPLC Method for the Determination of Losartan Potassium and Chlorthalidone in Pharmaceutical Formulations.

PURPOSE: A validated ultra performance liquid chromatography (UPLC) method has been developed and validated for the simultaneous determination of losartan potassium and chlorthalidone in pharmaceutical preparations. METHODS: Waters-Acquity UPLC system equipped with Auto Sampler, PDA detector and operated with Empower-2 software was used for the present study. Detection was done at wavelength of 230 nm, HSS C18, 100 mm x 2.1x 1.8 µm column with a reverse phase elution and mobile phase composed of A and B mixed in the ratio 56:44 v/v (Where mobile phase A consists of potassium dihydrogen phosphate buffer of pH 3.0 and Mobile phase B consists of acetonitrile and methanol mixed in the ratio of 90:10 v/v) used at a flow rate of 0.4ml per minute. RESULTS: The retention times for losartan potassium and chlorthalidone were observed at 0.72 and 1.89 minutes. The developed method was validated as per ICH guidelines. Linearity ranges were found to be 12.5-125 µg/ml and 3.125-31.25 µg/ml for losartan potassium and chlorthalidone, respectively. CONCLUSION: This method is fast, accurate, precise and sensitive hence it can be employed for routine quality control of tablets containing both drugs in industries.