PHARMACOKINETIC STUDY OF ATORVASTATIN AFTER SINGLE DOSE ADMINISTRATION AMONG PAKISTANI POPULATION

Pharmacokinetic Study of Atorvastatin

Abstract

Objective: To obtain pharmacokinetic data of Orvastin, a newly launched formulation of atorvastatin, in healthy males of Pakistan.
Study Design: It was quasi-experimental design.
Place and Duration of Study: Study was conducted at Centre for Research in Experimental and Applied Medicine (CREAM) Army Medical College, Rawalpindi and duration of study was about ten months.
Material and Methods: Twenty-four healthy male subjects were taken conveniently from Pakistani population. Two tablets of Orvastin, each containing atorvastatin 40mg, were administered orally as a single dose. Multiple blood samples were taken with small gaps in between up to the period of 48hrs. High Performance Liquid Chromatography (HPLC) with UV-detector was used for quantification of atorvastatin in plasma; wavelength of UV-detector was adjusted at 247nm. Mobile phase was made up of 60 percent acetonitrile and 40 percent  0.05M sodium phosphate buffer. Flow rate of mobile phase was maintained at 1.5ml/min with 5.5 pH. Progesterone was used as an internal standard. Stock solutions of atorvastatin were made by dissolving it into methanol and acetonitrile was used for making stock solution of progesterone. Calibration curves were made for atorvastatin and internal standard from  concentration time data, values for time to achieve maximum plasma concentration.
(Tmax) and maximum plasma concentration (Cmax) were directly calculated. Computer  program (APO, MW PHARM, and Ver. 3.60) was used for calculation of pharmacokinetic profile of atorvastatin.
Results: Atorvastatin was detected in plasma samples of all volunteers. The absorption rate constant (Ka) was 0.41 l/hr. Cmax was 26.69 ± 6.67 μg/l and Tmax was 3.33 ± 0.41 hrs. Apparent volume of distribution (Vd), of atorvastatin, was 3244.84 ± 1237.36 liters. The elimination rate constant was 0.15 l/hr. Elimination half-life of atorvastatin was 6.14 hours. Trapezoidal rule was used for calculation of AUC0–48 and AUC0–∞ and it was found to be 208.77 h/μg/l and 208.74 h/μg/l respectively. Clearance of atorvastatin was 420.87 ± 170.64 liters/hour and Mean Residence Time (MRT) was 8.86 ± 5.01 hours.
Conclusion: Pharmacokinetic data of new formulation of atorvastatin is in comparable range with other brands of atorvastatin used in different ethnic groups.
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