title: Evaluation of statistical power function for various diclofenac bioequivalence trials with different subject numbers.
abstract: This study presents application of statistical power function for the t-test and ANOVA F-test on the evaluation of diclofenac bioequivalence in trials with the wide variations in sample sizes (N = 12, 18 and 24). The power function, together with appropriate equations tables and figures, is used to calculate the power of the ANOVA for crossover design, the number of subjects for a given value of power and the minimum detectable difference in treatment means for different pharmacokinetic parameters of the formulations. The power of the trial with a small, sample size (N = 12) to detect 20% differences between diclofenac formulations is shown to be more than 0.9 and almost the same as the power of the trial with a large sample size (N = 24). In all trials for all pharmacokinetic parameters the power to detect 20% difference is shown to be more than 0.8. For the power of 0.8, the needed subject number to detect 20% difference in treatment means is the same or smaller than used and the minimum detectable difference is smaller than 20% in all our trials. This investigation shows that bioequivalence studies with small number of subjects (N = 12) may be quite adequate for valid conclusions.
authors: Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, Novi Sad, Republic of Serbia. jovapop@neobee.net
authors: Jovan
authors: J
authors: Popović
authors: Momir
authors: M
authors: Mikov
authors: Ana
authors: A
authors: Sabo
authors: Vida
authors: V
authors: Jakovljević
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001682:Biological Availability; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D003692:Delayed-Action Preparations; D004008:Diclofenac / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D018401:Sample Size; D013810:Therapeutic Equivalency
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D003692:Delayed-Action Preparations; D004008:Diclofenac