To describe the properties of the similarity factor (f2) as a measure for assessing the similarity of two dissolution profiles. Discuss the statistical properties of the estimate based on sample means.
The f2 metrics and the decision rule is evaluated using examples of dissolution profiles. The confidence interval is calculated using bootstrapping method. The bias of the estimate using sample mean dissolution is evaluated.
1. f2 values were found to be sensitive to number of sample points, after the dissolution plateau has been reached. 2. The statistical evaluation of f2 could be made using 90% confidence interval approach. 3. The statistical distribution of f2 metrics could be simulated using 'Bootstrap' method. A relatively robust distribution could be obtained after more than 500 'Bootstraps'. 4. A statistical 'bias correction' was found to reduce the bias.
The similarity factor f2 is a simple measure for the comparison of two dissolution profiles. But the commonly used similarity factor estimate f2 is a biased and conservative estimate of f2. The bootstrap approach is a useful tool to simulate the confidence interval.
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"Another study of Maggi et al. (Maggi et al., 2000), indicated that DTZ in a matrix tablet containing PEO was stable after one year storage at room temperature. Figure 3 depicted that all tablets were found to be stable after five-year storage as indicated by the value of (ƒ 2 ) (≥ 50) (FDA, 1997; Shah et al., 1998). Meanwhile, the similarity factor (ƒ 2 ) values between the fresh and the stored tablets were decreased as PEO M W increased (ƒ 2 = 96, 70 and 56 for F1, F2 and F3, respectively, Figure 3), indicating a sign for the decrease in system stability as PEO M W increased. "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to investigative the stability of poly(ethylene oxide) (PEO) matrix tablets containing diltiazem hydrochloride (DTZ) after five-year storage at room temperature. DTZ matrix tablets containing different molecular weights (MW) of PEO and electrolytes (sodium carbonate anhydrous Na2CO3, potassium chloride KCl and pentasodium tripolyphosphate anhydrous PSTPP) were prepared. The fresh and stored tablets were evaluated by DTZ content, in vitro drug release rates and kinetics as well as DSC. All the PEO's matrix tablets showed no significant changes in release rate, kinetics and drug content. The release rates of DTZ following five-year storage were slightly increased as the MW of PEO increased from 900,000 to 8,000,000. Also, it was clear that the addition of electrolyte drastically slowed the release rates of DTZ from fresh and stored tablets. DSC thermograms and similarity factor (ƒ2) depicted good system stability for all stored tablets. This is the first five-year long-term stability study reported concerning DTZ/PEO matrix tablets with different MW, which proved its stability for several years. This study might throw light on the dramatic difference observed between this study and the reported data of accelerated stability testing under stress conditions found in the literature.
"similarity factor, f 2 , aligns with the model results indicating similar in vivo release of the two products. In addition to quantitatively describing the similarity of the two dissolution curves, the f 2 is sensitive to large differences in any particular time point . The results of this analysis support findings from clinical trials in China  as well as more recent study results indicating that Sino-implant (II) performs as well as Jadelle in the first year of use. "
"Structure of PEA III Ac Bz. analyzed with SEM during the first two weeks. Sterilized and nonsterilized DX-loaded microspheres' release profiles were compared with the evaluation of the similarity factor f 2  "