Application of bootstrap f2 to dissolution data from biorelevant media and evidence of the conservative nature of bootstrap f2

f2 with or without bootstrapping is the most common method to compare in vitro dissolution profiles, but methods to compare dissolution profiles have become less harmonized. The objective was to compare outcomes from bootstrap f2 and f2 (i.e. not-bootstrapped f2) using a large set of in vitro dissolution data. Non-parametric bootstrapping was performed on the 104 profile comparisons that did not meet the percent coefficient of variation (CV%) criteria to use average dissolution data. Bootstrap f2 was taken as the lower 90 % confidence interval of bootstrapped samples. There was concordance between bootstrap f2 and f2 in 92 of the 104 comparisons (88 %). There were no false positives. However, 12 % were false negative. Inspection of these discordance pairs suggests that bootstrap f2 serves as a conservative approach to assess profile similarity, particularly when a value of 50 is being used as decision criteria.

Comparison of free software platforms for the calculation of the 90% confidence interval of f2 similarity factor by bootstrap analysis

INTRODUCTION

The calculation of the 90% confidence interval of f₂ based on the bootstrap methodology has been proposed and accepted by the main regulatory authorities when the dissolution data shows excessive variability. Different free software platforms allow the calculation of the 90% CI of f₂ by means of bootstrapping. Their use in regulatory submissions is growing, but divergent results have been observed between the available software platforms. Therefore, the objective of this work is to analyze the characteristics of these software platforms and evaluate their results.

METHODS AND MATERIALS

Highly variable in vitro dissolution data from two products were selected. Three different similarity factors, f₂, E(f₂) and bc-f₂, and their corresponding 90% confidence intervals were calculated with three free software platforms, Pheq_bootstrap, Bootf2bca and DDSolver, and computed by four different approaches, normal approximation, bootstrap-t-CI, percentile CI, and bias corrected and accelerated CI.

RESULTS

All three platforms report the same f₂ value, 49.66 upon comparison of products 1 and 3 and 54.87 for products 2 and 3 (no truncation rule). Bootf2bca and Pheq_bootstrap provided the same f₂ and E(f₂) also under other truncation rules (EMA or FDA), which are not implemented in DDSolver. Pheq_bootstrap allowed the calculation of bc-f₂. The conclusion of similarity is based on a bootstrap percentile CI of E(f₂) and f₂ in Pheq_bootstrap and DDSolver, respectively. Bootf2bca provides all four 90% CI.

DISCUSSION

Bootf2bca or Pheq_bootstrap should be considered for the estimation of the 90% CI of the f₂ similarity factor when dissolution profiles show high variability.