Alternative Methods for Dissolution Profile Comparison in the Dissolution Test

Introduction. The article discusses the problem of assessing the similarity of the dissolution profiles of two batches of the nebivolol. The use of a generally accepted similarity factor for assessing equivalence is unacceptable in some cases, for example, for drugs with a high variability in the values of the release of the active substance from the formulation. At the same time, at present, there are no generally accepted approaches to comparing the profiles of the dissolution kinetics of drugs, with the exception of the method for assessing the comparability of profiles based on the mathematical calculation of the similarity factor f2, which has certain criteria that limit its application.Aim. To demonstrate alternative methods for assessing the similarity between the dissolution profiles of two drugs using a practical example.Materials and methods. The results of the comparative dissolution test of two series of nebivolol at a dosage of 5 mg. Five model-independent methods for assessing the equivalence of drug dissolution were used. Statistical data processing was performed using Microsoft Excel software.Results and discussion. The paper presents a practical example of using five alternative model-independent methods for assessing the equivalence of the dissolution profile. An example is used to illustrate the proposed equivalence limits and statistical methodology. Also, various approaches to determining the boundaries of equivalence have been proposed to assess the similarity of the dissolution profiles of an active substance.Conclusion. According to the results of the comparative dissolution test of two batches of nebivolol, it was shown that the use of the similarity factor as a criterion for assessing dissolution profiles led to a false positive result. In such cases, the possibility of using alternative methods for assessing the equivalence of dissolution profiles described in the article, or other methods presented in the scientific literature, should be considered, with a justification of their acceptability in each specific case.

COMPARATIVE DISSOLUTION STUDIES OF WARFARIN SODIUM TABLETS: INFLUENCE OF AGITATION RATE, DISSOLUTION MEDIUM, AND USP APPARATUS

Objective: The aim of this study was to carry out comparative dissolution studies with warfarin sodium reference tablets under the hydrodynamic environments generated by the USP basket and paddle apparatus and flow-through cell using different agitation rates and dissolution media. Methods: Dissolution profiles were obtained with the USP basket and paddle apparatus at 50, 75, and 100 rpm and 900 ml of water as dissolution medium. After this, dissolution profiles of warfarin sodium were obtained with the USP paddle apparatus and flow-through cell method using 0.1 N hydrochloric acid, acetate buffer pH 4.5, phosphate buffer pH 6.8, and water. Spectrophotometric determination at 308 nm was carried out during 30 min. Dissolution profiles were compared with model-independent and model-dependent approaches. Results: Significant differences were found with mean dissolution time and dissolution efficiency at 50 and 75 rpm (*P<0.05). Makoid-Banakar was the best-fit model used to describe the in vitro release performance of warfarin sodium with 50-100 rpm and the USP basket and paddle apparatuses. Significant differences in all calculated parameters were found (*P<0.05) excepting percent dissolved at 30 min with 0.1 N hydrochloric acid and phosphate buffer pH 6.8. Conclusion: More research is necessary to identify the in vitro release performance of poorly soluble drugs under available USP apparatuses considering factors as agitation rate and kind of dissolution media. The knowledge of the in vitro release performance of reference drug products is important for the design of better generic formulations

Assessment of in Vitro Comparative Dissolution Kinetics of Moxonidine Products as a Factor Potentially Determining Effectiveness of Antihypertensive Treatment

Aim. Investigation of comparative dissolution kinetics of generic medicinal products containing moxonidine versus reference drug. Material and methods. Objects of the research were film-coated tablets containing moxonidine (INN) in a dose 0.4 mg: a reference drug Physiotens® and 4 generic drugs. In vitro dissolution test of moxonidine from the study drugs was performed using comparative dissolution kinetics test (CDKT). The CDKT was performed in the media with the following pH: 1.2 (1:9 mixture of 0.1 M hydrochloric acid and water), 4.5 (acetate buffer solution, prepared as per State Pharmacopoeia, XIII), and 6.8 (phosphate buffer solution, prepared as per State Pharmacopoeia, XIII). The sampling for dissolved moxonidine was performed 5, 10, 15, 20, and 30 min after the test was started. An high performance liquid chromatography method with ultraviolet detection at 220 nm was used to assay. Results. Within 15 min more that 85% of moxonidine dissolved from the reference drug and all study drugs at pH 1.2; dissolution profiles were similar without calculation of similarity factor f2. Similarly, at pH 4.5 dissolution profiles of study drugs #2 and #3 were similar to that of the reference drug, and the similarity factor f2 was not calculated. However, in case of study drugs #1 and #4 significant differences were observed at a single time point (15 min), which suggests that their dissolution profiles are non-similar to that of the reference drug. Similarity factors f2 were calculated 17.52 and 35.30, respectively (less than 50). At pH 6.8 similarity factors f2 for all study generic drugs were also less than 50 (23.8, 49.8, 38.6, and 35.9), so their dissolution curves were non-similar to that of reference drug. Conclusion. In our study we observed difference in release in vitro of medicinal products containing moxonidines: none of the study drugs was fully similar to the reference drug in all media. The differences observed at pH 6.8 were noteworthy, where the samples had or faster kinetics (study drugs #2 and #3), or slower dissolution kinetics (test drugs #1 and #4). Observed differences in moxonidine release rate may impact absorption of active pharmaceutical ingredient into the blood following drug administration.