The effect of amorphous and crystal sodium warfarin and its content uniformity on bioequivalence of tablets.

Warfarin is intensively discussed in terms of generic substitution due to particular cases of bleeding, which are attributable to fluctuations in API content or the substitution of crystalline (WSC) for amorphous (WSA) warfarin. The aim of this study was to assess to what extent the in vitro release was affected by the form of API depending on the composition and technology. Bioequivalent tablets containing 5 mg of WSA or WSC prepared by wet granulation or direct compression were used. Furthermore, tablets of the same composition with WSC or WSA prepared by direct compression were evaluated. Raman spectroscopy was used to confirm the presence of WSA or WSC. The dissolution was more influenced by the technology than by the form of API but even tablets with dissimilar profiles were bioequivalent. This is probably due to the precipitation of WSA and WSC in the stomach on a poorly soluble acidic form, which subsequently dissolves in the neutral environment of the small intestine. Recrystallization was demonstrated in the in vitro assay at a pH of 1.2 and 4.5 using Raman spectroscopy and X-ray diffraction. In summary, the content uniformity appears to be the main factor affecting the safety of the treatment.

[Development of dissolution method for warfarin sodium tablets]. / Vývoj disolucnej metódy pre tablety s obsahom warfarínu sodného.

Warfarin is intensively discussed drug with narrow therapeutic index. In the past, its generic substitution was identified as a cause of bleeding. Altered quality of the active substance or varying drug content was discussed. The substance quality can be evaluated with adequate dissolution method. An official dissolution method with aqueous medium exists, however this method is non-discriminatory. In the first 15 minutes the whole amount of the active pharmaceutical ingredient is released from a tested dosage form, which does not allow comparison between tablets from different producers and it also makes difficult to track the changes throughout stability testing. In the literature, there is a well known method using pH 6.8 buffer, which seems to be a suitable alternative to water. The aim of this study was to prove, that this alternative medium, when two stirring speeds for dissolution (50 or 25 rpm) are used, will be suitable for calculation of similarity and difference factor and if it will be eventually discriminatory with regard to particle size and radial hardness. For this purpose we prepared tablets with 10 mg of warfarin sodium in form of crystalline clathrate with isopropanol. Tablets differed by particle size of active pharmaceutical ingredient (d50 = 4.8, or d50 = 22.5 µm respectively) and by radial hardness (30, or 100 N respectively). The content uniformity of the tablets was determined using process capability index (Cpk) and Bergum method. It was confirmed that the dissolution medium with pH of 6.8 allows comparison of dissolution profiles by similarity and difference factors but under given conditions it is not discriminatory.Key words: warfarin dissolution method particle size distribution radial hardness similarity factor difference factor.

Factor analysis in optimization of formulation of high content uniformity tablets containing low dose active substance.

Warfarin is intensively discussed drug with narrow therapeutic range. There have been cases of bleeding attributed to varying content or altered quality of the active substance. Factor analysis is useful for finding suitable technological parameters leading to high content uniformity of tablets containing low amount of active substance. The composition of tabletting blend and technological procedure were set with respect to factor analysis of previously published results. The correctness of set parameters was checked by manufacturing and evaluation of tablets containing 1-10mg of warfarin sodium. The robustness of suggested technology was checked by using "worst case scenario" and statistical evaluation of European Pharmacopoeia (EP) content uniformity limits with respect to Bergum division and process capability index (Cpk). To evaluate the quality of active substance and tablets, dissolution method was developed (water; EP apparatus II; 25rpm), allowing for statistical comparison of dissolution profiles. Obtained results prove the suitability of factor analysis to optimize the composition with respect to batches manufactured previously and thus the use of metaanalysis under industrial conditions is feasible.

Pharmacokinetics of Ciclopirox Olamine after Buccal Administration in Rabbits.

BACKGROUND: Prevalence of oral mucosal fungal infections increases with the frequent administration of antibiotics, corticosteroids and immunosuppressive drugs. Therapeutically used antifungals are usually associated with a variety of drug interactions. Furthermore, there has been a noticeable increase in microorganisms resistant to these preparations. Mucoadhesive buccal films represent a modern therapeutic system for the treatment of oral mucosal fungal infection paired with a high degree of patient compliance. Ciclopirox olamine applied directly onto the oral mucosa offers an attractive alternative to treatment with systemic antifungals thanks to its low incidence of resistance and side effects. OBJECTIVE: The aim of this work was to evaluate the pharmacokinetic parameters of ciclopirox olamine after the buccal application of mucoadhesive film prepared by the solvent casting method. METHOD: A chromatographic method using an internal standard was developed and validated for evaluation of ciclopirox olamine plasma concentrations. Method accuracy was 88.5-104.6% and 89.5-99.7% for interday and intraday assays, respectively. RESULTS: The pharmacokinetic properties of ciclopirox olamine were studied in New Zealand White rabbits. The mucoadhesive films containing ciclopirox olamine in a total dose of 34.4 (33.0; 35.9) mg kg-1 were applied to all the rabbits. Plasma ciclopirox olamine concentrations were determined during the 12 h following application. The time taken to reach maximum plasma concentration was 1.7 (1.1; 2.2) h after the drug administration with cmax 5.73 (4.18; 7.28) µg mL-1. Overall elimination half-life was 3.8 (1.9; 10.8) h. CONCLUSION: The experiment suggests that oral mucoadhesive film may be a valuable alternative ciclopirox olamine administration.

Influence of process parameters on content uniformity of a low dose active pharmaceutical ingredient in a tablet formulation according to GMP.

The article describes the development and production of tablets using direct compression of powder mixtures. The aim was to describe the impact of filler particle size and the time of lubricant addition during mixing on content uniformity according to the Good Manufacturing Practice (GMP) process validation requirements. Processes are regulated by complex directives, forcing the producers to validate, using sophisticated methods, the content uniformity of intermediates as well as final products. Cutting down of production time and material, shortening of analyses, and fast and reliable statistic evaluation of results can reduce the final price without affecting product quality. The manufacturing process of directly compressed tablets containing the low dose active pharmaceutical ingredient (API) warfarin, with content uniformity passing validation criteria, is used as a model example. Statistic methods have proved that the manufacturing process is reproducible. Methods suitable for elucidation of various properties of the final blend, e.g., measurement of electrostatic charge by Faraday pail and evaluation of mutual influences of researched variables by partial least square (PLS) regression, were used. Using these methods, it was proved that the filler with higher particle size increased the content uniformity of both blends and the ensuing tablets. Addition of the lubricant, magnesium stearate, during the blending process improved the content uniformity of blends containing the filler with larger particles. This seems to be caused by reduced sampling error due to the suppression of electrostatic charge.