Compactibility improvement of metformin hydrochloride by crystallization technique

Effect of Polymer Additives on the Crystal Habit of Metformin HCl

The crystal habit can have a profound influence on the physical properties of crystalline materials, and thus controlling the crystal morphology is of great practical relevance across many industries. Herein, this work investigates the effect of polymer additives on the crystal habit of metformin HCl with both experiments and computational methods with the aim of developing a combined screening approach for crystal morphology engineering. Crystallization experiments of metformin HCl are conducted in methanol and in an isopropanol-water mixture (8:2 V/V). Polyethylene glycol, polyvinylpyrrolidone, Tween80, and hydroxypropyl methylcellulose polymer additives are used in low concentrations (1-2% w/w) in the experiments to study the effect they have on modifying the crystal habit. Additionally, this work has developed computational methods to characterize the morphology "landscape" and quantifies the overall effect of solvent and additives on the predicted crystal habits. Further analysis of the molecular dynamics simulations is used to rationalize the effect of additives on specific crystal faces. This work demonstrates that the effects of additives on the crystal habit are a result of their absorption and interactions with the slow growing {100} and {020} faces.

Enabling the direct compression of metformin hydrochloride through QESD crystallization

Metformin hydrochloride is a drug used in the treatment of type 2 diabetes. It shows very poor flowability and agglomeration under storage so that a direct compression of the material into tablets has not yet been successfully realized. In a previous study the authors showed that a quasi-emulsion solvent-diffusion (QESD) crystallization technique can be used to drastically improve the flowability and reduce storage agglomeration of this drug. This study set out to evaluate whether QESD metformin hydrochloride can be directly compressed into high dose (> 89.5% drug load) tablets without the use of an intermediary step such as granulation. The direct compression into tablets was successful, however it was important to evaluate the tabletability of the material under actual production speeds of the tablet press. The porous structure of the metformin agglomerates lead to deaeration issues, however these could be avoided by reducing the punch speed or using a precompression step. Furthermore, the influence of surfactants used to stabilize the QESD crystallization on the strength of tablets produced was analyzed because the literature is still scarce on this topic.

Comparison of the performance of two grades of metformin hydrochloride elaboration by means of the SeDeM system, compressibility, compactability, and process capability indices

Quality by design, applied to the development of a pharmaceutical drug, demands scientific methodologies, representing a source of information that will allow for a complete understanding the production process and the materials used for its manufacturing. Although the SeDeM system is a tool that enables a rational development of a product, result does not assure that an assessed material or mixture will be successful in terms of compression, hence, further research will be necessary on these features. The objective of this study was to assess and compare two grades of metformin hydrochloride elaboration: crystalline and direct compression using PXRD, the SeDeM expert system, the Heckel and Ryshkewitch-Duckworth models, as well as process control tools such as control charts and process capability indices to characterize and predict the performance of the materials in a direct compression process. The assessment identified that in spite of dealing with two different technical grades of a material with specific critical quality attributes for each one, PXRD analysis showed we dealt with the same crystalline structure, while the SeDeM system profiles obtained have very close values, and the main differences in materials were observed when subjecting them to conditions that simulate a compaction process with the Ryshkewitch-Duckworth model, in which a 46-times higher mechanical resistance was observed in the direct compression material compared with the crystalline one. The statistical control analysis revealed that only the direct compression material could be used to elaborate tablets whose weight variation was always maintained within the specification and control limits.

Fayed M, Alalaiwe A, B. Alsulays B, F. Aldawsari M, Khafagy ES. Design, Optimization, and Correlation of In Vitro/In Vivo Disintegration of Novel Fast Orally Disintegrating Tablet of High Dose Metformin Hydrochloride Using Moisture Activated Dry Granulation Process and Quality by Design Approach

Compression of cohesive, poorly compactable, and high-dose metformin hydrochloride into the orally disintegrating tablet (ODT) is challenging. The objective of this study was to develop metformin ODT using the moisture activated dry granulation (MADG) process. There are no reports in the literature regarding the development of ODT based on MADG technology. The feasibility of developing metformin ODT was assessed utilizing a 3² full factorial design to elucidate the influence of water amount (X₁) and the amount of pregelatinized starch (PGS; X₂) as independent variables on key granules and tablets’ characteristics. The prepared granules and tablets were characterized for granule size, bulk density, flow properties, tablets’ weight variation, breaking force, friability, capping tendency, in vitro and in vivo disintegration, and drug release. Regression analysis showed that X₁ and X₂ had a significant (p ≤ 0.05) impact on key granules and tablets’ properties with a predominant effect of the water amount. Otherwise, the amount of PGS had a pronounced effect on tablet disintegration. Optimized ODT was found to show better mechanical strength, low friability, and short disintegration time in the oral cavity. Finally, this technique is expected to provide better ODT for many kinds of high-dose drugs that can improve the quality of life of patients.

Expedited development of a high dose orally disintegrating metformin tablet enabled by sweet salt formation with acesulfame

Salt formation has been extensively used to improve drug properties, including solubility, stability and mechanical properties. A sweet salt of metformin with acesulfame, prepared though an anion exchange reaction, showed superior properties over the commercial hydrochloride salt. These included both remarkable improvement of taste and significant enhancement in tabletability, which is explained by the different crystal structures and lower hardness as measured by nanoindentation. The relationship among crystal structure, mechanical properties and tabletability was rationalized through an energy framework analysis. This approach led to the successful development of an orally disintegrating tablet product containing 60% of metformin-acesulfame salt by direct compaction.

Flow, packing and compaction properties of novel coprocessed multifunctional directly compressible excipients prepared from tapioca starch and mannitol

Novel multifunctional excipients were prepared by coprocessing tapioca starch with mannitol using two methods viz; co-grinding and co-fusion. The flow, packing and compaction properties of the native and novel excipients were evaluated by using density, Hausner's ratio, angle of repose, the maximum volume reduction, consolidation index, the rate of consolidation, angle of internal friction, morphological properties, Heckel analysis, tensile strength and dilution potential as evaluation parameters. The study revealed that the method of coprocessing, particle size and particle shape influenced the properties of the resulting novel excipients. Co-grinding was less effective than co-fusion in the preparation of excipients with enhanced properties. The study concluded that coprocessing tapioca starch and mannitol will enhance the flow, packing and compaction properties of the novel excipient and that the co-fusion method of coprocessing would produce novel excipients with enhanced direct compression potential compared to the co-grinding method.

Preparation and evaluation of agglomerated crystals by crystallo-co-agglomeration: an integrated approach of principal component analysis and Box-Behnken experimental design

Poor mechanical properties of crystalline drug particles require wet granulation technique for tablet production which is uneconomical, laborious, and tedious. The present investigation was aimed to improve flow and mechanical properties of racecadotril (RCD), a poorly water soluble antidiarrheal agent, by a crystallo-co-agglomeration (CCA) technique. The influence of various excipients and processing conditions on formation of directly compressible agglomerates of RCD was evaluated. Principal component analysis and Box-Behnken experimental design was implemented to optimize the agglomerates with good micromeritics and mechanical properties. The overall yield of the process was 88-98% with size of agglomerates between 351 and 1214 μm. Further, higher rotational speed reduced the size of agglomerates and disturbed sphericity. The optimized batch of agglomerates exhibited excellent flowability and crushing strength. The optimized batch of RCD agglomerates was characterized by fourier transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffractometry and gas chromatography which illustrated absence of drug-excipient interaction with minimal entrapment of residual solvent. Hence, it may be concluded that both excipients and processing conditions played a vital role to prepare spherical crystal agglomerates of RCD by CCA and it can be adopted as an excellent alternative to wet granulation.