Flow Function of Pharmaceutical Powders at Low-Stress Conditions Can Be Inferred Using a Simple Flow-Through-Orifice Device

A systematic comparison of four pharmacopoeial methods for measuring powder flowability

Powder flow is one of the crucial factors affecting several pharmaceutical manufacturing processes. Problems due to insufficient powder flow reduce production process efficiency and cause suboptimum product quality. The U.S. Pharmacopoeia has specified four methods to evaluate the flowability of pharmaceutical powders, including angle of repose (AoR), compressibility index (CI) and Hausner ratio (HR), Flow through an orifice, and shear cell. Comparison within and between those methods with 21 powders (covering a wide range of flowability) was performed in this study. Strong correlation was observed between fixed base cone AoR, and fixed height cone AoR (R2 = 0.939). CI and HR values calculated from a tapped density tester (meeting USP standards), manual tapping, and Geopyc® correlated strongly (R2 > 0.9). AoR, CI/HR, minimum diameter for flowing through an orifice (dmin), and shear cell results generally correlate strongly for materials with flowability worse than Avicel® PH102. Both shear cell and CI/HR methods can reliably distinguish powders exhibiting poor flow. For materials with good flow, the ability to distinguish powders follows the order of AoR ≈ CI/HR > shear cell > dmin. The systematic comparison of the four common methods provides useful information to guide the selection of methods for future powder flow characterization. Given the limitations observed in all four methods, we recommend that multiple techniques should be used, when possible, to more holistically characterize the flowability of a wide range of powders.

Optimization of the Preformulation and Formulation Parameters in the Development of New Extended-Release Tablets Containing Felodipine

Herein, new extended-release tablets containing felodipine were developed. For the orally administered formulations, optimization of the preformulation and formulation parameters was performed to assess the performance of the dosage form. Initially, the morphological and physical characterization of two forms of felodipine (microcrystalline and macrocrystalline) using Fourier transform infrared spectroscopy, differential scanning calorimetry and optical microscopy was performed. The pharmaco-technical properties of the two felodipine forms were also determined. Subsequently, formulation studies for felodipine extended-release tablets were performed. Mathematical modelling of release kinetics of felodipine from developed formulations using a power law model was also performed. Based on the influence of formulation factors on the in vitro availability of felodipine in experimental tablets, a new extended-release tablet formulation was established.

Development of Immediate Release Tablets Containing Calcium Lactate Synthetized from Black Sea Mussel Shells

Nowadays, the use of marine by-products as precursor materials has gained great interest in the extraction and production of chemical compounds with suitable properties and possible pharmaceutical applications. The present paper presents the development of a new immediate release tablet containing calcium lactate obtained from Black Sea mussel shells. Compared with other calcium salts, calcium lactate has good solubility and bioavailability. In the pharmaceutical preparations, calcium lactate was extensively utilized as a calcium source for preventing and treating calcium deficiencies. The physical and chemical characteristics of synthesized calcium lactate were evaluated using Fourier Transform Infrared Spectroscopy, X-ray diffraction analysis and thermal analysis. Further, the various pharmacotechnical properties of the calcium lactate obtained from mussel shells were determined in comparison with an industrial used direct compressible Calcium lactate DC (PURACAL^®). The obtained results suggest that mussel shell by-products are suitable for the development of chemical compounds with potential applications in the pharmaceutical domain.

Impact of Powder Properties on the Rheological Behavior of Excipients

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.