Anuranjan Pandeya

Rate-Dependent Mechanical Properties of Granulated Pharmaceutical Powder Formulations

Pharmaceutical tablets are formed using formulations consisting of ingredients such as filler, binder, disintegrant, and active pharmaceutical ingredients. These ingredients are granulated followed by compaction. In the present study, the granules were formed using 5 and 10% binders. These granulated formulations were tested to determine mechanical properties using a medium pressure (<10 MPa) flexible boundary cubical triaxial tester. Hydrostatic triaxial compression and conventional triaxial compression tests were conducted at 10 and 20 MPa/min loading rates. Fundamental elastic, elastoplastic, and rate-dependent properties such as bulk modulus, compression index, spring-back index, shear modulus, and failure stress were determined from these tests. Some of the key findings were bulk modulus, compression index, and spring-back index increased with pressure. Shear modulus and failure stress increased with confining pressure; Bulk modulus increased with binder content at 10 MPa/min while decreased at 20 MPa/min loading rate; bulk modulus increased with loading rate. Spring-back index increased with binder content.

Relationships Between Tablet Physical Quality Parameters and Granulated Powder Properties: Feasibility Study

This research was carried to study the feasibility of using mechanical properties of granulated powder formulations in low to medium pressure regime (<10 MPa) as predictors of tablet quality parameters. Mechanical properties of granulated powder formulations at three binder contents were determined using a flexible boundary cubical triaxial tester. Tablets formed at two pressures (70 and 90 MPa) were tested for four quality parameters, that is, diametral strength, axial penetration strength, indentation hardness, and friability. Some of the key findings were: bulk modulus, shear modulus, and spring-back index increased with pressure; binder had different effect on bulk modulus and compression index at different loading rates; at both loading rates, the spring-back index for 10% binder content was higher than for 5% binder content. In general, tablet hardness was highest without binder. Most of the powders’ properties related with tablet qualities, that is, had R2 > 0.80; that is, demonstrating the feasibility of using powder properties as initial predictors of tablet quality for formulations tested. An elastic energy based hypothesis was proposed to provide a fundamental basis for mechanical properties of powder formulations versus tablet quality relationships. The positive outcome of this feasibility study suggests that the approach could be used for other pharmaceutical formulations.

Comparison between Mechanical Properties of Dry Blended and Granulated Pharmaceutical Powder Formulations

Pharmaceutical tablets are formed using various powder ingredients such as filler, binder, disintegrant, and active pharmaceutical ingredients (APIs). Tablets are formed either by dry blending the above ingredients or wet granulation of the powder mix followed by compaction. In the present study, the powder ingredients were dry blended using a manual blender and granulated using a high shear mixer. The granules were oven dried and sieved to get the desired size range. Both the dry blend and granulated powders were tested to determine mechanical properties using a medium pressure flexible boundary cubical triaxial tester (CTT). Hydrostatic triaxial compression (HTC) tests were conducted at pressures upto 10 MPa. The data obtained from the HTC tests used for determining the various fundamental elastic, elastoplastic, and rate-dependent properties such as bulk modulus, compression index, and spring-back index. The bulk modulus increased linearly in all cases with pressure. At 10 MPa/min loading rate, the bulk modulus value increased with binder content. The increase in bulk modulus values were more in case of granulated powder formulation as compared to dry blended powder formulation. In case of dry blended powder formulation, the compression index values increased with pressure in all cases. At 10 MPa/min loading rate, for dry blended powder formulation the compression index generally decreased with binder content. In case of granulated formulation the compression index increased with binder content. In general, the compressibility of the powder was increased by granulation. The spring back index increased with increase in pressure in all cases. In case of dry blended formulation, at 10 MPa/min loading rate, the spring-back value decreased with binder content. In case of granulated powder formulation, the spring back index for 10% binder content was higher than for 5% binder content. Granulation decreased the spring-back index of the powder formulation.

Determination of Plastic and Rate-Dependent Properties of Bulk Solids Using Low Pressure Cubical Triaxial Tester

Since many of the issues in processes involving powder arise in lower pressure regime where self weight is the main source of the pressure, it is valuable to understand the behavior of powder in that pressure range. For this, a flexible-membrane cubical triaxial tester (CTT) with the capability to test a bulk solid’s mechanical properties under dynamic conditions was used. Herein, alumina’s mechanical responses were measured with the CTT. Three different loading rates of 6 kPa/min, 60 kPa/min, and 600 kPa/min were used to determine alumina’s mechanical properties. Hydrostatic compression triaxial tests and conventional compression triaxial tests were conducted. To validate and predict mechanical responses of the alumina powder, parameters were evaluated for the modified Cam-clay model. Test results showed that alumina’s mechanical properties were sensitive to the applied loading rate. Compression index values indicated that alumina became more compressible with the increase of loading rate. Shear strength increased with the loading rate whereas shear modulus decreased when the loading rate increased.

Mechanical Behavior of Powder Constituents and their Mixtures – An Experimental Study

A powder mixtures mechanical properties play a vital role with respect to the handling, processing, and product quality. In industries, powders are generally processed in mixed form rather than powder as individual constituents. Powder mixtures constituents have different characteristics. The present study was conducted to determine the fundamental mechanical properties namely bulk modulus, shear modulus, compression index, and spring-back index of components and their mixture; in addition, to measuring and quantifying the effect of constituents on the mixture. Towards this end, corn starch, Avicel (microcrystalline cellulose) and their mixture formulated in equal weight proportion were used. Two types of triaxial tests, namely, conventional triaxial compression (CTC) and hydrostatic triaxial compression (HTC), were conducted at different pressures using a medium pressure flexible boundary cubical triaxial tester (CTT). Overall, the bulk modulus, compression index and spring-back index values increased with increase in pressure. The bulk modulus of mixture was higher than that of corn starch and Avicel which demonstrated that the presence of corn starch influenced the bulk modulus property of Avicel. The compression index for the mixture was more than that of corn starch but less than Avicel which means addition of corn starch reduced Avicels compressibility. Similar trend was observed for spring-back index. At 2.0 MPa confining pressure, as expected, the shear modulus at stress difference of 500 kPa was higher than that at 1000 kPa stress difference. The shear modulus for Avicel was highest followed by Avicel-corn starch mixture, and corn starch.