Compaction Properties of Acrylic Resin Polymers with Plastic and Brittle Drugs

Influence of formulation factors on tablet formulations with liquid permeation enhancer using factorial design

For a drug with low bioavailability, a matrix tablet with liquid permeation enhancer (Labrasol) was formulated. Factorial design was used to evaluate the effect of three formulation factors: drug percentage, polymer type (Methocel K100M or Eudragit L 100-55), and tablet binder percentage (Plasdone S-630) on tablet characteristics. Tablets were prepared by direct compression and characterized. Compressibility index values ranged between 15.90% and 29.87% and tablet hardness values from 7.8 to 29.78 Kp. Eudragit-containing formulations had better compressibility index values with higher tablet hardness. Time for 75% of drug release (T75) was calculated, and formulations containing Eudragit L 100-55 had faster release rates than tablet formulations with Methocel K100M. Formulations with Methocel K100M fit well in the Higuchi model as indicated by their R2 values (>0.98). Among all the formulation factors studied, polymer type displayed the highest and statistically significant effect on compressibility index, tablet hardness, and dissolution rate. Statistical design helped in better understanding the effect of formulation factors on tablet characteristics important for designing formulations with desired characteristics.

An evaluation of three-dimensional modeling of compaction cycles by analyzing the densification behavior of binary and ternary mixtures

The aim of the study is to use the 3D modeling technique of compaction cycles for analysis of binary and ternary mixtures. Three materials with very different deformation and densification characteristics [cellulose acetate (CAC), dicalcium phosphate dihydrate (EM) and theophylline monohydrate (TM)] have been tableted at graded maximum relative densities (rhorel, max) on an eccentric tableting machine. Following that, graded binary mixtures from CAC and EM have been compacted. Finally, the same ratios of CAC and EM have been tableted in a ternary mixture with 20 vol% TM. All compaction cycles have been analyzed by using different data analysis methods. Three-dimensional modeling, conventional determination of the slope of the Heckel function, determination of the elastic recovery during decompression, and calculations according to the pressure-time function were the methods of choice. The results show that the 3D model technique is able to gain the information in one step instead of three different approaches, which is an advantage for formulation development. The results show that this model enables one to better distinguish the compaction properties of mixtures and the interaction of the components in the tablet than 2D models. Furthermore, the information by 3D modeling is more precise since in the slope K of the Heckel-plot (in die) elasticity is included, and in the parameters of the pressure-time function beta and gamma plastic deformation due to pressure is included. The influence of time and pressure on the displacement can now be differentiated.

The use of carrageenan in mixture with microcrystalline cellulose and its functionality for making tablets

The modulation of tableting and release behavior of combinations of kappa-carrageenan Gelcarin((R)) GP 911 NF and microcrystalline cellulose (MCC) Avicel((R)) PH 101 has been evaluated. Graded binary mixtures were tableted to a maximum relative density of 0.850 at the maximum displacement of the upper punch. Additionally, ternary mixtures with the same ratios of kappa-carrageenan and MCC and a constant percentage of theophylline monohydrate (20% (v/v)) were tested for their release behavior. Tablets produced from pure kappa-carrageenan deformed more elastically than pure MCC, the tablets produced were stable but not at the same degree as those made from MCC. Scanning electron microscopy (SEM) pictures showed that for MCC a smooth surface of the tablets resulted, tablets made from kappa-carrageenan showed less 'fusion' and thus more mechanical interlocking is responsible for their stability. Binary mixtures showed a continuous change in compaction properties from plastic to elastic deformation. All ternary mixtures with theophylline deformed more plastically than the binary mixtures, the change in deformation properties remained the same. Theophylline reduced the crushing strength due to its different fracture properties. The ternary mixtures showed different release mechanisms: Fast release up to 20% (v/v) kappa-carrageenan, slower release starting from 30% (v/v). The kinetics of release tended at 70% (v/v) more clearly towards zero-order kinetics. This change in release is in accordance with a change in swelling of tablets made of the binary mixtures.

Prediction of the Hiestand bonding indices of binary powder mixtures from single-component bonding indices

A priori predictions of the bonding indices of binary powder mixtures from the single-component indices were attempted. The binary mixtures were classified according to the mechanism of deformation of the single-components as plastic-plastic, brittle-brittle, and plastic-brittle. When the components of a binary mixture consolidated by the same mechanism (plastic-plastic and brittle-brittle mixtures), a straight line could be fit to a plot of bonding index versus composition. This linearity indicates that the bonding index can be reliably estimated by interpolation between the two single-component bonding indices. When the mixtures were such that one component was brittle while the other was plastic, a linear function did not fit the data. For these cases, a second-degree polynomial equation could be fit to a plot of bonding index versus composition. A combination of multiple linear regression and trial and error was used to generate a single generalized equation. For pairs of compounds wherein each compound has a different compaction mechanism, this new equation appears to allow satisfactory predictions of the bonding indices of mixtures with varying compositions using only the single-component bonding indices.

The effect of composition on the tableting indices of binary powder mixtures

The purpose of this study was to investigate the effect of the composition of a binary powder mixture on the bonding index, the brittle fracture index, and the strain index, as defined by Hiestand. The studies involved tensile strength and dynamic indentation hardness determinations of square compacts, the solid fractions of which were 0.83. The mixtures were such that both components consolidated by plastic deformation, both components consolidated by brittle fracture, or one component was brittle while the other was plastic. The measured quantities were then used to compute the bonding index, the brittle fracture index, and the strain index. The bonding indices and tensile strengths of the individual plastic materials were greater than those of the individual brittle materials. It was concluded that the bonding indices were linearly related to composition when both materials consolidated by the same mechanism. It was further concluded that the bonding indices were related to compact composition by a second-degree polynomial equation for mixtures with one brittle and one plastic component. This latter relationship was consistent for four pairs of components.