Eugene L. Parrott

Effect of Lubricants on Tensile Strengths of Tablets

AbstractThe effect of concentration of lubricant on the axial and radial tensile strengths of tablets was determined for four directly compressible pharmaceutical materials: anhydrous lactose, aspirin, microcrystalline cellulose, and dibasic calcium phosphate dihydrate. The lubricants investigated were: hydrogenated vegetable oil, magnesium stearate, polyethylene glycol 4000, stearic acid, and talc. For plastic materials the tensile strengths were reduced as the concentration of the lubricant was increased. For brittle material the tensile strength was not changed significantly as the concentration of lubricant was increased.

Comparative Evaluation of A New Direct Compression Excipient, Soludex™ 15

AbstractSoludex™15, a new corn-based maltodextrin, has been evaluated and compared to nine frequently used commercial excipients for direct compression. The properties of the excipients reported are median size, particle size distribution, bulk density, flow rate, repose angle, moisture content, and hardness and compressibility at several compaction pressures. The influence of concentration of lubricant and mixing time with a lubricant on hardness of Soludex 15 compacts were determined. The effect of 1% magnesium stearate on the hardness of compacts was determined for the ten excipients. Model formulations for direct compression tablets using Soludex 15 are presented, and for a batch of these tablets the weight variation, friability, hardness, disintegration and dissolution are reported. Soludex 15 exhibited excellent flow and compressibility, and model tablets using Soludex 15 as the direct compression diluent met USP specifications and provided a rapid dissolution of the active ingredient.

Effects of Temperature, Humidity, and Aging on the Disintegration and Dissolution of Acetaminophen Tablets

AbstractThe effect of storage for 8 weeks at 40°C in moderate and high humidity on acetaminophen tablets prepared by the wet granulation method using povidone or pregelatinized starch as a binder was studies. Storage at 52% relative humidity produced an increase in hardness of acetaminophen tablets and storage at 94% relative humidity caused a decrease in hardness. In all cases tablets granulated with pregelatinized starch were less susceptible to change caused by humidity than tablets granulated with povidone. The disintegration of tablets containing starch or povidone was slowed as the humidity was increased. Tablets stored at 40 =C and 94 V. relative humidity showed a substantial slowing of dissolution, but there was little change of dissolution of tablets when aged at 40 -C / 52% relative humidity. In comparing starch and povidone as binders, acetaminophen tablets prepared with pregelatinized starch were less effected by high humidity than tablets prepared with povidone.

Diffusivity and dissolution rate in polymeric solutions

AbstractThe diffusivity of benzoic acid was measured in various concentrations of aqueous solutions of methylcellulose, hydroxypropyl cellulose and guar gum. An increase in concentration of the polymer increases the viscosity of the polymeric solution to a greater degree than it decreases diffusivity. Dissolution rates of benzoic acid in various concentrations of polymeric solutions were measured. An equation is presented for calculating the relative dissolution rates in polymeric solutions.

Effect of anionic surfactants on the release on clorpheniramine malete from an inert, heterogeneous matrix

AbstractThe release from a matrix compressed from a physical mixture of chlorpheniramine maleate, chlorinated poly(propylene), lactose and an anionic surfactant (sodium lauryl sulfate and dioctyl sodium sulfosuccinate) has been investigated. The formation of a poorly water-soluble complex between the chlorpheniramine and the anionic surfactant slows the release to a minimum at low concentrations of surfactant; however, at higher concentrations of surfactant the release is faster due to solubilization in the micellar phase of the ion-pair. The interactin between the chlorpheniramine maleate and the anionic surfactant also influences the release of a second, noninteracting compound from the matrix.

Effect of Tablet Lubricants on Axial and Radial Work of Failure

AbstractDuring diametral compression and axial tensile strength testing force-displacement curves were obtained for tablets of microcrystalline cellulose. The area under the curve, termed work of failure, was determined by planimetry. For each of the five lubricants studied as the concentration of the lubricant was increased in the tablet, the work of failure was considerably less. The effect was especially marked in the axial plane.

Formulation of a Foaming Vaginal Tablet and Suppository

Formulations for a foaming, spermicidal vaginal tablet and a foaming, spermicidal suppository are presented. Some pharmaceutical characteristics peculiar to both dosage forms were measured. A simple method is suggested for the evaluation of the quantity and collapse resistance of the foam.

Relationship of dissolution rate in anionic polymeric solutions to viscosity

AbstractThe influence of viscosity on the dissolution rate of m-acetotoluidide in aqueous solutions of acacia, gelatin type B, sodium carboxymethylcellulose, sodium alginate and xanthan gum was investigated. The viscosity was measured by a rotational viscometer. The dissolution rates decreased as the viscosities of solutions of anionic polymers increased. The curves representing the relationship of dissolution rate and viscosity varied for each polymeric solution depending on the structural characteristics of the polymer.

Comparison of Several Diffusion Equations in the Calculation of Viscosity and its Relation to Dissolution Rate

The viscosity of polymeric solutions as measured by a rotational viscometer may not be the viscosity of the environment through which a solute molecule diffuses. By use of the Stokes-Einstein equation a viscosity, which is not affected by the mechanics of the viscometer, may be calculated if the size and diffusivity of the solute molecule are determined. The values of such viscosity calculated by using several diffusion equations compare favorably with the value calculated with the Stokes-Einstein equation. The dissolution rates of benzoic acid in aqueous solutions of three non-ionic suspending agents is related to the viscosity.

Effect of a Lubricant on Wear Rate of Tablets

AbstractThe rate of wear and hardness of tablets of Emcompress and sodium chloride compressed at various applied pressures in a lubricated and an unlubricated die are compared. The effect of applied pressure and concentration of magnesium stearate blended with several direct compression excipients on the wear rate constant, hardness and tensile strength of a tablet is reported. The data allow a comparison of the methods used to express the mechanical strength of tablets.