PubMed · 14400554
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J J HEFFERREN. Identification guide for solid dosage forms.. https://pubmed.ncbi.nlm.nih.gov/14400554/
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The stability of encapsulated D-limonene, which was prepared by spray drying, was studied in view of the release characteristics and oxidation stability. Gum arabic, soybean water-soluble polysaccharide, or modified starch, blended with maltodextrin were used as the wall materials. The powders were stored under the conditions of 23-96% relative humidity at 50 degrees C. The release rate and the oxidation rate were closely related to the relative humidity. The relationship was not simple. Initially, the release rate and the oxidation rate increased with increasing water activity, but around the glass transition temperature, the rates decreased sharply to increase again at a further increase of water activity. The results could be explained by a change in the powder structure, where a glass capsule matrix was changed into rubbery state during storage.
Shellac is a natural enteric polymer, which results in good gastric resistance; however, it often dissolves too slowly in intestinal fluids. The objective of this study was to improve the disintegration of shellac-coated soft gelatin capsules in simulated intestinal fluids (phosphate buffer pH 6.8) through the addition of pore-formers, such as organic acids and hydrophilic polymers, while retaining gastric resistance. The mechanical properties (% elongation at rupture, puncture strength at break and modulus at puncture), media uptake and weight loss of shellac films were determined upon exposure in 0.1 N HCl and/or phosphate buffer pH 6.8. Organic acids (e.g., sorbic acid) acted as plasticizers, they reduced the glass transition temperature of ethanol-cast shellac films. The addition of additives effectively decreased the disintegration times in phosphate buffer pH 6.8, while the behavior in 0.1 N HCl remained unchanged. In addition, the hardness and disintegration of shellac-coated soft gelatin capsules were monitored through the whole disintegration experiments. The best disintegration was achieved with sorbic acid as pore-former. Sorbic acid remained in the shellac coating at low pH, but leached in pH 6.8 buffer, thus resulting in good gastric resistance and rapid disintegration in simulated intestinal fluids. The disintegration time of ethanolic shellac-coated soft gelatin capsules decreased with increasing amount of pore-former. The slow disintegration of aqueous shellac-coated soft gelatin capsules could be also improved by the addition of hydrophilic polymers, such as hydroxypropyl methylcellulose (HPMC). However, higher HPMC concentrations were required when compared to sorbic acid.
This work evaluated the use of a commercially available 200 ml vessel for dissolution of five drug products with various solubilities. Each of the five drug products (four with USP monographs and one proprietary tablet formulation) was run at four different conditions (USP 25 monograph, six dosage units in single 1l vessel, 200 ml at the USP Monograph speed, and 200 ml at calculated paddle speed which matches the hydrodynamics of the USP vessel). Six dosage units in a single vessel were used as a comparison to increase the drug concentration for dissolution testing. Due to the different dissolution hydrodynamics, drug dissolution from the dosage forms was slower using the 200 ml conversion kit than when the USP method with a 1l vessel was used. However, use of the 200 ml vessel at higher paddle speeds calculated by the power/volume equation, yielded similar results as the monograph method. Thus, it appears that using the power/volume ratio calculation to obtain comparable hydrodynamics lends utility to the 200 ml vessel as a means for characterizing the dissolution profile of low dose solid oral drug products. The results of the multiple dosage units per vessel also gave similar results to that of the USP monograph method.