ABSTRACT
With the extracts of Puerariae Lobatae Radix as the research object, the moisture absorption isotherm at 298, 308 and 318 K was determined through dynamic water vapor adsorption. Moisture absorption isotherm models were applied to the simulation of moisture absorption behavior. The enthalpy, entropy and Gibbs free energy for moisture adsorption were calculated according to the model and the enthalpy-entropy compensation was used to analysis moisture adsorption process. It was shown that the adsorption isotherm coincided with GAB model or Ferro-Fontan model. Moisture absorption process was an exothermic process which was driven by entropy. The effect of moisture on compressibility was evaluated through tensile strength and elastic recovery with water content, pressure force and speed variation. It was supposed that right amount of moisture was required to compression and compaction.
ABSTRACT
Os excipientes são materiais amplamente utilizados para formular fármacos através de compressão direta. No entanto, as propriedades do pó e compressão desses materiais são afetadas pela presença de lubrificantes e ingredientes ativos. Este estudo utilizou uma metodologia para avaliar a eficácia destes materiais como agentes de compressão direta. O efeito de três lubrificantes (estearato de magnésio, ácido esteárico e talco) na compressibilidade e compactação dos materiais foi avaliado pelo índice de compressibilidade e sensibilidade do lubrificante, respectivamente. Da mesma forma, a capacidade da diluição foi avaliada com um fármaco pouco compressível como o acetaminofeno. Finalmente, a recuperação elástica dos comprimidos foi avaliada aos cinco dias após a produção. Todos os lubrificantes aumentaram a compressibilidade destes materiais e a sua fluidez. No entanto, os lubrificantes hidrofóbicos, tais como o estearato de magnésio tem um efeito negativo sobre a compactação, em especial em materiais plásticos com uma superfície lisa, como o amido 1500. O amido de arroz e de mandioca e ácido algínico apresentaram a maior recuperação elástica (> 5%), indicando uma elevada tendência para a laminação. Além disso, os materiais plásticos com alta deformação, tais como o sorbitol, e polivinilpirrolidona (PVP-K30), exibiram a melhor potencial de diluição (~10%), enquanto que o ácido algínico mostrou um valor muito elevado (~ 70%). Em termos de desempenho, o sorbitol, o PVP-K30, alginato de sódio, Avicel PH-101, e de amido pré-gelatinizado são os materiais mais adequados para a compressão direta de fármacos.
Excipients are widely used to formulate solid drug forms by direct compression. However, the powder-forming and tableting properties of these excipients are affected by the presence of lubricants and active ingredients. In this study, a screening methodology was employed to test the performance of an excipient for direct compression. The effects of three lubricants (magnesium stearate, stearic acid and talc) on the compressibility and compaction of these excipients were assessed by the compressibility index and lubricant sensitivity ratio, respectively. Likewise, the dilution potential in blends with a poorly compactible drug such as acetaminophen was also assessed. Finally, the elastic recovery of tablets was evaluated five days after production. All lubricants increased the compressibility of these excipients and improved their flowability. However, hydrophobic lubricants such as magnesium stearate had a marked negative effect on compactibility, especially in plastic-deforming and more regularly-shaped materials with a smooth surface such as Starch 1500. Alginic acid, rice and cassava starches had the largest elastic recovery (>5%), indicating a tendency to cap. Moreover, highly plastic deforming materials such as sorbitol and polyvinylpyrrolidone (PVP-K30) exhibited the best dilution potential (~10%), whereas alginic acid showed a very high value (~70%). In terms of performance, sorbitol, PVP-K30, Avicel PH-101, sodium alginate and pregelatinized starch were the most appropriate excipients for the direct compression of drugs.
Subject(s)
Dilution , Pharmaceutic Aids/analysis , Pharmaceutical Preparations , LigandsABSTRACT
The purpose of this study was to search the influences of the increase of the contents of sodium algi-nate in the experimental alginates on the some mechanical properties. 3 commercial alginates were selected for the purpose of comparison of the results of experiments. 7 experimental alginates were manufactured with the rise of contents of sodium alginate from 8.8% to 18.3% with the decrease of contents of diatomaceous earth and with the constant contents of calcium sulfate 12.5%, sodium phosphate 2.2%, zinc fluoride 2.0%. Splitable metal mold with 12.5mm diameter and 20.0mm height was filled with mixed alginate to prepare the cylinder shaped specimens. Strain in compression, elastic recovery, compressive strength were tested using the ISO specification number 1563, alginate impression material. Experimental groups were 7, and 10 specimens were used for each test items and each groups. Following results were obtained; 1. Strain in compression was decreased with the increase of sodium alginate contents (p=0.0077, r2=0.6302). 2. Elastic recovery was decreased with the increase of sodium alginate contents but was not significant(p=0.0639, r2=0.7449). 3. Compressive strength was increased with the increase of sodium alginate contents (p<0.0001, r2=0.9617). These results mean that the increase of sodium alginate contents make alginate harder but may result the increased permanent deformation.