ABSTRACT
Estudo das propriedades físico-químicas envolvidos no processo de compactação de uma formulação experimental contendo como fármaco modelo a zidovudina. O objetivo foi caracterizar o comportamento físico-químico de comprimidos produzidos por compressão direta usando-se diferentes pressões de compactação. Nas análises foram empregadas metodologias convencionais e não convencionais. A metodologia não convencional foi o uso da técnica da atenuação de raios-gama na determinação da porosidade. As metodologias convencionais utilizadas foram os testes de friabilidade, dureza e dissolução. Os modelos teóricos utilizados para explicar o comportamento físico-químico da formulação sob compressão são os proposto por Heckel e Walker. Os estudos mostraram que o processo de densificação é governado principalmente por deformações do tipo plásticas e pressões em torno de 246MPa são suficientes para induzir deformação plástica e consolidação do sistema compactado. Os resultados da análise de Walker indicam que a formulação tem propriedades de compressão que podem ser melhoradas.
This paper presents a study of the physical-chemical properties involved in powder compaction of an experimental formulation containing as model drug the zidovudine. The aim of this work was to characterize the physical-chemical behavior of experimental tablets produced by direct compression applying different strengths. In these analyses were employed conventional and non-conventional methodologies. The non-convectional methodology was the use of gamma-ray attenuation technique for tablet porosity determination. The conventional methodologies used were the tests of hardness, friability and dissolution. The theoretical models used to explain the physical-chemical behavior of the formulation under compression were those proposed by Heckel and Walker. These tests showing that the densification process is to take mainly by plastic deformation and pressures about 246 MPa are enough to produce robust tablets. Results obtained from the analysis of the Walker equation, indicate that the formulation has compression properties that could be improved.
Subject(s)
Tablets/chemical synthesis , Gamma Rays , ZidovudineABSTRACT
The aim of the present work is the determination of porosity in tablets by using the gamma-ray transmission technique. Tablet dissolution depends on some inherent characteristics of the manufacturing process, such as compression force, tablet volume, density and porosity, nature of excipients, preparation methods and its physical-chemical properties. Porosity is a measure of empty spaces in a material and can be determined by various techniques. In this paper, we propose the use of a gamma-ray transmission technique to obtain the porosity of experimental formulation of tablets. The results of porosity were compared with those obtained by using conventional methodology (density and mercury intrusion). The experimental setup for gamma-ray transmission consists of a gamma-ray source of (241)Am (photons of 59.6 keV and an activity of 3.7 × 10(9)Bq), an NaI(Tl) scintillation detector, collimators and a standard gamma-ray spectrometry electronics. Our results suggest that the gamma-ray transmission technique is a powerful tool for non-destructive porosity quantification of solid pharmaceutical forms and presents smaller errors than those obtained with conventional methodologies.