Precise and Sensitive Ambient Temperature Based Analytical Colorimetric Method for Pregabalin

Abstract Pregabalin, a GABA analogue is used to treat epilepsy and neuropathic pain. The drug poses problems in analytical quantification when estimated at a shorter UV wavelength. The expensive and non-repetitive reported analytical methods necessitate the utility and development of an accurate, precise, repetitive, simple and highly sensitive colorimetric method for pregabalin in solution as well as sustained release mini matrices. Pregabalin (having primary amino group) was derivatized at alkaline pH of mixture with optimized ninhydrin solution at ambient temperature (25oC). The ninhydrin-pregabalin derivatized complex (Ruhemann's Purple) was analyzed for drug concentration at absorption maximum (λmax) of 570nm. The linearity was observed in the concentration range of 5-150 µg/mL with coefficient of correlation, 0.998. The developed analytical method was validated according to ICH guidelines and proved to be highly sensitive (LOD 0.917µg/mL, LOQ 3.055µg/mL), with good inter-day as well as intra-day accuracy and precision as 4.65% and 3.75%, respectively. The proposed method was proved to be a simple, sensitive, precise and accurate for the estimation of the minute concentrations of pregabalin in pure form and the developed formulations. Results verified that the proposed method could determine pregabalin at the ambient temperature without requiring high temperatures used in the existing methods. It was concluded that developed method was easier and more suitable for analysis of pregabalin in quality control of commercial preparations

Effect of cellulose acetate phthalate and polyethylene glycol on physical properties and release of theophylline from microcapsules

ABSTRACT The present study describes the development of theophylline microcapsules by a non-solvent addition method and the effect of plasticizer addition on microencapsulation. The release was studied in distilled water and the data were analysed by various mathematical models for determining the mechanism of release. Prepared microcapsules were found to be spherical, free flowing and having more than 80% entrapped drug. The polymer - cellulose acetate phthalate and plasticizer - polyethylene glycol was considered to be affecting the properties of microcapsules including drug release (time for 50% drug release, T50). The formulation with the highest proportion of polymer and without plasticizer (F3) showed the slowest release with T50 = 4.3 h, while the formulation with lower proportion of polymer and 20% (w/w) plasticizer (F13 &14) showed the fastest release of drug with T50 values of 1.2 h and 1.3 h, respectively. The drug release from most of the formulations was found to be following Higuchi model. It is concluded from the results of the present study that cellulose acetate phthalate significantly affects the sustained release of the drug in water, whereas the addition of polyethylene glycol slightly enhances the drug release.

RESUMO O presente estudo descreve o desenvolvimento de microcápsulas de teofilina pelo método sem adição de solvente e o efeito da adição de plastificante na microencapsulação. A liberação foi estudada em água destilada e os dados foram analisados por vários modelos matemáticos para determinação do mecanismo de liberação. As microcápsulas preparadas mostraram-se esféricas, livres de corrente e com mais de 80% de fármaco encapsulado. O polímero - ftalato de acetato de celulose e o plastificante - polietileno glicol - afetaram as propriedades das microcápsulas, incluindo a liberação do fármaco (tempo para liberação de 50% do fármaco, T50). A formulação com a maior proporção de polímero e sem plastificante (F3) se mostrou como a de liberação mais lenta, com T50 = 4,3 h, enquanto as formulações com menor proporção de polímero e 20% de plastificante (m/m) (F13 &14) apresentaram a liberação mais rápida do fármaco, com T50 de 1,2 h e 1,3 h, respectivamente. A liberação do fármaco para a maioria das formulações seguiu o modelo de Higuchi. Concluiu-se, dos resultados do presente estudo, que o ftalato do acetato de celulose afeta significativamente a liberação controlada do fármaco em água, enquanto que a adição de polietileno glicol aumenta ligeiramente a liberação do fármaco.

Disposition and tissue distribution of imatinib in a liposome formulation after intravenous bolus dose to mice / 药学学报

Imatinib is an efficacious anticancer drug with a spectrum of potential antitumour applications limited by poor biodistribution at therapeutic concentrations to the tissues of interest. We assess the pharmacokinetic and tissue distribution profile of imatinib in a liposome formulation. Its single dose (6.25 mg x kg(-1)) in a liposome formulation was administered iv to male mice. Imatinib concentration was measured in plasma, spleen, liver, kidney and brain using a HPLC assay. Non-compartmental pharmacokinetic approach was used to assess the disposition parameters. The plasma disposition profile was biphasic with a plateau-like second phase. The AUC(0-->infinity) was 11.24 microg x h x mL(-1), the elimination rate constant (k(el)) was 0.348 h(-1) and the elimination half life (t(1/2)) was 2.0 h. The mean residence time (MRT) was 2.59 h, V(SS) was 1.44 L x kg(-1) and clearance was 0.56 L x h x kg(-1). Liver achieved the highest tissue exposure: CMAX = 18.72 microg x mL(-1); AUC(0-->infinity)= 58.18 microg x h x mL(-1) and longest t(1/2) (4.29 h) and MRT (5.31 h). Kidney and spleen AUC(0-->infinity) were 47.98 microg x h x mL(-1) and 23.46 microg x h x mL(-1), respectively. Half-life was 1.83 h for the kidney and 3.37 h for the spleen. Imatinib penetrated into the brain reaching approximately 1 microg x g(-1). Upon correction by organ blood flow the spleen showed the largest uptake efficiency. Liposomal imatinib presented extensive biodistribution. The drug uptake kinetics showed mechanism differences amongst the tissues. These findings encourage the development of novel imatinib formulations to treat other cancers.