Formulation Development, Characterization and In-vitro Evaluation of Tamoxifen Loaded Liposomes

Background: The study was aimed to prepare and evaluate tamoxifen loaded controlled release liposomes to reduce the side effects of tamoxifen during cancer treatment. Methods: Different tamoxifen loaded liposomes were prepared by modified ether injection (MEIM) and thin film hydration method (TFHM) under prescribed conditions. The prepared liposomes were characterized by using optical microscopy, evaluating encapsulation efficiency, in-vitro and ex-vivo diffusion studies by using dialysis membrane and chicken intestinal sac respectively.Results: The data revealed that all of the liposomes were spherical in shape and stable under three physical conditions i.e. 4, 25 and 37 ± 2°C temperatures and 60 ±5% relative humidity. Additionally most of the liposomes followed zero order and class II release kinetics. It was also observed that with the increase of phospholipids and cholesterol, entrapment efficiency of liposome vesicles increased thus giving a controlled release drug delivery system but further increase reduced this efficiency at a certain level.Conclusion: The formulated control release liposomes might be a good drug delivery system for target oriented drug delivery with minimum side effects of tamoxifen during cancer treatment

A preformulation strategy for the selection of controlled-release components to simulate a subcutaneous implant / Una estrategia de preformulación para la selección de componentes de liberación controlada para simular un implante subcutáneo

Many chronic diseases require repetitive injections as maintenance treatment. It is therefore important to investigate a possible alternative. A simulated subcutaneous implant prototype was fabricated as a polymer matrix covered by cylinder-shape tubing having a porous membrane. Sucrose, bovine serum albumin, and gelatin were selected as matrix excipients. Eight APIs with different physiochemical properties were used to investigate the releasing mechanism. Drug release was tested through an in vitrodissolution apparatus. Drug release of eight APIs followed zero-order kinetics with a minimum 12-hour duration. Release rates also showed linear correlations with the APIs' solubilities under physiological pH. For releasing mechanism studies, different combinations of matrix and membrane were investigated in detail. A 144-hour continuous zero-order release of caffeine was achieved as the best controlled simulated prototype. The results showed that drug release of our simulated prototype was primarily achieved by drug diffusion rather than dissolution.

Muchas enfermedades crónicas requieren inyecciones repetitivas como tratamiento de mantenimiento. Por lo tanto, es importante investigar una posible alternativa. Se fabricó un prototipo de implante subcutáneo simulado a partir de una matriz de polímero cubierta por un tubo en forma de cilindro que tiene una membrana porosa. La sacarosa, la albúmina de suero bovino y la gelatina se seleccionaron como excipientes matriciales. Se utilizaron ocho APIs con diferentes propiedades fisicoquímicas para investigar el mecanismo de liberación. La liberación del fármaco se probó a través de un aparato de disolución in vitro. La liberación del fármaco de las ocho APIs siguió una cinética de orden cero con una duración mínima de 12 horas. Las tasas de liberación también mostraron correlaciones lineales con las solubilidades de las APIs a pH fisiológico. Para los estudios de mecanismos de liberación, se investigaron en detalle diferentes combinaciones de matriz y membrana. El prototipo simulado con mejor control logró una liberación continua de cafeína de orden cero durante 144 horas. Los resultados mostraron que la liberación del fármaco del prototipo simulado ocurrió principalmente mediante la difusión del fármaco en lugar de la disolución.

Numerical analysis of effects from atherosclerotic plaque on drug diffusion in drug-eluting stent / 医用生物力学

Objective To study the effect from drug diffusion coefficient of atherosclerotic plaque on drug diffusion within the arterial wall, so as to truly reflect the drug distributions. Methods Using computational fluid dynamics (CFD) method, five plaque models with different diffusion coefficients were employed to numerically investigate the distributions of drug concentration both within the arterial wall and the plaque. Results The drug concentration in the arterial wall was increased gradually with the diffusion coefficient of the plaque increased; however, the increment would become gentle. Conclusions When the diffusion coefficient in the plaque was smaller than the tissue, the plaque inhibited the drug diffusion within the arterial wall, or conversely, it would promote the diffusion. Especially when the diffusion coefficient in the plaque was much larger than the tissue, it no longer affected the drug diffusion within the arterial wall. It is necessary to consider the impact of plaque in further research, which is beneficial to the optimization design of drug-eluting stents.