Chemistry Department, Bahauddin Zakarya University, Multan, Pakistan.
Daru. 2013 Jan 18;21(1):10. doi: 10.1186/2008-2231-21-10.
Hydrogels, being stimuli responsive are considered to be effective for targeted and sustained drug delivery. The main purpose for this work was to study the release behavior and kinetic evaluation of Tramadol HCl from chemically cross linked ter polymeric hydrogels.
Ter-polymers of methacrylate, vinyl acetate and acrylic acid cross linked with ethylene glycol dimethacrylate (EGDMA) were prepared by free radical polymerization. The drug release rates, dynamic swelling behavior and pH sensitivity of hydrogels ranging in composition from 1-10 mol% EGDMA were studied. Tramadol HCl was used as model drug substance. The release behavior was investigated at pH 8 where all formulations exhibited non-Fickian diffusion mechanism.
Absorbency was found to be more than 99% indicating good drug loading capability of these hydrogels towards the selected drug substance. Formulations designed with increasing amounts of EGDMA had a decreased equilibrium media content as well as media penetrating velocity and thus exhibited a slower drug release rate. Fitting of release data to different kinetic models indicate that the kinetic order shifts from the first to zero order as the concentration of drug was increased in the medium, showing gradual independency of drug release towards its concentration. Formulations with low drug content showed best fitness with Higuchi model whereas those with higher concentration of drug followed Hixson-Crowell model with better correlation values indicating that the drug release from these formulations depends more on change in surface area and diameter of tablets than that on concentration of the drug. Release exponent (n) derived from Korse-Meyer Peppas equation implied that the release of Tramadol HCl from these formulations was generally non-Fickian (n > 0.5 > 1) showing swelling controlled mechanism. The mechanical strength and controlled release capability of the systems indicate that these co-polymeric hydrogels have a great potential to be used as colon drug delivery device through oral administration.
水凝胶作为一种对刺激有响应的物质，被认为是用于靶向和持续药物输送的有效物质。这项工作的主要目的是研究盐酸曲马多从化学交联的三聚合物水凝胶中的释放行为和动力学评价。
通过自由基聚合制备了甲基丙烯酸盐、醋酸乙烯酯和丙烯酸的三聚合物，与乙二醇二甲基丙烯酸酯（EGDMA）交联。研究了组成范围为 1-10mol% EGDMA 的水凝胶的药物释放速率、动态溶胀行为和 pH 敏感性。盐酸曲马多被用作模型药物。在 pH 8 下研究了释放行为，所有制剂都表现出非菲克扩散机制。
吸水性超过 99%，表明这些水凝胶对所选药物具有良好的药物负载能力。随着 EGDMA 用量的增加，制剂的平衡介质含量以及介质穿透速度降低，从而表现出较慢的药物释放速率。不同动力学模型拟合释放数据表明，随着介质中药物浓度的增加，动力学顺序从一级转变为零级，表明药物释放逐渐独立于其浓度。药物含量低的制剂与 Higuchi 模型拟合最好，而药物浓度较高的制剂则遵循 Hixson-Crowell 模型，具有更好的相关值，表明这些制剂的药物释放更多地取决于片剂表面积和直径的变化，而不是药物浓度的变化。从 Korsmeyer-Peppas 方程得出的释放指数（n）表明，盐酸曲马多从这些制剂中的释放通常是非菲克扩散（n>0.5>1），表现出溶胀控制机制。该系统的机械强度和控释能力表明，这些共聚物水凝胶具有作为口服结肠递药装置的巨大潜力。
