Studies On Levamlodipine Besylate And Losartan Potassium Osmotic Pump Tablets

In the present study, Levamlodipine Besylate and Losartan Potassium were selected as the model drugs to prepare bi-layer osmotic pump tablets (BOPT). The drug release characteristics, mechanism, as well as the stability of the Levamlodipine Besylate and Losartan Potassium BOPT were studied.In the preparation of BOPT, the tablet core was prepared using several accessories such as polyethylene oxid (PEO), sodium chloride, polyvinylpyrrolidine K-29-32 (PVP, K-29-32), and hydroxypropyl methylcelluse (HPMC). Cellulose acetate (CA) and polyethylene glycol 400 (PEG400) were selected as the coating material and acetone was employed as the coating medium. The effects of many factors including formulation of drug layer, push layer and coating membrane, hardness of tablet core and the condition of drug release on the release behavior of BOPT were investigated. Based on the single-factor experiments, amount of NaCl, PEO in the push layer and coating thickness were selected as the main factors, the property of sustained release of Losartan Potassium and the release degree of Levamlodipine Besylate were used as the indexs to optimize the formulations according to orthogonal design. The results indicated that the optimal formulation exhibited the excellent zero-order release characteristics for LB and LP, and favorable release amount for LB. The mechanism investigation of the in vitro drug release suggested that the main driving force of drug release was the osmotic pressure difference between the tablet core and the dissolution medium during drug release.In addition, we investigated the stability of three batch samples according to the optimal formulation in terms of the influence test, accelerated test and long period stability test. The results indicated that all the samples exhibited excellent stability under the test condition.