Formulation and Evaluation of Bilayer tablet of Lisinopril and Gliclazide for Diabetic Hypertension

Bilayer tablet technology offers an effective approach for the management of chronic diseases requiring combination therapy. The present study focuses on the formulation and evaluation of bilayer tablets containing Lisinopril and Gliclazide for the treatment of hypertension associated with type 2 diabetes mellitus. The objective of the study was to develop a formulation providing immediate release of Lisinopril for rapid antihypertensive action and sustained release of Gliclazide for prolonged glycemic control. Bilayer tablets were prepared by direct compression method using different concentrations of superdisintegrants and matrix forming polymers such as Hydroxypropyl Methylcellulose (HPMC), Hydroxypropyl Cellulose (HPC), Hydroxyethyl Cellulose (HEC) and Ethyl Cellulose (EC). Precompression parameters including angle of repose, bulk density, Carr’s index and Hausner ratio were found within acceptable pharmacopeial limits, indicating good flowability and compressibility of powder blends. Postcompression evaluation showed satisfactory hardness (3.40–3.83 kg/cm²), friability below 1%, uniform thickness and acceptable drug content. The optimized immediate release formulation CC8 showed 96.65% drug release of Lisinopril within 30 min, whereas sustained release formulations prolonged the release of Gliclazide for more than 8 h following zero-order kinetics with super case-II transport mechanism. The optimized bilayer tablet formulation BCC8F14 exhibited satisfactory physicochemical properties and desired bimodal drug release profile. Stability studies revealed no significant changes under accelerated conditions. The developed bilayer tablet formulation may improve therapeutic efficacy, patient compliance and effective management of diabetic hypertension.