Corresponding Author Page | 2286 Ashok Thulluru; DOI- http://dx.doi.org/10.21746/ijcls.2022.11.1.3 ISSN: 2234-8638 International Journal of Chemical and Life Sciences Volume 11, Issue 1 (2022) 2286-2297 Formulation and In Vitro Evaluation of Enalapril Maleate Gastro- Retentive Effervescent Floating Tablets with the Combination of Natural and Synthetic Polymers Sireesha Reddy Pilaka 1 , Anand Addagalla 2 , Varun Srighakolapu 1 , Sasi Praveen Varma Vegesna 1 , Uday Sai Nekkalapu 1 , Rama Rao Vadapalli 3 and Ashok Thulluru 1 * 1 Dept. of Pharmaceutical Quality Assurance, Shri Vishnu College of Pharmacy (Autonomous), Vishnupur, Bhimavaram-534 202, West Godavari Dist., Andhra Pradesh, India. 2 Dept. of Pharmaceutics, Shri Vishnu College of Pharmacy (Autonomous), Vishnupur, Bhimavaram-534 202, West Godavari Dist., Andhra Pradesh, India. 3 Dept. of Pharmaceutics, KGRL College of Pharmacy, Dirusumarru Road, Bhimavaram-534 201, West Godavari Dist., Andhra Pradesh, India Abstract: The aim of present study was to convert enalapril maleate (EM) into Gastro Retentive effervescent Floating Tablet (GRFT), which can extend its release up to 12 h in gastric pH and simultaneously to study the effect of combination of synthetic (HPMC K100M) with natural polymers [Sodium alginate (SA), guar gum (GG) and xanthan gum (XG)] in extending the release of EM Methods: The drug- excipient compatibility studies of EM and the polymers were carried by FT-IR studies. The effervescent EMFTs were prepared by direct compression. All Formulations were evaluated for pre-compression, post-compression, in vitro buoyancy studies. Accelerated stability studies were conducted for the optimized formulation (F6). Results: The drug- excipients compatibility studies reveals that combination of EM and the polymers used are compatible. Pre- and post- compression parameters were within the acceptable limits for all formulations. In vitro dissolution studies, showed the formulation F6 (10% SA and 35% HPMC K100M and the ratio of SA: HPMC; 1: 3.5 respectively) is exhibiting better extended release of EM up to 12 h, with a floating lag time (FLT) of 58 ± 0.04 sec, total floating time (TFT) and matrix integrity (MI) maintained up to 12 h. Drug release kinetics of formulation (F6) suggests it follows zero order kinetics, drug release is predominantly by diffusion and the release mechanism is by super case-II transport. Comparative DSC & FT-IR studies of pure EM and optimized formulation (F6) accelerated stability 3 M samples further confirmed the integrity of drug and it passes the test for stability as per ICH guidelines. It was finally concluded that EMFTs was formulated and evaluated. Key words: Enalapril maleate, gastro retentive floating tablets (GRFTs), hydroxy propyl methyl cellulose (HPMC K100M), sodium alginate, xanthan gum, guar gum, in vitro buoyancy studies Introduction A gastro-retentive drug delivery systems (GRDDS) can be defined as a system which remains in the stomach for a sufficient time interval against all the physiological barriers, releasing the active moiety in a controlled manner (Bhandwalkar, M. J. et al., 2020). A GRDDS can be a useful tool in delivery of drugs that are primarily absorbed in the duodenum and upper jejunum or those that have an absorption window in the gastrointestinal tract (Niharika, M. G. et al., 2018). Various GRDDS include floating systems, bio adhesive, swelling, expanding and high density systems. Floating systems are more popular in comparison with the other described GRDDS because they do not have any adverse effect on the motility of the GIT (Patil, H. et al., 2016; Lopes, C. M. et al., 2016). Based on the mechanism of floating, two systems of FDDS are effervescent and non-effervescent systems. Effervescent systems contains carbonates (eg. sodium bicarbonate) and / or organic acids (eg. Research Article Open Access