Original Article BOX-BEHNKEN DESIGN FOR OPTIMIZATION OF FORMULATION VARIABLES FOR CONTROLLED RELEASE GASTRORETENTIVE TABLET OF VERAPAMIL HYDROCHLORIDE INDURKHYA ARPNA * , KHAN AHMED MASHEER School of Pharmacy, DAVV, Indore, Madhya Pradesh 452020, India Email: indurkhyarpana@gmail.com Received: 30 Sep 2022, Revised and Accepted: 08 Nov 2022 ABSTRACT Objective: To develop a Verapamil hydrochloride controlled release gastro-retentive (CRGR) tablet for once-daily dosing using the response surface Box-Behnken Design (BBD) approach for the improvement of bioavailability and reduction in dosing frequency to overcome the issues related to the conventional tablet formulation. Methods: For the optimization, 3 3 Box-Behnken design was used. The independent variables were selected, the amount of Compritol 888 ATO (A), HPMC K15M (B), and Sodium bicarbonate (C). The dependent variables were Cumulative % drug release in 1.5 h (Q1.5), 8 h (Q8), 24 H (Q24) and floating lag time (FLT). Flow properties of pre-compressed powder, physical characteristics, drug content, floating lag time, total floating time and in vitro dissolution study of all formulation were assessed. In vitro dissolution study of optimized formulation that was prepared experimentally was performed and compared with predicted data obtained from the software. Drug release kinetics of the optimized formulation was also assessed to know the mechanism of drug release from the CRGR tablets. Results: Responses of experimental runs were found as Q1.5: 12.78-33.62 (%), Q8: 43.03-64 (%), Q24: 78.77 to 103.57 (%) and floating lag time as 3.01 min to 5.08 min. The predicted optimized formula with the highest desirability value of 0.963 containing amount 126.030 mg, 160.00 mg and 80.955 mg of Compritol 888 ATO, HPMC K15M and Sodium biarbonate respectively was prepared and evaluated. The experimental values from optimized formulation were obtained as Q1.5: 23.397%, Q8; 57.744%, Q24: 97.150% and FLT: 3.12 min. Predicted and experimental results were found comparable for all the responses. The release data from the optimized formulation were best fitted in the Higuchi (r 2 = 0.999) and the Korsmeyer-Peppas ((r 2 = 0.998, n=0.54) model. The in vitro drug release studies indicated that the Verapamil hydrochloride gastroretentive tablet releases the drug in controlled manner for 24 h. Conclusion: This study found that using Box-Behnken Design with the response and variable relation, it is possible to achieve an optimum formulation with desirable characteristics. This study also established the suitability of Compritol 888 ATO-HPMC K15M combination with Sodium bicarbonate to increase the gastric residence time tablet formulation had once-daily dosing of the Verapamil Hcl with improved bioavailability for effective management of hypertension. Keywords: Box Behnken Design, Verapamil Hcl, Controlled release gastroretentive tablet © 2023 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2023v15i1.46489. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Verapamil Hydrochloride is an L-type voltage-gated calcium channel blocker antihypertensive of BCS-I drug having low absolute bioavailability (20%) due to short biological half-life (4.0±1.5 h), pH- dependent solubility (pKa 8.6), lower solubility in intestines with higher pH (0.44 mg/ml at pH=7.32), and first-pass metabolism by the intestinal wall too [1, 2]. The bioavailability of verapamil hydrochloride can be increased by gastric retention [3, 4]. The use of an oral controlled release gastro retentive drug delivery system (GRDDS) for the treatment of hypertension is an effective approach [5, 6]. Among the various gastroretentive drug delivery methods, the floating drug delivery system (FDDS) is a known effective method for delivering drugs specifically to the stomach [4, 7, 8]. Design of experiments (DoE) has been an exceptionally valuable method for building design spaces [9, 10]. The response surface methods Central Composite Design (CCD) and Box-Behnken designs (BBD) are strong, effective, and systematic response surface methodology (RSM) that speed up the process of developing pharmaceutical dosage forms and enhance research productivity [11]. Box-Behnken designs (BBD) use fewer experimental runs, which makes the application more practical and effectively estimates first-order and second-order coefficients than CCD [12]. The goal of this study was to develop once-daily dosing of controlled release gastro-retentive (CRGR) floating formulation of Verapamil hydrochloride with desirable characteristics using BBD with the response and variable relation. This study might be used in the numerous experiments with different variables and outcomes. MATERIALS AND METHODS Verapamil HCl (VH) was made available as a gift sample by Matrix Laboratories Ltd. Hyderabad, India. Compritol 888 ATO was provided as gift samples by Gattefose Ltd., HPMC K15Mwas supplied by Colorcon Asia Pvt. Ltd. India, sodium bicarbonate, citric acid, xantham gum, microcrystalline cellulose, talc, and magnesium stearate were procured from the department were of analytical grade. All other substances including solvents were of analytical grade. Selection of excipients In the selection of excipients, preliminary batches were prepared using Compritol 888 ATO (lipid-based excipient) and various HPMC (HPMC K4M, HPMC K15M, and HPMC K100M), effervescent generating agents (in different concentration) with half the concentration of citric acid as pH modifier along with other excipients like magnesium stearate, talc and xantham gum. Drug excipient compatibility study To check for any potential interactions, the Differential Scanning Calorimeter (DSC) of Mettler-Toledo (RJC) was used to conduct DSC analyses of both pure drugs and drug-polymer mixtures. Triturating drugs, polymers, and their mixtures reduced their size such that they could be heated at a rate of 10 °C/min from 30 °C to 180 °C in sealed aluminum pans and 40 ml/min nitrogen flow was present [13]. Methods Preparation of verapamil HCl CRGR tablet formulations Verapamil HCl CRGR Tablets were prepared using the direct compression method [14]. The following ingredients were processed International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 15, Issue 1, 2023