FORMULATION AND CHARACTERIZATION OF SUSTAIN RELEASE TABLETS OF LABETALOL HYDROCHLORIDE

Abstract

The present study aimed to formulate and evaluate sustained-release floating tablets of Labetalol
hydrochloride, a non-selective β-blocker used in the management of hypertension, to improve gastric
retention and achieve prolonged drug release. Preformulation studies confirmed the drug’s
physicochemical suitability, revealing it as a white to off-white, odorless crystalline powder with high
solubility across multiple solvents and a melting point of 178–180°C. UV spectrophotometric analysis
exhibited excellent linearity (10–50 μg/ml) at 295 nm with a correlation coefficient (R² = 0.999), while
FTIR analysis confirmed the presence of characteristic functional groups without structural alteration.
Tablets were prepared by direct compression using polymers such as Chitosan and Carbopol 940P,
along with sodium bicarbonate as an effervescent agent. Pre- and post-compression evaluations
indicated satisfactory flowability, mechanical strength, and uniformity, with all parameters within
pharmacopeial limits. In-vitro buoyancy studies showed that formulation F8 achieved the shortest
floating lag time (34 ± 4 sec) and remained buoyant for over 12 hours. The in-vitro drug release profile
demonstrated sustained release up to 12 hours, with F8 exhibiting 98.12% cumulative drug release,
attributed to the formation of a stable gel matrix. Kinetic modeling revealed that drug release followed
first-order kinetics (R² = 0.9899) with a non-Fickian diffusion mechanism, as indicated by Higuchi (R² =
0.9147) and Korsmeyer–Peppas (R² = 0.9487) models. The optimized formulation (F8) demonstrated
excellent buoyancy, prolonged gastric residence, and controlled drug release, ensuring better therapeutic
efficacy and patient compliance. Thus, the developed floating matrix tablets of Labetalol hydrochloride
present a promising approach for sustained antihypertensive therapy with improved bioavailability and
reduced dosing frequency.