Formulation and Evaluation of Controlled Release Matrix Tablets of Labetalol HCl

Oral controlled drug delivery systems have received much attention of the researchers during the past two decades. The rationale for developing a controlled release formulation is to enhance its therapeutic benefits, reducing its side effects and improving the management of diseased condition.

Studies have been carried out for developing oral controlled release matrix tablet formulations of labetalol by using polymeric materials like polyox WSR 301, polyox WSR 303, polymethacrylates, ethyl cellulose, xanthan gum, guar gum, karaya gum and sodium alginate.

The prepared matrix tablets were evaluated for weight uniformity, hardness, friability and drug content. The matrix tablets were then evaluated for the influence of polymer concentration, polymer type and nature of diluents on the drug release from matrix by in vitro dissolution studies. FTIR Spectral studies shown that drug and excipients used were compatible with each other. Selected formulations of Labetalol were subjected to accelerated stability studies. The formulations were stored at 400C±2°C, 75±5%RH for 3 months. No significant changes were observed from the prepared tablets during the study period.

The results of present research work clearly indicated that the nature and level of poly (ethylene oxides) in the matrix tablets greatly influenced the drug release properties. Both the Polyox WSR 301 and Polyox WSR 303 were suitable for preparing the matrix tablets of labetalol. Among the two polymers used, high molecular weight polymer, POLYOX WSR 303 effectively extended the drug release for prolonged period of time than low molecular weight POLYOX WSR 301. Insoluble diluents like microcrystalline cellulose, dicalcium phosphate and slightly soluble diluent like starch 1500 can be used as release rate modifiers in the formulation of controlled release matrix tablets.

A combination of hydrophilic gums, hydrophobic eudragits and ethyl cellulose with high molecular weight poly (ethylene oxides) led to prolonged release of drug up to 22 hrs. Thus present research work fulfilled the objective of developing once a day formulations of Labetalol as matrix tablets employing poly (ethylene oxides).