Formulation and evaluation of press coated tablets of salbutamol sulphate for time controlled release

Abstract

The objective of the present study was to formulate and evaluate a press coated pulsatile drug delivery system of salbutamol sulphate in order to attain a time controlled release for treatment of nocturnal asthma. The core was prepared by direct compression, while press coating technique was used in coating the outer layer there by preparing a press coated tablet. The immediate release core formulations comprised of salbutamol sulphate and disintegrants like crospovidone, croscarmellose sodium and sodium starch glycolate in different ratios with the drug. The outer coat formulations were prepared using a hydrophilic (HPMC) and hydrophobic (EC) polymer of similar viscosity. The polymers were reviewed individually for their influence on lag time further obtaining the lag time using polymer combinations were assessed by employing central composite design. All the preliminary trials were evaluated for various post compression parameters along with the dissolution study that was performed using USP paddle method at 50 rpm in 0.1 N HCl and phosphate buffer pH 6.8. The formulation containing 300 mg of EC N50 and 75‑100 mg of HPMC E50 may be regarded as the minimum quantity required in outer press coat so as to attain a predetermined lag time of 6 h. Key words: Central composite design, ethylcellulose, hydroxypropyl methylcellulose, press coat, salbutamol sulphate, time controlled release