Abstract
A time dependent pulsed release system consisting of an effervescent core surrounded by consecutive layers of swelling and rupturable polymers was prepared and evaluated. The cores containing salbutamol sulphate as bioactive agent were prepared by direct compression method using different ratios of microcrystalline cellulose and effervescent agent and then coated sequentially with an inner swelling layer containing a hydrocolloid, hydroxypropylmethylcellulose E5 and an outer rupturable layer having Eudragit RL/RS (1:1). The effects of various processing and formulative parameters on the performance of system were studied. The rupture and dissolution tests were studied using the USP paddle method at 50 rpm in 0.1 N HCl and phosphate buffer pH 6.8. The lag time of the drug release decreased by increasing the inner swelling layer and increased by increasing the rupturing layer level. All the results obtained in the present study suggest that osmotic pumping effect was involved which eventually lead to the drug release.