Development of terbutaline sulfate sustained-release coated pellets.

Sustained-release coated pellets containing terbutaline sulfate (TS) 1.8% w/w were prepared. The suitable core formulation that gave round-shape TS pellets was preformulated and was composed of microcrystalline cellulose:lactose 38.61%:57.92%, hydroxypropyl cellulose (HPC-M) 1.67%, and water 40%, respectively. The core pellets containing active drug were coated with various amounts of ethylcellulose (EC) and a combination of EC/HPC-M polymers. The effects of fluidized bed polymeric film coats on drug release were studied in vitro. The dissolution characteristics were also investigated. The release of the active drug decreased as the amount of EC increased. This may be due to water-insoluble EC film, leading to decreased permeability in water. In the case of the combination of EC/HPC-M, the release of the active drug increased as the amount of HPC-M in the coating solution increased. Since HPC-M is a water-soluble polymer, it may be suggested that formation of pores were increased in the coating layer. Among five coating formulas in this study, formulation 1 (F1) (at 1.1% EC concentration) shows a similar dissolution profile to Bricanyl Durules; however, lag time for the release occurred. In conclusion, the formulation that gave an insignificant release profile (p < .01) when compared with commercial product was the capsule containing F1 (at 1.1% EC concentration) mixed with uncoated pellets at a ratio of 7:1, and the release was found to be reproducible.