Comparison between ethylcellulose aqueous colloidal dispersion and ethylcellulose ethanolic solution as rupturable coating materials for pulsatile release tablets

Pulsatile release dosage forms which time of drug release can be determined have shown advantages for various drugs such as chronopharmacological drugs and drugs with high first pass metabolism. The pulsatile release tablets consisting of drug-containing cores coated with inner swelling layer containing a superdisintegrant (croscarmellose sodium (Ac-Di-Sol®)) and outer rupturable layer (ethylcellulose (EC)) were previously developed. In this study, two different types of EC coating membrane, EC ethanolic solution (ECS) versus EC aqueous colloidal dispersion (ECD), were compared. Propranolol HCl was used as a model drug. Effect of rupturable coating level on lag time and drug release was investigated. The results demonstrated that using ECS could provide the pulsatile release tablets with obviously longer lag time than ECD. With ECS, increasing of rupturable coating level increased lag time of the pulsatile release tablets because of the lowered water uptake. In addition, rapid drug release after the predetermined lag time was achieved in the pulsatile release tablets using ECS. However, the pulsatile tablets with ECD ruptured within a few minutes even high levels of rupturable coating were used. It was suggested that the different performance of the pulsatile release tablets with different types of EC might be related to the discrepancy in physical properties of the obtained EC membrane.