Ethocel standard 20 premium

Matrix tablets of HCTZ were coated with an insoluble barrier membrane (BM) using aqueous ethylcellulose coating, Surelease® (containing medium chain triglyceride as plasticizer) and an HPMC-based Opadry® (HPMC low viscosity grade, 6 cps, triacetin, and talc) as a pore former, at 85:15 and 60:40 w/w ratios. The ratio of Surelease to Opadry was calculated based on total dry solids. Prior to application, the coating systems were dispersed in water at 10% w/w solids content. Tablets (batch size, 1 kg) were then coated to 2%–8% w/w weight gain (WG) in a fully perforated coating pan (LABCOAT I, O’Hara Technologies, Canada) using a 1-mm nozzle (970/7-1S75, Schlick, Germany). Standard coating processing parameters were used for application of aqueous ethylcellulose barrier membrane coating (i.e., product temperature, 42°C–45°C; spray rate of 6–8 g/min; air flow of 290 m³/h).
It is generally known that organic application of ethylcellulose coating can result in stronger film compared to the aqueous system. For comparison, the HCTZ matrix tablet cores containing lactose were also coated using a combination of ethylcellulose (ETHOCEL™ Standard 20 Premium) and hypromellose (METHOCEL E5LV) (The Dow Chemical Company, USA), as a pore former, at 85:15 and 60:40 w/w in a solvent mixture of isopropanol and water, 90:10 w/w, at 7% solids content.