PROCESSING CONSIDERATIONS FOR AN EC LATEX COATING SYSTEM - INFLUENCE OF CURING TIME AND TEMPERATURE

The influence of curing time and curing temperature for a commercially available ethylcellulose latex coating dispersion (Aquacoat((R))) wer e evaluated using response surface methodology. Levels for the factor curing time ranged from 30 to 300 minutes while levels for curing temp erature ranged from 45 degrees to 75 degrees C. Responses, A, kappa, a nd gamma, were derived from regression analysis of the dissolution pro files and correspond to the maximum amount of drug released over the 1 2 hour sampling period, the rate of release, and the inflection point of the dissolution profile, respectively. The nature of the response s urface was dramatically influenced by the plasticizer incorporated int o the coating formula. When dibutyl sebacate was employed as the plast icizer, faster release resulted (higher A and kappa values, lower gamm a values) when samples were exposed to higher curing temperatures or w ere stored for longer periods of time. Paradoxically, when tributyl ci trate was used as the plasticizer, slower release resulted when sample s were exposed to more rigorous conditions. Overall, curing temperatur e had a more dramatic effect than curing time.