Starch/Carbopol® spray-dried mixtures as excipients for oral sustained drug delivery

The present study evaluated if mixtures prepared by spray-drying an aqueous dispersion of Amioca® starch and Carbopol® 974P could be used as matrix for oral sustained drug delivery. The influence of the Amioca®/Carbopol® 974P ratio (0/100, 25/75, 50/50, 60/40, 85/15, 90/10, 95/5 and 100/0) and the pH and ionic strength (μ) of the dissolution medium on the drug release was investigated. The matrices composed of the spray-dried mixtures with 10% or 15% Carbopol® 974P sustained the drug release over the longest time period. At this Carbopol® concentration, shear viscosity measurements indicated the formation of an optimal network between the polymer chains of Amioca® starch and Carbopol® 974P, forming a rigid gel layer offering resistance to erosion during the dissolution experiments.