Development and evaluation of dapsone tablets coated for specific colon release.

Drug release systems based on colonic microbiota have been explored with the use of polysaccharides, which are biodegradable. In order to modulate the release into the colon, dapsone tablets were developed, coated with Surelease® and chondroitin sulfate. : The formulation was developed using the wet granulation method, in the form of 9-millimetre circular tablets. The coating was applied in a perforated basin-type coating using different proportions of Surelease and chondroitin sulfate. The tablets were assessed according to the criteria of mean weight, hardness, and friability. The dissolution test was performed in the dissolver IV apparatus, in media simulating the gastrointestinal system environments (pH 1.2 - pH 6.0 and pH 7.2) for 420 minutes. The results were analyzed by statistical analysis and factorial design. : The results of mean weight, hardness, and friability met the pharmacopoeial specifications. In the dissolution test, the results obtained demonstrated that Surelease is able to offer effective protection to the drug, releasing minimum rates when used at 6% or 10% of the tablet's weight gain. The experiments showed that the drug was not able to spread through the coatings manufactured exclusively with Surelease or even when SC was incorporated in different proportions. Only in the formulation where SC was included in the highest proportion (10%), and the weight gain of the tablet was lower (6%), the release of dapsone increased, reaching 9.5% of drug released. Through factorial planning, it was observed that the drug release rate increases when the weight gain of the tablet remains at the lower level (6%), while the amount of polysaccharide is increased (90:10). : The data indicate that the proportion of polysaccharide for ethyl cellulose in the film and the thickness of the coating are the key parameters in controlling the release of the drug from the system.