Directly compressed mini-tablets coated in a solid wall pan for the sustained release of drugs

Sustained release mini-tablets can be produced either as matrix or by coating the mini-tablets in a fluid bed apparatus. Until now the coating of mini-tablets in a pan has not been extensively utilised; however this process shows advantages over the fluid bed providing higher production capabilities, lower waste of coating materials and faster equipment cleaning time. The aim of this research was to investigate the possibility of manufacturing a sustained release multiple dosage form by coating in a solid wall pan mini-tablets produced by direct compression; theophylline was employed as a model drug and WAS, an innovative ready to use pigment dispersion, was tested to evaluate the possibility of reducing production time. The results obtained showed that: ·mini-tablets having a high amount of theophylline, low friability and high crushing strength were obtained by direct compression ·a solid wall pan represents a suitable technique for mini-tablets coating ·the use of a ready to mix pigment dispersion represents a suitable method to shorten coating suspension preparation time. Therefore a sustained release multiple dosage form was successfully manufactured by using a tablet press and a solid wall pan