A NEW-GENERATION STARCH PRODUCT AS EXCIPIENT IN PHARMACEUTICAL TABLETS .3. PARAMETERS AFFECTING CONTROLLED DRUG-RELEASE FROM TABLETS BASED ON HIGH-SURFACE-AREA RETROGRADED PREGELATINIZED POTATO STARCH

This paper describes the general applicability of a new pregelatinized starch product in directly compressible controlled-release matrix sys tems. It was prepared by enzymatic degradation of potato starch follow ed by precipitation (retrogradation), filtration and washing with etha nol. The advantages of the material include ease of tablet preparation , the potential of a constant release rate (zero-order) for an extende d period of time and the possibility to incorporate high percentages o f drugs with different physicochemical properties. Constant release pr ofiles are the result of solvent penetration into the tablet. For theo phylline as test drug, constant release profiles could be realized up to a drug content of 75%. This illustrates the possibility to control the release of highly dosed drugs. Release rates from retrograded preg elatinized starch tablets can be enhanced or decreased to the desired profile by different parameters, like geometries of the tablet, compac tion force and the incorporation of additional excipients. For procain e HCl it is demonstrated that larger tablets show slower release rates . The incorporation of soluble excipients like lactose and mannitol re sults for paracetamol in enhanced release rates. The delivery of bases and their salts can be modified by the incorporation of organic acid or alkaline excipients, as is demonstrated for lidocaine and procaine HCl. (C) 1997 Elsevier Science B.V.