Effect of storage on crushing strength, disintegration and drug release from mixed tablet bases

Abstract

Several studies have been reported (Horhota et al., 1976; Lausier et al., 1977; Chowhan and Palagyi, 1978; Molokhia et al., 1982) on the changes in behavior of tablets upon storage. Such changes were found to be responsible for some bioavailability problems (York, 1977; Gouda et al., 1980). In a previous communication (Molokhia et al., 1982), the effect of two storage conditions 5O”C/50% relative humidity (R.H.) and 40 ‘C/90% R.H. on crushing strength, disintegration and drug release from single component tablet bases were reported. While lactose-, mannitoland sorbitol-based tablets were subjected to significant physical changes, tricalcium phosphate and powdered cellulose-based tablets were resistant to changes over a period up to 53 days. In this study, binary blends of the previously used tablet bases were incorporated with 25% benzoic acid, 4% starch, 2% talc and 1% magnesium stearate. Mixing was carried for 10 min in a tumbling mixer rotating at 60 rpm. The product was then compressed into tablets and examined for the effect of storage at 40 o C/90% R.H. on crushing strength, disintegration and drug release. The tablets, stored in paper bags, were examined at different time intervals over 10 weeks. The crushing strength and disintegration were determined as before (Molokhia et al., 1982). The drug release was determined by following the amount of benzoic acid dissolved as function of time using a USP dissolution apparatus and phosphate buffer 0.05 M, pH 6.0, as solvent. Samples were taken every 5 min for 35 min, filtered through 0.45 pm Millipore filter and assayed by measuring UV absorption at 222 nm. Fig. 1 shows the effect of storage on the crushing strength of tablets made of lactose and tricalcium phosphate. Similar graphs were obtained for each group of