THE USE OF A FACTORIAL DESIGN TO EVALUATE THE PHYSICAL STABILITY OF TABLETS PREPARED BY DIRECT COMPRESSION .2. SELECTION OF EXCIPIENTS SUITABLE FOR USE UNDER TROPICAL STORAGE-CONDITIONS

A factorial design has been used to study the influence of disintegrant concentration, storage temperature and relative humidity upon storage on the physical stability of tablets prepared by direct compression. Tablets prepared from a binary mixture of a filler-binder and a disintegrant were stored at different conditions. The ratios of the tablet parameters after storage to the initial parameters (Storage to Initial Ratio:SIR) of the crushing strength and the disintegration time were calculated and used as dependent variables. Filler-binders used were alpha-lactose monohydrate, beta-lactose and dicalcium phosphate dihydrate. Disintegrants (corn, potato, rice and tapioca starch, sodium starch glycolate and crospovidone) were added in a high and in a low concentration. With aid of multiple linear regression, the influence of three adjustable variables (disintegrant concentration, storage temperature and storage relative humidity) on the storage to initial ratio of the tablet parameters was calculated. A selection was made as to which excipients are least influenced by storage conditions and can be used in tablet formulations for tropical countries