The effect of low- and high-humidity ageing on the hardness, disintegration time and dissolution rate of dibasic calcium phosphate-based tablets.

The effect of low- and high-humidity ageing on hardness, disintegration time and dissolution rate of dibasic calcium phosphate dihydrate-based tablets prepared at different initial moisture concentrations was studied. Hardness increased while distintegration and dissolution rate decreased on ageing in low humidity. The dissolution rate of tablets containing higher initial moisture was slower than the tablets containing lower initial moisture. On ageing in high humidity, hardness, disintegration and dissolution rates decreased at all initial moistures. The results suggest that the effects of moisture and humidity should be thoroughly investigated for dibasic calcium phosphate dihydrate-based tablets in order to ensure stability and bioavailability of the drug.