Bioavailability and dissolution parameters of seven lithium carbonate products

Seven commercial products and a standard powder of lithium carbonate were administered to healthy human volunteers in a crossover study. An analysis of variance of saliva levels and urinary excretion as well as an analysis of variance of peak concentration and the area under the curve from 0 to 24 hr for the saliva levels showed no significant difference between the powder and products, but a significant difference between subjects. A significant difference was found between the time of peak saliva levels, which was attributed to faster powder absorption. A dissolution study using the USP basket method at 50 and 100 rpm and the Levy beaker at 50 rpm also showed no significant difference between products after the lag time for the capsule dosage forms. With a regression analysis, a significant correlation was found between the saliva levels of the products at 2 hr and dissolution in the USP basket at 50 rpm at 4 min.