Evaluation of a two-point method for prediction of lithium maintenance dosage

A lithium test dose method, based on the two-point method of Perry et al. (1982), was evaluated in 20 patients for the prediction of maintenance dosage of slow-release lithium carbonate tablets. These predictions were compared with the predictions obtained from the dosing chart of Cooper et al. (1973). The two-point method accurately predicted the maintenance dosage within clinically acceptable limits, but dosages predicted from the dosing chart would have yielded much higher serum lithium concentrations.