Lithium kinetics in single daily dosing.

The feasibility of single daily dosing of lithium carbonate was tested in eight recurrent manic-depressives being treated with lithium prophylaxis. The patients received their entire 24-h maintenance dose at 8:00 p.m. for 12 consecutive days. The suitability of single daily dosing was determined by comparing 1) lithium through levels; 2) lithium kinetic parameters of half-life, clearance, and volume of distribution; and 3) renal function parameters of serum creatinine, creatinine clearance, and mean 24-h urine output during the initial divided daily dosage trial and the subsequent single daily dosage trial. The observation of no significant changes in either serum half-lives or renal lithium clearance levels supports the conclusion that the average steady-state lithium serum concentration (Cpss) is unchanged by conversion to single daily doses. No significant changes were observed in either serum creatinine or creatinine clearance. However, a significant decrease in the 24-h urine output was noted on the single daily dose.