[Pharmacokinetics of low-dose lithium in healthy volunteers]

The pharmacokinetics of lithium in healthy volunteers receiving low doses of lithium as Lithium Oligosol by sublingual route were investigated in two randomized crossover studies (lithium vs placebo) with a two week wash-out period. In the first study, 8 volunteers received a single dose (1.68 mg) of lithium and in the second 8 another volunteers received repetitive doses of lithium (0.56 mg twice a day) during 11 days. The plasma concentration of lithium was determined by an electrothermal atomic absorption spectrometry. The plasma concentrations of lithium measured during the placebo period were about 1 microgram/L, the peak concentration was 99.4 +/- 22.2 micrograms/L in the single dose study and 49.6 +/- 5.4 micrograms/L in the multiple doses study. In this last one, the residual plasma levels of lithium were between 20 and 25 micrograms/L. The pharmacokinetics parameters measured were: T1/2 = 22.6 +/- 3.1 h; Vd/F = 0.70 +/- 0.09 L/kg and Cl/F = 1.53 +/- 0.12 L/h. The plasma concentrations of lithium are strictly dependent on intake from food or drugs.