Maintenance lithium levels could be lowered: based on Taiwanese and Danish studies

Abstract

Twenty-two patients, 8 males and 14 females, who had been lithium-free for at least 1 week were included in this study. All patients took 900 mg of Lithonate at 8:00 a.m. while in a fasting state. A 5 ml blood sample was taken at 9:00 a.m., 10 a.m., 12 noon, 3 p.m., 5 p.m., 11 p.m., and at 9 a.m. and 3 p.m. on the next day. Plasma was separated immediately, and the lithium level was measured by atomic absorption spectrophotometry. The pharmacokinetic parameters were as follows: K12 (microconstant) = 0.3455 +/- 0.5345 (mean +/- SD) h-1; K21 (microconstant) = 0.1691 +/- 0.1242 h-1; K10 (microconstant) = 0.1320 +/- 0.1112 h-1; Vl (volume of distribution of central compartment) = 16.9057 +/- 5.9384 1; Vss (volume of distribution at steady state) = 38.8917 +/- 11.4540 1; V-beta (volume of distribution of elimination phase) = 46.3809 +/- 13.8742 1; alpha (distribution rate constant) = 0.5932 +/- 0.7090; and beta (excretion rate constant) = 0.0361 +/- 0.0141. The mean elimination half-life, AUC (the area under the curve) and clearance were 22.5 +/- 9.9 h (range from 9.6 to 50.4 h), 16.33 +/- 5.52 mmoll-1h (8.69 to 31.81 mmoll-1 h), and 1.65 +/- 0.53 1h-1 (0.76 to 2.28 1h-1) or 28.59 +/- 9.58 ml/kg-1 h-1, respectively. There were no statistically significant differences in beta, AUC and clearance between Taiwanese/Chinese and Danish results. The possibility of lowering the traditional prophylactic therapeutic range of lithium to around 0.5-0.8 mmol/L is supported by the results of this study.