Pharmacokinetics and toxic effects of lithium chloride after intravenous administration in conscious horses

Twenty 3-mmol boluses of LiCl (0.15 mmol/l) were injected IV into healthy Standardbred horses (n=6) at 3-min intervals (60 mmol/horse total dose) during a 1-h period. Blood samples for measurement of serum lithium concentrations were collected before injection and up to 24 h after injection. Behavioural and systemic toxic effects of LiCl were assessed. Lithium elimination could best be described by a 3-compartment model for 5 of the 6 horses. Mean peak serum concentration was 0.561 mmol/l (range of 0.529-0.613 mmol/l), with an actual measured mean serum value of 0.575 mmol/l (range of 0.52-0.67 mmol/l) at 2.5 min after administration of the last bolus. Half life was 43.5 h (range of 32-84 h), and after 24 h, mean serum lithium concentration was 0.13+or-0.05 mmol/l (range of 0.07-0.21 mmol/l). The 60-mmol dose of LiCl did not produce significant differences in any measured haematologic or biochemical variables, gastrointestinal motility, or ECG variables evaluated during the study period. Distribution of lithium best fits a 3-compartment model, and clearance of the electrolyte was slow. Healthy horses remained unaffected by LiCl at doses that exceeded those required for determination of cardiac output. Peak serum concentrations were less than steadystate serum concentrations that reportedly cause toxic effects in other species..