Optimizing lithium dosing in hemodialysis

We studied a 62-year-old female hemodialysis patient during initiation and maintenance of lithium carbonate therapy. Three different methods were applied to estimate the regimen: a scenario based on volume of distribution (V-d) a scenario based on glomerular filtration rate (GFR), and a scenario in which we developed an algorithm based on a 2-compartment distribution without elimination. The GFR estimate led to plasma concentrations 3-4 times lower than those anticipated. In contrast, the estimates based on V-d and the algorithm derived from pharmacokinetic modeling led to comparable loading dose estimates. Furthermore, the maintenance dose estimated from the central compartment (V-1) led to plasma concentrations within the therapeutic range. Thus, a regimen where 12.2mmol lithium was given after each hemodialysis session resulted in stable between-dialysis plasma lithium concentrations in this patient with no residual kidney function. We did not observe adverse effects related to this regimen, which was monitored from 18 days to 8 months of therapy, and the patient experienced relief from her severe depressive disorder. In conclusion, dialysis patients may be treated with lithium administrated immediately post-dialysis. Further observations are necessary to obtain robust long-term safety data and to optimize the monitoring schedule.