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 (V1) led to plasma concentrations within the therapeutic range. Thus, a regimen where 12.2 mmol 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 postdialysis. Further observations are necessary to obtain robust long-term safety data and to optimize the monitoring schedule.