Symptoms and course of intoxication with mesuximide--a case report.

We report on a 31-year-old, female patient who presented with somnolence due to an intoxication by the antiepileptic drug, mesuximide (MSM). The serum concentration of its metabolite n-desmethyl-mesuximide (85.7 mg/L) was above the so-called therapeutic range (10-40 mg/L) but below the concentration range that led to an impairment of consciousness in previous cases according to the German SPC (>150 mg/L). The symptoms remitted quickly under hemodialysis. In somnolent patients treated with MSM, the treating physicians should be aware of drug intoxication as a possible etiology. Therefore, the serum concentration should be measured early. Due to the, often, long latency until the results are available, treatment initiation may be necessary based on suspicion.