Clozapine is a tricyclic dibenzodiazepine derivative that is classified as an "atypical
neuroleptic" drug for treatment of psychotic diseases. A 19-year-old schizophrenic
female, treated with 400 mg clozapine per day, was admitted to the emergency department
after ingestion of 5000 mg (50 × 100 mg tablets) of clozapine. Clozapine plasma level
2.5 hours after ingestion was 3.8 μg/ml (normal range 0.2 - 0.7 p.g/ml) and very high
in gastric lavage. Contrary to reported cases with such high plasma concentrations
the patient suffered only from somnolence with intermittent periods of agitation and
a mild anticholinergic syndrome with sinus tachycardia and slight hypotension. After
detoxication with gastric lavage and short-term administration of pyridostigmine she
remained stable, and 24 hours after ingestion she was transferred to the psychiatric
unit without further sequelae. To prevent late-onset complications she was carefully
monitored for five days. The clozapine plasma level 24 hours after the first measurement
was normal. This case and others reported in the literature confirm that signs and
symptoms after clozapine intoxication are variable and that high plasma levels are
not lethal in every case.
