High doses of haloperidol in schizophrenia. A clinical, biochemical, and pharmacokinetic study

The effects of high doses of haloperidol on clinical status and plasma neuroleptic and prolactin concentrations and CSF levels of homovanillic acid (HVA) and gamma-aminobutyric acid (GABA) were investigated in three paranoid schizophrenic patients over six weeks. The patients had been receiving haloperidol. Oral dosages were increased at weekly intervals from 10 to 200 mg/day and then reduced to 10 mg/day. The increase did not affect paranoid symptoms. Neurological side effects were slightly increased in two patients and moderately reduced in one. Plasma prolactin levels, initially high, increased when the dosage was increased to 100 mg/day but did not increase further. The CSF levels of HVA and GABA increased to day 7 but returned to initial values on day 28 in two patients; they were decreased to day 28 in one patient.