Guidelines for the dosage of antipsychotic drugs.

When commonly recommended guidelines for the dosage of neuroleptic drugs are critically reviewed, unanswered questions outnumber accepted rules. The relationship between dose and therapeutic efficacy remains far from clear, and despite lack of data there has been a trend in recent years to escalate dosage. Average clinical antipsychotic potency correlates closely with the affinity of the drug for dopamine (D2) receptors. Correlations of blood levels of neuroleptics with clinical efficacy are inconsistent. Assessments of immediate and follow-up treatment indicate that moderate doses are adequate for most psychotic patients and fail to support the use of high doses (more than the approximate equivalent of 300-600 mg chlorpromazine daily). Occasionally however, patients, perhaps because of idiosyncratic pharmacokinetics, require higher doses and do not conform to the statistical data for outcome. More precise results for determining the optimum dose of antipsychotic compounds in schizophrenics in the future, may be available from positron emission tomographic (PET) techniques.