What is the recommended dosing of Thorazine (chlorpromazine) for an outpatient with delusions?

Chlorpromazine Dosing for Outpatient Delusions

For outpatient management of delusions, start chlorpromazine at 10 mg three times daily or 25 mg twice to three times daily, with gradual increases of 20-50 mg at semi-weekly intervals until symptoms are controlled, typically reaching 400 mg daily as an effective dose. 1

Initial Dosing Strategy

• Begin with 10 mg three times daily (TID) or four times daily (QID), or alternatively 25 mg twice daily (BID) or three times daily for outpatients 1
• After 1-2 days, increase the daily dosage by 20-50 mg at semi-weekly intervals until the patient becomes calm and cooperative 1
• The typical effective dose for outpatient management is approximately 400 mg daily 1

Important Dosing Considerations

• Chlorpromazine should be considered a second-line option for delusions, as current guidelines recommend atypical antipsychotics (olanzapine, quetiapine, risperidone) as first-line agents due to lower risk of extrapyramidal symptoms 2, 3, 4
• If chlorpromazine is used, it carries significant risk of extrapyramidal symptoms, orthostatic hypotension, and anticholinergic effects 2
• For elderly patients, dosages in the lower range are sufficient and should be increased more gradually, as they are more susceptible to hypotension and neuromuscular reactions 1

Dose Titration and Maintenance

• Maximum improvement may not be seen for weeks or even months 1
• Continue optimum dosage for 2 weeks, then gradually reduce to the lowest effective maintenance level 1
• Daily dosage of 200 mg is not unusual, though some patients may require higher doses (up to 800 mg daily in discharged mental patients) 1
• Research suggests that lower doses (≤400 mg/day) are associated with fewer extrapyramidal side effects compared to medium doses (401-800 mg/day), while maintaining similar efficacy 5

Clinical Context and Alternatives

• The European Society for Medical Oncology recommends chlorpromazine starting at 12.5 mg every 4-12 hours IV/IM or 25-100 mg every 4-12 hours rectally for delirious patients, with usual effective parenteral doses of 37.5-150 mg/day 2
• However, for outpatient delusions specifically, atypical antipsychotics should be strongly considered first: olanzapine 2.5-5 mg daily or quetiapine 25 mg twice daily offer superior tolerability profiles 3, 4
• Chlorpromazine remains effective for psychosis control, with research showing complete or partial relief in terminal restlessness at median doses of 25 mg every 4-12 hours rectally or 12.5 mg every 4-12 hours IV 6

Critical Safety Monitoring

• Monitor closely for orthostatic hypotension, particularly during initial titration 2, 1
• Watch for extrapyramidal symptoms including parkinsonism and acute dystonic reactions, which occur significantly more often than with atypical antipsychotics 5, 7
• Sedation is common and occurs in approximately one in five patients 8
• Weight gain is substantial, with chlorpromazine causing nearly 5 times the risk compared to placebo 8