Chlorpromazine

FGA / Phenothiazine·Psychiatry - Oral Antipsychotics

Schizophrenia, acute mania, severe behavioral disturbance, intractable hiccups, severe nausea in terminal illness

PBSFGALargactil100 mg tabletS4+1

Max Dose

1000 mg/day

Half-life

30 h

Sedation

SEVERE

Orthostasis

HIGH RISK

Rapid Summary

Overview

The first antipsychotic ever discovered (1952). Low-potency FGA. Exceptionally sedating and highly anticholinergic. Rarely used for primary psychosis today, but heavily utilized in palliative care and for intractable hiccups.

Maximum Dose

Max 1000 mg/day (Modern doses rarely exceed 100-300 mg).

Clinical Focus

Causes profound orthostatic hypotension. The patient will collapse if they stand up quickly after a large dose.

Bottom Line

Chlorpromazine is the original first-generation antipsychotic still used for refractory psychosis and intractable hiccups, but causes severe sedation, photosensitivity, and significant anticholinergic and extrapyramidal effects.

Formulation & Access

Brand Names

Largactil

Oral Routes

Tablets (10, 25, 100 mg). Oral syrup (5 mg/mL).

Parenteral

Ampoules (50 mg/2 mL) for IM or IV infusion.

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Schizophrenia, acute mania, severe behavioral disturbance, intractable hiccups, severe nausea in terminal illness.

Clinical Place

Relegated to a rescue sedative or palliative antiemetic. The heavy side effect burden makes it obsolete for chronic maintenance therapy.

Quick reference

Class & Role

FGA / Phenothiazine — The first antipsychotic ever discovered (1952).

Route / Formulation

Tablets (10, 25, 100 mg). Oral syrup (5 mg/mL). (Largactil)

Usual Dose & Max

PO 25-100 mg TDS to QID. Max 1000 mg/day (Modern doses rarely exceed 100-300 mg).

Key Indication Doses

Acute Psychosis / Agitation: PO 25-100 mg TDS to QID. Intractable Hiccups: PO 25-50 mg TDS. Palliative Agitation / Nausea: PO or IV 12.5 - 25 mg q4-8h PRN. Elderly: Start at 10-25 mg/day. High risk of falls and delirium.

Best Uses

Avoid / Cautions

Severe CNS depression, coma, bone marrow depression, narrow-angle glaucoma. Pregnancy Category C.

Key Risks

Cardiovascular: Severe orthostatic hypotension, reflex tachycardia, QTc prolongation. Neurological: Profound sedation, hangover, EPS, lowers seizure threshold. Neuroleptic Malignant Syndrome (NMS). Gastrointestinal: Severe anticholinergic toxidrome (constipation, urinary retention, dry mouth). Dermatological: Photosensitivity, blue-grey skin pigmentation (with chronic high-dose use).

Key Interactions

Additive hypotension with BP meds. Additive severe CNS depression with Opioids/Benzos. Additive anticholinergic toxicity with TCAs or Oxybutynin (can trigger toxic megacolon).

Monitoring

Check lying/standing BP. Restrict patient to bed rest for 1-2 hours after an acute large dose to prevent syncopal falls. Baseline ECG.

Clinical Pearl

Chlorpromazine is the only FDA/TGA approved drug for intractable hiccups (lasting > 48 hours). It suppresses the medullary reflex arc that drives the diaphragm spasms.

Access

Largactil100 mg tablet

Brand: Largactil
Formulation: Tablets (10, 25, 100 mg)