FGA / Phenothiazine·Psychiatry - Oral Antipsychotics

cHLORPROMAZine

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

PBSFGALargactil100 mg tabletS4+1

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At a glance

Max Dose

1000 mg/day

Half-life

30 h

Caution: Sedation

SEVERE

Caution: Orthostasis

HIGH RISK

Cautions

Avoid / Cautions

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

Where it stands

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.

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

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). Oral syrup (5 mg/mL).

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