Chlorpromazine injection
THORAZINE IM
Pronunciation: klor-PROE-ma-zeen
“Thor’s Color promising”
Photosensitive skin discoloration
Polka dots on pink → α1 blocker → syncope if titrated too quickly (hit the floor)
Spooky mascot → antipsychotic
What it isIntramuscular D2 and 5-HT2A antagonist with strong H1, alpha-1, and muscarinic blockade; agitation, psychosis, emesis, and hiccups.
Why this oneIts parenteral intractable-hiccup indication is unusual among antipsychotics.
What limits itOrthostatic hypotension can be profound — keep the patient supine; local tissue irritation, antimuscarinic toxicity, and QT prolongation also matter.
FDA-approved for
- acute agitation / psychosis (~1954)
- intractable hiccups (~1954)
- nausea/vomiting (~1954)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Acute schizophrenia/manic states (hospitalized) | Adults | 25 mg IM | Add 25–50 mg IM in 1 h if needed; increase over days | Up to 400 mg every 4–6 h in exceptionally severe cases |
| Nausea and vomiting | Adults | 25 mg IM | 25–50 mg IM every 3–4 h PRN until vomiting stops | |
| Presurgical apprehension | Adults | 12.5–25 mg IM 1–2 h before surgery | ||
| Intractable hiccups / acute intermittent porphyria / tetanus (adjunct) | Adults | 25–50 mg IM (hiccups/tetanus); 25 mg IM TID–QID (porphyria) | ||
| Severe behavioral problems / nausea and vomiting | Children 6 months–12 yr | 0.25 mg/lb IM every 6–8 h PRN | ≤5 yr (≤50 lb): 40 mg/day; 5–12 yr (50–100 lb): 75 mg/day |
Renal Use with caution in renal disease.
Hepatic Use with caution in hepatic disease; increased CNS sensitivity in cirrhosis/hepatic encephalopathy.
Instructions
- Inject slowly, deep into upper outer quadrant of the buttock
- Keep patient lying down ≥30 minutes after injection (hypotension)
- Reserve parenteral use for bedfast/acute cases; IV only for severe hiccups, surgery, tetanus
- Contains sulfites
Available strengths
- inj 25 mg/mL
- tab 10, 25, 50, 100, 200 mg
- sol 30, 100 mg/mL
Contraindications
- Comatose states or presence of large amounts of CNS depressants (alcohol, barbiturates, narcotics)
Cautions
- Tardive dyskinesia
- Neuroleptic malignant syndrome
- Hypotension (especially parenteral)
- Leukopenia/neutropenia/agranulocytosis
- Jaundice/hepatic effects
- Sulfite sensitivity
- Avoid in suspected Reye's syndrome
Adverse reactions
- Drowsiness
- Hypotension
- Extrapyramidal reactions
- Jaundice
- Hematologic disorders
- Anticholinergic effects
Pregnancy Undefined.
Lactation Undefined.
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 25 mg/mL | inj | per unit | not offered |
Other forms: Chlorpromazine (THORAZINE)
⚠ BOXED WARNING
- Increased mortality in elderly patients with dementia-related psychosis
Classes and tags
Clinical profile
Serotonicity
This drug is routinely called serotonergic. By Gillman’s human-effect criteria it does not raise serotonin in the synapse.
No established clinically meaningful SRI or MAO-A mechanism; receptor antagonism should not be mislabeled as serotonin toxicity.
It binds the serotonin transporter, and its SERT peg is drawn to that textbook affinity. The pale halo around the peg marks binding that, by Gillman’s human-effect criteria, does not produce clinical serotonin reuptake inhibition.
Gillman’s four human testsA measurable SERT affinity that fails all four is not clinical serotonicity.
- Retarded orgasm
- Efficacy in OCD and cataplexy
- Clonus and hyperreflexia in single-drug overdose
- Serotonin toxicity when combined with an MAOI
Evidence confidenceModerate
Background: what serotonicity is · what is and is not an SRI · what counts as a relevant MAOI.
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