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Drug dosage identifier

Chlorpromazine Hydrochloride

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Dose and administration

Neonatal Abstinence Syndrome

  • 2.2-3mg/kg/24 hours (given in divided doses every 6 hours) PO or IM1.
  • Use full dosage for 2-4 days. Reduce dosage by approximately 20% every 2-3 days according to neonatal abstinence score sheet, if clinical condition permits2.


  • Neonatal abstinence syndrome. Used as a second line drug or alternative to morphine. Indications for starting treatment are according to the neonatal abstinence clinical score sheet.
  • In terminal care situations where sedation is needed and secretions are a problem.

Contraindications and precautions

  • Contraindicated in pre-existing CNS depression 3.
  • Use with caution, or not at all, with impaired liver, kidney, cardiovascular, cerebrovascular and respiratory function.
  • Use cautiously with hypothyroidism, acute infections, jaundice and leucopenia3,4.

Clinical pharmacology

Chlorpromazine is a phenothiazine neuroleptic (antipsychotic) agent3. It inhibits dopamine, has strong sedative effects to which tolerance may develop rapidly, strong anticholinergic, antiemetic and adrenergic blocking activity, moderate extrapyramidal effects and weak ganglionic block, antihistaminic and antiserotonergic activity 3,6. Chlorpromazine has been used in neonatal opioid abstinence syndrome for sedation and to reduce irritability, tremors and gastrointestinal symptoms1,7. Its sedative effect is prompt and effective.

After oral administration it is readily, but erratically absorbed. Extensive metabolism occurs in the gut wall and during the first-pass through the liver, hence peak plasma concentrations are much lower following oral administration than IM.

There may be some enterohepatic recycling. The metabolic pathways are hydroxylation and conjugation with glucuronic acid, N-oxidation, oxidation of a sulphur atom, and dealkylation 3,6. (The adult half life = 30 hours). Plasma protein binding is 95-98% (primarily to albumin). There is wide distribution into body tissues and fluids. After crossing the blood/brain barrier concentrations achieved in the brain are higher than those in plasma. Excretion of active and inactive metabolites occurs in the urine and the bile-elimination of metabolites may be prolonged. Elimination (adults) is biphasic with a rapid initial phase and a prolonged secondary phase; elimination rate from the brain is unknown3,6,8.

Possible adverse effects

  • Pain and irritation at site of injection3.
  • Sedation (tolerance develops rapidly), convulsions (rarely).
  • Tachycardia ECG changes, hypotension, cardiac arrhythmias.
  • Haemolytic anaemia, aplastic anaemia, agranulocytosis, mild leucopenia (high dose, long term).
  • Gastro-intestinal: Constipation
  • Jaundice: photosensitisation.
  • Hyperglycaemia.
  • Hypo/hyperthermia.
  • Extra pyramidal effects.
  • Possible suppression of cough and gag reflex.
  • Skin sensitisation and rashes3,4.

Special considerations and drug interactions

  • CNS depressant effect may be enhanced with other CNS depressant drugs, e.g. sedatives, opiates3. Infants should be monitored for apnoea.
  • Avoid abrupt withdrawal of the drug4.
  • Largactil injection contains sodium sulphate which may cause an allergic reaction, e.g., anaphylaxis and/or asthmatic episodes in susceptible patients6.
  • Largactil Forte Suspension contains the additives sodium benzoate, sorbitol (adverse effect = diarrhoea), propylene glycol and povidone K30.
  • Chlorpromazine may cause severe contact dermatitis in sensitised personnel. Nursing staff should avoid skin contact with the drug at administration times3,4,6.

Management of Chlorpromazine administration


  • Largactil injection 50mg/2ml is a clear liquid. pH 3-5.
  • Do not use coloured solutions.
  • Largactil oral mixture is an orange suspension. Contact Pharmacy for a diluted suspension.


  • Chart on prescription chart as mg/dose.


IM Injection

  • Wear gloves when preparing. Contact may cause severe contact dermatitis.
  • Administer undiluted, deep into a quadriceps muscle. If irritation at IM site occurs, dilute with NS6.
  • Compatible with NS5, D5W and D10W.
  • Do not mix with other medications in syringe5.
  • Must not be given subcutaneously as solution is very irritating. Should not be given by direct IV or intermittent infusion because of tissue irritation3,5.


  • Shake the bottle well before use.
  • Add required volume to milk6.

Nursing considerations

  • Monitor vital signs including BP for hypotension.
  • Apnoea monitoring whilst on medication.
  • Observe for signs of adverse effects.
  • Patients should remain supine for 30 minutes after IM injection, monitor BP (tachycardia may occur with IM injection)3,5.


  • Largactil injection - store unopened ampoule at room temperature. Protect from light. Opened not suitable for storage.
  • Oral mixture - follow instructions on bottle label.


  1. Neonatal Drug Withdrawal. Committee on Drugs. American Academy of Pediatrics. Pediatrics. 1983;72(6):895-902.
  2. Zelson C, Estrallita R, Wasserman E. Neonatal Narcotic Addition: 10 year observation. Pediatrics. 1971;48(2):178-189.
  3. Reynolds JF, (ed). Martindale - The Extra Pharmacopoeia (30th ed). London: The Pharmaceutical Press, 1993.
  4. Prasad AB, (ed). BNF British National Formulary (Sept 95). London: The Pharmaceutical Press, 1995.
  5. Squire M, (ed). Notes on Injectable Drugs (2nd ed). Wellington: New Zealand Hospital Pharmacists' Association Inc, 1994.
  6. McEvoy GK(ed). AHFS 94 Drug Information. Bethesda: American Society of Hospital Pharmacists, Inc, 1994.
  7. Anand KJS, Arnold JH. Opoid Tolerance and Dependence in Infants and Children. Critical Care Medicine. 1994;22(2):334-342.
  8. Saunders R, (ed). New Ethicals Compendium (5th ed). Auckland: Adis International Ltd, 1994.
  9. Nursing 97 Drug Handbook Springhouse p454.

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Document Control

  • Date last published: 29 September 1998
  • Document type: Drug Dosage Guideline
  • Services responsible: ADHB Pharmacy, Neonatology
  • Editor: Sarah Bellhouse
  • Review frequency: 2 years