Chlorpromazine

Chlorpromazine (中文:[[ ]]) is a typical antipsychotic medication. It is used to treat psychotic disorders such as

• schizophrenia
• Bipolar disorder
• Severe anxiety
• Attention deficit hyperactivity disorder
• Hiccups that do not improve following other measures

Pronunciation

Chlorpromazine 50mg

Drug Names

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Chlorpromazine Tablet 25 mg	CHLO44	P1S1S3
Chlorpromazine Tablet 50 mg	CHLO46	P1S1S3

Mechanism of Action

Chlorpromazine and other typical antipsychotics are primarily blockers of D2 dopamine receptor. The presumed effectiveness of antipsychotic drugs relied on their ability to block dopamine receptors. This assumption arose from the dopamine hypothesis that maintains that both schizophrenia and bipolar disorder are a result of excessive dopamine activity. In addition, chlorpromazine also acts as an antagonist (blocking agent) on different postsynaptic and presynaptic receptors:

• Dopamine receptors (subtypes D1, D2, D3 and D4), which account for its antipsychotic properties
• Serotonin receptors (5-HT2, 5-HT6 and 5-HT7), with anxiolytic, antidepressant, and anti-aggressive properties
• Histamine receptors (H1 receptors) accounting for sedation, antiemetic effect
• α1- and α2-adrenergic receptors accounting for lowering of blood pressure, reflex tachycardia, vertigo, sedation, hypersalivation and incontinence as well as sexual dysfunction
• M1 and M2 muscarinic acetylcholine receptors causing anticholinergic symptoms such as dry mouth, blurred vision, constipation, difficulty to urinate, sinus tachycardia, and loss of memory.

Dosage

Indication	Dose
Acute and chronic schizophrenia Reduce acute mania in bipolar disorder Control severely violent behaviour Adjunctive management of severe anxiety	By mouth ADULT: Initially 25 mg 3 times a day, adjusted according to response Or initially 75 mg once daily, taken at night, adjusted according to response Maintenance 75 – 300 mg daily ELDERLY or debilitated patients: A third to half adult dose By rectum ADULT: 25 – 50 mg 3 – 4 times a day
Intractable hiccup	By mouth ADULT: 25 – 50 mg 3-4 times a day
Nausea and vomiting of terminal illness	By mouth ADULT: 10 – 25 mg every 4-6 hours CHILD 1-5 years: 500 micrograms/kg every 4-6 hours; max. 40 mg per day CHILD 6-11 years: 500 micrograms/kg every 4-6 hours; max. 75 mg per day CHILD 12-17 years: 10 – 25 mg every 4-6 hours By rectum ADULT: 100 mg every 6-8 hours

Chlorpromazine is given orally as the hydrochloride and the embonate.

For both salts, the doses are expressed as the hydrochloride. Chlorpromazine embonate 144 mg is equivalent to 100 mg of chlorpromazine hydrochloride.

If the oral route is not suitable, it may be given rectally as suppositories containing 100 mg of chlorpromazine base

Side Effects

Chlorpromazine generally produces less central depression than the benzodiazepines, and tolerance to its initial sedative effects develops quickly in most patients. Tardive dyskinesia (involuntary, repetitive body movements) and akathisia (a feeling of inner restlessness and inability to stay still) are less commonly seen with chlorpromazine than they are with high potency typical antipsychotics such as haloperidol or trifluoperazine.

Possible side effects include:

It has antimuscarinic properties and may cause the following side effects such as	Dry mouth Constipation Difficulty to urinate Blurred vision Mydriasis Tachycardia ECG changes (particularly Q- and T-wave abnormalities) Orthostatic hypotension is common
Other adverse effects include	Delirium Agitation sedation Insomnia Nightmares Glaucoma Inhibition of ejaculation Impotence
Hypersensitivity reactions include	Urticaria Exfoliative dermatitis Prolonged therapy may lead to deposition of pigment, producing a bluish-purple discoloration in the skin Corneal and lens opacities Photosensitivity reaction
	Haematological disorders	Haemolytic anaemia Thrombocytopenic purpura Most cases of agranulocytosis occurred within 4 to 10 weeks starting treatment	Extrapyramidal dysfunction include	Acute dystonia A parkinsonism-like syndrome Tardive dyskinesia Neuroleptic malignant syndrome
	Altered endocrine and metabolic functions	Developed amenorrhoea, galactorrhoea and gynaecomastia due to hyperprolactinaemia Weight gain Hyperglycaemia Body temperature regulation is impaired and may result in hypo- or hyperthermia depending on environment.