Study Guide for Chlorpromazine CHLORPROMAZINE
Study Guide for Chlorpromazine
| CHLORPROMAZINE |
| Description |
|
· Chlorpromazine is an antipsychotic medication mainly used for the treatment of schizophrenia disorder. · Generic Name: Chlorpromazine · Brand Names: Ormazine, Thorazine spansule and Thorazine. · Approved FDA Indications: Schizophrenia, the acute manic phase of bipolar I disorder, persistent hiccups, acute agitation, relief of anxiety preoperatively, acute intermittent porphyria, and as an adjunctive treatment for tetanus (Mann & Marwaha, 2020). · Off-label Uses: Treatment for migraine-associated nausea and vomiting and treatment for serotonin syndrome. |
| Drug Classification |
| · Chlorpromazine is a low-potency typical antipsychotic belonging to the class of drugs known as phenothiazines based on their chemical structure (Mann & Marwaha, 2020). |
| Pharmacokinetics |
|
· Has approximately 10-80% bioavailability. · Half-life: 23 to 37 hours. · About 90-99% is protein bound. · It undergoes hepatic metabolism via the CYPA12 and the CYP2D6 enzymes (Mann & Marwaha, 2020). · Excretion is via urine and feces. |
| Pharmacodynamics |
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· Chlorpromazine is a dopamine D2 receptor antagonist. The drug works by blocking the dopamine receptors, inhibiting the binding of the neurotransmitter to the forebrain, resulting in decreased neural activity. · Initially, the patients may experience increased dopaminergic neural activity due to rebound production of dopamine. With the continued blockade, reduced neural activity ensues. |
| Mechanism of Action |
| · The exact mechanism of action of chlorpromazine is unknown. However, it is thought that chlorpromazine causes post-synaptic blockage of the D2 receptors in the nigrostriatal pathway and mesolimbic pathway. Blockade in the former pathway causes extrapyramidal effects. The antiemetic effects are produced through the combined blockade of muscarinic, histamine, and dopamine receptors. |
| Dosing and Administration |
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· Chlorpromazine is available for parenteral and enteral route (Keepers et al.,2020). o Oral intake: Tablets of various dosages between 10–200mg. o Parenteral use: Can be administered intramuscularly and intravenously. · Dosing varies and is dependent on the indication for use. · For schizophrenia, the initial dose is 25-75mg orally twice a day and maintenance of 200 mg once daily. If it is to be administered as an intravenous or intramuscular injection, the initial dose is 25 mg, followed by 25-50 mg every 1-4 hours (Keepers et al., 2020). · Caution should be taken for patients with hepatic failure or liver disease. · No need for dose adjustment for patients with renal disease. |
| Special Considerations |