Chlorpromazine in the Treatment of Psychosis

Introduction

Chlorpromazine (Largactil) is a first generation typical antipsychotic. It is primarily used for the treatment of adult psychosis including schizophrenia, mania, and childhood schizophrenia.[1] However, chlorpromazine has shown effectiveness in the treatment of nausea and childhood autism.[1]

Mechanism of Action

The exact mechanism of action is unclear. Chlorpromazine is a phenothiazine, meaning it has tranquilizing properties and potentiates general CNS depression.[2] It is understood that chlorpromazine inhibits dopamine at the postsynaptic D2 receptors.[2] It is also an antagonist at alpha 1 adrenergic receptors.[2] The tranquilizing properties and general depression potentiated by chlorpromazine are important for the physical therapist to monitor. Therapy sessions may need to be altered due to tiredness or other side effects.

Dosing

Dosage is dependent on the indication for chlorpromazine and is most commonly administered either orally or intramuscularly (IM).[1] When used for the treatment of psychosis, adults typically ingest 50-300 mg/day in oral tablet or an IM injection of 25-50 mg/day. Nausea and vomiting will take 10-25 mg every 4-6 hours orally or 25-50 mg IM every 3-4 hours.[1] Prescribed dosing for childhood schizophrenia and autism vary widely. It is valuable for a physical therapist to understand the dosing schedule of a patient’s medication. For chlorpromazine, the route of administration may have differing side effects. Inconsistent administration could also alter a patient’s mental state.

Pharmacokinetics

The pharmacokinetics of chlorpromazine is also not fully understood and varies per the individual and route of administration. However, the kidneys excrete approximately 43-65% of the daily dose within 24 hours.[1] There are 5 clinically important metabolites, 4 of which are biologically active. The elimination half-life is thought to be a series of phases, with the early phase in 2-3 hours, an intermediate phase of 15 hours, and a late phase of up to 60 days.[1] A lingering half-life could prolong the effects of this medication in a person’s body. Because of this, the physical therapist should be aware that side effects may linger after the dose is administered.

Adverse Effects

Like most typical antipsychotics, chlorpromazine has an extensive side effect profile. Some of the more common side effects exclusive to chlorpromazine include contact dermatitis, photosensitivity, hyperglycemia, and prolactin elevation.[1]

Physical Therapy Implications

Physical therapists should be aware of these side effects when treating a patient taking chlorpromazine. Postural hypotension could increase the risk of falls. Heart rate, respiration, blood sugar, and blood pressure should be monitored during the treatment session. Certain therapeutic modalities should be avoided due to skin sensitivities and photosensitivity, as well as caution with manual techniques. As chlorpromazine is a general sedative, scheduling the patient around dosages may be necessary to prevent drowsiness during exercises. The patient’s mental state may also be affected by the time of dosage. Psychotic disorders in general increase the risk of suicidal thoughts and behaviors.[3] Because of this, the physical therapist should be conscious of the patient’s mental state.

For more information regarding chlorpromazine (Largactil) please visit the manufacturer's fact sheet at https://genesight.com/wp-content/uploads/2017/05/Chlorpromazine-Thorazine-FDA-Label.pdf

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  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Sanofi-Aventis New Zealand Limited. (2013). [PDF] Largactil (Chlorpromazine). https://genesight.com/wp-content/uploads/2017/05/Chlorpromazine-Thorazine-FDA-Label.pdf. Accessed from September 21, 2018
  2. 2.0 2.1 2.2 Dollery CT. Therapeutic Drugs. Vol 1. Edinburgh: Churchill Livingstone; 1992
  3. Bertolote, J., & Fleischmann, A. Suicide and psychiatric diagnosis: a worldwide perspective. World Psychiatry (2002). 1(3), 181–185. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1489848 Accessed September 21, 2018.