Chlorpromazine

Chlorpromazine

[1 vial $2.60]

ADMINISTRATION ROUTES:

  • PO, IV, IM

ALTERNATIVE NAMES:

  • Largactil

ICU INDICATIONS:

  1. nausea and vomiting
  2. intractable hiccups
  3. psychosis

PRESENTATION AND ADMINISTRATION:

  • IV:
    50mg/2ml vial
    dilute required dose in 500-1000ml of normal saline to a concentration of no greater than 1mg/ml and administer at 1mg/min in adults or 0.5mg/min in children
    Dilute with normal saline only. Do not mix with other medications in the syringe or in IV fluids
    Solutions that develop a pink or yellow colouration on exposure to light should be discarded. Store at room temperature. Protect from light
  • PO:
    10mg, 25mg, 100mg tablets (white or off white)
    Note: swallow whole; do not break, crush or chew.

DOSAGE:

  • PO:
    Not suitable for nasogastric administration.
    Large doses (up to 300mg per day) may be required to treat adults with Schizophrenia; however, such doses are not appropriate in the critically ill. The usual starting dose in the intensive care unit is 10mg 8 hourly.
  • IV/IM:
    The usual starting dose in the critically ill is 12.5mg IV 8 hourly. 50mg via continuous infusion over 24hrs may be used in patients with intractable hiccups.

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

  • Dose in renal impairment [GFR (ml/min)]
    <10: use a small dose
    10-20: dose as in normal renal function
    >20-50: dose as in normal renal function
  • Dose in renal replacement therapy
    CAPD: dose as in normal renal function
    HD: dose as in normal renal function
    CVVHDF: dose as in normal renal function

DOSAGE IN PAEDIATRICS:

  • PO:
    0.5-2mg/kg 8 hourly
  • IM/IV:
    0.25-1mg/kg 8 hourly

    Note: Chlorpromazine should generally not be used in children under 6 months of age except where potentially lifesaving. It should not be used in conditions for which specific children’s dosages have not been established.

CLINICAL PHARMACOLOGY:

  • The precise mechanism whereby the therapeutic effects of chlorpromazine are produced is not known. Chlorpromazine has actions at all levels of the central nervous system as well as on multiple organ systems. Chlorpromazine has strong antiadrenergic and weaker peripheral anticholinergic activity; ganglionic blocking action is relatively slight. It also possesses slight antihistaminic and antiserotonin activity.

CONTRAINDICATIONS:

  1. hypersensitivity to phenothiazines.
  2. depressed conscious state (unless the airway is protected)
  3. hypotension or requiring vasopressoror inotropic support

WARNINGS

  • The extrapyramidal symptoms which can occur secondary to chlorpromazine may be confused with the CNS signs of an undiagnosed primary disease responsible for the vomiting

PRECAUTIONS

  • General:
    Given the likelihood that some patients exposed chronically to antipsychotics will develop tardive dyskinesia, it is advised that all patients in whom chronic use is contemplated be given, if possible, full information about this risk. The decision to inform patients and/or their guardians must obviously take into account the clinical circumstances and the competency of the patient to understand the information provided.
    Chlorpromazine should be administered cautiously to persons with cardiovascular, liver or renal disease. There is evidence that patients with a history of hepatic encephalopathy due to cirrhosis have increased sensitivity to the CNS effects of chlorpromazine (i.e., impaired cerebration and abnormal slowing of the EEG).
    Because of its CNS depressant effect, chlorpromazine should be used with caution in patients with chronic respiratory disorders such as severe asthma, emphysema, and acute respiratory infections, particularly in children (1-12 years of age).
  • Laboratory Tests:
    No tests in addition to routine ICU tests are indicated
  • Drug/Laboratory Test Interactions:
    Chlorpromazine may cause false positive urinary pregnancy tests
  • Pregnancy
    Safety for the use of chlorpromazine during pregnancy has not been established. Reproductive studies in rodents have demonstrated potential for embryotoxicity, increased neonatal mortality, and nursing transfer of the drug. Tests in the offspring of the drug-treated rodents demonstrate decreased performance. The possibility of permanent neurological damage cannot be excluded.
  • Nursing Mothers
    There is evidence that chlorpromazine is excreted in the breast milk of nursing mothers. Because of the potential for serious adverse reactions in nursing infants from chlorpromazine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
  • Paediatric Use
    Chlorpromazine should generally not be used in children under 6 months of age except where potentially lifesaving. It should not be used in conditions for which specific children’s dosages have not been established.

IMPORTANT DRUG INTERACTIONS FOR THE ICU

  • Chlorpromazine prolongs and intensifies the action of CNS depressants Chlorpromazine diminishes the effect of oral anticoagulants. Phenothiazines can produce alpha-adrenergic blockade. Chlorpromazine may lower the convulsive threshold; dosage adjustments of anticonvulsants may be necessary. Potentiation of anticonvulsant effects does not occur. However, it has been reported that chlorpromazine may interfere with the metabolism of phenytoin and thus precipitate phenytoin toxicity. Concomitant administration with propranolol results in increased plasma levels of both drugs.

ADVERSE REACTIONS

  • Body as a whole:
    Neuroleptic malignant syndrome Central nervous system: Drowsiness, seizures, dystonias, motor restlessness, pseudo-parkinsonism, and tardive dyskinesia
  • Cardiovascular system:
    Hypotension, tachycardia, non-specific T wave changes
  • Gastrointestinal system:
    Jaundice, nausea, constipation, dry mouth
  • Haematological system:
    agranulocytosis, eosinophilia, leukopenia, hemolytic anemia, aplastic anemia, thrombocytopenic purpura, and pancytopenia

Critical Care Drug Manual

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