Promethazine

Administration

  • Type: Antiemetic; Phenothiazine Derivative; Sedative
  • Dosage Forms: 12.5,25,50; 6.25/5 mL sol; IM; IV
  • Routes of Administration: Oral
  • Common Trade Names: Phenadoz; Phenergan; Promethegan

Adult Dosing

  • Nausea/vomiting: 12.5-25mg PO/IM/IV q4-6h
    • Max: 50mg/dose PO/IM; 25mg/dose IV
    • IM preferred over IV
  • Motion sickness: 25mg PO bid
    • Start: 0.5-1h prior to travel
  • Sedation: 25-50mg PO/IM/IV x1
    • Max: 50mg/dose PO/IM; 25mg/dose IV
    • IM preferred over IV

Pediatric Dosing

Only Approved for >2 years

  • Allergic conditions: 0.1mg/kg PO q6h
    • Max: 12.5mg/dose during day, 25mg/dose qhs
    • May give additional dose of up to 0.5mg/kg PO qhs
    • Use lowest effective dose
    • Avoid other resp. depressants
  • Nausea/vomiting: 0.25-1mg/kg PO/IM/IV q4-6h PRN;
    • Max: 25mg/dose
  • Motion sickness: 0.5mg/kg PO q12h PRN; Start: 0.5-1h before travel
    • Max: 25mg/dose; Info: use lowest effective dose
    • Avoid other resp. depressants
  • Sedation: 12.5-25mg PO/IM/IV x1
    • Max: 25mg/dose
    • IM preferred over IV
    • Use lowest effective dose
    • Avoid other resp. depressants

Special Populations

Renal Dosing

  • No adjustment

Hepatic Dosing

  • Caution advised with hepatic impairment

Contraindications

  • Hypersensitivity to drug/component
  • Patients <2 yo
  • Comatose patients
  • Respiratory depression
  • SC injection
  • intra- or periarterial administration

Adverse Reactions

Serious

  • extravasation/tissue damage (IV use > IM use)
  • apnea
  • respiratory depression
  • respiratory depression, fatal (infants)
  • seizures
  • leukopenia
  • thrombocytopenia
  • agranulocytosis

Common

  • drowsiness
  • sedation
  • blurred vision
  • dizziness
  • confusion
  • disorientation

Pharmacology

  • Half-life: 7-14 hrs
  • Metabolism: urine, feces
  • Excretion: CYP450

Mechanism of Action

  • nonselective antagonist of central and peripheral H1 receptors; anticholinergic

See Also

References

<UpToDate, Micromedex>