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

• Allergic conditions: 6.25-12.5 mg PO tid
  • May give additional dose of 12.5-25 mg PO qhs

• Nausea/vomiting: 12.5-25 mg PO/IM/IV q4-6h
  • Max: 50mg/dose PO/IM; 25 mg/dose IV
  • IM preferred over IV

• Motion sickness: 25 mg PO bid
  • Start: 0.5-1h prior to travel

• Sedation: 25-50mg PO/IM/IV x1
  • Max: 50mg/dose PO/IM; 25 mg/dose IV
  • IM preferred over IV

Pediatric Dosing

Only Approved for >2 years

• Allergic conditions: 0.1mg/kg PO q6h
  • Max: 12.5 mg/dose during day, 25 mg/dose qhs
  • May give additional dose of up to 0.5 mg/kg PO qhs
  • Use lowest effective dose
  • Avoid other resp. depressants

• Nausea/vomiting: 0.25-1mg/kg PO/IM/IV q4-6h prn;
  • Max: 25 mg/dose

• Motion sickness: 0.5 mg/kg PO q12h prn; Start: 0.5-1h before travel
  • Max: 25 mg/dose; Info: use lowest effective dose
  • Avoid other resp. depressants

• Sedation: 12.5-25 mg PO/IM/IV x1
  • Max: 25 mg/dose
  • IM preferred over IV
  • Use lowest effective dose
  • Avoid other resp. depressants

Special Populations

• Pregnancy Risk Factor: C

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

• Antiemetics

References

<UpToDate, Micromedex>