Dimenhydrinate
Mechanism :
Dimenhydrinate is an antihistamine with anticholinergic and sedative side effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.
Indication :
- Motion sickness
- Radiation sickness
- Postoperative vomiting
- Drug induced nausea and vomiting
- Symptomatic relief of nausea and vertigo due to ménière disease and other labyrinthine disturbances
Contraindications :
Glaucoma, chronic lung disease, difficulty in urination due to prostatic hypertrophy.
Use with caution in patients with a history of seizure disorder.
Dosing :
IV/IM:
1.25 mg/kg or 37.5 mg/m² every 6 hours. Max: 300 mg/day
Oral:
2 to 12 years:
12.5 to 25 mg every 6 to 8 hours as necessary to a maximum of 75 mg in 24 hours for children between 2-6 years and 150 mg/24 hours for those between 6-12 years.
>12 years:
50 mg every 4 to 6 hours as necessary to a maximum of 400 mg in 24 hours.
Adverse Effect :
Drowsiness, dizziness, dry mouth, lassitude, paradoxical CNS stimulation, rash, hemolytic anemia, blurring of vision.
Interaction :
Alcohol and other CNS depressants: Diphenhydramine hydrochloride has additive effects.
MAO inhibitors: prolong and intensify the anticholinergic effects of antihistamines.
Hepatic Dose :
Dose reduction may be required as dimenhydrinate is eliminated primarily by hepatic metabolism.