Gravol (Dimenhydrinate) IV Dosing
The standard intravenous dose of dimenhydrinate for adults is 50 mg IV, which can be repeated every 4-6 hours as needed, with a maximum of 400 mg in 24 hours.
Adult Dosing
For nausea and vomiting in adults, administer 50 mg IV every 4-6 hours, not exceeding 8 doses (400 mg) in 24 hours 1. This dosing is derived from the oral formulation equivalency, where each tablet contains 50 mg dimenhydrinate 1.
In clinical practice, 62 mg IV has been used successfully as a single dose after induction of anesthesia for prevention of postoperative nausea and vomiting, with repeat dosing every 8 hours during the 48-hour postoperative period 2.
For emergency department treatment of vertigo, 50 mg IV has been studied and shown effective, though it demonstrated superior efficacy compared to lorazepam 2 mg IV in relieving vertigo symptoms 3.
Pediatric Dosing
For children, the IV dosing should be weight-based:
- Children 6 to under 12 years: 25-50 mg (0.5-1 tablet equivalent) every 6-8 hours, maximum 150 mg in 24 hours 1.
- Children 2 to under 6 years: 12.5-25 mg (0.25-0.5 tablet equivalent) every 6-8 hours, maximum 75 mg in 24 hours 1.
Administration Considerations
Dimenhydrinate demonstrates incomplete systemic bioavailability (58-69%) when given orally or sublingually, with peak plasma concentrations occurring 2-3 hours after administration 4. When IV access is available, this route provides more predictable drug delivery.
Important Clinical Caveats
The drug has significant anticholinergic properties and can cause sedation, drowsiness, and in supratherapeutic doses (>2400 mg/day), euphoria and hallucinations with addiction potential 5.
Dimenhydrinate is as effective as ondansetron 4 mg IV for preventing postoperative nausea and vomiting in laparoscopic cholecystectomy patients, with comparable rates of rescue antiemetic use (29% vs 34%) and significantly lower cost 6.
For vertigo management, dimenhydrinate 50 mg IV was more effective than lorazepam 2 mg IV, with better ambulation ability at 2 hours and 1.8 units less drowsiness on a 10-point scale 3.
Monitor for hypotension and excessive sedation, particularly when combined with other sedating medications 7.