Dimenhydrinate (Gravol®)

Section 1.1

Midwives may independently prescribe, order and administer this drug.

(Gravol®) is categorized in a class of drugs called antihistamines. Competes with histamine for H1-receptor sites on effector cells in the respiratory tract, gastrointestinal tract and blood vessels; blocks chemoreceptor trigger zones.

Indications and Clinical Use:

To counteract the side effects of nausea and vomiting. While it is considered safe, Gravol® may produce some sedation and as such, may be used for therapeutic rest during prodromal or early labour, particularly where anxiety is a factor.

Contraindications:

Hypersensitivity or previous reactions to dimenhydrinate or any component of the formulation.

Warnings and Precautions:

Use with caution in patients with asthma, peptic ulcer, cardiac arrhythmias and thyroid dysfunction.

Pregnancy:

Compatible

Lactation:

Category L2 – No Human Data – Probably Compatible

Adverse Reactions:

Palpitations, hypotension, confusion, nervousness, restlessness, headache, insomnia, tingling, heaviness and weakness of hands, vertigo, dizziness, blurred vision, nasal stuffiness, dryness of nose and throat, nausea, vomiting, diarrhea, constipation, dry mouth, tightness of chest and wheezing.

Dosage and Administration:

Usual Concentration: each mL contains 50 mg
50-100 mg PO every 4-6 hours, maximum dose 400 mg/day
25-50 mg IM, IV, every 4 hours, maximum dose 100 mg every 4 hours
25 mg IV should be administered slowly over 2 min

Dimenhydrinate in the injectable form is indicated when the oral or suppository form is impractical.
For severe nausea and vomiting in hospital setting, Gravol® may also be administered through the IV route.

Onset of Action:

20 to 30 minutes

Half-Life:

8.5 hours