DrugindexOnline^{2nd edition}

Pronouncation: (die-men-HIGH-drih-nate)
Class: Anticholinergic

Trade Names:
Calm-X
- Tablets 50 mg

Trade Names:
Children's Dramamine
- Liquid 12.5 mg/5 mL

Trade Names:
Dimetabs
- Tablets 50 mg

Trade Names:
Dinate
- Injection 50 mg/mL

Trade Names:
Dramamine
- Liquid 15.62 mg/5 mL
- Liquid 12.5 mg/4 mL
- Tablets 50 mg
- Tablets, chewable 50 mg

Trade Names:
Dramanate
- Injection 50 mg/mL

Trade Names:
Dymenate
- Injection 50 mg/mL

Trade Names:
Triptone
- Tablets 50 mg/mL

Apo-Dimenhydrinate (Canada)
Gravol (Canada)

Mechanism of Action

Pharmacology

Directly inhibits labyrinthine stimulation for up to 3 h.

Pharmacokinetics

Distribution

Small amounts excreted in breast milk.

Elimination

Renally eliminated.

Onset

20 to 30 min (IM).

Duration

3 to 6 h.

Indications and Usage

Prevention and treatment of motion sickness, dizziness, nausea, vomiting.

Unlabeled Uses

Treatment of Meniere disease, nausea and vomiting of pregnancy, postoperative nausea, and vomiting.

Contraindications

Use in newborns; allergic reactions to diphenhydramine.

Dosage and Administration

Motion Sickness
Adults

PO 50 to 100 mg 30 min prior to travel, followed by 50 to 100 mg every 4 to 6 h (max 400 mg/day). IM 50 mg as needed. IV 50 mg in 10 mL of sodium chloride for injection administered over 2 min.

Children (6 to 12 yr of age)

PO 25 to 50 mg every 6 to 8 h (max 150 mg/day). IM 1.25 mg/kg 4 times daily (max 300 mg/day).

Children (2 to 6 yr of age)

PO Up to 12.5 to 25 mg every 6 to 8 h (max 75 mg/day). IM 1.25 mg/kg 4 times daily (max 300 mg/day).

General Advice

• When administering drug IM, use Z-track method to avoid subcutaneous irritation.
• When administering drug IV, confirm correct catheter or needle placement. Note that this drug should never be given intra-arterially.

Drug Interactions

Alcohol, CNS depressants

Enhances CNS depressant effects.

Aminoglycosides

May mask signs of aminoglycoside-related ototoxicity.

Anticholinergic drugs

Causes additive anticholinergic effects.

Incompatibility

Ammonium chloride, amobarbital, butorphanol, chlorpromazine, glycopyrrolate, heparin, hydrocortisone, hydroxyzine, midazolam, pentobarbital, phenobarbital, phenytoin, prednisolone, prochlorperazine, promethazine, tetracycline, theophylline, thiopental, trifluoperazine.

Laboratory Test Interactions

May cause false elevation in serum theophylline levels.

Adverse Reactions

Cardiovascular

Palpitations; hypotension; tachycardia.

CNS

Sedation; hallucinations; delirium; drowsiness; confusion, nervousness; restlessness; headache; insomnia; tingling, heaviness and weakness of hands; vertigo; dizziness; lassitude; excitation.

Dermatologic

Fixed drug eruption; photosensitivity.

EENT

Diminished night vision; decreased color discrimination; exacerbation of narrow-angle glaucoma; blurred vision; diplopia; nasal stuffiness; dryness of nose and throat.

GI

Nausea; vomiting; diarrhea; GI distress; constipation; anorexia; dry mouth.

Genitourinary

Prostatic enlargement; difficult or painful urination.

Respiratory

Tightness of chest; wheezing; thickening of bronchial secretions.

Miscellaneous

Anaphylaxis.

Precautions

Monitor Take safety precautions if drowsiness or dizziness occurs. Note paradoxical effect occurs (eg, insomnia, CNS stimulation), and visual or auditory disturbances (eg, blurred vision/tinnitus, hearing loss).

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Children

Safety and efficacy in children younger than 2 yr of age not established.

Hypersensitivity

Previous reactions to diphenhydramine.

Special Risk Patients

Use caution in patients with asthma, prostatic hypertrophy, narrow-angle glaucoma, stenosing peptic ulcer, cardiac arrhythmias.

Overdosage

Symptoms

Drowsiness, hallucinations, convulsions, coma, respiratory depression.

Patient Information

• Advise patient to take medication 30 to 60 min before activity that may produce nausea or motion sickness.
• Instruct patient to report these symptoms to health care provider: drowsiness, nervousness, dry mouth, insomnia, constipation, blurred vision.
• If dimenhydrinate is being given as antiemetic, instruct patient to report nausea and vomiting to the health care provider.
• Instruct patient to take sips of water frequently, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs and to relieve constipation with increased fiber in diet and good hydration.
• Caution patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.