dimenhydrinate

dimenhydrinate

 [di″men-hi´drĭ-nāt]

an antihistamine used as an antinauseant, antiemetic, and antivertigo agent, especially in prevention and treatment of motion sickness, but also in other conditions in which nausea or vertigo may be a feature, administered orally, rectally, or by intramuscular or intravenous injection.

dimenhydrinate

Apo-Dimenhydrinate (CA), Arlevert (UK), Dramamine, Dramanate (CA), Gravol (CA), PMS-Dimenhydrinate (CA), Travamine (CA), TripTone

Pharmacologic class: Anticholinergic

Therapeutic class: Antiemetic, antivertigo agent

Pregnancy risk category B

Action

Prevents nausea and vomiting by inhibiting vestibular stimulation of chemoreceptor trigger zone and inhibiting stimulation of vomiting center in brain

Availability

Injection: 50 mg/ml

Tablets: 50 mg

Tablets (chewable): 50 mg

Indications and dosages

➣ Prevention and treatment of nausea, vomiting, dizziness, and vertigo

Adults and children ages 12 and older: 50 to 100 mg P.O. q 4 hours (not to exceed 400 mg/day), or 50 mg I.M. or I.V. q 4 hours p.r.n.

Children ages 6 to 12: 25 to 50 mg P.O. q 6 to 8 hours (not to exceed 150 mg/day), or 1.25 mg/kg I.M. (37.5 mg/m²) q 6 hours p.r.n.

Children ages 2 to 6: 12.5 to 25 mg P.O. q 6 to 8 hours (not to exceed 75 mg/day)

Contraindications

• Hypersensitivity to drug or tartrazine

• Alcohol intolerance

Precautions

Use cautiously in:

• angle-closure glaucoma, seizure disorders, prostatic hypertrophy

• children younger than age 2.

Administration

• For I.V. use, dilute with dextrose 5% in water or normal saline solution.

• Give each 50-mg I.V. dose over 2 minutes.

☞ Don't administer by I.V. route to premature or low-birth-weight infants. Solution contains benzyl alcohol, which can cause fatal "gasping" syndrome.

Adverse reactions

CNS: drowsiness, dizziness, headache, paradoxical stimulation (in children)

CV: hypotension, palpitations

EENT: blurred vision, tinnitus

GI: diarrhea, constipation, dry mouth

GU: dysuria, urinary frequency

Skin: photosensitivity

Other: decreased appetite, pain at I.M. site

Interactions

Drug-drug. Disopyramide, quinidine, tricyclic antidepressants: increased anticholinergic effects

MAO inhibitors: intensified and prolonged anticholinergic effects

Other CNS depressants (such as antihistamines, opioids, sedative-hypnotics): additive CNS depression

Ototoxic drugs (such as aminoglycosides, ethacrynic acid): masking of signs or symptoms of ototoxicity

Drug-diagnostic tests. Allergy skin tests: false-negative results

Drug-behaviors. Alcohol use: increased CNS depression

Patient monitoring

• Assess for lethargy and drowsiness.

• Monitor for dizziness, nausea, and vomiting (possible indicators of drug toxicity).

Patient teaching

• To prevent motion sickness, advise patient to take drug 30 minutes before traveling and to repeat dose before meals and at bedtime.

• Instruct patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Caution patient to avoid alcohol and sedative-hypnotics during therapy.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.

dimenhydrinate

(dī′mĕn-hī′drə-nāt′)

n.

A drug composed of two chemicals, diphenhydramine and 8-chlorotheophylline, used to prevent motion sickness.