dimenhydrinate

Inhibits vestibular stimulation.
Has significant CNS depressant, anticholinergic, antihistaminic, and antiemetic properties.

Therapeutic effects:

Decreased vestibular stimulation, which may prevent motion sickness.

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed after oral or IM administration. IV administration results in complete bioavailability.

Distribution: Extensively distributed to tissues.

Metabolism/Excretion: Metabolized by the liver.

Half-Life: Unknown.

Time/Action Profile ⬆ ⬇

(antimotion sickness, antiemetic activity)

ROUTE	ONSET	PEAK	DURATION
PO	15–60 min	1–2 hr	3–6 hr
IM	20–30 min	1–2 hr	3–6 hr
IV	rapid	unknown	3–6 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Some products contain alcohol or tartrazine; in patients with known intolerance.

Use Cautiously in:

Angle-closure glaucoma;
Seizure disorders;
Prostatic hyperplasia.
Geri: Appears on Beers list. risk of anticholinergic adverse reactions in older adults, including falls, delirium, and dementia. Avoid use in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

CV: hypotension, palpitations

Derm: photosensitivity

EENT: blurred vision, tinnitus

GI: anorexia, constipation, diarrhea, dry mouth

GU: dysuria, urinary frequency

Local: pain at IM site

Neuro: drowsiness, dizziness, headache, paradoxical excitation (children)

Interactions ⬆ ⬇

Drug-drug:

↑CNS depression with other antihistamines, alcohol, opioid analgesics, and sedative/hypnotics.
May mask signs or symptoms of ototoxicity in patients receiving ototoxic drugs (aminoglycosides, ethacrynic acid).
↑anticholinergic properties with tricyclic antidepressants, quinidine, or disopyramide.
MAO inhibitors intensify and prolong the anticholinergic effects of antihistamines.

Route/Dosage ⬆ ⬇

PO (Adults ): 50–100 mg every 4 hr (not to exceed 400 mg/day).
PO (Children 6–12 yr): 25–50 mg every 6–8 hr (not to exceed 300 mg/day).
IM IV (Adults ): 50 mg every 4 hr as needed.
IM IV (Children ): 1.25 mg/kg (37.5 mg/m²) every 6 hr as needed (not to exceed 300 mg/day).

Availability ⬆ ⬇

(Generic available)

Tablets: 50 mg^OTC
Chewable tabletsorange flavor: 50 mg^OTC
Solution for injection: 10 mg/mL; 50 mg/mL

Assessment ⬆ ⬇

Assess nausea, vomiting, bowel sounds, and abdominal pain before and after administration of this drug. Dimenhydrinate may mask the signs of an acute abdomen.
Monitor intake and output, including emesis. Assess for signs of dehydration (excessive thirst, dry skin and mucous membranes, tachycardia, increased urine specific gravity, poor skin turgor).

Lab Test Considerations:

Will cause false-negative allergy skin test results; discontinue 72 hr before testing.

Implementation ⬆ ⬇

Do not confuse dimenhydrinate with diphenhydramine. Do not confuse Dramamine (dimenhydrinate) with Dramamine (ginger root) or Dramamine (meclizine).
When used for prophylaxis of motion sickness, administer at least 30 min and preferably 1–2 hr before exposure to conditions that may precipitate motion sickness.
PO: Administer tablets without regard for meals.
IM: Inject into well-developed muscle over 2 min; massage well.

IV Administration:

Diluent: Dilute 50 mg in 10 mL of 0.9% NaCl for injection.Concentration: 5 mg/mL.
Rate: Inject over 2 min. When used for nausea and vomiting, infuse over 20 min.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take dimenhydrinate as directed.
May cause drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to the drug is known.
Inform patient that this medication may cause dry mouth. Frequent oral rinses, good oral hygiene, and sugarless gum or candy may minimize this effect.
Caution patient to avoid alcohol and other CNS depressants, including opioids, concurrently with this medication.
Advise patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. May be used for treatment of pregnancy-associated nausea and vomiting. Monitor infants exposed to dimenhydrinate through breast milk for irritability or drowsiness.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇