Dimenhydrinate

You should not use dimenhydrinate if you are allergic to it.

Ask a doctor or pharmacist if it is safe for you to use this medicine if you have other medical conditions, especially:

• liver or kidney disease;

• enlarged prostate and urination problems;

• heart disease, high pressure;

• a history of seizures;

• blockage in your digestive tract (stomach or intestines);

• overactive thyroid;

• glaucoma; or

• asthma, bronchitis, emphysema, or other breathing disorder.

Do not give this medicine to a child younger than 2 years old. Always ask a doctor before giving an antihistamine to a child. Death can occur from the misuse of antihistamines in very young children.

It is not known whether dimenhydrinate will harm an unborn baby. Do not use this medicine without a doctor's advice if you are pregnant.

It is not known whether dimenhydrinate passes into breast milk or if it could harm a nursing baby. Do not use this medicine without a doctor's advice if you are breast-feeding a baby.

Ask a doctor or pharmacist before using this medicine if you are also using any other drugs, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or dangerous effects when used together. Not all possible interactions are listed in this medication guide.

Taking this medicine with other drugs that make you sleepy or slow your breathing can worsen these effects. Ask your doctor before taking dimenhydrinate with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Motion Sickness

Used principally in the prevention and treatment of nausea, vomiting, and/or vertigo associated with motion sickness, although scopolamine, promethazine, or meclizine may be more effective.b

Most effective when given prophylactically.b

Ménière’s Disease and Other Vestibular Disturbances

Has been used for symptomatic treatment (e.g., nausea, vomiting, vertigo) of Ménière’s disease† and other vestibular disturbances†.b

Nausea and Vomiting

May be less effective than phenothiazines in controlling nausea and vomiting not related to vestibular stimulation.b

Allergic Conditions

Although a histamine antagonist, use in allergic conditions† has not been evaluated.b

Administration

Administer orally or by IM or IV injection.a b

IV Injection

For solution and drug compatibility information, see Compatibility under Stability.

Each 50 mg must be diluted with 10 mL of 0.9% sodium chloride injection.b

Inject IV slowly over a period of 2 minutes.b

Dosage

Pediatric Patients

For prevention, take 30 minutes before exposure to motion.b

Children <2 Years of Age: Give only under the direction of a clinician.100 101

Children 2 to <6 Years of Age: 12.5–25 mg every 6–8 hours, not to exceed 75 mg in 24 hours, or as directed by a clinician.100 101 102

Children 6 to <12 Years of Age: 25–50 mg every 6–8 hours, not to exceed 150 mg in 24 hours, or as directed by a clinician.100 101 102

Children ≥12 Years of Age: Usually, 50–100 mg every 4–6 hours, not to exceed 400 mg in 24 hours, or as directed by a clinician.100 101 102

Children: Alternatively, 1.25 mg/kg or 37.5 mg/m2 4 times daily, up to a maximum of 300 mg daily.b

Children: 1.25 mg/kg or 37.5 mg/m2 4 times daily, up to a maximum of 300 mg daily.b

Not established for children.b

Adults

For prevention, take 30 minutes before exposure to motion.b

Usually 50–100 mg every 4–6 hours, not to exceed 400 mg in 24 hours, or as directed by a clinician.100 101 102

50–100 mg every 4–6 hours, not to exceed 400 mg in 24 hours, or as directed by a clinician.b

50–100 mg every 4–6 hours, not to exceed 400 mg in 24 hours, or as directed by a clinician.b

25–50 mg has been given 3 times daily.b

50 mg.b

Prescribing Limits

Pediatric Patients

Children 2 to <6 Years of Age: Maximum 75 mg in 24 hours, or as directed by a clinician.100 101 102

Children 6 to <12 Years of Age: Maximum 150 mg in 24 hours, or as directed by a clinician.100 101 102

Children ≥12 Years of Age: Maximum 400 mg in 24 hours, or as directed by a clinician.100 101 102

Children: Alternatively, maximum 300 mg daily when given as 1.25 mg/kg or 37.5 mg/m2.b

300 mg daily.b

Adults

Maximum 400 mg in 24 hours, or as directed by a clinician.100 101 102

Maximum 400 mg in 24 hours, or as directed by a clinician.b

Maximum 400 mg in 24 hours, or as directed by a clinician.b

Special Populations

Hepatic Impairment

No specific dosage recommendations for hepatic impairment.a b

Renal Impairment

No specific dosage recommendations for renal impairment.a b

Geriatric Patients

No specific geriatric dosage recommendations.a

Neonates and patients with a history of hypersensitivity to Dimenhydrinate or its components (diphenhydramine or 8-chlorotheophylline) should not be treated with Dimenhydrinate.

Note: This product contains Benzyl Alcohol.  Benzyl Alcohol has been associated with a fatal “Gasping Syndrome” in premature infants and infants of low birth weight.

Caution should be used when Dimenhydrinate is given in conjunction with certain antibiotics that may cause ototoxicity, since Dimenhydrinate is capable of masking ototoxic symptoms, and an irreversible state may be reached.

This drug may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery.  The concomitant use of alcohol or other central nervous system depressants may have an additive effect. Therefore, patients should be warned accordingly.

Dimenhydrinate should be used with caution in patients having conditions which might be aggravated by anticholinergic therapy (i.e., prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, bladder neck obstruction, narrow-angle glaucoma, bronchial asthma, or cardiac arrhythmias).

The preparation should not be injected intra-arterially.

Pediatric Patients

For infants and children especially, antihistamines in overdosage may cause hallucinations, convulsions, or death.

As in adults, antihistamines may diminish mental alertness in pediatric patients.  In the young child, particularly, they may produce excitation (see CONTRAINDICATIONS).

• Dramamine [OTC]
• Driminate [OTC]
• Motion Sickness [OTC]

Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract; blocks chemoreceptor trigger zone, diminishes vestibular stimulation, and depresses labyrinthine function through its central anticholinergic activity

Absorption

Well absorbed

Distribution

3 to 4 L/kg (Gravol Canadian labeling 2016)

Metabolism

Extensive in the liver to metabolites (diphenyl-methoxy-ethylamine, diphenyl-methoxy-acetic, diphenyl-methoxy-N-methylamine) (Gravol Canadian labeling 2016)

Excretion

Renal (Gravol Canadian labeling 2016)

US labeling: Motion sickness: Treatment and prevention of nausea, vertigo, and vomiting associated with motion sickness.

Canadian labeling: Nausea, vomiting and/or vertigo: Treatment and prevention of nausea, vomiting and/or vertigo associated with motion sickness, radiation sickness, postoperative recovery, use of other drugs, Mènière disease and other labyrinthine disturbances.

Solution for injection: Store at 20°C to 25°C (68°F to 77°F). Protect from light.

Suppository [Canadian product]: Store at 15°C to 30°C (59°F to 86°F).

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). Other CNS effects which may be observed, particularly at higher dosages include euphoria, hallucinations, confusion, temporary amnesia and paranoia.

• Dermatologic reactions: Rare cases of serious skin reactions (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme) have been reported; discontinue use if skin rash develops and consult health care provider.

Disease-related concerns:

• Cardiovascular disease: Use with caution in patients with cardiovascular disease (including arrhythmias, hypertension and ischemic heart disease).

• Hepatic impairment: Use with caution in patients with hepatic impairment.

• Increased intraocular pressure/glaucoma: Use with caution in patients with increased intraocular pressure or angle-closure glaucoma (contraindicated in the Canadian labeling).

• Prostatic hyperplasia/urinary obstruction: Use with caution in patients with prostatic hyperplasia (contraindicated in the Canadian labeling) and/or GU obstruction.

• Pyloroduodenal obstruction: Use with caution in patients with pyloroduodenal obstruction (including stenotic peptic ulcer).

• Respiratory disease: Use with caution in patients with a history of asthma or lower respiratory tract symptoms. The Canadian labeling contraindicates in patients with chronic pulmonary disease.

• Seizures: Use with caution in patients with seizure disorders.

• Thyroid dysfunction: Use with caution in patients with thyroid dysfunction.

Concurrent drug therapy issues:

• Antibiotics: Use caution if used in conjunction with antibiotics that have the potential to cause ototoxicity. Dimenhydrinate may mask symptoms of ototoxicity.

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Special populations:

• Elderly: Use with caution in the elderly; may be more sensitive to adverse effects.

• Pediatric: Antihistamines may cause excitation in young children. Not for OTC use in children <2 years of age. The Canadian labeling contraindicates use in patients <2 years of age.

Dosage form specific issues:

• Benzyl alcohol and derivatives: Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity ("gasping syndrome") in neonates; the "gasping syndrome" consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension and cardiovascular collapse (AAP 1997; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer's labeling.

• Parenteral formulations: Do not inject intra-arterially.

• Phenylalanine: Some products may contain phenylalanine.

• Polysorbate 80: Some dosage forms may contain polysorbate 80 (also known as Tweens). Hypersensitivity reactions, usually a delayed reaction, have been reported following exposure to pharmaceutical products containing polysorbate 80 in certain individuals (Isaksson 2002; Lucente 2000; Shelley 1995). Thrombocytopenia, ascites, pulmonary deterioration, and renal and hepatic failure have been reported in premature neonates after receiving parenteral products containing polysorbate 80 (Alade 1986; CDC 1984). See manufacturer's labeling.

• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures and respiratory depression; use caution (AAP 1997; Zar 2007). See manufacturer's labeling.

Other warnings/precautions:

• Abuse/withdrawal: Has abuse potential due to its hallucinogenic and euphoric effects; discontinuation after chronic abuse may lead to withdrawal symptoms (eg, lethargy, agitation, hostility, hallucinations, confusion, aggression, nausea/vomiting).

INJECTABLE: 50 to 100 mg IM or IV every 4 hours as needed; Maximum Dose: 400 mg within 24 hours.

ORAL:
-Immediate Release: 50 to 100 mg every 4 to 6 hours as needed; Maximum Dose: 400 mg within 24 hours.
-Extended Release: 100 mg every 8 to 12 hours as needed; Maximum Dose: 300 mg within 24 hours.

RECTAL: 50 to 100 mg every 6 to 8 hours as needed.

Comments:
-ORAL: To prevent motion sickness, the first dose should be taken at least 30 minutes to 1 to 2 hours before starting activity.
-Parenteral therapy is indicated when oral or rectal therapy is inappropriate.

Use: Prevention and treatment of nausea, vomiting, dizziness, and/or vertigo associated with motion sickness.