Source: Health Products and Food Branch (CA) Revision Year: 2017
Dimenhydrinate Injection USP for IM administration contains 50% (v/v) propylene glycol and is for intramuscular injection only. In exceptional circumstances, if Dimenhydrinate Injection USP for IM administration is required for intravenous use, it must be diluted at least 1:10 with a compatible physiological solution such as sterile saline or 5% dextrose in water, to prevent propylene glycol-associated cardiogenic shock (see DOSAGE AND ADMINISTRATION, Dosing Considerations).
DIMENHYDRINATE INJECTION USP AND SANDOZ DIMENHYDRINATE ARE NOT INTENDED FOR PROLONGED USE EXCEPT ON THE ADVICE OF A PHYSICIAN.
Dimenhydrinate may impair the ability to perform hazardous activities requiring mental alertness or physical coordination such as operating machinery or driving a car.
The concomitant use of alcohol or other central nervous system depressants may have an additive effect and should be avoided.
Dimenhydrinate Injection USP and Sandoz Dimenhydrinate (dimenhydrinate) have substance abuse potential due to their hallucinogenic and euphoric effects. At higher doses, confusion, hallucinations, temporary amnesia and paranoia may occur. Chronic abuse of antihistamines can lead to drug interaction accidents, overdose, and in extreme cases to death (see OVERDOSE). Withdrawal symptoms may include lethargy, agitation, hostility, clumsiness, nausea, vomiting, hallucinations, confusion and aggression.
Use with caution in patients with cardiac arrhythmias or cardiovascular disease (including hypertension and ischemic heart disease).
Dimenhydrinate may mask the presence of underlying organic abnormalities or the toxic effects of certain antibiotics and other drugs, particularly those drugs causing ototoxicity.
Use with caution in patients who are poor CYP2D6 metabolizers and in patients with thyroid dysfunction.
Use with caution in patients with pyloroduodenal obstruction (including stenotic peptic ulcer).
Dimenhydrinate Injection USP and Sandoz Dimenhydrinate are contraindicated in patients with prostatic hyperplasia (see CONTRAINDICATIONS). Use with caution in patients with other genitourinary obstruction.
Rarely, prolonged therapy with antihistaminic drugs can produce blood dyscrasia. Use with caution in patients with porphyria.
Use with caution in patients with hepatic impairment.
Dimenhydrinate should be used with caution in patients with seizure disorders.
Dimenhydrinate Injection USP and Sandoz Dimenhydrinate are contraindicated in patients with increased intraocular pressure or narrow angle glaucoma (see CONTRAINDICATIONS).
Dimenhydrinate may cause euphoria, hallucination, confusion, and paranoia at higher doses (see WARNINGS AND PRECAUTIONS, Abuse/Dependence/Tolerance).
Dimenhydrinate Injection USP and Sandoz Dimenhydrinate are contraindicated in patients with chronic lung disease such as chronic obstructive pulmonary disease (see CONTRAINDICATIONS). Use with caution in patients with a history of asthma or lower respiratory tract symptoms.
In rare cases, serious skin reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and erythema multiform have been associated with the use of dimenhydrinate. Because the rate of these reactions is low, they have usually been noted during post-marketing surveillance in patients taking other medications also associated with the potential development of these serious skin reactions. Thus, causality is NOT clear. These reactions are potentially life threatening but may be reversible if the causative agent is discontinued and appropriate treatment instituted. Patients should be advised that if they experience a skin rash they should discontinue dimenhydrinate and contact their physician for assessment and advice, including which additional therapies to discontinue.
The use of dimenhydrinate by women who are pregnant or may become pregnant requires that the potential benefits be weighed against the potential hazards. There are no adequate and well-controlled studies with dimenhydrinate in pregnant women. Reproduction studies in rats and rabbits using dimenhydrinate doses up to 20 and 25 times the human dose (mg/kg), respectively, have not revealed evidence of harm to the fetus or impaired fertility.
Small amounts of dimenhydrinate are excreted in breast milk. Because of the potential for adverse reactions in nursing infants from dimenhydrinate, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
The safety of dimenhydrinate injection given during labour and delivery has not been established. Reports have indicated dimenhydrinate may have oxytocic effect. Caution is advised when this effect is unwanted or in situations where it may prove detrimental.
Older adults may be more sensitive to the side effects of this drug, especially drowsiness, confusion, constipation, or trouble urinating. Drowsiness and confusion can increase the risk of falling. Dimenhydrinate may be inappropriate in older adults depending on comorbidities (e.g. dementia, delirium, etc.) due to its potent anticholinergic effects.
For infants and children especially, antihistamines in overdosage may cause hallucinations, convulsions, or death (see CONTRAINDICATIONS). As in adults, antihistamines may diminish mental alertness in pediatric patients. Antihistamines may also produce excitation in younger children.
Dimenhydrinate Injection USP is not recommended for children under 6 years of age.
Sandoz Dimenhydrinate is not recommended for children under 12 years of age.
Discontinue use and contact the physician if symptoms of paradoxical excitation (restlessness, nervousness, hallucinations, delirium, or seizures), especially in small children, occur.
Drowsiness and dizziness are reported most frequently, particularly on high dosage. Pain may occur at the site of IM injection. Since dimenhydrinate contains 50% diphenhydramine, the possibility of diphenhydramine side effects must also be considered.
The following adverse reactions have also been reported:
Blood and lymphatic system disorders: anemia, thrombocytopenia, agranulocytosis, leukopenia, pancytopenia.
Body as a whole – general disorders: lassitude, fatigue, drug withdrawal syndrome, injection site inflammation.
Cardiac disorders: tachycardia, palpitations, hypotension, arrhythmia.
Ear and labyrinth disorders: tinnitus, labyrinthitis, vertigo.
Eye disorders: mydriasis, vision blurred, diplopia.
Gastrointestinal disorders: epigastric distress, nausea, dry mouth, constipation, diarrhea, vomiting
General disorders and administration site conditions: oedema.
Immune system disorders: hypersensitivity, anaphylactic reaction.
Metabolism and nutrition disorders: anorexia, decreased appetite.
Nervous system disorders: dizziness, headache, impaired coordination, somnolence, tremor, paraesthesia, ataxia, athetosis, convulsion, seizure, memory impairment, loss of consciousness.
Psychiatric disorders: depression, insomnia, hallucination, anxiety, confusional state, excitation, euphoric mood, nightmares, delirium, irritability, nervousness, restlessness, agitation.
Respiratory, thoracic, and mediastinal disorders: thickening of bronchial secretions, respiratory depression, dyspnoea.
Renal and urinary disorders: dysuria, urinary retention.
Skin and subcutaneous tissue disorders: angioedema, hyperhidrosis, rash, rash erythematous, rash maculopapular, pruritus, urticaria, fixed drug eruption, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiform, photosensitivity.
Vascular disorders: hypotension, hypertension, flushing.
Dimenhydrinate may enhance the effects of alcohol, barbiturates, tranquilizers, sedatives, or hypnotics. Caution must therefore be used, to avoid overdose.
Because dimenhydrinate also has anticholinergic activity, it may potentiate the effects of other drugs with anticholinergic activity including tricyclic antidepressants, MAO inhibitors, and antihistamines. Solid potassium dose forms should be avoided as anticholinergics may slow gastrointestinal transit resulting in local exposure to high potassium concentrations.
When given concurrently with aminoglycoside antibiotics or other ototoxic drugs, dimenhydrinate may mask the early symptoms of ototoxicity (see WARNINGS AND PRECAUTIONS).
The incompatible substance with injectable preparations of dimenhydrinate include: phenothiazine derivatives, aminophylline, ammonium chloride, sodium amobarbital, diphenylhydantoin, sodium heparin, hydrocortisone sodium succinate, pentobarbital, phenobarbital, thiopental and certain types of antibiotics (tetracycline HCl).
As for other antihistamines, dimenhydrinate may inhibit the cutaneous histamine response in skin tests using allergen extracts, thus producing false-negative results. It is recommended that dimenhydrinate be discontinued at least 72 hours before testing.
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