DIMENHYDRINATE INJECTION (CPS)
Pharmacology: While the precise mode of action of dimenhydrinate is not known, it has a depressant action on hyperstimulated labyrinthine function.
Indications: Prevention and relief of motion sickness and the nausea or vomiting incident to these conditions. The treatment or prophylaxis of the nausea and vomiting of radiation sickness, postoperative vomiting, and drug-induced nausea and vomiting; also for the symptomatic treatment of nausea, vomiting, and vertigo due to Meniere’s disease and other labyrinthine disturbances.
Warnings: Antiemetics must be used with caution since they may mask the presence of underlying organic abnormalities or the toxic effects of certain antibiotics and other drugs, particularly those drugs causing ototoxicity.
Occupational hazards: Patients receiving dimenhydrinate should be cautioned against operating automobiles or dangerous machinery because of the drowsiness associated with the drug. If drowsiness is excessive, dosage should be reduced.
Precautions: Pregnancy: The use of dimenhydrinate by women who are pregnant or may become pregnant requires that the potential benefits be weighed against the potential hazards.
Rarely, prolonged therapy with antihistaminic drugs can produce blood dyscrasia.
Dimenhydrinate should be used with caution in patients in whom anticholinergics may aggravate other clinical conditions.
An additive effect may be produced if alcohol or other CNS-depressant drugs are given concomitantly with dimenhydrinate.
Adverse Effects: Drowsiness may be experienced by some patients, especially at high dosages. Dizziness may also occur. Symptoms of dry mouth, lassitude, excitement and nausea have been reported.
Overdose: Symptoms: Drowsiness is the usual clinical side effect. Convulsions, coma and respiratory depression may occur with massive overdosage.
Children are very susceptible to the convulsant action of antihistamines and doses of from 150 to 800 mg of diphenhydramine in children aged 1? to 3? have been reported to produce convulsions.
Dosage: Substances which are physically incompatible with injectable solutions of dimenhydrinate include: phenothiazine derivatives, aminophylline, ammonium chloride, sodium amobarbital, phenytoin, heparin, hydrocortisone sodium succinate, pentobarbital, phenobarbital, thiopental and certain antibiotics.
Adults: 25-50 mg; repeat every 4 hours. This dosage regimen may cause some degree of drowsiness in some patients and 100 mg every 4 hours may be given in conditions in which drowsiness is not objectionable and may be desirable.
I.M.: Administration: 50 to 100 mg as needed.
I.V.: Administration: 10 mg/mL given slowly. Do not use i.v. the preparation designed for i.m. use (50 mg/mL), unless it has been diluted at least 1:10 with a compatible i.v. solution, such as Sodium Chloride Injection USP. The maximum daily dose should not exceed 300 mg for adults.
Children: 6 to 8 years: 12.5 to 25 mg, 2 or 3 times daily; 8 to 12 years: 25 to 50 mg, 2 or 3 times daily; over 12 years: 50 mg, 2 or 3 times daily.
Supplied: Dimenhydrinate 10 mg/mL in water with 15% ethyl alcohol. Available for i.v. use in 5 mL Uni-vials.
Dimenhydrinate, 50 mg/mL in a mixture of propylene glycol and water. Available for i.m. and, when appropriately diluted, for i.v. use in Uni-vials of 1 mL and 2 mL.
Dimenhydrinate, 50 mg/mL in a mixture of propylene glycol and water with 5% benzyl alcohol as a preservative. Available for i.m. or, when appropriately diluted, for i.v. use in 5 mL multidose vials.