Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.
Active Ingredient / Synonyms
(O-Benzhydryl(dimethylamino)ethanol) 8-chlorotheophyllinate | 8-chloro-1,3-Dimethyl-3,7-dihydro-1H-purine-2,6-dione - 2-(diphenylmethoxy)-N,N-dimethylethanamine (1:1) | Benzhydryl-beta-dimethylaminoethylether 8-chlorotheophylline | beta-Dimethylaminoethyl benzhydryl ether 1,3-dimethyl-8-chloroxanthine | Dimenhidrinato | Dimenhydrinatum | Diphenhydramine 8-chlorotheophyllinate | Diphenhydramine 8-chlorotheophylline | Diphenhydramine theoclate | Diphenhydrinate | N,N-Dimethyl-2-diphenylmethoxyethylamine 8-chlorotheophyllinate | O-Benzhydryldimethylaminoethanol 8-chlorotheophyllinate | Dimenhydrinate |
Dimenhydrinate, also known as Dramamine or Gravol, is an over-the-counter drug used to prevent nausea, vomiting, and dizziness caused by motion sickness. Dimenhydrinate is a combination drug composed of [DB01075] and [DB14132] in a salt form, with 53%-55.5% of diphenhydramine, and not less than 44%-47% of 8-chlorotheophylline, calculated on the dried basis. The antiemetic properties of dimenhydrinate are primarily thought to be produced by diphenhydramine's antagonism of H1 histamine receptors in the vestibular system [A1540] while the excitatory effects are thought to be produced by 8-chlorotheophylline's adenosine receptor blockade [A33889]. The addition of 8-chlorotheophylline was initially intended to counteract the sedative effects of diphenhydramine. When used in large doses, dimenhydrinate has been shown to cause a "high" characterized by hallucinations, excitement, incoordination, and disorientation [A1539].
Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness.
Mechanism of Action
The mechanism by which some antihistamines exert their antiemetic, anti-motion sickness, and anti-vertigo effects is not precisely known but may be related to their central anticholinergic actions. They diminish vestibular stimulation and depress labyrinthine function. An action on the medullary chemoreceptive trigger zone may also be involved in the antiemetic effect. Dimenhydrinate is a competitive antagonist at the histamine H1 receptor, which is widely distributed in the human brain. Dimenhydrinate's anti-emetic effect is probably due to H1 antagonism in the vestibular system in the brain.
Dimenhydrinate is an antiemetics drug combination that contains diphenhydramine and theophylline. It is not effective in the treatment of nausea associated with cancer chemotherapy. Dimenhydrinate directly inhibits the stimulation of certain nerves in the brain and inner ear to suppress nausea, vomiting, dizziness, and vertigo. Diphenhydramine and dimenhydinate both reduce vestibular neuronal excitation due to angular or linear acceleration motions.
Well absorbed after oral administration.
Hepatic (cytochrome P-450 system).
1 to 4 hours
Symptoms of overdose include delerium, hallucinations, and excitment. Patients may be violent and confused.
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