Indication |
Used for treating vertigo, motion sickness, and nausea associated with pregnancy. |
Pharmacodynamics |
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. |
Mechanism of action |
The mechanism by which some antihistamines exert their antiemetic,
anti–motion sickness, and antivertigo 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. |
Absorption |
Well absorbed after oral administration. |
Volume of distribution |
Not Available |
Protein binding |
98 to 99%. |
Metabolism |
Hepatic (cytochrome P-450 system). |
Route of elimination |
Not Available |
Half life |
1 to 4 hours |
Clearance |
Not Available |
Toxicity |
Symptoms of overdose include delerium, hallucinations, and excitment. Patients may be violent and confused. |
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