Understanding Anesthesiology - The Global Regional Anesthesia ...

DIMENHYDRINATE
Class
Antihistamine, antiemetic. In anesthetic practice, used
as a second or third line treatment of post-operative
nausea and vomiting (PONV). No role in prevention of
PONV.
Misc.
May cause dry mouth, blurred vision, difficult urination;
more rarely causes acute glaucoma or worsening
of asthma. These side effects reflect its anticholinergic
activity which is additive with other anticholinergics
and monoamine oxidase inhibitors (MAOI).
Mechanism of Action
Dimenhydrinate is a competitive antagonist at the histamine
H1 receptor. The antiemetic effects is related to
central anticholinergic actions as well as histamine antagonism
in the vestibular system in the brain.
Dose
50-100 mg IV q4-6h, max. 400 mg/day (adults)
1.25 mg/kg IV q6h (children)
Onset
5 minutes after IV administration
Duration
4-6 hours
Elimination
Hepatic
Effects
CNS
Sedation (which is additive with alcohol and sedative
hypnotics), dizziness ,restlessness.
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