Dimenhydrinate

"Dramamine" redirects here. For other uses, see Dramamine (disambiguation).

Dimenhydrinate

Combination of
diphenhydramine	antihistamine
8-chlorotheophylline	stimulant
Clinical data
AHFS/Drugs.com	monograph
MedlinePlus	a607046
Pregnancy cat.	A (AU) B (US)
Legal status	Pharmacy Only (S2) (AU) OTC (US)
Routes	Oral, Rectal, I.V.
Identifiers
CAS number	523-87-5 Y
ATC code	R06AA52
PubChem	CID 10660
DrugBank	DB00985
ChemSpider	10210 Y
UNII	JB937PER5C Y
KEGG	D00520 Y
ChEMBL	CHEMBL1200406 N
N (what is this?)  (verify)

Dimenhydrinate (in US marketed under brand names Dramamine, Driminate, Gravol, Gravamin, Vomex, and Vertirosan) is an over-the-counter drug used to prevent nausea and motion sickness. It is marketed in Brazil as Dramin, in Canada as Gravol, in Ecuador as Anautin, in Hungary as Daedalon, in Italy as Xamamina, in Indonesia as Antimo, in Portugal as Viabom, and in Thailand as ไดเมนนีน (Dị men nīn). It is most commonly used as pills, although it is also available in liquid form and in suppositories. Chemically, dimenhydrinate is a salt of two drugs: diphenhydramine, and 8-chlorotheophylline, a chlorinated derivative of theophylline.

Pharmocology

The effects of dimenhydrinate are very similar to those of diphenhydramine. The main differences are a lower potency, and a longer latency. 50 mg dimenhydrinate contains 27.2 mg of diphenhydramine, so it is less potent at equal doses. Also, dimenhydrinate must dissociate into diphenhydramine and its counterion in the body before it is active, so it produces effects more slowly than diphenhydramine. The drug typically takes a minimum of 4 hours to fully take effect.

Theophylline was added in order to counteract drowsiness. Theophylline is very closely related to caffeine and theobromine, mild central nervous system stimulants. It was thought by scientists that by combining the antiemetic effects of diphenhydramine with a stimulant, the extreme drowsiness induced by the former could be mitigated somewhat by the latter. The sedation caused by diphenhydramine, however, is substantially stronger than the stimulation caused by chlorotheophylline, so the overall effect is still mostly sedating. Diphenhydramine, an ethanolamine-class antihistamine, is found in most OTC sleep aids and allergy preparations, such as Tylenol PM and Benadryl. It is primarily a H₁-antagonist, but also possesses an antimuscarinic effect. It is used in Dramamine to prevent nausea and emesis; however, the development of the chemical meclozine has overtaken its usage (marketed as "Dramamine II") because meclizine is less likely to cause drowsiness.

Veterinary use

Dimenhydrinate has successfully been used as an antiemetic and sedative in housepets. It is commonly used to reduce the effects of idiopathic vestibular syndrome. The suggested dosage is 50 mg for dogs and 10 mg for cats; duration of effect is 8 hours.

This dosage though is not a proper measure for all pets and should be adjusted by weight.