Dimenhydrinate, marketed as Dramamine and Gravol among others, is an over-the-counter drug used to treat motion sickness and nausea. Dimenhydrinate is a combination, or a salt of two drugs: diphenhydramine and 8-Chlorotheophylline.
|Trade names||Draminate, Gravol, Dramamine, others|
|Oral, rectal, intravascular, intramuscular|
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Diphenhydramine is the primary constituent of dimenhydrinate and dictates the primary effect. The main difference relative to pure diphenhydramine is a lower potency due to being combined with 8-chlorotheophylline. By weight, dimenhydrinate is between 53% to 55.5% diphenhydramine.
8-Chlorotheophylline, a chlorinated derivative of theophylline, was added in order to counteract drowsiness. Theophylline is very closely related to caffeine and theobromine, mild central nervous system stimulants. 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 8-chlorotheophylline, so the overall effect is still mostly sedating.
Dimenhydrinate is recreationally used as a deliriant. Slang terms for Dramamine used this way include "drama", "dime", "dime tabs", "D-Q", "substance D", "d-house", and "drams". Abusing Dramamine is sometimes referred to as Dramatizing or "going a dime a dozen", a reference to the amount of Dramamine tablets generally necessary for a trip.
Many users report a side effect profile consistent with tropane alkaloid (e.g. atropine) poisoning as both show antagonism of muscarinic acetylcholine receptors in both the central and autonomic nervous system, which inhibits various signal transduction pathways. In the CNS, diphenhydramine readily crosses the Blood–brain barrier, exerting effects within the visual and auditory cortex.
Other CNS effects occur within the limbic system and hippocampus, causing confusion and temporary amnesia due to decreased acetylcholine signaling. Toxicology also manifests in the autonomic nervous system, primarily at the neuromuscular junction, resulting in ataxia and extrapyramidal side effects and the feeling of heaviness in the legs, and at sympathetic post-ganglionic junctions, causing urinary retention, pupil dilation, tachycardia, irregular urination, and dry red skin caused by decreased exocrine gland secretions, and mucous membranes. Considerable overdosage can lead to myocardial infarction (heart attack), serious ventricular dysrhythmias, coma, and death. Such a side effect profile is thought to give ethanolamine-class antihistamines a relatively low abuse liability. The specific antidote for dimenhydrinate poisoning is physostigmine, usually given by IV in a hospital.
Dimenhydrinate is marketed under many brand names: in the USA, Mexico, and Serbia as Dramamine; in Ukraine as Driminate; in Canada, Costa Rica, and India as Gravol; in Iceland as Gravamin; in Russia and Croatia as Dramina; in South Africa and Germany as Vomex; in Australia and Austria as Vertirosan; in Brazil as Dramin; in Ecuador as Anautin; in Hungary as Daedalon; in Sweden as Calma or Arlevert; in Indonesia as Antimo; in Italy as Xamamina or Valontan; in Peru as Gravicoll; in Poland and Slovakia as Aviomarin; in Portugal as Viabom, Vomidrine, and Enjomin; in Spain as Biodramina; in Thailand as Daimenin; in Israel as Travamin; in Pakistan as Gravinate; and in Ethiopia as dimenhydrinate.
Modest Mouse titled a song "Dramamine" on their 1996 debut album This Is a Long Drive for Someone with Nothing to Think About. The song uses side effects of the drug as a metaphor for the deteriorating state of a personal relationship. 
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