Also Known As: Dimenhydrinate, Dramamine, Driminate, Gravol, Gravamin, Vomex, Anautin
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 Canada as Gravol, in Portugal as Viabom, in Brazil as Dramin, in Ecuador as Anautin, in Hungary as Daedalon, and in Indonesia under the brand name Antimo, and in Thailand, Dimenhydrinate ).™. 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.
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. While dimenhydrinate is still used to prevent nausea and emesis, the development of the chemical meclozine has overtaken its usage (marketed as "Dramamine II") because meclozine is less likely to cause drowsiness.
Dimenhydrinate "has been reported to be abused for non-medicinal purposes. Street drug users abuse DMH for the acute effects of euphoric sensations and hallucinations, while psychiatric patients abuse DMH for its anxiolytic or anti-cholinergic effects...Further support comes from reports of acute and chronic abuse of DMH by humans. Collectively, results confirm the abuse liability of DMH.