Dimenhydrinate is an over-the-counter drug used to prevent nausea and motion sickness. 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 on its own. 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 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 chlorotheophyllinate, so the overall effect is still mostly sedating.

Dimenhydrinate is used as a deliriant at doses of 400 to 1200 mg, although body weight plays a significant part in dosing of this drug. Slang terms for Dramamine used this way include "dime," "dime tabs," "D-Q," "substance D," "d-house," and "drams." Frequent users of Dramamine are sometimes called Dramatists, a pun on the name. Tripping on Dramamine is sometimes referred to as Dramatizing or "going a dime a dozen," a reference to the amount of Dramamine tabs generally necessary for a trip. The auditory/visual hallucinations coupled with the ensuing confusion and short-term memory loss often leads to mild or intense paranoia among the users. Though auditory hallucinations are more common than visual hallucinations, the visuals of a "Dramamine Trip" can seem very real. At higher doses the hallucinations are more frequent, realistic and in some cases, frightening. Taking Dramamine at higher doses is neither advised nor recommended -- potential for overdose is a risk. Hallucinations induced by Dramamine abuse are sometimes shared among users; that is, it is common for Dramamine users to hear their own name being called, to see frightening creatures (such as insects or zombies), and to have conversations with non-existent people. When taken before going to sleep, users tend to sit up and look around at their surroundings at random, sometimes within 2-5 minute intervals.

Formal Chemical Name (IUPAC)
2-(diphenylmethoxy)-N,N-dimethylethanamine and 8-chloro-1,3-dimethyl-7H-purine-2,6-dione

References

http://en.wikipedia.org/wiki/Dimenhydrinate