Dimehydrinate was first described in the literature in 1949,[A233120] and patented in 1950.[L32995] Early research into dimenhydrinate focused on its role as an antihistamine for urticaria; the treatment of motion sickness was an accidental discovery.[A233130] Dimenhydrinate, also known as B-dimethylaminoethyl benzohydrol ether 8-chlorotheophyllinate, is indicated to prevent nausea, vomiting, and dizziness caused by motion sickness.[L32980,L32985,L32995] Dimenhydrinate is a combination of [Diphenhydramine] and [8-chlorotheophylline] in a salt form, with 53%-55.5% dried diphenhydramine, and 44%-47% died 8-chlorotheophylline.[L32985] The antiemetic properties of dimenhydrinate are primarily thought to be produced by diphenhydramine's antagonism of H1 histamine receptors in the vestibular system[A1540] while the excitatory effects are thought to be produced by 8-chlorotheophylline's adenosine receptor blockade.[A33889] When used in large doses, dimenhydrinate has been shown to cause a "high" characterized by hallucinations, excitement, incoordination, and disorientation.[A1539] Dimenhydrinate was granted FDA approval on 31 May 1972.[L32975]