Dimenhydrinate

Absorption

A 50 mg oral film coated tablet reaches a Cmax of 72.6 ng/mL with a Tmax of 2.7 hours. A 100 mg suppository reaches a Cmax of 112.2 ng/mL with a Tmax of 5.3 hours.

Toxicity

Infants and children experiencing an overdose may lead to hallucinations, convulsions, or death. Adults experiencing an overdose may present with drowsiness, convulsions, coma, or respiratory depression. Treat overdoses with symptomatic and supportive measures including mechanically assisted ventilation.
In mice the oral LD50 is 203 mg/kg, while in rats it is 1320 mg/kg. The intraperitoneal LD50 in mice is 149 mg/kg.

Description

Dimenhydrinate (16.1.2) is a complex compound of N, N-dimethyl (2- diphenylmethoxy)ethylamine—diphenhydramine with 8-chlorotheophylline. While blocking the H1 receptor, dimenhydrinate simultaneously acts on the vomiting center.

Chemical properties

White Solid
Dimenhydrinate is freely soluble in ethanol and chloroform, slightly soluble in water, and almost in-soluble in ether.

Originator

Dramamine,Searle,US,1949

The Uses of Dimenhydrinate

Dimenhydrinate is used for preventing and stopping sea or airsickness, and for nausea and vomiting. Synonyms of this drug are dramamine, dadalon, emedyl, travelin, and others.

The Uses of Dimenhydrinate

An antihistamine with antiemetic properties used to prevent nausea and motion sicknes composed of two drugs 8-Chlorotheophylline (C411440) and Diphenhydramine (D486900).

The Uses of Dimenhydrinate

Used for treating vertigo, motion sickness, and nausea associated with pregnancy

Background

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

Indications

Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness.

Definition

ChEBI: The diphenhydramine salt of 8-chlorotheophylline. Its effects are similar to those of diphenhydramine, but it is less potent. It was thought that by combining the antiemetic effects of diphenhydramine with the mild stimulant effects of 8-chlorotheophyline, the extreme drowsiness induced by the former would be mitigated. However, the sedation caused by diphenhydramine is considerably stronger than the stimulation caused by 8-chlorotheophylline. Dimenhydrinate is used mainly as an antiemetic in the prevention nd treatment of motion sickness.

Manufacturing Process

58.8 grams of 8-chlorotheophylline and 70 grams of β-dimethylaminoethyl benzohydryl ether are dissolved in 150 cc of hot methanol. Then 5 grams of activated charcoal are added and the mixture is boiled for an hour. It is filtered hot and the filtrate cooled. The crystalline precipitate of βdimethylaminoethyl benzohydryl ether 8-chlorotheophyllinate is collected on a filter, washed with ether and dried. It melts at 96-99°C. It is dissolved in boiling ethyl acetate, filtered hot to remove any insoluble material, and then chilled. The salt so obtained melts at 102.5°-104°C after filtration, washing with ether and drying.

brand name

Dommanate (Forest).

Therapeutic Function

Antinauseant

General Description

Crystalline white powder.

General Description

The 8-chlorotheophyllinate (theoclate) salt of diphenhydramine, 8-chlorotheophylline 2-(diphenylmethoxy)-N,N-dimethylethylamine (Dramamine), is a white crystalline, odorless powder that is highly soluble in water and freely soluble in alcohol and chloroform. Dimenhydrinate is recommended for nausea of motion sickness and for hyperemesis gravidarum (nausea of pregnancy).

Air & Water Reactions

Slightly soluble in water. Slightly acidic.

Health Hazard

SYMPTOMS: Symptoms associated with Dimenhydrinate include: drowsiness, lethargy, fatigue hypnosis and coma. Initial sedation may be followed by central nervous system hyperexcitability. Also, the victim may experience dry mouth, anorexia, nausea, vomiting, abdominal distress, constipation, and/or diarrhea.

Fire Hazard

Flash point data for Dimenhydrinate are not available but Dimenhydrinate is probably non-flammable.

Pharmacokinetics

Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness. It has a short duration of action of 4-8 hours. Patients should be counselled regarding pronounced drowsiness, avoiding alcohol and other sedatives, and exercising caution when operating a motor vehicle or heavy machinery.

Safety Profile

Poison by intraperitoneal and intravenous routes. Moderately toxic by ingestion. A drug much used for motion sickness. Human systemic effects by ingestion: arrhythmias, convulsions, distorted perceptions, hallucinations, intracranial pressure increase. Mutation data reported. When heated to decomposition it emits very toxic fumes of NOx, and Cl-. See also AMINES.

Veterinary Drugs and Treatments

In veterinary medicine, dimenhydrinate is used primarily for its antiemetic effects for vomiting and in the prophylactic treatment of motion sickness in dogs and cats. Dimenhydrinate may be useful as an adjunctive treatment for feline pancreatitis. As dimenhydrinate is often thought of as “half-strength diphenhydramine” it can be employed whenever a histmine-1 blocker is desired.

Metabolism

Dimenhydrinate is a theoclate salt that separates into diphenhydramine and 8-chlorotheophylline. diphenhydramine can either be N-glucuronidated by UGTs to diphenhydramine N-glucuronide or N-demethylated by CYP2D6, CYP1A2, CYP2C9, and CYP2C19 to N-desmethyldiphenhydramine. N-desmethyldiphenhydramine can be N-demethylated again by the same enzymes to N,N-didesmethyldiphenhydramine, which undergoes oxidative deamination to form diphenylmethoxyacetic acid.