Dimenhydrinate

Dimenhydrinate is a drug from the group of antihistamines. The active substance is a salt of diphenhydramine and 8-chlorotheophylline. After ingestion, the salt is broken down by the body and the two substances are released. Dimenhydrinate is therefore a combination of 2 active substances. The actual antihistamine is diphenhydramine, while 8-chlorotheophylline is stimulant and counteracts the fatigue-producing effect of the drug. Dimenhydrinate is usually used to treat nausea and vomiting and as a sedative. Dimenhydrinate is mainly taken as a tablet or chewable tablet/gum and does not require a prescription.

Pharmacodynamics

Diphenhydramine is CNS mobile and acts at histamine receptors in the brain. In doing so, it acts as an inverse agonist. This means that diphenhydramine binds to the H1 receptor and decreases its activity. It is therefore activated less often. Since histamine is involved in the H1-receptor development of nausea, this reduces the accompanying nausea. 8-Chlortheophylline binds to A receptors and prevents the development of fatigue.

Pharmacokinetics

The protein binding of the substance is about 98% and the half-life is about 1-4 hours. The substance is degraded in the liver by enzymes of the CYP450 system and excreted in the urine.

Side effects

Chewing dimenhydrinate medicines may cause numbness in the mouth. Other possible side effects are dry mouth, increase in heart rate, stuffy nose, blurred vision, and increase in intraocular pressure.

Signs of overdose include hallucinations, delirium, confusion, and increased violent tendencies.

Toxicological data

1320 mg-kg-1 (LD50, Rat, Oral)