Tofisopam (marketed under brand names Emandaxin and Grandaxin) is a 2,3-benzodiazepine drug which is a benzodiazepine derivative. In contrast to classical 1,4-benzodiazepines, the compound does not bind to the benzodiazepine binding site of the gamma-aminobutyric acid receptor and its psychopharmacological profile differs from such compounds. Although Tofisopam is not approved for sale in North America, it is approved for use in various countries worldwide, including parts of Europe. The D-enantiomer (dextofisopam) is currently in phase II trials in the U.S. for the treatment of irritable bowel syndrome.
- Metabolism: Hepatic. Half Life: 6-8 hours
- Uses/Sources: For the treatment of anxiety and alcohol withdrawal.
- Symptoms: The onset of impairment of consciousness is relatively rapid in benzodiazepine poisoning. Onset is more rapid following larger doses and with agents of shorter duration of action. The most common and initial symptom is somnolence. This may progress to coma (Grade I or Grade II) following very large ingestions.
- Treatment: General supportive measures should be employed, along with intravenous fluids, and an adequate airway maintained. Hypotension may be combated by the use of norepinephrine or metaraminol. Dialysis is of limited value. Flumazenil (Anexate) is a competitive benzodiazepine receptor antagonist that can be used as an antidote for benzodiazepine overdose. In particular, flumazenil is very effective at reversing the CNS depression associated with benzodiazepines but is less effective at reversing respiratory depression. Its use, however, is controversial as it has numerous contraindications. It is contraindicated in patients who are on long-term benzodiazepines, those who have ingested a substance that lowers the seizure threshold, or in patients who have tachycardia or a history of seizures. As a general rule, medical observation and supportive care are the mainstay of treatment of benzodiazepine overdose. Although benzodiazepines are absorbed by activated charcoal, gastric decontamination with activated charcoal is not beneficial in pure benzodiazepine overdose as the risk of adverse effects often outweigh any potential benefit from the procedure. It is recommended only if benzodiazepines have been taken in combination with other drugs that may benefit from decontamination. Gastric lavage (stomach pumping) or whole bowel irrigation are also not recommended.
- Carcinogenicity: No indication of carcinogenicity to humans (not listed by IARC).
- Toxicity: Oral, Rat: LD50 = 825 mg/kg.