Midazolam (Molecule of the Month for May 2009)
Dormicum, Hypnovel, Midacum, Versed
Midazolam is an ultra short-acting benzodiazepine derivative. It has potent anxiolytic, amnestic, hypnotic, anticonvulsant, skeletal muscle relaxant, and sedative properties. Midazolam is water-soluble and fat-soluble in physiologic pH. Freely soluble in alcohol and acetone. It is considered an ultra short-acting benzodiazepine, with an elimination half-life of about 2 hours. It is used in some countries for the short term treatment of insomnia and in many countries as a premedication before surgery. It is therefore a very useful drug to use for short minor procedures such as dental extraction. Midazolam was first synthesized in 1976 by Fryer and Walser.
Intravenous midazolam is indicated for procedural sedation (often in combination with an opioid, such as fentanyl), for pre-op sedation, for the induction of general anesthesia, and for sedation of ventilated patients in critical care units. Oral midazolam is indicated for the short term treatment of moderately severe insomnia in patients who did not adequately react to other hypnotics, and who have persistent trouble in falling asleep. Because of midazolam's extremely short duration, midazolam is not used for patients who have trouble staying asleep through the night; moderate to long acting benzodiazepines like temazepam, nitrazepam, flunitrazepam and lormetazepam are used for those purposes.
Midazolam can cause a rapid development of drug tolerance and benzodiazepine dependence. Upon discontinuation a benzodiazepine withdrawal syndrome can occur, including rebound insomnia. Gradual reduction of midazolam after regular use can minimise withdrawal and rebound effects. Midazolam overdose is considered a medical emergency and generally requires the immediate attention of medical personnel. The antidote for an overdose of midazolam (or any other benzodiazepine) is flumazenil (Anexate). The risk of midazolam overdose is increased significantly if midazolam is abused in conjunction with opiates.
Formal Chemical Name (IUPAC)
8-chloro- 6-(2-fluorophenyl)- 1-methyl- 4H-imidazo[1,5-a] [1,4]benzodiazepine
Update by Karl Harrison
(Molecule of the Month for May 2009 )