Midazolam, (marketed under brand names Versed®, Hypnovel® and Dormicum®) is a drug which is a benzodiazepine derivative. It has anxiolytic, amnestic, hypnotic, anticonvulsant, skeletal muscle relaxant and sedative properties. It is considered a fast-acting benzodiazepine, with a short elimination half-life.
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| Clinical data | |
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| Routes of administration | Oral, I.M., I.V., parenteral |
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| Pharmacokinetic data | |
| Bioavailability | 97% |
| Metabolism | Hepatic |
| Elimination half-life | 1.8-6.4 hours |
| Excretion | Renal |
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| ECHA InfoCard | 100.056.140 |
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| Formula | C18H13ClFN3 |
| Molar mass | 325.78 |
Midazolam was first synthesized in 1976 by Fryer and Walser.
This drug is considered quite addictive [1], as should be expected given its potent anxiolytic properties and rapid onset of action.
Pharmacology
Unlike other benzodiazepines such as diazepam and lorazepam, midazolam is water soluble because the imidazole ring is open at pH under 4. However, when it is injected and the pH is 7.4, the imidazole ring closes and it becomes much more lipid soluble, facilitating its rapid uptake into nerve tissue. This partly accounts for its rapid onset of action and its high protein binding in the blood (up to 97%).
Indications
Midazolam is frequently used (usually in combination with other agents, such as morphine) by anesthesiologists for sedating patients prior to surgery or other invasive medical procedures, such as endoscopy.
Due to its high potency and fast onset of effects, it is rarely prescribed outside of hospitals. An exception is buccal midazolam, used for the rapid treatment of prolonged seizures. This is an off-label use usage of midazolam, although it has become increasingly common. The drug is squirted slowly between the gums and the inside of the cheek, where it is absorbed directly into the blood stream.
- Intramuscular or intravenous:
- Preoperative sedation, anxiolysis, amnesia,
- Treatment of epileptic seizures.
- Intravenous:
- For sedation, anxiolysis, and amnesia prior to endoscopic procedures. Often used in combination with other CNS depressants.
- For general anesthesia, often in combination with other anesthetic agents.
- Continuous I.V. infusion:
- For sedation of intubated patients in an intensive care setting.
Dosage
Side Effects
Interactions
Contraindications
Overdose
An individual who has consumed too much midazolam will display one or more of the following symptoms:
- Somnolence (difficulty staying awake)
- Mental confusion
- Hypotension
- Impaired motor functions
- Impaired reflexes
- Impaired coordination
- Impaired balance
- Dizziness
- Coma
In animal models, the oral LD50 of midazolam is 825 mg/kg.
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®).
Legal Status
Midazolam is a Schedule IV drug under the Convention on Psychotropic Substances[2].
External links
References
- Status Epilepticus: Clinical Analysis of a Treatment Protocol Based on Midazolam and Phenytoin, Brevoord, J. D. et al., Journal of Child Neurology 2005;20(6):476-48
- Successful treatment of 75 patients in status epilepticus with intravenous midazolam., Galvin GM, Jelinek GA., Emerg Med 1992;4:11-12.
- ^ "FDA-sourced list of all drugs with black box warnings (Use Download Full Results and View Query links.)". nctr-crs.fda.gov. FDA. Retrieved 22 Oct 2023.