Midazolam

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Midazolam chemical structure Midazolam
8-chloro-6-(2-fluorophenyl)-1-methyl- 4H-Imidazo(1,5-a)(1,4)benzodiazepine IUPAC name
CAS number 59467-70-8	ATC code N05CD08
PubChem 4192	DrugBank APRD00680
Chemical formula	{{{chemical_formula}}}
Molecular weight	325.78
Bioavailability	Oral ~36% I.M. 90%+
Metabolism	Hepatic
Elimination half-life	1.8-6.4 hours
Excretion	Renal
Pregnancy category	D (USA) C (Aus)
Legal status	Schedule IV(US)
Routes of administration	Oral, I.M., I.V., parenteral

Midazolam (marketed under brand names Versed®, Hypnovel®, Dormicum® and Dormonid®, pronounced mɪˈdæzəlæm) is a drug which is a benzodiazepine derivative. It has powerful anxiolytic, amnestic, hypnotic, anticonvulsant, skeletal muscle relaxant and sedative properties. It is considered a fast-acting benzodiazepine, with a short elimination half-life. 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.

Interactions

Midazolam is metabolized almost completely by cytochrome P450-3A4. Vmax in microsomes is reported as 850 pmol/min/mg microsomal protein. Km is reported as 3.7 uMol. Metabolism in the gut wall is reported as nearly equal to metabolism in liver by CYP3A4. Therefore, midazolam will interact with other 3A4 substrates and inhibitors. Grapefruit juice reduces intestinal 3A4 and results in less gut wall metabolism and higher plasma concentrations, which could result in overdose.

Contraindications

Hypersensitivity, acute narrow angle glaucoma, shock, hypotension, head injury, and drug or alcohol use. Some may be relative contraindications.

Overdose

Symptoms of midazolam overdose include:

• 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.

See Also

• Automatism (toxicology)
• Minor tranquilizers

External links

• Rx-List - Midazolam (Versed)
• Inchem - Midazolam

References

• EMEA Summary of Product Characteristics: Hypnovel and associated names.
• Clinical Use of Midazolam by John Shou.
• Brevoord J, Joosten K, Arts W, van Rooij R, de Hoog M (2005). Status epilepticus: clinical analysis of a treatment protocol based on midazolam and phenytoin.. J Child Neurol 20 (6): 476-81. PMID 15996395.
• Wolfe T, Macfarlane T (2006). Intranasal midazolam therapy for pediatric status epilepticus.. Am J Emerg Med 24 (3): 343-6. PMID 16635708.
• Johnson T, Rostami-Hodjegan A, Goddard J, Tanner M, Tucker G (2002). Contribution of midazolam and its 1-hydroxy metabolite to preoperative sedation in children: a pharmacokinetic-pharmacodynamic analysis.. Br J Anaesth 89 (3): 428-37. PMID 12402721.
• Prediction of the disposition of midazolam in surgical patients by a physiologically based pharmacokinetic model, Bjorkman, S et al, J Pharm Sci 2001:90(9)1226-1241.
• Merritt P, Hirshman E, Hsu J, Berrigan M (2005). Metamemory without the memory: are people aware of midazolam-induced amnesia?. Psychopharmacology (Berl) 177 (3): 336-43. PMID 15290003.

Anticonvulsants

{Topiramate}

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Barbiturates
{Phenobarbital} {Methylphenobarbital} {Metharbital} {Barbexaclone}

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