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Revision as of 13:43, 28 August 2009

Midazolam
Clinical data
Pregnancy
category
Routes of
administration
Oral, I.M., I.V., parenteral
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityOral ~36%
I.M. 90%+
MetabolismHepatic
Elimination half-life1.8-6.4 hours
ExcretionRenal
Identifiers
  • 8-chloro- 6-(2-fluorophenyl)- 1-methyl- 4H-imidazo[1,5-a] [1,4]benzodiazepine
CAS Number
PubChem CID
DrugBank
ChemSpider
CompTox Dashboard (EPA)
ECHA InfoCard100.056.140 Edit this at Wikidata
Chemical and physical data
FormulaC18H13ClFN3
Molar mass325.78 g·mol−1

Midazolam, pronounced mɪˈdæzəlæm (and marketed in English-speaking countries under brand names Dormicum, Hypnovel, Midacum and Versed)[2] is an ultra short-acting benzodiazepine derivative. It has potent anxiolytic, amnestic[3], hypnotic, anticonvulsant, skeletal muscle relaxant, and sedative properties.[4] 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.[5] 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.

Indications

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. Like other benzodiazepines, midazolam produces a decrease in delta activity, though the effect of benzodiazepines on delta may not be mediated via benzodiazepine receptors. Delta activity is an indicator of depth of sleep within non-REM sleep; it is thought to reflect sleep quality, with lower levels of delta sleep reflecting poorer sleep. Thus midazolam and other benzodiazepines cause a deterioration in sleep quality. Cyproheptadine may be superior to nitrazepam in the treatment of insomnia as it enhances sleep quality based on EEG studies.[6]

Midazolam is also indicated for the acute management of aggressive or delirious patients and also is sometimes used for the acute management of seizures such as status epilepticus. Long term use for the management of epilepsy is not recommended however, due to the significant risk of tolerance which renders midazolam and other benzodiazepines ineffective and as well the significant side effect of sedation.[7] In mice given chronic midazolam a slowly evolving tolerance developed to the anticonvulsant properties of midazolam over 15 days, although some anticonvulsant effects were still apparent after 15 days of continued administration.[8]

Availability

Dormicum brand midazolam is marketed by Roche as white, oval 7.5 mg tablets in boxes of 2 or 3 blisterstrips of 10 tablets, and as blue, oval 15 mg tablets in boxes of 2 blisterstrips of 10 tablets. The tablets are imprinted with "Roche" on one side and the dose of the tablet on the other side. Dormicum is also available as 1ml, 3ml and 10ml ampoules at a concentration of 5 mg/ml. Another manufacturer, Novell Pharmaceutical Laboratories, makes it available as Miloz in 3 ml and 5 ml ampoules.

Side effects

Residual 'hangover' effects after nighttime administration of midazolam such as sleepiness, impaired psychomotor and cognitive functions may persist into the next day which may impair the ability of users to drive safely and increase risks of falls and hip fractures.[9] Confusion and amnesia are reported with midazolam.[10]

Midazolam has been known to cause a paradoxical reaction in susceptible individuals, a well-documented complication with benzodiazapines. When this occurs, the individual may experience anxiety, involuntary movements, aggressive or violent behavior, uncontrollable crying or verbalization, and other similar effects. This seems to be related to the altered state of consciousness or disinhibition produced by the drug.

Case studies have suggested that this type of negative reaction may be more likely in individuals with a history of psychiatric disorder or substance abuse, though it has also been shown to occur in patients with no such history. This reaction may be linked to use of midazolam in higher doses, among children, or among the elderly. Case studies involving identical twins have demonstrated a possible genetic susceptibility. Paradoxical behavior is often not recalled by the patient due to the amnesia-producing properties of the drug. In extreme situations, flumazenil can be administered to inhibit or reverse the effects of midazolam. Anti-psychotic medications such as haloperidol have also been used for this purpose.[11]

Tolerance, dependence and withdrawal

Midazolam can cause a rapid development of drug tolerance, benzodiazepine dependence and upon discontinuation a benzodiazepine withdrawal syndrome can occur, including rebound insomnia. Gradual reduction of midazolam after regular use can minimise withdrawal and rebound effects. Tolerance and the resultant withdrawal syndrome may be due to alterations in gene expression which results in long term changes in the function of the GABAergic neuronal system.[12][13][14] A study in rats found that midazolam is cross tolerant with barbiturates and is able to effectively substitute for barbiturates and suppress barbiturate withdrawal signs.[15] Patients who are chronic users of benzodiazepine medication who are given midazolam experience reduced therapeutic effects of midazolam, due to tolerance to benzodiazepines.[16]

Contraindications

Hypersensitivity, acute narrow angle glaucoma, shock, hypotension, head injury, and drug or alcohol use. Most are relative contraindications.

Pregnancy

Midazolam when taken during the third trimester of pregnancy may cause severe risk to the neonate, including benzodiazepine withdrawal syndrome with possible symptoms including hypotonia, apnoeic spells, cyanosis, and impaired metabolic responses to cold stress. Symptoms of hypotonia and the neonatal benzodiazepine withdrawal syndrome have been reported to persist from hours to months after birth.[17]

Interactions

Midazolam is metabolized almost completely by cytochrome P450-3A4. Grapefruit juice reduces intestinal 3A4 and results in less metabolism and higher plasma concentrations, which could result in overdose.

Mechanism of action

Like other benzodiazepines, midazolam acts on the benzodiazepine binding site of GABAA receptors. When bound it enhances the binding of GABA to the GABAA receptor which results in inhibitory effects on the central nervous system.[18]

Overdose

Symptoms of midazolam overdose include:

  • Somnolence (difficulty staying awake)
  • Mental confusion
  • Hypotension
  • Impaired motor functions
    • Impaired reflexes
    • Impaired coordination
    • Impaired balance
    • Dizziness
  • Coma
  • Death

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). The risk of midazolam overdose is increased significantly if midazolam is abused in conjunction with opiates as was highlighted in a review of deaths of users of the opioid buprenorphine in Singapore.[19]

In the Netherlands, midazolam is a List II drug of the Opium Law. Midazolam is a Schedule IV drug under the Convention on Psychotropic Substances.[20] In the United Kingdom midazolam is a Schedule III controlled drug.[21]

Law enforcement and criminal justice

Midazolam is offered to death row inmates before execution in the United States, according to the 1992 film The Execution Protocol. A Missouri prison doctor interviewed in the film said virtually no prisoners turned down the drug when it was offered a few hours prior to execution.The doctor also reported to HBO that Versed(R) (midazolam)is about 5 times as potent as Valium(R)(diazepam/Roche)which makes it beneficial for the inmate and staff.

The drug is also used by trained Paramedics to assist in controlling psychotic or mentally disturbed patients.[22][23]

See also

Notes

  1. ^ "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.
  2. ^ "Benzodiazepine Names". non-benzodiazepines.org.uk. Retrieved 2008-12-29.
  3. ^ http://www.mayoclinic.com/health/drug-information/DR600929
  4. ^ Mandrioli R, Mercolini L, Raggi MA (2008). "Benzodiazepine metabolism: an analytical perspective". Curr. Drug Metab. 9 (8): 827–44. doi:10.2174/138920008786049258. PMID 18855614. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  5. ^ Kanto JH (1985). "Midazolam: the first water-soluble benzodiazepine. Pharmacology, pharmacokinetics and efficacy in insomnia and anesthesia". Pharmacotherapy. 5 (3): 138–55. PMID 3161005.
  6. ^ Tokunaga S (2007). "Effects of some H1-antagonists on the sleep-wake cycle in sleep-disturbed rats" (pdf). J Pharmacol Sci. 103 (2): 201–6. doi:10.1254/jphs.FP0061173. PMID 17287588. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  7. ^ Isojärvi, JI (1998). "Benzodiazepines in the treatment of epilepsy in people with intellectual disability". J Intellect Disabil Res. 42 (1): 80–92. PMID 10030438. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  8. ^ Garratt JC (January 5, 1988). "Can benzodiazepines be classified by characterising their anticonvulsant tolerance-inducing potential?". Eur J Pharmacol. 145 (1): 75–80. doi:10.1016/0014-2999(88)90351-2. PMID 2894998. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  9. ^ Vermeeren A. (2004). "Residual effects of hypnotics: epidemiology and clinical implications". CNS Drugs. 18 (5): 297–328. doi:10.2165/00023210-200418050-00003. PMID 15089115. {{cite journal}}: Cite has empty unknown parameters: |month= and |coauthors= (help)
  10. ^ Lieberherr S, Scollo-Lavizzari G, Battegay R (1991). "[Confusional states following administration of short-acting benzodiazepines (midazolam/triazolam)]". Schweiz. Rundsch. Med. Prax. (in German). 80 (24): 673–5. PMID 2068441. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  11. ^ Carissa E. Mancuso, Maria G. Tanzi, Michael Gabay (2004). "[Paradoxical Reactions to Benzodiazepines: Midazolam] [language=English". Pharmacotherapy.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Fukuda K, Shoda T, Mima H, Uga H (2002). "Midazolam induces expression of c-Fos and EGR-1 by a non-GABAergic mechanism". Anesth. Analg. 95 (2): 373–8, table of contents. doi:10.1097/00000539-200208000-00024. PMID 12145054. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  13. ^ Kales A, Soldatos CR, Bixler EO, Goff PJ, Vela-Bueno A (1983). "Midazolam: dose-response studies of effectiveness and rebound insomnia". Pharmacology. 26 (3): 138–49. doi:10.1159/000137795. PMID 6132414.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ Cho HH, O'Connell JP, Cooney MF, Inchiosa MA (2007). "Minimizing tolerance and withdrawal to prolonged pediatric sedation: case report and review of the literature". J Intensive Care Med. 22 (3): 173–9. doi:10.1177/0885066607299556. PMID 17569173.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ^ Yutrzenka GJ, Patrick GA, Rosenberger W (1989). "Substitution of temazepam and midazolam in pentobarbital-dependent rats". Physiol. Behav. 46 (1): 55–60. doi:10.1016/0031-9384(89)90321-1. PMID 2573097. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  16. ^ Potokar J, Coupland N, Wilson S, Rich A, Nutt D (1999). "Assessment of GABA(A)benzodiazepine receptor (GBzR) sensitivity in patients on benzodiazepines". Psychopharmacology (Berl.). 146 (2): 180–4. doi:10.1007/s002130051104. PMID 10525753. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  17. ^ McElhatton PR. (1994). "The effects of benzodiazepine use during pregnancy and lactation". Reprod Toxicol. 8 (6): 461–75. doi:10.1016/0890-6238(94)90029-9. PMID 7881198. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help); Unknown parameter |month= ignored (help)
  18. ^ Skerritt JH (May 6, 1983). "Enhancement of GABA binding by benzodiazepines and related anxiolytics". Eur J Pharmacol. 89 (3–4): 193–8. doi:10.1016/0014-2999(83)90494-6. PMID 6135616. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  19. ^ Lai, SH (2006). "A survey of buprenorphine related deaths in Singapore". Forensic Sci Int. 162(1-3): 80–6. doi:10.1016/j.forsciint.2006.03.037. PMID 16879940. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  20. ^ List of psychotropic substances under international control
  21. ^ Blackpool NHS Primary Care Trust (2007). "Medicines Management Update" (PDF). United Kingdom: National Health Service.
  22. ^ Demetria Kalodimos. "I-Team: Injection Used To Subdue Prisoners:Medical Expert Says Practice Is Troubling". WSMV Nashville.
  23. ^ Jacob Goldstein. "Taking Sedatives to the Streets". The Wall Street Journal Health Blog.

References