Active ingredient: Midazolam - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

• Anesthetics, Intravenous
• Anti-anxiety Agents
• Hypnotics and Sedatives
• Adjuvants, Anesthesia
• GABA Modulators

Dosage Forms

• Liquid
• Solution

Brands / Synonyms

Dea No. 2884; Dormicum; Midazolam; Midazolam Base; Midazolam Hcl; Midazolam Injection; Midazolamum [Inn-Latin]; Versed

Indications

For use in pediatric patients for sedation, anxiolysis, and amnesia prior to diagnostic, therapeutic, or endoscopic procedures or before induction of anesthesia.

Pharmacology

Midazolam is a short-acting benzodiazepine central nervous system (CNS) depressant. Pharmacodynamic properties of midazolam and its metabolites, which are similar to those of other benzodiazepines, include sedative, anxiolytic, amnesic and hypnotic activities. Benzodiazepine pharmacologic effects appear to result from reversible interactions with the (gamma)-amino butyric acid (GABA) benzodiazepine receptor in the CNS, the major inhibitory neurotransmitter in the central nervous system. The action of midazolam is readily reversed by the benzodiazepine receptor antagonist, flumazenil.

Mechanism of Action

It is thought that the actions of benzodiazepines such as midazolam are mediated through the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), which is one of the major inhibitory neurotransmitters in the brain. Benzodiazepines increase the activity of GABA, thereby producing a calming effect, relaxing skeletal muscles, and inducing sleep. Benzodiazepines act as agonists at the benzodiazepine receptors, which form a component of the benzodiazepine-GABA receptor-chloride ionophore complex. Most anxiolytics appear to act through at least one component of this complex to enhance the inhibitory action of GABA.

Absorption

Rapidly absorbed after oral administration (absolute bioavailability of the midazolam syrup in pediatric patients is about 36%, and intramuscular is greater than 90%).

Toxicity

LD₅₀=825 mg/kg (Orally in rats). Signs of overdose include sedation, somnolence, confusion, impaired coordination, diminished reflexes, coma, and deleterious effects on vital signs.

Biotrnasformation / Drug Metabolism

Midazolam is primarily metabolized in the liver and gut by human cytochrome P450 IIIA4 (CYP3A4) to its pharmacologic active metabolite, (alpha)-hydroxymidazolam, and 4-hydroxymidazolam.

Contraindications

Midazolam is contraindicated in patients with a known hypersensitivity to the drug. Benzodiazepines are contraindicated in patients with acute narrow-angle glaucoma. Benzodiazepines may be used in patients with open-angle glaucoma only if they are receiving appropriate therapy. Measurements of intraocular pressure in patients without eye disease show a moderate lowering following induction with Midazolam; patients with glaucoma have not been studied.

Midazolam is not intended for intrathecal or epidural administration due to the presence of the preservative benzyl alcohol in the dosage form.

Drug Interactions

Drug Interactions:    Inhibitors of CYP3A4 Isozymes: Caution is advised when midazolam is administered concomitantly with drugs that are known to inhibit the cytochrome P450 3A4 enzyme system (ie, some drugs in the drug classes of azole antimycotics, protease inhibitors, calcium channel antagonists, and macrolide antibiotics). Drugs such as erythromycin, diltiazem, verapamil, ketoconazole, fluconazole and itraconazole were shown to significantly increase the C _max and AUC of orally administered midazolam. These drug interactions may result in increased and prolonged sedation due to a decrease in plasma clearance of midazolam. Although not studied, the potent cytochrome P450 3A4 inhibitors ritonavir and nelfinavir may cause intense and prolonged sedation and respiratory depression due to a decrease in plasma clearance of midazolam. Caution is advised when VERSED Syrup is used concomitantly with these drugs. Dose adjustments should be considered and possible prolongation and intensity of effect should be anticipated.

Inducers of CYP3A4 Isozymes:   Cytochrome P450 inducers, such as rifampin, carbamazepine, and phenytoin, induce metabolism and caused a markedly decreased C _max and AUC of oral midazolam in adult studies. Although clinical studies have not been performed, phenobarbital is expected to have the same effect. Caution is advised when administering VERSED Syrup to patients receiving these medications and if necessary dose adjustments should be considered.

CNS Depressants:   One case was reported of inadequate sedation with chloral hydrate and later with oral midazolam due to a possible interaction with methylphenidate administered chronically in a 2-year-old boy with a history of William's syndrome. The difficulty in achieving adequate sedation may have been the result of decreased absorption of the sedatives due to both the gastrointestinal effects and stimulant effects of methylphenidate.

The sedative effect of VERSED Syrup is accentuated by any concomitantly administered medication which depresses the central nervous system, particularly narcotics (eg, morphine, meperidine and fentanyl), propofol, ketamine, nitrous oxide, secobarbital and droperidol. Consequently, the dose of VERSED Syrup should be adjusted according to the type and amount of concomitant medications administered and the desired clinical response.

No significant adverse interactions with common premedications (such as atropine, scopolamine, glycopyrrolate, diazepam, hydroxyzine, and other muscle relaxants) or local anesthetics have been observed.