Midazolam

Anxiolytic and Hypnotic Drugs

Drug class: Benzodiazepine, BDZs

Midazolam (DORMICUM)（中文：咪達唑侖）

Pronunciation

Midazolam 15mg

Common Strengths of Midazolam

Midazolam are available in the following strengths:

• Injectable Solution:
  • 1 mg/mL
  • 2 mg/mL
  • 5 mg/mL
• Oral Solution:
  • 10 mg/5 mL
• Tablet:
  • 15 mg

Drug Trade Names of Midazolam

Dormicum

Drug Usage

Midazolam is used for:

• Procedural sedation
• Induction of anesthesia
• Sedation in intensive care settings
• Treatment of status epilepticus
• Preoperative sedation

Mechanism of Action

Midazolam enhances the effect of GABA (gamma-aminobutyric acid), the primary inhibitory neurotransmitter in the brain, by binding to GABA_A receptors. This results in sedative, anxiolytic, muscle relaxant, and anticonvulsant effects.

Route of Administration

Midazolam can be administered via:

• Oral (tablets, solution)
• Intravenous (IV)
• Intramuscular (IM)
• Intranasal

Dosages

• Sedation:
  • IV: 1 to 2.5 mg, may repeat every 2-3 minutes as needed (max 5 mg).
  • IM: 0.07 to 0.08 mg/kg, max 10 mg.
• Induction of Anesthesia:
  • IV: 0.1 to 0.2 mg/kg, may repeat as needed.
• Elderly or Debilitated Patients:
  • Start with lower doses (e.g. 0.5 mg to 1 mg) and titrate carefully.

Side Effects

Frequency	Adverse reactions
Commmon Side Effects	Anterograde amnesia
	Drowsiness
	Ataxia
	Falls
	Confusion (especially in the elderly)
Serious Side Effects	Respiratory depression, especially when used with opioids or in the elderly with COPD
	Paradoxical reactions like agitation, aggression, and uncontrollable crying in those with a history of alcohol abuse
	Dependence and withdrawal symptoms with long-term use
	Hypotension and tachycardia with rapid IV administration
	Midazolam infusion syndrome requiring continuous ventilator support with higher doses
	Severe allergic reactions
	Suicidal thoughts or behavior
	Neonatal withdrawal symptoms (hypotonia, cyanosis, apnea) with late 3rd trimester use
Midazolam toxicity is rare but can occur, especially when combined with other CNS depressants. Symptoms include ataxia, hypotension, coma, and death. Flumazenil is the antidote.

Pharmacokinetics

• Onset of drug action:
  • IV: 1 to 3 minutes
  • IM: 15 to 30 minutes
  • Oral: 30 to 60 minutes
• Duration: 1-6 hours, depending on the route and dose.
• Half-Life: 1.5 to 2.5 hours in adults; longer in elderly and children.
• Metabolism: Hepatic via CYP3A4 to active metabolites.
• Excretion: Primarily renal.

Drug Precautions

Pregnancy

Use only if benefits outweigh risks; potential risk to the fetus.

Breastfeeding

Excreted in breast milk; not recommended.

Children and Elderly

Use with caution; Elderly may require lower doses due to increased sensitivity.

Monitoring Requirements

Respiratory rate, blood pressure, sedation level, signs of respiratory depression.

Drug Interactions

• Inhibitors of CYP3A4 enzyme like macrolide antibiotics, azole antifungals, protease inhibitors, calcium channel blockers.
  • Can prolong sedation.
• Avoid Opioids, barbiturates, alcohol, and other benzodiazepines.
  • Increased risk of respiratory depression.
• Herbal products like St. John's wort.
  • Can affect metabolism of midazolam.

FAQ

How Should I Take the Tablet?

Take exactly as prescribed, usually 1 to 2 times daily with or without food.

What Should I Avoid While Taking?

Avoid alcohol and other CNS depressants, and be cautious when driving or operating machinery until you know how midazolam affects you.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember, but skip it if it is close to the next dose. Do not double up.