Midazolam: an essential palliative care drug
Abstract
Introduction
Structure of midazolam

Pharmacodynamics
Pharmacokinetics and metabolism
| Drug | Bioavailability (oral) | Half-life (h) | Tmax (h) |
|---|---|---|---|
| Midazolam | 40–50% | 1–4 | 0.5–1.0 |
| Lorazepam | 90% | 10–20 | 2.5 |
| Diazepam | 90% | 25–50 | 0.5–1.5 |
| Clonazepam | >80% | 20–40 | 1–4 |
Dosing in special populations
Liver disease
Renal disease
Advanced illness
Elderly
Pediatric
Drug interactions
| Drug | Effect | Mechanism of action | Clinical importance |
|---|---|---|---|
| Glucocorticoids | Decreased AUC (64%) and increased clearance of midazolam (127%)40 | Induction of CYP3A | Prednisone does not affect pharmacokinetics of midazolam41 |
| Phenytoin | Phenytoin lowers midazolam levels. Bioavailability may be reduced as much as 90% according to some studies42 | Induction of CYP3A4 | Unknown |
| Herbal medicine St John’s wort | Increased midazolam clearance43–45 | Induction of CYP3A4 | Unknown |
| Non-nucleoside reverse transcriptase inhibitor (efavirenz) | Oral clearance increased by 70%, and midazolam systemic clearance after intravenous administration was significantly increased by 27%46 | Induction of CYP3A4 | Unknown |
| Fluconazole Itraconazole47 Ketoconazole47 Posaconazole47 | Increase AUC and half-life of midazolam48,49 | Inhibition of CYP3A | Unknown |
| Chemotherapy agents Nilotinib Idelalisib Crizotinib Pazopanib Paclitaxel Ceritinib | Nilotinib inhibits CYP3A450 Idelalisib increases the AUC of midazolam fivefold51 Crizotinib inhibits CYP3A452 Pazopanib only weakly inhibits CYP3A53 Midazolam may interfere with paclitaxel metabolism54 and AUC of midazolam47 | Inhibition of CYP3A4 | Unknown |
| Grapefruit juice | Delays absorption and reduces first-pass effect on midazolam resulting in increased blood plasma levels of midazolam of 56% and increased midazolam bioavailability of 35%55 | Inhibition of CYP3A4 | Unknown |
| Protease inhibitors (ritonavir, atazanavir, darunavir, fosamprenavir) | Inhibit CYP3A4 leading to increased midazolam levels56,57 | Inhibition of CYP3A4 | May prolong sedation and increase sedation risk58 |
| Simeprevir (treatment of hepatitis C infection) | Increased AUC of midazolam (oral) by 1.3–1.459 | Inhibition of CYP3A4 | Unknown |
| Calcium channel blockers | Increase the AUC for midazolam60,61 | Inhibition of CYP3A4 | Unknown |
| Antidepressants Fluvoxamine Paroxetine Citalopram | Nefazodone (now discontinued) inhibits CYP3A4 and increases the AUC by 400%62 | Inhibition of CYP3A4 | No reported interaction with mirtazapine |
| Aprepitant | Increases the AUC63–66 | Inhibition of CYP3A4 | Especially at doses of 125 mg aprepitant63 Oral midazolam |
| Netupitant/palonosetron combination | Increases Cmax by 40% and AUC increased by 144%67 | Inhibition of CYP3A4 | Unknown |
Adverse effects
Clinical applications of midazolam in palliative care
Palliative sedation therapy
Dyspnea
Seizures
Analgesic effect
Insomnia and terminal illness
Delirium and agitation
Ketamine emergence phenomena
Hiccups
Pruritis and biliary obstruction
Muscle spasm
| Indication | Dosing | Comment |
|---|---|---|
| Palliative sedation | 1–5 mg IV bolus every 5 min until comfortable or maximum of 20 mg.99,100 Continuous infusion is started generally 0.5–1 mg/h101 Usual effective dose range is 1–20 mg/h subcutaneously or intravenously100 | If the continuous infusion rate reaches 20 mg/h, then some have recommended switching to another sedating agent.102 Can also be given subcutaneously103 |
| Terminal agitation | Wide dosing range. Usual starting dose 0.4–0.8 mg/h15 Doses may go up to 3 mg/h. Patients may become tolerant to midazolam necessitating dose increase. As needed dosing can match the hourly dose and can be given as frequently as q 15 min | If necessary, increase both the as-needed dose and the infusion until the patient is calm. Some experts recommend considering adding an antipsychotic if the dose reaches >30 mg/24 h by continuous infusion27 Haloperidol is suggested as an antipsychotic |
| Dyspnea | Midazolam dosing for dyspnea is up to 5 mg subcutaneously or intravenously every 4 h.69 Oral midazolam at 2 mg orally as often as every 4 h has been shown to be beneficial.70 Rescue doses at 50–100% of the scheduled dose are given as frequent as every 15 min | |
| Seizures | Midazolam boluses of 0.1–0.3 mg/kg are used for status epilepticus.104 Continuous infusions of 0.05–0.4 mg/kg/h can also be used.105 Other dosing recommendations for seizures include 10 mg intranasally, intramuscularly, or buccally for patients with a body weight of >40 kg or 5 mg for a patient with a body weight of 13–40 kg89 | It may take up to 10 min to abort the seizure; doses can be repeated if the seizure persists after 5 min |
| Catastrophic bleeding | 5–10 mg IV every 5 min to a maximum dose of 20 mg106 | |
| Insomnia | Midazolam 2.0 mg subcutaneously/IV to maximum dose of 18 mg qhs93,94 |
Pediatric dosing
Route conversions and conversions from other benzodiazepines
| Drug | Dose (mg) |
|---|---|
| Diazepam | 5 |
| Lorazepam | 0.5 |
| Midazolam | 5 |
| Alprazolam | 0.5 |
Pharmacoeconomics
Conclusion
Conflict of interest statement
Funding
ORCID iD
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This article was published in Palliative Care and Social Practice.
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Crossref: 51
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