What is the recommended dexmedetomidine (Precedex) dosing for procedural or intensive‑care sedation in adults, including adjustments for elderly patients or those with hepatic impairment, and for pediatric patients aged ≥1 month?

Dexmedetomidine (Precedex) Dosing

For adult ICU sedation, start with a loading dose of 1 μg/kg over 10 minutes in hemodynamically stable patients, followed by a maintenance infusion of 0.2–0.7 μg/kg/hour, titrating up to 1.5 μg/kg/hour as tolerated; omit the loading dose entirely in hemodynamically unstable patients, elderly patients, or those with severe hepatic impairment. 1

Adult ICU Sedation: Standard Protocol

Loading Dose Decision Algorithm

Hemodynamically stable patients:

• Administer 1 μg/kg IV over 10 minutes 1
• Monitor blood pressure and heart rate every 2–3 minutes during bolus 1
• Have atropine immediately available for bradycardia 1

Hemodynamically unstable patients (hypotension, bradycardia, severe cardiac disease):

• Omit loading dose entirely 1, 2
• Start directly with maintenance infusion at 0.2 μg/kg/hour 1
• Never administer loading dose faster than 5 minutes in any circumstance 1

Maintenance Infusion

• Start at 0.2–0.7 μg/kg/hour 1
• Titrate up to maximum 1.5 μg/kg/hour based on Richmond Agitation-Sedation Scale (RASS) target 1
• Target RASS -2 to +1 for light sedation with easy arousability 1

Standard Preparation

• Dilute to 4 μg/mL concentration using 0.9% normal saline 1
• For 100 μg ampoule: add to 25 mL normal saline 1
• For 200 μg ampoule: add to 50 mL normal saline 1
• Example for 70 kg patient: loading dose = 70 μg = 17.5 mL over 10 minutes; maintenance at 0.5 μg/kg/hour = 35 μg/hour = 8.75 mL/hour 1

Special Populations

Elderly Patients

• Omit or extend loading dose to 15–20 minutes if deemed necessary 1
• Start maintenance at lower end of range (0.2 μg/kg/hour) 1
• Context-sensitive half-time becomes prolonged with age, particularly in those with hypoalbuminemia 1, 3
• Dexmedetomidine clearance decreases with increasing age 3

Hepatic Impairment

• Omit or significantly reduce loading dose due to hemodynamic instability risk 1, 4
• Start maintenance at 0.2 μg/kg/hour (lower end of range) 1, 4
• Severe hepatic dysfunction impairs clearance, requiring lower doses and prolonged monitoring 1, 2, 4
• Elimination half-life is prolonged in patients with hypoalbuminemia 3
• Volume of distribution at steady state increases with low albumin, further prolonging effects 3

Cirrhotic Patients (Specific Considerations)

• Dexmedetomidine preferred over benzodiazepines to preserve cognitive function and reduce delirium (54% vs 76.6%, p<0.001) 4
• Reduces need for benzodiazepines in alcohol withdrawal, preventing hepatic encephalopathy 4
• Hypotension occurs in 10–40% of cirrhotic patients, usually resolving without intervention 4

Pediatric Dosing (≥1 Month)

Ages 1 month to <17 years:

• Loading dose: 0.5–1 μg/kg IV over 10 minutes 1, 5
• Maintenance: 0.2–0.7 μg/kg/hour 1, 5
• May titrate up to 2.0 μg/kg/hour for procedural sedation 5
• Use same 4 μg/mL dilution for precise dosing 1

Neonates (≥28 weeks gestational age to <1 month):

• Loading dose: 0.1 μg/kg 5
• Maintenance: 0.05–0.2 μg/kg/hour 5

Procedural Sedation (Non-ICU)

Awake Intubation or Airway Procedures

• Bolus: 0.5–1 μg/kg over 5 minutes (faster onset acceptable in controlled airway setting) 1
• Maintenance: 0.3–0.6 μg/kg/hour 1

Perioperative/VATS Surgery

• Single bolus: 1 μg/kg IV 20 minutes before end of surgery reduces postoperative pain and opioid requirements 1
• Alternative: loading dose before induction + 0.5 μg/kg/hour infusion until 20 minutes before surgery end 1
• Postoperative low-dose: 0.15 μg/kg/day reduces pain scores 1

Critical Monitoring Requirements

Cardiovascular Monitoring

• Continuous blood pressure and heart rate monitoring mandatory 1, 2, 4
• Hypotension occurs in 10–20% of patients due to central sympatholytic effects 1, 2
• Bradycardia occurs in 10–18% within 5–15 minutes of administration 1
• More serious arrhythmias include first-degree and second-degree AV block, sinus arrest, AV dissociation, and escape rhythms 1
• Loading doses cause biphasic response: transient hypertension followed by hypotension within 5–10 minutes 1

Respiratory Monitoring

• Continuous pulse oximetry mandatory in non-intubated patients 1
• Dexmedetomidine does not significantly affect respiratory drive, unlike benzodiazepines, propofol, and opioids 1
• Critical caveat: Can cause loss of oropharyngeal muscle tone leading to airway obstruction in non-intubated patients 1, 2
• Monitor for both hypoventilation and hypoxemia 1, 2
• Only sedative approved in the United States for non-intubated ICU patients 1

Contraindications and Precautions

Absolute Contraindications

• Sinus node disease 2
• Second- or third-degree AV block 2
• Active hemodynamic instability (unless loading dose omitted) 1
• Primary sedative for alcohol or benzodiazepine withdrawal delirium 1

Relative Contraindications

• Baseline hypotension or severe bradycardia 1
• Compromised cerebrovascular reserve (dexmedetomidine decreases cerebral blood flow by ~33%) 2

Pharmacokinetics

• Terminal elimination half-life: 1.8–3.1 hours (83–159 minutes) in normal hepatic function 1, 3
• Onset of sedation: within 15 minutes 2
• Peak effects: approximately 1 hour after starting IV infusion 2
• Clearance decreases with decreasing cardiac output and increasing age 3

Clinical Advantages

• Reduces delirium compared to benzodiazepines (9% vs 23%, OR 0.35, p<0.0001) 1
• Opioid-sparing effects, significantly reducing narcotic requirements 1, 2, 4
• Preserves sleep architecture, inducing stage N3 non-REM sleep mimicking natural sleep 1
• Patients remain easily arousable and interactive with minimal respiratory depression 1
• Can continue infusions safely after extubation 1, 2

Combination Therapy Considerations

With Antipsychotics

• Obtain baseline QTc before combining with antipsychotics 1
• Avoid combination if QTc prolonged, concurrent QT-prolonging medications, or history of torsades de pointes 1
• Antipsychotics are adjunctive only, not first-line for delirium 1

With Neuromuscular Blockade

• Must combine with GABA agonist (propofol or midazolam) to provide amnesia 1