Dexmedetomidine (Precedex)

• Core Feature: Cooperative, arousable sedation with minimal respiratory depression; patients can often follow commands and maintain airway
• Hemodynamic Effects: Bradycardia and hypotension are common; transient hypertension possible during loading dose due to peripheral α2 effects
• ICU Infusion Range: 0.2–0.7 mcg/kg/hr (many units allow up to 1–1.5 mcg/kg/hr) for sedation of mechanically ventilated or non-intubated patients
• Loading Dose: 1 mcg/kg over 10 minutes on label, but frequently omitted in hemodynamically fragile patients due to bradycardia/hypotension risk
• Best Use: When you want to avoid delirium, wean off propofol/benzodiazepines, facilitate extubation, or sedate non-intubated patients (e.g., HFNC/BiPAP)
• Limitation: Not appropriate for deep sedation or induction/RSI; onset slower than propofol/etomidate with ceiling on depth of sedation

• Generic Name: Dexmedetomidine hydrochloride
• Brand Names: Precedex, generics

Highly selective α2-adrenergic receptor agonist; sedative and analgesic adjunct

Mechanism of Action:

• Selective α2-adrenergic agonist acting on receptors in the locus coeruleus and spinal cord
• Presynaptic α2 activation decreases norepinephrine release, reducing sympathetic outflow and locus coeruleus activity → sedation, anxiolysis, and some analgesia
• Postsynaptic α2 activation in the dorsal horn contributes to analgesic and opioid-sparing effects
• Peripheral α2 stimulation in vascular smooth muscle can cause transient vasoconstriction and hypertension during loading or rapid dose escalation
• Unlike GABAergic sedatives (propofol, benzodiazepines), dexmedetomidine produces an "awake-like" sleep state and typically preserves respiratory drive at sedative doses

Pharmacokinetics:

• Onset: Within 5–15 minutes of starting infusion; steady-state sedation over ~30–60 minutes
• Distribution: Rapid distribution phase; volume of distribution ~1–2 L/kg; about 90% protein bound
• Metabolism: Extensive hepatic metabolism via glucuronidation and CYP-mediated oxidation
• Elimination: Metabolites excreted mainly in urine; elimination half-life ~2 hours in healthy adults
• Special Considerations: Hepatic impairment reduces clearance; lower doses and slower titration needed. Renal impairment has less effect on parent drug but metabolites may accumulate

• Sedation of intubated, mechanically ventilated patients in the ICU, targeting light sedation (e.g., RASS -2 to 0)
• Sedation of non-intubated patients requiring monitored sedation: agitated hypoxic respiratory failure on HFNC/BiPAP, awake fiberoptic intubation, some minor procedures
• Adjunct to reduce benzodiazepine and opioid requirements and potentially mitigate delirium compared with benzo-based strategies
• Bridge during weaning from other sedatives (propofol, midazolam) to facilitate neurological assessment and extubation

Available Forms:

• Concentrated vials: e.g., 100 mcg/mL in 2 mL vials (200 mcg total)
• Premixed bags: 400 mcg/100 mL (4 mcg/mL) or 200 mcg/50 mL
• For infusion, typically prepared at 4 mcg/mL and run via infusion pump in mcg/kg/hr

Adult Dosing (IV):

Contraindications:

• Known hypersensitivity to dexmedetomidine or formulation components
• Advanced heart block (second- or third-degree) without functioning pacemaker
• Severe, unstable hemodynamics where bradycardia/hypotension would be poorly tolerated

Major Precautions:

• Baseline bradycardia or use of negative chronotropes (beta-blockers, some calcium channel blockers) increases risk of significant bradycardia/asystole
• Hypovolemia or vasodilatory shock: dexmedetomidine can unmask or worsen hypotension; optimize volume status and vasopressors first
• Abrupt discontinuation after prolonged or high-dose infusions may cause rebound hypertension, tachycardia, and agitation; taper when feasible
• Use caution in severe hepatic impairment due to reduced clearance and increased drug exposure
• Provides limited analgesia; ensure adequate pain control with opioids or regional anesthesia when needed

Common:

• Bradycardia (often sinus, sometimes junctional)
• Hypotension, particularly in hypovolemic or vasoplegic patients
• Dry mouth
• Nausea, vomiting
• Mild fever or chills

Serious:

• Profound bradycardia or asystole, especially with concomitant nodal-blocking agents or high vagal tone
• Severe hypotension with organ hypoperfusion, occasionally requiring vasopressors or fluid resuscitation
• Paradoxical hypertension during loading or rapid titration due to peripheral vasoconstriction
• Withdrawal phenomena (hypertension, tachycardia, agitation) after abrupt cessation of prolonged infusions

Elderly Patients:

• Start at 0.1–0.2 mcg/kg/hr and titrate cautiously
• Avoid loading dose
• Higher risk of bradycardia and hypotension

Renal Impairment:

• Less effect on parent drug clearance, but metabolites may accumulate
• No specific dose adjustment recommended, but monitor closely

Hepatic Impairment:

• Reduced clearance; lower doses required
• Start at 0.1–0.2 mcg/kg/hr with slow titration
• Monitor for exaggerated hemodynamic effects

Pregnancy:

• Category C: Limited human data; use only if benefit justifies potential risk
• Crosses placenta; fetal effects unknown

Lactation:

• Unknown if excreted in breast milk; use caution

Clinical Monitoring:

• Continuous ECG and blood pressure monitoring during initiation and titration; frequent vitals when stable
• Watch for bradycardia and hypotension; adjust infusion or provide fluids/vasopressors as needed
• Assess sedation using a standardized scale (e.g., RASS) and titrate to target level
• Ensure concurrent analgesia for painful conditions; do not rely on dexmedetomidine alone for pain control
• Monitor for withdrawal symptoms when discontinuing after prolonged high-dose infusions and taper if possible

• 1. Lexicomp. (2024). Dexmedetomidine: Drug information. Wolters Kluwer.
• 2. Reade, M. C., & Finfer, S. (2014). Sedation and delirium in the intensive care unit. New England Journal of Medicine, 370(5), 444–454. https://doi.org/10.1056/NEJMra1208705
• 3. Riker, R. R., Shehabi, Y., Bokesch, P. M., et al. (2009). Dexmedetomidine vs midazolam for sedation of critically ill patients: A randomized trial. JAMA, 301(5), 489–499. https://doi.org/10.1001/jama.2009.56
• 4. Pandharipande, P. P., Pun, B. T., Herr, D. L., et al. (2007). Effect of sedation with dexmedetomidine vs lorazepam on acute brain dysfunction in mechanically ventilated patients. JAMA, 298(22), 2644–2653. https://doi.org/10.1001/jama.298.22.2644
• 5. Barr, J., Fraser, G. L., Puntillo, K., et al. (2013). Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit. Critical Care Medicine, 41(1), 263–306. https://doi.org/10.1097/CCM.0b013e3182783b72