Propofol

Propofol is a short-acting intravenous anesthetic agent used primarily for the induction and maintenance of anesthesia, procedural sedation, and sedation in intensive care settings. Its rapid onset, short duration of action, and antiemetic properties make it a popular choice in clinical practice.

Uses

• Induction of Anesthesia: Rapid onset for surgical and diagnostic procedures.
• Maintenance of Anesthesia: Continuous infusion to maintain anesthesia depth.
• Sedation: Utilized for procedural sedation and sedation of mechanically ventilated patients in the ICU.
• Postoperative Nausea and Vomiting (PONV): May reduce incidence due to antiemetic properties.
• Status Epilepticus: Effective in refractory seizures when other treatments fail.

Dosage and Administration

Induction of Anesthesia

• Adults: 1.5-2.5 mg/kg IV bolus.
• Elderly Patients: 1-1.5 mg/kg due to increased sensitivity.
• Pediatrics (>3 years): 2.5-3.5 mg/kg IV bolus.

Maintenance of Anesthesia

• Adults and Pediatrics: Continuous infusion of 100-200 mcg/kg/min, titrated to effect.

Sedation

• Adults: 0.5-1 mg/kg IV bolus, followed by continuous infusion of 25-75 mcg/kg/min.
• Pediatrics: Continuous infusion of 50-150 mcg/kg/min, titrated to effect.

Status Epilepticus

• Initial dose: 1-2 mg/kg IV, followed by continuous infusion at 20-100 mcg/kg/min.

Dose Adjustments in Different Diseases

• Renal Impairment: No significant adjustment required; caution with prolonged use.
• Hepatic Impairment: Use with caution due to metabolism in the liver.
• Elderly: Reduced dose recommended due to increased sensitivity.
• Hypovolemic or Critically Ill Patients: Lower initial doses to avoid hypotension.

Drug Combinations in Use

• Lidocaine: Co-administration to reduce injection site pain.
• Opioids (Fentanyl, Morphine): Synergistic effect for enhanced sedation and analgesia.
• Benzodiazepines (Midazolam): Used to enhance sedation and reduce propofol dosage.
• Neuromuscular Blockers: Commonly combined for surgical anesthesia.

Presentation/Form

• Intravenous Emulsion:
  • 1% (10 mg/mL) solution in 10 mL, 20 mL, 50 mL, or 100 mL vials.

Pharmacokinetics

• Onset: Rapid (within 30 seconds of IV administration)
• Duration: Short (3-10 minutes after a bolus dose)
• Metabolism: Extensive hepatic metabolism
• Elimination: Primarily renal excretion
• Half-Life: 2-24 hours (context-sensitive half-time increases with prolonged infusions)

Pharmacodynamics

• Propofol enhances GABA-A receptor activity, leading to sedation, hypnosis, and amnesia.
• Dose-dependent effects on cardiac output and systemic vascular resistance.

Drug Interactions

• CNS Depressants: Potentiates sedative effects.
• Opioids: Increased risk of respiratory depression.
• Antihypertensives: Enhanced hypotensive effect.
• Benzodiazepines: Synergistic sedative effects.
• Enzyme Inhibitors: May prolong propofol clearance.

Comparison with Other Drugs in Same Category

Drug	Onset Time	Duration	Anti-Emetic Property	Risk of PRIS	Recovery Profile
Propofol	30 seconds	3-10 min	Yes	Yes	Fast
Thiopental	30-60 sec	5-10 min	No	No	Moderate
Etomidate	30-60 sec	3-5 min	No	No	Moderate
Ketamine	30-40 sec	5-10 min	No	No	Slow

Precautions and Special Considerations

• Aseptic Technique: Propofol supports bacterial growth; discard unused portions within 12 hours.
• Hypotension: Use with caution in hypovolemic or elderly patients.
• Pediatric Use: Avoid prolonged infusions in children due to risk of PRIS.
• Emergence Delirium: Lower incidence compared to inhaled anesthetics.
• Propofol Abuse: Potential for abuse, particularly among healthcare workers.
• Green Urine Phenomenon: Rare but benign side effect.
• Pain on Injection: Minimized by using larger veins or co-administration with lidocaine.
• Propofol Infusion Syndrome (PRIS): Monitor for metabolic acidosis, rhabdomyolysis, and cardiac failure during long-term infusions.

Side Effects

• Common: Hypotension, bradycardia, respiratory depression, injection site pain, apnea.
• Serious: Propofol infusion syndrome (PRIS), metabolic acidosis, rhabdomyolysis, and cardiac failure.

Recent Updates and Guidelines

• Updated guidelines recommend the cautious use of propofol in critically ill patients due to PRIS risk.
• Enhanced monitoring protocols during prolonged infusions.
• Guidelines suggest pre-treatment with lidocaine to reduce injection pain.

Facts to Remember

• Propofol has a rapid onset and short duration, making it ideal for outpatient procedures.
• Anti-emetic properties differentiate it from many other anesthetic agents.
• Strict aseptic techniques are essential due to the lipid emulsion formulation.
• Monitor for PRIS during high-dose or prolonged infusions.
• Faster recovery profile compared to other anesthetics.

References

1. NCBI StatPearls - Propofol: https://www.ncbi.nlm.nih.gov/books/NBK430884/
2. Stoelting’s Pharmacology and Physiology in Anesthetic Practice, 5th edition
3. Miller’s Anesthesia, 9th edition
4. Barash Clinical Anesthesia, 8th edition
5. Propofol: Clinical Guidelines and Updates (Latest 2023 Version)