Propofol

Used for:

• First choice induction agent because of its rapid onset and recovery.

Mechanism:

• Produces its inhibitory effects by activating gamma-aminobutyric (GABA) receptors in the central nervous system (CNS). Causes reduced consciousness and inhibits central output to cardiovascular and respiratory centers.

• Rapid onset/offset due to high lipophilicity. Propofol rapidly diffuses through the blood-brain barrier where it exerts its effects.

CNS Effects:

• Decreases cerebral oxygen consumption, blood flow, and intracranial pressure: Due to reduced brain activity/metabolism.

• Antiemetic effects: Decreases postoperative nausea and vomiting (PONV). May be due to its serotonin antagonistic effect. 

Cardiovascular (CV) Effects: 

• Decreases blood pressure (BP): 

  • • Causes systemic vasodilation by inhibiting sympathetic tone. 

    • Reduces cardiac output due to negative inotropic effects.

• Stable heart rate (HR): Blocks the baroreceptor reflex, so the drop in BP does not trigger a sympathetic increase in heart rate (HR).

Respiratory Effects:

• Decreases tidal volume (TV) and respiratory rate (RR): Inhibits CNS sensitivity to hypercapnia. 

• Reduces airway muscles and reflexes: Increases risk of airway obstruction and aspiration.

Adverse Effects:

• Hypotension and bradycardia 

• Painful when injected 

• Propofol-related Infusion Syndrome: Rare side effect where prolonged infusion can lead to metabolic acidosis and hyperkalemia. 

Contraindications:

• Patients who are hemodynamically compromised (e.g., shock), as propofol causes dose-dependent hypotension 

• Hypersensitivity reaction to egg and soy (propofol preparation contains these ingredients)