Which drug given in JSAL could most commonly cause bradycardia?

Which drug given in JSAL could most commonly cause bradycardia?

• A. Morphine
• B. Fentanyl
• C. Dexmedetomidine
• D. Ephedrine

Answer: (C)

Bradycardia from anesthesia drugs often comes from either increased vagal (parasympathetic) activity or decreased sympathetic outflow. Dexmedetomidine is a highly selective alpha-2 adrenergic agonist used for sedation; its main effect is to dampen central sympathetic outflow, which lowers heart rate in a dose‑dependent way. By reducing norepinephrine release in the brainstem, the heart rate slows as a direct result of reduced sympathetic drive, making bradycardia a common and expected side effect with this drug, especially when given with other depressants or in hypovolemia. In comparison, ephedrine tends to raise heart rate by releasing norepinephrine and stimulating adrenergic receptors, so it is unlikely to cause bradycardia. Opioids like morphine and fentanyl can cause bradycardia through vagal stimulation, but this effect is less predictable and generally less pronounced than the bradycardia associated with dexmedetomidine.

Bradycardia from anesthesia drugs often comes from either increased vagal (parasympathetic) activity or decreased sympathetic outflow. Dexmedetomidine is a highly selective alpha-2 adrenergic agonist used for sedation; its main effect is to dampen central sympathetic outflow, which lowers heart rate in a dose‑dependent way. By reducing norepinephrine release in the brainstem, the heart rate slows as a direct result of reduced sympathetic drive, making bradycardia a common and expected side effect with this drug, especially when given with other depressants or in hypovolemia.

In comparison, ephedrine tends to raise heart rate by releasing norepinephrine and stimulating adrenergic receptors, so it is unlikely to cause bradycardia. Opioids like morphine and fentanyl can cause bradycardia through vagal stimulation, but this effect is less predictable and generally less pronounced than the bradycardia associated with dexmedetomidine.