Beta-2 agonist side effect involves which potassium change?

• A. Hyperkalemia
• B. Hypercalcemia
• C. Hypokalemia
• D. Hypocalcemia

Answer: (C)

Beta-2 agonists cause potassium to shift into cells, leading to a fall in plasma potassium (hypokalemia). When these drugs activate β2 receptors, they raise intracellular cAMP and increase the activity of Na+/K+ ATPase in tissues like skeletal muscle, pulling potassium from the bloodstream into cells. This is usually mild but can be more noticeable with high-dose or prolonged therapy.

Hyperkalemia would mean too much potassium in the blood, which is not how β2 agonists behave. Calcium changes (hypercalcemia or hypocalcemia) aren’t the primary effect of these drugs. In practice, the relevant effect is the potassium drop described above.