Which medication is a skeletal muscle relaxant that reduces calcium release from the sarcoplasmic reticulum and treats malignant hyperthermia?

Which medication is a skeletal muscle relaxant that reduces calcium release from the sarcoplasmic reticulum and treats malignant hyperthermia?

• A. Atracurium
• B. d-Tubocurarine
• C. Vecuronium
• D. Dantrolene

Answer: (D)

The key concept is that malignant hyperthermia is treated by a drug that directly decreases calcium release from the skeletal muscle sarcoplasmic reticulum. Dantrolene achieves this by inhibiting the ryanodine receptor (RyR1) on the SR, which curtails calcium flowing into the cytoplasm. With less intracellular calcium, the excessive actin–myosin activity driving sustained muscle contraction, heat production, and metabolic crisis in MH is reduced, helping to stop the hypermetabolic cascade. The other medications listed do not affect calcium release from the sarcoplasmic reticulum. They are neuromuscular blocking agents that act at the neuromuscular junction to prevent acetylcholine from stimulating muscle, producing paralysis, but they do not address the abnormal calcium handling that underlies malignant hyperthermia. Therefore they are not used to treat MH, whereas dantrolene is the specific therapy that targets the underlying calcium dysregulation.

The key concept is that malignant hyperthermia is treated by a drug that directly decreases calcium release from the skeletal muscle sarcoplasmic reticulum. Dantrolene achieves this by inhibiting the ryanodine receptor (RyR1) on the SR, which curtails calcium flowing into the cytoplasm. With less intracellular calcium, the excessive actin–myosin activity driving sustained muscle contraction, heat production, and metabolic crisis in MH is reduced, helping to stop the hypermetabolic cascade.

The other medications listed do not affect calcium release from the sarcoplasmic reticulum. They are neuromuscular blocking agents that act at the neuromuscular junction to prevent acetylcholine from stimulating muscle, producing paralysis, but they do not address the abnormal calcium handling that underlies malignant hyperthermia. Therefore they are not used to treat MH, whereas dantrolene is the specific therapy that targets the underlying calcium dysregulation.