Dantrolene

Dantrolene is a skeletal muscle relaxant and a derivative of the hydantoins. Unlike most centrally acting muscle relaxants, dantrolene acts directly on skeletal muscle cells and therefore has a peripheral mechanism of action. During normal muscle contraction, an action potential travels along the T-tubule and activates the dihydropyridine receptor, which in turn stimulates the opening of the ryanodine receptor (RyR) channel. This allows the sarcoplasmic reticulum (SR) to release calcium ions into the cytoplasm, triggering muscle contraction. Dantrolene directly inhibits the opening of the ryanodine receptor channel, thereby causing muscle relaxation.