Dantrolene sodium hemiheptahydrate

C1C (=NC (=O) N1N=CC2=CC=C (O2) C3=CC=C (C=C3) [N+] (=O) [O-]) [O-].C1C (=NC (=O) N1N=CC2=CC=C (O2) C3=CC=C (C=C3) [N+] (=O) [O-]) [O-].O.O.O.O.O.O.O.[Na+].[Na+]

Dantrolene sodium hemiheptahydrate (Dantrium) is a skeletal muscle relaxant that acts by interfering with excitation-contraction coupling in the muscle fiber.