Myonal contains the active ingredient, Eperison hydrochloride, which acts as a striated muscle relaxant and vasodilator. The drug has been shown to improve symptoms associated with increased muscle tone, by breaking the pathological spiral of skeletal muscle spasm. The drug relieves symptoms in shoulder stiffness, neck pain. muscle spasm headache, dizziness, back pain and spasticity of limb muscles in encephalopathy.