Muscle-relaxant drugs a group of drugs used to relieve muscle spasm and spasticity. Muscle-relaxant drugs are used mainly in the treatment of nervous system disorders such as multiple sclerosis and painful muscular conditions such as torticollis. They are occasionally used to relieve muscle rigidity caused by injury Some types are used to cause temporary paralysis during surgery under general anaesthesia.
Except for dantrolene, muscle-relaxant drugs partly block nerve signals that stimulate muscle contraction Dantrolene interferes with the chemical activity in muscle cells needed for contraction The drugs may cause muscle weakness and drowsiness In rare cases, dantrolene causes liver damage.
Many drugs have been marketed as muscle relaxants, even though most do not seem to have any direct effect on muscle. Perhaps they should be called "brain relaxants" since they are all sedating and this may be how they actually work. Some also have analgesic (pain reducing) properties. Muscle relaxants have limited efficacy in chronic pain, but may be used to treat acute flare-ups.