These drugs produce partial or complete paralysis of skeletal muscle (see under MUSCLE – Structure of muscle). Drugs in clinical use are all reversible and are used to help insert a breathing tube into the TRACHEA (endotracheal tube) during general ANAESTHESIA and ARTIFICIAL VENTILATION OF THE LUNGS. The only commonly-used depolarising drug is succinylcholine which has a rapid onset of action and lasts approximately three minutes. Non-depolarising muscle relaxants such as dantrolene and diazepam are used in the relief of skeletal muscle spasms in TETANUS, PARKINSONISM and spastic disorders.