Diazepam is a benzodiazepine first discovered at Hoffman-La Roche in the late 1950s. Diazepam was approved by FDA for the treatment of anxiety disorders as well as for such conditions as skeletal muscle spasm, alcohol withdrawal syndrom and convulsions (under the most known brand Valium). The drug acts by binding to GABA-A receptors and potentiating GABA evoked current. Chronic diazepam use is associated with tolerance, dependence, and withdrawal.

Chlorzoxazone is a centrally acting central muscle relaxant with sedative properties. It is claimed to inhibit muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles. Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.

Methocarbamol is a central muscle relaxant for skeletal muscles, used to treat spasms. It is structurally related to guaifenesin. Methocarbamol's exact mechanism of causing skeletal muscle relaxation is unknown. It is thought to work centrally, perhaps by general depressant effects. It has no direct relaxant effects on striated muscle, nerve fibers, or the motor endplate. It will not directly relax contracted skeletal muscles. The drug has a secondary sedative effect. Methocarbamol is used for use as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. Under the trade name Robaxin, Methocarbamol is marketed by Actient Pharmaceuticals in the United States and Pfizer in Canada.

Nafomine is the muscle relaxant. It was tested on lower extremity spasms in spinal cord injuries.

Fenamole is a muscle relaxant. It is effectively inhibits muscle spasms at good levels for a four hours and at significant levels for six hours. Clinical benefits were derived in patients with spasticity-spasm for periods up to 24 hours after a single oral dose. Fenamole is relatively free of adverse side effects particularly in the central nervous system. It is a potent copper chelator. It was once investigated as a potential antirheumatic agent in man.

SL651498 was identified as a drug development candidate from a research program designed to discover subtype-selective GABA(A) receptor agonists for the treatment of generalized anxiety disorder and muscle spasms. SL651498 displayed high affinity for GABA(A) receptors containing alpha(1) and alpha(2 subunits, and weaker affinity for alpha5-containing GABA(A) receptors, it behaved as a full agonist at recombinant t GABA(A) receptors containing alpha(2) and alpha(3) subunits, and as a partial agonist at recombinant GABA(A) receptors expressing alpha(1) and alpha(5) subunits. It was shown, that SL651498 represented a promising alternative to agents currently used for the treatment of anxiety disorders and muscle spasms without the major side effects seen with classical benzodiazepines).

Beta-erythroidine is an organic heterotetracyclic indole alkaloid isolated from the seeds and other parts of Erythrina species. A drug used to produce muscle relaxation (excepting neuromuscular blocking agents). Its primary clinical and therapeutic use is the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. Also used for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in multiple sclerosis. Beta-erythroidine is a neuronal nicotinic acetylcholine receptor antagonist. The beta-erythroidine and its more potent derivative (2,7-dihydro) have been used as muscular relaxants in numerous clinical applications. This activity is attributed to a antagonistic action of the dihydro-beta-erythroidine with the nicotinic receptors of acetyl choline.

Chlorphenesin carbamate (Maolate, Musil) is a centrally acting muscle relaxant used to treat muscle pain and spasms. Сhlorphenesin acts in the central nervous system (CNS) rather than directly on skeletal muscle. It also has antifungal and some antibacterial properties. The major adverse effects are drowsiness and dizziness.

Mephenoxalone is an oxazolidinone compound. It is a skeletal muscle relaxant as well as anxiolytic. Mephenoxalone is indicated for the treatment of muscle spasms.

Chlormezanone (TRANCOPAL®) is a non-benzodiazepine that is used in the management of anxiety. It has been suggested for use in the treatment of muscle spasm. It binds to central benzodiazepine receptors which interact allosterically with GABA receptors. This potentiates the effects of the inhibitory neurotransmitter GABA, increasing the inhibition of the ascending reticular activating system and blocking the cortical and limbic arousal that occurs following stimulation of the reticular pathways. Chlormezanone (TRANCOPAL®) was discontinued worldwide in 1996 by Sanofi due to confirmed serious and rare cutaneous reactions (toxic epidermal necrolysis also known as Stevens-Johnson syndrome).