The hydrochloride salt form of tizanidine, an imidazoline derivative structurally similar to clonidine and an adrenergic agonist with muscle relaxant property. Tizanidine stimulates alpha-2 adrenergic receptors in the central nervous system, thereby inhibiting presynaptic release of norepinephrine and increasing the inhibitory effect on alpha motor neurons and motor reflexes. Tizanidine exerts some activity at the postsynaptic excitatory amino acid receptors and imidazoline receptors which may contribute to the overall reduction in facilitation of spinal motor neurons. Overall, tizanidine hydrochloride causes muscle relaxation, reduces spasticity and antinociceptive effects. Check for active clinical trialsusing this agent.