Peripherally acting muscle relaxant

Muscle relaxants (peripherally acting) and cholinesterase inhibitors... 

This is a peripherally acting muscle relaxant. Peripherally acting muscle relaxants depress neuron activity at the skeletal muscles and have a minimal effect on the central nervous system. These are most effective for spasticity or muscle contractions caused by chronic neurologic disorders. This is also used to treat malignant hypertension which is an allergic reaction to anesthesia. 

Muscle relaxants may act either peripherally, that is directly on the muscle, or centrally, in the spinal cord. Most such drugs act centrally, though how they perform their task is not understood. These drugs do not act directly on the muscle to relax it, they do not interfere with conduction along the nerve fiber, they do not stop the neurotransmitter from being released or crossing the nerve-muscle junction, and they do not alter the ability of the muscle to respond to the neurotransmitter. Somehow they act centrally to depress the central nervous system and may have a sedative effect. 

Muscle relaxants are used to treats muscle spasms. There are two groups of muscle relaxants centrally acting and peripherally acting. Centrally acting muscle relaxants depress neuron activity in the spinal cord or in the brain. They are used to treat acute spasms from muscle trauma, but are less effective for treating spasms caused by chronic neurological disorders. 

StmcturaHy related to nitrofurantoias are Dantrolene [7261-97-4] (38), a peripherally acting muscle relaxant, and its analogues (39), which can be used as an antidote against succiaylcholine-iaduced myopathy and ia autoimmune myasthenia gravis therapy (136,137). 

Skeletal muscle relaxants act peripherally at the neuromuscular junction or centrally in the cerebrospinal axis to reduce muscle tone. 

Systemic heat Large whirlpool Hubbard tank Decreased muscle/joint stiffness in large areas of the body Opioid and nonopioid analgesics skeletal muscle relaxants Severe hypotension may occur if systemic hot whirlpool is administered to patients taking peripheral vasodilators and some antihypertensive drugs (eg., alpha-1 antagonists, nitrates, direct-acting vasodilators, calcium channel blockers)... 

These drugs act on postsynaptic acetylcholine receptors (cholinoceptors) at all the sites in the body where acetylcholine is the effective neurotransmitter. They initially stimulate and usually later block transmission. In addition, like acetylcholine, they act on the noninnervated receptors that relax vascular smooth muscle in peripheral blood vessels. 

Peripherally acting muscle relaxants are primarily used for chronic neurologic disorders because they depress neuron activity at the skeletal muscles and have a minimal effect on the central nervous system. 

Cyclobenzaprine, a tricyclic amine structurally very similar to amitriptyline (see Figure 34-10), is used as a centrally acting skeletal muscle relaxant. Like amitriptyline, cyclobenzaprine causes sedation, produces central and peripheral muscarinic blockade, and potentiates adrenergic actions. In overdose, cyclobenzaprine may cause a typical anticholinergic toxidrome and cardiac arrhythmias, hypotension, and coma. However, cyclobenzaprine overdose is not as frequent nor as lethal as amitriptyline overdose. 

Tolperisone is an arylalkyl p-aminoketone having an asymmetric carbon atom a to the carbonyl group. The R(—)-enantiomer is a centrally acting muscle relaxant used in the treatment of spastic paralysis, whereas the S(+)-enantiomer shows broncho and peripheral dilating properties. 

Dantrolene is a new type of skeletal muscle relaxant with a peripheral site of action. It resembles structurally diphenyl-hydantoin but acts primarily within the muscle fibre. In vitro studies indicate that the drug blocks the intracellular release of calcium without altering intracellular calcium uptake. It has been used to decrease skeletal muscle spasticity in patients with... 

Nifedipine is a calcium-channel blocker of the dihydropyridine group. It relaxes smooth muscle and dilates both coronary and peripheral arteries by interfering with the inward displacement of calcium-channel ions through the active cell membrane. Unlike verapamil, nifedipine can be given with beta-blockers. Long-acting formulations of nifedipine are preferred in the long-term treatment of hypertension. 

In particular, postsynaptic Oi-blockers act on the o-receptive regions located on the smooth muscle of blood vessels and counteract the pressor, vasoconstricting effect of epinephrine and norepinephrine. In addition, they exhibit a direct relaxant effect on smooth muscle, which leads to peripheral dilation of blood vessels, which in turn raises blood pressure. However, they also exhibit a cardiostimulatory effect, which is frequently a cause of tachycardia. 

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