Polysynaptic inhibitors

It is not clear, however, exactly how these drugs inhibit neurons involved in the polysynaptic pathways. There is preliminary evidence that one of these compounds (cyclobenzaprine) might block serotonin receptors on spinal interneurons, thereby decreasing the excitatory influence of serotonin on alpha motor neuron activity.50,55 Although this effect has been attributed to cyclobenzaprine in animals (rats), the effect of this drug and other muscle relaxants in humans remains to be determined. 

On the other hand, these compounds have a general depressant effect on the CNS that is, they cause a global decrease in CNS excitability that results in generalized sedation. It therefore seems possible that some of their muscle relaxant effects are caused by their sedative powers rather than a selective effect on specific neuronal reflex pathways.11,92 This observation is not to say that they are ineffective, because clinical research has shown that these drugs can be superior to a placebo in producing subjective muscle relaxation.8 20 80 97 However, the specific ability of these drugs to relax skeletal muscle remains doubtful, and it is generally believed that their muscle relaxant properties are secondary to a nonspecific CNS sedation. 

These drugs are typically used as adjuncts to rest and physical therapy for the short-term relief of 

DRUGS commonly used to treat skeletal muscle spasms  

Chlorphenesin carbamate (Maolate) Initially 800 TID reduce to 400 QID or less — — 

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Consequently, polysynaptic inhibitors can help provide short-term relief for muscle spasms associated with certain musculoskeletal conditions, and they may work synergistically with physical therapy and other interventions during acute episodes of back pain, neck pain, and so forth. Nonetheless, they have some rather serious side effects and potential for abuse, and the long-term use of these drugs should be discouraged. 

RELATIVE SIDE EFFECTS OF POLYSYNAPTIC INHIBITORS USED AS ANTISPASM AGENTS ... 

Polysynaptic inhibitors (inhibit interneuron transmission in the spinal cord)... 

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