Skeletal muscle relaxant drugs spasms

Skeletal muscle relaxants are used to treat conditions associated with hyperexcitable skeletal muscle— specifically, spasticity and muscle spasms. Although these two terms are often used interchangeably, spasticity and muscle spasms represent two distinct abnormalities. The use of relaxant drugs, however, is similar in each condition because the ultimate goal is to normalize muscle excitability without a profound decrease in muscle function. Considering the number of rehabilitation patients with muscle hyperexcitability that is associated with either spasm or spasticity, skeletal muscle relaxants represent an important class of drugs to the rehabilitation specialist. 

Consequently, various skeletal muscle relaxants attempt to decrease skeletal muscle excitation and contraction in cases of spasticity and spasm. Specific drugs and their mechanisms of action are discussed here. 

Cyclobenzaprine is structurally closely related to the tricyclic antidepressants (see later) and therefore shares many of their adverse reactions. These include drowsiness (CNS effects), dry mouth (anticholinergic effects), and dizziness. The potential for serious interactions with MAO inhibitors also exists. Nevertheless, the drug s centrally acting skeletal muscle relaxation is useful for short-term treatment of local muscle spasms. 

Various drugs have been used to treat muscle spasm. Most compounds in this group act as simple sedative-hypnotic agents and produce skeletal muscle relaxation indirectly. The drugs commonly used as skeletal muscle relaxants are listed in Table 11-53. Carisoprodol (Soma ) and baclofen have been abused as recreational drugs. I. Mechanism of toxicity... 

Although it has been clinically available for a number of years, the United States Food and Drug Administration in early 1968 allowed labeling changes for diazepam (XXIV) to allow for new indications of use for the relief of muscle spasm and adjunctive use in convulsive disorders . It was reported that in cats the brain stem reticular system is the major locus of central nervous system depressant action of this centrally acting skeletal muscle relaxant. 

Skeletal muscle can also be relaxed by drugs that act in the CNS, the spinal cord, or even in the muscle itself. These spasmolytics reduce excessive muscle tone or spasm in acute muscle injury and CNS dysfunction (e.g., cerebral palsy, MS, stroke), in most cases without loss of muscle strength. 

The skeletal muscle ma5 be relaxed by two different groups of drugs, namely first, by those exerting an aetion on the central nervous system (CNS) and used mainly for the relief of painful muscle spasms of spasticity taking place either in neuromuseular or musculoskeletal disorders secondly, those aflfeeting neuromuscular transmission that are employed as adjrmcts in anaesthesia in order to modify the musele relaxation ability. 

The drug is observed to minimise voluntary muscle spasm by a central effect. However, the indications for the citrate are considered usually as an adjunct for the relief of discomfort amalgamated with severe painful musculoskeletal conditions, which is not yet vividly understood, but that may be associated with the analgesic characteristics of the drug substance. It has been duly observed that it does not exert its action by relaxing directly the tense skeletal muscles in man. However, the observed peripheral atropine-like actions are relatively mild in nature. Importantly, it helps to minimise voluntary muscle spasm by virtue of its central inhibitory activity specifically on the cerebral motor areas of eourse, an apparent central effect very much identical to that of atropine. 

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