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Chapter 4Chapter 4Skeletal Muscle-Skeletal Muscle-Relaxant DrugsRelaxant Drugs

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Muscle Spasm and Muscle Spasm and SpasticitySpasticity

Spasticity is a central nervous system Spasticity is a central nervous system dysfunction. dysfunction.

Spasticity is technically not a disease Spasticity is technically not a disease process but a result of motor interruption process but a result of motor interruption (lesion), typically in the upper motor (lesion), typically in the upper motor complex of the central nervous system.complex of the central nervous system.

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Muscle Spasm and Muscle Spasm and Spasticity (Spasticity (cont.cont.))

A muscle stretch reflex is exaggerated in the A muscle stretch reflex is exaggerated in the individual’s limb or limbs. individual’s limb or limbs.

Rapid lengthening of the affected muscle Rapid lengthening of the affected muscle results in a contraction of the stretched results in a contraction of the stretched muscle.muscle.

Spasticity is more commonly associated with Spasticity is more commonly associated with the cerebral palsy or para/quadriplegia and the cerebral palsy or para/quadriplegia and is considered a more permanent disorder.is considered a more permanent disorder.

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Muscle SpasmMuscle Spasm

Tension developed in muscle spasm is Tension developed in muscle spasm is involuntary and the athlete is unable to involuntary and the athlete is unable to completely relax the muscle. completely relax the muscle.

This muscle spasm will create pain This muscle spasm will create pain impulses from the muscle to the CNS. impulses from the muscle to the CNS. Increases in pain = increases in spasm Increases in pain = increases in spasm (pain-spasm-pain cycle). (pain-spasm-pain cycle).

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Muscle Spasm (Muscle Spasm (cont.cont.))

Chronic muscle spasm can result in Chronic muscle spasm can result in muscle atrophy in the specific muscle or muscle atrophy in the specific muscle or muscle group.muscle group.

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Muscle Relaxant Drugs Muscle Relaxant Drugs

Centrally ActingCentrally Acting The exact mechanism of action of skeletal The exact mechanism of action of skeletal

muscle relaxants is not well known at this muscle relaxants is not well known at this time. time.

The use of these drugs may result in a mild The use of these drugs may result in a mild general sedative effect producing an overall general sedative effect producing an overall relaxation of the entire athlete. relaxation of the entire athlete.

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Muscle Relaxant Drugs Muscle Relaxant Drugs ((cont.cont.))

It is suggested that It is suggested that Centrally ActingCentrally Acting drugs drugs create a sedative effect, which allows the create a sedative effect, which allows the athlete to relax, rest, and allow the muscle to athlete to relax, rest, and allow the muscle to repair itself, thus reducing the amount of repair itself, thus reducing the amount of muscle spasm the athlete experiences. muscle spasm the athlete experiences.

Muscle relaxants are usually combined with Muscle relaxants are usually combined with an analgesic an analgesic —— aspirin or acetaminophen. aspirin or acetaminophen.

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Table 4-1: Drugs Commonly Table 4-1: Drugs Commonly Used to Treat Skeletal Used to Treat Skeletal

Muscle Spasms Muscle Spasms CarisoprodolCarisoprodol

SomaSoma®®

ChlorzaxazoneChlorzaxazoneParafon ForteParafon Forte®®

CyclobenzaprineCyclobenzaprineFlexerilFlexeril®®

DiazapamDiazapamValiumValium®®

Orphenadrine citrateOrphenadrine citrateNorflexNorflex®®

350 mg TID350 mg TIDOnset 30 min.Onset 30 min.Duration 4 to 6 hrs.Duration 4 to 6 hrs.

250250––750 mg TID or QID750 mg TID or QIDOnset < 60 min.Onset < 60 min.Duration 3 to 4 hrs.Duration 3 to 4 hrs.

10 mg TID10 mg TIDOnset <60 min.Onset <60 min.Duration 12-24 hrs.Duration 12-24 hrs.

22––10 mg TID or QID10 mg TID or QIDOnset 15 to 45 min.Onset 15 to 45 min.Duration = VariableDuration = Variable

100 mg BID100 mg BIDOnset < 60 min.Onset < 60 min.Duration 4 to 6 hrs.Duration 4 to 6 hrs.

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Adverse EffectsAdverse Effects

Main adverse effect is drowsinessMain adverse effect is drowsiness Muscle relaxants are known to be Muscle relaxants are known to be

addictiveaddictive

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Box 4-1: Adverse Effects of Box 4-1: Adverse Effects of Skeletal Muscle RelaxantsSkeletal Muscle Relaxants

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Specific Principles to Specific Principles to RememberRemember

Skeletal muscle relaxants do have a Skeletal muscle relaxants do have a depressing effect on the CNSdepressing effect on the CNS

Have an onset of action between 30 and Have an onset of action between 30 and 60 minutes60 minutes

Duration of action varies among the Duration of action varies among the drugs drugs

Effect how the athlete participates in Effect how the athlete participates in activity or rehabilitation – time/effortactivity or rehabilitation – time/effort

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Implications for ActivityImplications for Activity Remind the athlete of the mild general Remind the athlete of the mild general

sedative effect producing an overall sedative effect producing an overall relaxation. relaxation.

May result in an inability of the athlete to May result in an inability of the athlete to practice or compete due to being tired or practice or compete due to being tired or even sleepy from the medication. even sleepy from the medication.

The combination of skeletal muscle relaxants The combination of skeletal muscle relaxants with alcohol or other CNS depressants can with alcohol or other CNS depressants can be dangerous or even lethal to the athlete. be dangerous or even lethal to the athlete.

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Physical Activity Physical Activity ImplicationsImplications

Need to schedule rehabilitation around Need to schedule rehabilitation around peaks in the therapeutic window.peaks in the therapeutic window.

Need to incorporate modalities into the Need to incorporate modalities into the treatment regimen – not just a drug-treatment regimen – not just a drug-induced sedation.induced sedation.