Muscle Relaxers Overview PDF

Dr. Sandra Joiner Skeletal Muscle Relaxants Muscle Relaxants: Generic and Brand Names Here is a table of commonly encountered muscle relaxants, their generic names, and brand names: Centrally Acting Skeletal Muscle Relaxants baclofen (Lioresal) carisoprodol (Soma)...

Dr. Sandra Joiner Skeletal Muscle Relaxants Muscle Relaxants: Generic and Brand Names Here is a table of commonly encountered muscle relaxants, their generic names, and brand names: Centrally Acting Skeletal Muscle Relaxants baclofen (Lioresal) carisoprodol (Soma) chlorzoxazone (Paraflex) cyclobenzaprine (Flexeril) methocarbamol (Robaxin) orphenadrine (Banflex, Flexoject) tizanidine (Zanaflex) Direct Acting Skeletal Muscle Relaxants botulinum toxin type A (Botox) botulinum toxin type B (Myobloc) dantrolene (Dantrium) incobotulinumtoxin A (Xeomin Skeletal Muscle Relaxants Muscle Spasm A disturbance to the normal flow of information in the CNS caused by diseases, infections, toxins, and injuries can lead to disturbances ranging from spasms to paralysis. Muscle spasm results from violent and painful involuntary muscle contraction usually caused by muscle overstretching, joint wrenching, and tendon or ligament tearing. When this happens, the injured area floods sensory impulses to the spinal cord and it responds by eliciting intense muscle contraction. Pain from muscle spasms is due to lactic acid accumulation that occurs when blood flow is cut off during contractions. Sensory impulses continue to flood and a vicious cycle of contraction develops. Antispasmodic agents- used to treat musculoskeletal pain Skeletal Muscle Relaxants Spasticity Muscle spasticity occurs when damaged neurons are within the CNS rather than the peripheral areas. The site of damage makes this abnormality permanent. There is an interruption in the balance of excitatory and inhibitory influences within the CNS which can lead to hypertonia (excessive muscle stimulation) and consequent contractures and structural changes. There is now loss of coordinated muscle activity. Antispastic medications are used to treat chronic conditions such as Cerebral Palsy and Upper Motor Neuron disorders Anti-Spasmodic Agents Carisoprodol  Schedule IV drug with high abuse potential  Blocks Interneural activity and depress neuronal transmission within the reticular formation and spinal cord.  Not 1st line therapy for muscle spasms due to the potential to produce physical and psychological dependence following prolonged use  AE: sedation, dizziness, headache, GI discomfort Anti-Spasmodic Agents Cyclobenzeprine (Flexeril)  1st line of therapy for skeletal muscle relaxant therapy/economical  Structurally related to the TCA as 5HT3 receptor antagonist in the CNS  Strong antimuscarinic effects = sedation  Potentiates NE so may increase HR  Should be used with MAO-I inhibitors within a 14 day window  May enhance effects of alcohol and other CNS depressants Anti-Spasmodic Agents Metaxolone (Skelaxin)  Fewest reported side effects and lowest potential for sedation  Used in caution with hepatic and renal impairment  Indicated as adjunct to physical therapy and Rest for the relief of acute, painful muscle spasms  MONITOR: LFTs Anti-Spasmodic Agents Methocarbamol (Robaxin)  Approved for use in parts of Europe  Indicated: Adjunct treatment of muscle spasm associated with acute, painful, musculoskeletal conditions  May be used to treat tetanus in children although not 1st line  AE: anaphylaxis, seizures, leukopenia Anti-Spastic Skeletal Muscle Relaxants Baclofen  Act as agonists at the gamma-aminobutyric acid (GABA) receptors in the CNS  Primarily used for upper motor neuron spasticity  Considered as effective as Diazepam in reducing spasticity with less sedative effects  Used orally or intrathecally- Black box warning for Intrathecal dose  CI: DM secondary to may elevate blood sugar, preexisting psychiatric conditions (bipolar, depression, psychosis, schizophrenia)  Dose should be tapered to prevent psychoses 7-14 days Dantrolene- Anti-Spastic Agents  Dantrolene- Anti-Spastic Agents Children Safety and effectiveness not established in children. However, children older than age 12 may be given with metaxalone. Baclofen, on the other hand, is used to relieve spasticity associated with cerebral palsy. Methocarbamol is the drug of choice for children with tetanus. Children should be monitored closely for CNS and GI toxicity. Adults They should be cautioned to avoid activities that require alertness (e.g. driving) because drugs can cause confusion and drowsiness. Muscle spasm in adults related to anxiety can be treated with diazepam. Pregnant and lactating women should be advised to use contraception and alternative method of feeding, respectively. Older adults They are more likely to experience adverse effects associated with these drugs. Carisoprodol is the centrally acting skeletal muscle relaxant of choice for older patients and for those with hepatic or renal impairment Antispasmodic AND Antispastic SMR  Two medications have BOTH properties: Tizanidine (Zanaflex) and Diazepam (Valium)  Effects are equal in regards to MS when comparing Tizanidine and Baclofen Antispasmodic AND Antispastic SMR Tizanidine  Treat muscle spasms and spasticity of MS and CP.  Not 1st line option in treating neck and back pain  Short duration of action BUT should not be used more than tid  May cause urinary retention in older males (decrease urine flow)  Alpha 2 adrenergic receptor agonist that can cause HYPOTENSION  Use in caution with Ciprofloxacin, antiarryhthmics, cimetidine, Oral contraceptives, as they can cause hypotension. Antispasmodic AND Antispastic SMR Diazepam  Treatment of pain related to spasms and local muscle trauma  Have anxiolytic, sedative, hypnotic, amnestic and anticonvulsant action in the CNS  Acts on the brain and the spinal cord Antispasmodic AND Antispastic SMR Botox (OnabotulinumtoxinA)  It is an acetylcholine release inhibitor and a neuromuscular blocking agent  Indicated for Upper limb spasticity, chronic migraine, cervical dystonia, blepharospasm, strabismus, and primary axiallary hyperhidrosis  Age limit dependent on the indication  AE: anaphylactic reactions characterized by generalized muscle weakness, dysphagia, dysphonia, dysarthria, UI, headache, Questions  What is the centrally acting muscle relaxant of choice for children with tetanus? A. Botulinum Toxin type B B. Dantrium C. Baclofen D. Methocarbomol Questions  How long should baclofen be tapered to prevent the development of pyschoses and hallucinations? A. 12-21 days B. 1-10 days C. 7-14 days D. 7-21 days Questions A patient who had a dose of botulinum toxin type A complained of headache and dizziness. What is the most appropriate nursing response? A. Provide comfort measures B. Institute safety measures C. Assess for possible anaphylactic reactions D. Both A and B