ppt chapter 20

Chapter 20

Drugs Affecting Muscle Spasm and Spasticity

Chapter 20

Drugs Affecting Muscle Spasm and Spasticity

Physiology Physiology • The human body contains approximately 600 skeletal

muscles.

• Skeletal muscle movement is voluntary.

• Striated muscle is composed of two contractile proteins.

• Muscle contraction is triggered by a sudden inflow of calcium ions (Ca2+).

• In the resting state, the protein tropomyosin winds around actin and covers the myosin-binding sites.

• Muscle contraction stops when Ca2+ is removed from the immediate environment of the myofilaments.

Muscle FibersMuscle Fibers

Pathophysiology Pathophysiology

• Muscle spasm

– A muscle spasm is a sudden, violent involuntary contraction of a muscle or group of muscles.

– Spasms are related to a localized skeletal muscle injury or an imbalance in electrolytes.

– Tonic spasm is characterized by an unusually prolonged and strong muscular contraction.

Pathophysiology (cont.)Pathophysiology (cont.)

• Spasticity

– Spasticity is a condition in which certain muscles are continuously contracted.

– This contraction causes stiffness or tightness of the muscles.

– Spasticity may be associated with spinal cord injury.

Centrally Acting Muscle Relaxants Centrally Acting Muscle Relaxants

• They act in the central nervous system (CNS).

• Prototype drug: cyclobenzaprine (Flexeril)

Cyclobenzaprine: Core Drug Knowledge Cyclobenzaprine: Core Drug Knowledge

• Pharmacotherapeutics

– Manages muscle spasms associated with acute musculoskeletal disorders

• Pharmacokinetics

– Administered: oral. Metabolism: liver. Excreted: urine and bile. Onset: 1 hour. Duration: 12 to 24 hours.

• Pharmacodynamics

– Relieves muscle spasms through a central action

Cyclobenzaprine: Core Drug Knowledge(cont.) Cyclobenzaprine: Core Drug Knowledge(cont.) • Contraindications and precautions

– Hyperthyroidism

– 14 days within use of MAOIs

• Adverse effects

– CNS depression and anticholinergic activity

– Arrhythmias, seizures, and MIs

• Drug interactions

– Tramadol, guanethidine, MAOIs, histamine-1 blocking agents, and various herbal remedies

Cyclobenzaprine: Core Patient Variables Cyclobenzaprine: Core Patient Variables

• Health status

– Assess past medical history and drug allergies.

• Life span and gender

– Pregnancy Category B drug

– Use precaution in administration to the elderly.

• Lifestyle, diet, and habits

– Avoid alcohol and other CNS depressant use.

• Environment

– Assess the environment where the drug will be given.

Cyclobenzaprine: Nursing Diagnoses and Outcomes Cyclobenzaprine: Nursing Diagnoses and Outcomes

• Risk for Injury related to CNS depressant effects and potential cardiovascular effects.

– Desired outcome: The patient will remain free from injury throughout therapy.

Cyclobenzaprine: Planning and InterventionsCyclobenzaprine: Planning and Interventions

• Maximizing therapeutic effects

– Take with full glass of water at evenly spaced intervals.

– Coordinate physical therapies with administration.

• Minimizing adverse effects

– Assess for excessive sedation.

– Caution the patient about the potential for orthostatic hypotension.

Cyclobenzaprine: Teaching, Assessment, and EvaluationCyclobenzaprine: Teaching, Assessment, and Evaluation

• Patient and family education

– Take medication as prescribed.

– Explain adverse effects.

– Do not take with other OTC medications.

• Ongoing assessment and evaluation

– Evaluate the patient’s safety.

– Monitor the level of sedation.

QuestionQuestion

• Cyclobenzaprine is chemically similar to which of the following drugs?

– A. Adrenergic agents

– B. Benzodiazepines

– C. Tricyclic antidepressants

– D. MAOIs

AnswerAnswer

• C. Tricyclic antidepressants

• Rationale: Cyclobenzaprine is structurally similar to the tricyclic antidepressants.

Centrally Acting Spasmolytics Centrally Acting Spasmolytics

• The centrally acting spasmolytics work in the CNS to reduce excessive reflex activity.

• Allow muscle relaxation

• Prototype drug: baclofen (Lioresal)

Baclofen: Core Drug Knowledge Baclofen: Core Drug Knowledge

– Relieves some components of spinal spasticity

– Administered: oral. Distribution: crosses blood–brain barrier. Metabolism: liver. Excreted: urine and bile. Peaks: 2 to 3 hours

– Acts specifically at the spinal end of the upper motor neurons at GABAB receptors to cause hyperpolarization

Baclofen: Core Drug Knowledge (cont.)Baclofen: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Hypersensitivity and spasticity of cerebral origin

• Adverse effects

– Drowsiness, weakness, dizziness and light-headedness, headache, nausea and vomiting, hypotension, constipation, lethargy and fatigue, confusion, insomnia, and increased urinary frequency

– CNS depressants or TCAs

Baclofen: Core Patient Variables Baclofen: Core Patient Variables • Health status

– Assess past medical history and allergies.

– Perform physical assessment.

– Older patients are more susceptible to sedation.

– Caution the patient about the concurrent use of alcohol.

• Environment

– Assess the environment where the drug will be given. It is usually given at the home.

Baclofen: Nursing Diagnoses and Outcomes Baclofen: Nursing Diagnoses and Outcomes • Acute Pain related to headache, muscle pain, GI

disturbances, or rash

– Desired outcome: The patient will be provided with measures to decrease the discomfort of drug therapy and the possibility of nonadherence.

• Risk for Disturbed Sensory Perception related to visual changes, vestibular dysfunction, and somatosensory changes

– Desired outcome: The patient will be protected from injury if dizziness, weakness, visual changes, or perceptual changes occur.

Baclofen: Planning and InterventionsBaclofen: Planning and Interventions

– Take with full glass of water at evenly spaced intervals.

– If GI distress occurs, coordinate with meals.

– Ensure patient safety.

– Do not abruptly stop the medication.

Baclofen: Teaching, Assessment, and EvaluationBaclofen: Teaching, Assessment, and Evaluation

– Teach the importance of patient safety.

– Caution the patient about the concurrent use of alcohol.

– Monitor for the emergence of hallucinations or psychotic episodes.

– Assess for improved symptoms of spasticity.

QuestionQuestion

• Baclofen therapy is effective at treating muscle spasms due to a cerebral vascular accident.

– A. True

– B. False

AnswerAnswer

• B. False

• Rationale: Baclofen therapy does not affect skeletal muscle spasms resulting from CVA or parkinsonism. Baclofen does not treat this condition because of the mechanism of action of the drug.

Peripherally Acting Spasmolytics Peripherally Acting Spasmolytics

• Peripherally acting spasmolytics relax muscles through direct action on the skeletal muscle fibers.

• They do not interfere with neuromuscular communication.

• They have no CNS effects.

• Prototype drug: dantrolene (Dantrium)

Dantrolene: Core Drug Knowledge Dantrolene: Core Drug Knowledge

– Used to treat malignant hyperthermia

– Administered: oral or IV. Metabolism: liver. Excreted: kidneys. Peak: 5 hours. T½: 7.3 hours

– Reduces the amount of Ca2+ released from the sarcoplasmic reticulum, thereby relaxing the muscle

Dantrolene: Core Drug Knowledge (cont.)Dantrolene: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Liver disease

• Adverse effects

– Muscle weakness, fatal hepatitis, seizures, and pleural effusion with pericarditis

– CNS depressants, clofibrate, estrogens, verapamil, and warfarin

Dantrolene: Core Patient Variables Dantrolene: Core Patient Variables

• Health status

– Assess past medical and physical assessment.

– Consider the age before administration.

– Assess for lactose intolerance.

• Environment

– Can cause photosensitivity

Dantrolene: Nursing Diagnoses and Outcomes Dantrolene: Nursing Diagnoses and Outcomes

• Risk for Injury related to muscular weakness

– Desired outcome: The patient will be injury free despite muscular weakness.

• Risk for diarrhea or constipation related to drug effects

– Desired outcome: The patient will maintain baseline bowel habits.

Dantrolene: Nursing Diagnoses and Outcomes (cont.)Dantrolene: Nursing Diagnoses and Outcomes (cont.)

• Risk for Disturbed Sensory Perception: Kinesthetic related to dizziness, malaise, and fatigue

– Desired outcome: The patient will remain free of injury from adverse effects.

• Disturbed Body Image related to drug-related dermatologic effects

– Desired outcome: Any adverse effects will be resolved by the end of therapy.

Dantrolene: Planning and InterventionsDantrolene: Planning and Interventions

– Administer with food or milk to avoid gastric distress.

– Do not crush extended release capsules.

– Provide for patient safety.

– Advise the use of sunscreen.

– Titrate dose to maximum effectiveness.

Dantrolene: Teaching, Assessment, and EvaluationDantrolene: Teaching, Assessment, and Evaluation

– Explain why the drug is prescribed.

– Discuss adverse effects of the drug.

– Monitor for improvement in symptoms of spasticity and decrease in resistance to passive movement.

– Monitor for adverse effects.

QuestionQuestion

• Dantrolene is used to treat which of the following condition(s)?

– A. Hypertensive crisis

– B. Malignant hyperthermia

– C. Pain associated with lumbar stenosis

– D. All of the above

AnswerAnswer

• B. Malignant hyperthermia

• Rationale: IV dantrolene is the drug of choice for acute treatment of malignant hyperthermia. Preoperatively, it can be used orally or intravenously to prevent malignant hyperthermia in patients considered at risk.

ppt chapter 20

muscle contraction

muscle spasms

muscle fiberscopyright

striated muscle

pathophysiology muscle

acting muscle relaxants

drug allergies

core drug knowledgecont

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