McKenna's Pharmacology for Nursing, 2e

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Muscle relaxants

Learning objectives Upon completion of this chapter, you should be able to: 1. Describe a spinal reflex and discuss the pathophysiology of muscle spasm and muscle spasticity. 2. Describe the therapeutic actions, indications, pharmacokinetics, contraindications, most common adverse reactions and important drug–drug interactions associated with the centrally-acting and the direct-acting skeletal muscle relaxants. 3. Discuss the use of muscle relaxants across the lifespan. 4. Compare and contrast the prototype drugs baclofen and dantrolene with other muscle relaxants in their classes. 5. Outline the care considerations, including important teaching points for people receiving muscle relaxants as adjunct to anaesthesia.

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Glossary of key terms basal ganglia: lower area of the brain, associated with coordination of unconscious muscle movements that involve movement and position cerebellum: lower portion of the brain, associated with coordination of muscle movements, including voluntary motion, as well as extrapyramidal control of unconscious muscle movements extrapyramidal tract: cells from the cortex and subcortical areas, including the basal ganglia and the cerebellum, which coordinate unconsciously controlled muscle activity; allows the body to make automatic adjustments in posture or position and balance hypertonia: state of excessive muscle response and activity interneuron: neuron in the CNS that communicates with other neurons, not with muscles or glands pyramidal tract: fibres within the CNS that control precise, intentional movement spasticity: sustained muscle contractions spindle gamma loop system: simple reflex arcs that involve sensory receptors in the periphery that respond to stretch and spinal motor nerves and cause muscle fibre contraction: responsible for maintaining muscle tone and keeping an upright position against the pull of gravity

CENTRALLY-ACTING SKELETAL MUSCLE RELAXANTS baclofen diazepam orphenadrine

DIRECT-ACTING SKELETAL MUSCLE RELAXANTS botulinum toxin type A dantrolene