McKenna's Pharmacology for Nursing, 2e

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P A R T 4  Drugs acting on the central and peripheral nervous systems

Care considerations for people receiving centrally-acting skeletal muscle relaxants

■■ The centrally-acting skeletal muscle relaxants interfere with the reflexes that are causing the muscle spasm. ■■ The centrally-acting skeletal muscle relaxants cause central CNS depression, and the adverse effects associated with them are related to the CNS depression (insomnia, dizziness, confusion, anticholinergic effects). ■■ The centrally-acting muscle relaxants are used for the relief of discomfort associated with acute, painful musculoskeletal conditions as an adjunct to rest, physical therapy and other measures. The direct-acting skeletal muscle relaxants enter the muscle to prevent muscle contraction directly. Direct-acting skeletal muscle relaxants (Table 25.2) include dantrolene ( Dantrium ) and botulinum toxin type A ( Botox, Dysport ). Therapeutic actions and indications Dantrolene directly affects peripheral muscle contrac- tion and has become important in the management of spasticity associated with neuromuscular diseases. Dantrolene acts within skeletal muscle fibres, interfer- ing with the release of calcium from the muscle tubules (see Figure 25.2). This action prevents the fibres from contracting. Dantrolene does not interfere with neu- romuscular transmissions, and it does not affect the surface membrane of skeletal muscle. Botulinum toxin A binds directly to the receptor sites of motor nerve termi- nals and inhibits the release of acetylcholine, leading to local muscle paralysis. This drug is injected locally and used to paralyse or prevent the contractions of specific muscle groups. Long-term use of dantrolene commonly results in a decrease of the amount and intensity of required care. Continued long-term use is justified as long as the drug reduces painful and disabling spasticity. This agent is ■ ■ Monitor for adverse effects (CNS changes, GI depression, urinary urgency). ■ ■ Evaluate the effectiveness of the teaching plan (person can give the drug name and dosage, name possible adverse effects to watch for and specific measures to prevent them and describe, if necessary, proper intrathecal administration). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. DIRECT-ACTING SKELETAL MUSCLE RELAXANTS KEY POINTS

Assessment: History and examination

■ ■ Assess for contraindications or cautions for the use of the drug, including any known allergies, to prevent hypersensitivity reactions ; cardiac depression, epilepsy, muscle weakness or rheumatic disorder, which could be exacerbated by the effects of these drugs ; pregnancy or breastfeeding, which would be contraindications to use of the drugs ; and renal or hepatic dysfunction, which alter metabolism and excretion of the drugs . ■ ■ Assess temperature; skin colour and lesions; CNS orientation, affect, reflexes, bilateral grip strength and spasticity evaluation; bowel sounds and reported output; and liver and renal function tests to determine baseline status before beginning therapy and for any potential adverse effects. Implementation with rationale discomfort—heat, rest for the muscle, NSAIDs, positioning— to augment the effects of the drug at relieving the musculoskeletal discomfort. ■ ■ Discontinue drug at any sign of hypersensitivity reaction or liver dysfunction to prevent severe toxicity. ■ ■ If using baclofen, taper the drug slowly over 1 to 2 weeks to prevent the development of psychoses and hallucinations. Use baclofen cautiously in people whose spasticity contributes to mobility, posture or balance to prevent loss of this function. ■ ■ If person is receiving baclofen through a delivery pump, the person should understand the pump, the reason for frequent monitoring and how to adjust the dose and program the unit to enhance knowledge and promote compliance. ■ ■ Monitor respiratory status to evaluate adverse ■ ■ Provide thorough teaching, including drug name, prescribed dosage, measures for avoidance of adverse effects, warning signs that may indicate possible problems and the need for monitoring and evaluation to enhance knowledge about drug therapy and to promote compliance. ■ ■ Offer support and encouragement to help the person cope with the drug regimen. Evaluation ■ ■ Monitor response to the drug (improvement in muscle spasm and relief of pain; improvement in muscle spasticity). effects and arrange for appropriate dose adjustment or discontinuation of the drug. ■ ■ Provide additional measures to relieve