Agents Used to Treat Musculoskeletal Health Alterations

Skeletal Muscle Also called striated muscle; is attached to the skeleton Contraction is under voluntary control Contraction controlled by the nervous system 2

Agents: Musculoskeletal Disorders Nerve impulses travel down the motor neurons of the nervous system Cause skeletal muscle contraction The neuromuscular junction contains the terminal of a motor neuron and a muscle fiber Motor axon terminals contain thousands of vesicles filled with acetylcholine 3

Classes:Musculoskeletal Drugs Neuromuscular blocking agents Centrally acting skeletal muscle relaxants Direct-acting skeletal muscle relaxants Skeletal muscle stimulants 4

Neuromuscular Blocking Agents Action Block the action of acetylcholine Mimic acetylcholine action and prevent cholinesterase from working; the muscle becomes overtired and the client is unable to use the muscle 5

Neuromuscular Blocking Agents Relax or paralyze the skeletal muscles Used for: Surgery Electroconvulsive therapy Endotracheal intubation Tetanus treatment 6

Neuromuscular Blocking Agents Used to relax one or more muscles Neuromuscular blockade Paralyze skeletal muscle groups Does not affect cardiac muscle To assist intubation and mechanical ventilation Usually administered IV Close monitoring required Antidotes should be readily available 7

Neuromuscular Blocking Agents Not useful for spasticity or rigidity of muscles caused by neurological disease or trauma Many drug interactions 8

Centrally Acting Skeletal Muscle Relaxants Depress the CNS in the brainstem, basal ganglia, and neurons of the spinal cord Do not act on the neuromuscular junction Relieve pain associated with skeletal muscle spasms—cerebral palsy High risk: sedation 9

Centrally-acting musculoskeletal agents Baclofen – PO (Kemstro), intrathecal (Lioresal) Spasticity from multiple sclerosis or spinal injury Carisoprodol (Soma) – PO Metaxalone (Skelaxin) – PO Should be taken with food 10

Centrally-acting musculoskeletal agents (cont’d) Diazepam (Valium) – PO, IM, IV May cause dependence Cannot be mixed in syringe with other drugs Discontinue gradually to avoid withdrawal reactions 11

Centrally Acting Skeletal Muscle Relaxants Use cautiously with other CNS depressants Administered orally or parenterally Patients should be cautious when performing activities due to sedation May cause dependence 12

Direct-Acting Skeletal Muscle Relaxants Inhibit calcium release from the skeletal muscles Muscle is then less responsive to nerve impulses Dantrolene acts directly on skeletal muscle; relaxes spastic muscle Used in the treatment of multiple sclerosis, cerebral palsy, spinal cord injury, and stroke 13

Adverse Effects Diarrhea GI upset Photosensitivity Changes in sensory perception Insomnia Depression Hepatotoxicity Hepatitis 14

Myasthenia Gravis Affects 1 in 20,000 people Development of skeletal muscle weakness Symptoms include drooping eyelids, difficulty swallowing, and inability to perform simple tasks 15

Myasthenia Gravis May be caused by damage to acetylcholine receptors at the neuromuscular junction Autoimmune reaction Therapy is aimed at increasing the concentration of acetylcholine at the neuromuscular junction 16

Myasthenia Gravis Neostigmine (Prostigmin) Pyridostigmine bromide (Mestinon) – most popularly used for PO Longer duration, better tolerated PO than neostigmine Edrophonium (Tensilon, Reversol) – parenteral (IV) used for diagnosis or MG crisis 17

Skeletal-Muscle Stimulants Correct muscular weakness such as myasthenia gravis Inhibits the action of anticholinesterase; more acetylcholine is available to cause and maintain the muscle contraction 18

Skeletal-Muscle Stimulants Side effects/adverse effects Caused by unusual cholinergic activity Increased salivation Diarrhea Intestinal cramping Bradycardia Miosis 19

Myasthenia Gravis: Nursing Considerations - assess muscle functioning with vital signs - watch for symptoms of myasthenic crisis - take medication before eating or activity - plan activities after taking medications - patients need to carry identification of condition 20