Muscle Relaxants Flashcards
What is spasticity?
Continuous muscle contraction, causing stiffness and tightness.
What conditions are treated with antispastics?
Cerebral palsy, multiple sclerosis, post-stroke syndrome, and spinal cord injury.
What do muscle relaxants modulate in the stretch reflex arc?
They modulate excitatory or inhibitory synapses between the spinal cord and skeletal muscles.
How do muscle relaxants affect inhibitory and excitatory effects in the stretch-reflex arc?
They enhance inhibitory effects and suppress excitatory effects.
What additional beneficial effects can some muscle relaxants have?
Some may have beneficial effects at higher centers in the central nervous system.
What are the therapeutic effects of antispastics?
They reduce muscle tone, decrease stiffness, exaggerated tendon reflexes, involuntary movements, and spasms.
What is Baclofen (Kemstro) a derivative of, and what does it treat?
Derivative of GABA, treats spasticity from multiple sclerosis, spinal cord injury, and cerebral palsy.
What drugs are approved as antispastics?
Baclofen (Kemstro), Dantrolene (Dantrium), Tizanidine (Zanaflex).
When does Dantrolene (Dantrium) treat?
treats muscle spasticity disorders.
How does Baclofen (Kemstro) work?
Acts as a GABAB receptor agonist, inhibiting excitatory neurotransmitter release.
How does Dantrolene (Dantrium) work?
Acts on ryanodine receptors in muscle cells to prevent calcium release.
What else does Dantrolene (Dantrium) treat?
Malignant hyperthermia from inhaled anesthetics.
What does Tizanidine (Zanaflex) treat?
Muscle spasms from multiple sclerosis and spinal injuries.
What causes muscle spasms?
Acute muscle damage from partial muscle tear (strain) or ligament rupture (sprain), leading to spasms.
How does Tizanidine (Zanaflex) work?
Agonist at alpha-2 receptors, impairing excitatory neurotransmitter release.
How do muscle spasms affect muscle or ligament damage?
Spasms worsen muscle or ligament damage.
When are skeletal muscle relaxants used for acute muscle spasms?
They are used alone or with NSAIDs for sprains, strains, lower back pain, and fibromyalgia.
What is the role of skeletal muscle relaxants in muscle spasms?
Skeletal muscle relaxants interrupt the cycle of spasms and damage.
What is the first-line treatment for acute muscle spasms?
Nonsteroidal anti-inflammatory drugs (NSAIDs).
What does Orphenadrine (Norflex, Flexon) treat?
Acute muscle spasms.
How does Diazepam (Valium) work?
It facilitates GABA activity at GABAA receptors, enhancing inhibitory activity.
What are the contraindications for Orphenadrine (Norflex)?
Enlarged prostate, glaucoma, stomach ulcers, or gastrointestinal disorders.
What is a rare side effect of Chlorzoxazone (Muscol, Paraflex)?
Severe liver toxicity.
What does Chlorzoxazone (Muscol, Paraflex) treat?
Discomfort from acute musculoskeletal conditions and tension headaches.
What else is Diazepam (Valium) used to treat?
Anxiety.
What is Carisoprodol (Soma) used for, and what is its potential for abuse?
It is an early muscle relaxant with off-label use for fibromyalgia. It has a potential for abuse and is classified as a DEA Schedule IV drug.
What is the mechanism of action of Carisoprodol (Soma)?
The mechanism is unclear, but its metabolite, meprobamate, acts as a GABAA receptor modulator.
What does Cyclobenzaprine (Flexeril) treat, and what are its contraindications?
It treats acute muscle spasms and is contraindicated for cardiovascular disorders.
What does Metaxalone (Skelaxin) treat, and how does it work?
It treats acute muscle injury and does not act directly on motor neurons. Its mechanism is unknown.
What are some off-label uses of Cyclobenzaprine (Flexeril)?
Chronic myofascial pain, migraine, temporomandibular joint disorders, and fibromyalgia.
Why is Metaxalone (Skelaxin) high-risk for elderly patients?
Due to potential side effects.
How does Methocarbamol (Robaxin) work?
Its mechanism is unknown, but it likely works as a central nervous system depressant.
What are some general side effects of muscle relaxants?
Sedation, drowsiness, dizziness, confusion, and abuse potential (especially with benzodiazepines and carisoprodol).
What can muscle relaxants cause when combined with alcohol, antihistamines, benzodiazepines, or opioids?
Sedation, which is intensified with these substances.
What is the fetal risk associated with Methocarbamol (Robaxin)?
It has some fetal risk and should be avoided in early pregnancy.
