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21 Cards in this Set
- Front
- Back
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Indications and goal for skeletal muscle relaxants?
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Treat conditions associated with hyperexcitable skeletal mm
Goal: Normalize excitability without decreasing mm function |
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Difference between muscle spasm and spasticivity
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Spasm: Increase in mm tension after msk injury, inflammation, or PNS injury = continuous invol. contraction
Spasticity: Increase in mm excitability due to velocity dependent stretch reflex |
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How do polysynaptic inhibitors work?
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Mechanism not well understood. Thought to decrease SC polysnyaptic reflex activity, thus dec a-MN excitabiilty via altering interneuron activity
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Two agents used to treat mm spasms
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Diazepam and polysynaptic inhibitors
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Example of polysnaptic inhbitors
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cycylobenzaprine (Flexeril)
Oral |
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Is Diazepam (valium) good for muscle spasms?
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Has mm relaxant properties, but is not used often b/c of side effects at doses needed to relax muscles
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Side effects for antispasmotics?
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Sedation (dec CNS activity)
Physical dependence Tolerance |
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How long should you use antispasmotics?
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Short term use only, PT tx is usally used together with these drugs
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Agents used to treat spasticity?
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Baclofen (Lioresal)
Diazepam (valium) Dantrolene sodium (Dantrium) Tizanidine (Zanaflex) (Botulinum toxin A (Botox) |
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How is bacolfen administered?
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Oral or intrathecal
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Mechanism for baclofen
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Gaba agonist - inhibit transmission at synapses, which inhibits a-MN
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How can Diazepam reduce spasticity?
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Inhibits CNS, thus reducing spasticity, but causes sedation. Long-term use for this condition is avoided
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Mechanism of Dantrolene sodium (Dantrium)
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Impairs release of Ca2+ from SR within mm cell during excitation
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Major side/adverse effects of Dantrium?
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Generalized mm weakness
Liver toxicity |
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What type of durg is Tizanidine (Zanaflex) and what is it's mechanism of action?
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alpha-2 adrenergic agonist
Binds to alpha 2 receptors in CNS and stimulates them, which inhibits a-MN |
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Indications of use for Tizanidine (Zanaflex)
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Usually after spinal lesion, possibly after cerebral lesion (but not acutely)
Milder side effects, less generalize mm weakness Finding a balance in amt of spasticity is important functionally |
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Indications for Botulinum toxin A (Botox)
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Control localized mm dystonias
Reduce spasticity in specific m groups for a variety of fxt benefits Control m hyperexcitability for other purposes |
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Administration and mechanism of Botox
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Injection into selected mm
Inhibits ACh release at NMJ |
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Adverse effects of of Botox
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Systemic use can cause widespread paralysis - resp failure
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Botox Cons
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Does not cure spasticity
Limited # of m groups at a time b/c could cuase immune response SIDE EFFECTS: small incidence of severe side effects, even tho drug is potentially lethal |
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In general, absorption, metabolism, and excretion of skeletal mm relexants (pharmokinetics)
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Absorption: thru GI tract
Metabolism: liver enzyme Excretion: intact drug or metabolite thru kindneys |
