Module 4 Chapter 22/27 Flashcards
True or False:
Drugs that treat spasticity don’t relieve acute muscle spasm and drugs that treat acute muscle spasm don’t treat muscle spasticity
True they are not interchangeable
THE ONLY EXCEPTION IS DIAZEMPAM (VALIUM)
What is spasticity?
movement of group disorders of the CNS; characteristics are heightened muscle tone, spasm, and loss of dexterity
what are the 4 drugs that relieve spasticity?
All act on the CNS except which drug?
Baclofen, Diazepam, Dantrolene, and Tizanidine
Dantrolene is the only one that does not act within the CNS; it acts on skeletal muscle
What is Baclofen’s mechanism of action?
acts within the spinal cord to suppress hyperactivity reflexes
thought to mimic actions of GABA on spinal movement
Does baclofen cause muscle weakness?
It does not decrease muscle strength which is why its preferred over dantrolene
what are the CNS and anticholinergic adverse effects of baclofen?
CNS effects: drowsiness, dizziness, weakness, fatigue
- this decreases with continued use
- can cause coma and respiratory depression if overdose occurs
anticholinergic effects: can cause urinary retention, hypotension can also occur
How should you discontinue baclofen? and WHY?
it should be d/c slowly over 1-2 weeks
abrupt withdrawal can cause visual hallucinations, paranoid ideations, and seizures
what are contraindications for patients taking baclofen?
Should not be given with alcohol, opioids, 1st gen antihistamines, or benzos because it can cause severe respiratory depression.
Don’t give to schizophrenia pts b/c they could have an exacerbation psychosis and confusion
What is important to know about Diazepam (valium)?
it is used to treat both muscle spasticity and muscle spasm
what is the generic name for Zanaflex?
Tizanidine
what is the mechanism of action for Tizanidine?
promotes inhibition of spasticity by acting as an agonist at presynaptic alpha 2 receptors
in discontinuing Tizanidine you should taper the dose because of?
rebound hypertension
taking food with Tizanidine does what?
increases bioavailability
What is an adverse effect of TIzanidine?
can cause hallucinations and psychosis, more sedating than most
What is dantrolene’s mechanism of action?
Acts directly on skeletal muscles and relieves spasms by suppressing calcium (causes muscle to contract less)
What is significant about dantrolene in regards to muscle spasticity?
It can cause a significant reduction in strength
When should dantrolene be discontinued?
If beneficial effects don’t develop within 45 days the med should be d/c
What are the common adverse effects of dantrolene?
It can cause liver damage or hepatotoxicity which is common in women over 35. Rare in children
Muscle weakness, drowsiness, diarrhea, dysphasia and erectile dysfunction can occur
what are muscle spasms?
its an involuntary contraction of a muscle or a muscle group.
they can be painful and reduce ability to function
what are the two drug classes used to treat muscle spasms?
analgesics (NSAIDs) and centrally acting muscle relaxants
what is the drug of choice for acute muscle spasms?
Cyclobenzaprine
What 3 adverse effects does cyclobenzaprine have?
CNS depressant (drowsiness, dizziness, and fatigue are common though diminish over time
Anticholinergic effects: dry mouth, blurred vision, photophobia, urinary retention, and constipation.
Cardiac rhythm disturbances: can cause sinus tachycardia and conduction delays (similar to TCAs)
what drug class is a major contraindication for cyclobenzaprine?
MAOIs, SSRIs, SNRIs, and TCAs as they can cause serotonin syndrome
how long should MOAIs be discontinued when about to use MAOIs.
MAOI should be discontinued for at least 2 weeks before therapy begins as serotonin syndrome may result.