Drugs for Fibromyalgia and Spasticity Flashcards
What is the suspected cause of fibromyalgia?
Elevated levels of neurotransmitter function in the
ascending pathways of the spinal cord and diminished levels in the descending, modulatory pathways of people with fibromyalgia. This
would lead to amplification of all nociceptive signals arriving in the brain
from peripheral tissues.
What are some of the symptoms of fibromyalgia?
- stiffness
- unrefreshing sleep
- tension headache
- irritable bowel or bladder
- difficulty concentrating
What are some of the currently most commonly used drugs for fibromyalgia (not just symptom relief)?
- acetaminophen
- NSAIDs
- TCAs
- Cyclobenzaprine
What are the serotonin-Nor repute inhibitors used in fibromyalgia treatment?
- Duloxetine (Cymbalta)
- Milnacipran (Savella)
both labeled for use
Which does Doloxetine prevent uptake of more, serotonin or Nor?
Serotonin
Which does Milnacipran prevent uptake of more, serotonin or Nor?
NE 3x more
T or F. Neither Sero/NE Reuptake Inhibitor acts on a receptor
T. and neither affects Dopamine
How is Doloxetine metabolized?
CYP 2D6 and eliminated in urine
How is Milnacipran metabolized?
Does not involve CYP activity; eliminated in the urine as a mix of parental drug and metabolites.
Contraindications of Doloxetine or Milnacipran?
- liver dysfunction
- chronic alcoholism
- pre-existing CV conditions
- closed-angle glaucoma
- MAOIs
Why cant Doloxetine or Milnacipran be given to patients with underlying CV problems?
they increase heart rate and BP
BBW of Sero/NE reuptake inhibitors?
suicidal ideation
T or F. Both Sero/NE reuptake inhibitors can cause hyponatremia
T. Via SIADH potential
How does Pregabalin (Lyrica) work?
Fibromyalgia drug that is an analog of gabapentin (anti-seizure drug) that acts by inhibiting presynaptic alpha-2-delta subunits of L-type Ca2+ channels, thus, inhibiting the excitatory transmission of glutamate
What is the clinical of Lyrica?
Glutamate inhibition seems to alleviate
neuropathic pain, anxiety and pain syndromes
How is Lyrica eliminated?
it is rapidly absorbed and eliminated in urine mostly unchanged with some tubular reabsorption (no known DD interactions)
Contraindications of Pregabalin (Lyrica)?
Rebound worsening of symptoms upon drug withdrawal. May cause dependence with continued use.
Additive sedation may occur with other agents that affect the CNS in this manner. Patients should be monitored for worsening depression or suicidal thoughts /behavior.
AEs of Pregabalin?
Dizziness, sedation, blurred vision and xerostomia may occur; these are especially problematic in the elderly.
What should be monitored when giving Pregabalin (Lyrica)?
serum creatinine
What are the off-label drugs for Fibromyalgia?
- Amitriptyline (Elavil)-TCA
- Fluoxetine (Prozac)
- Cyclobenzaprine
What is Fluoxetine (Prozac)?
selective serotonin reuptake inhibitor (SSRI)
What are some skeletal muscle relaxers?
- Carisoprodol (Soma)
- Cyclobenzaprine (Flexeril)
- Methocarbamol (Relaxin)
- Tizanidine (Zanaflex)
How does Methocarbamol (Relaxin) work?
No direct effect on muscle or excitation-contraction coupling.
Effects thought to be due to generalized sedative action. Pain relief due to altered pain perception.
What are the FDA indications for Relaxin?
- tetanus
- muscle spasm
How is Methocarbamol metabolized?
Hepatic dealkylation and hydroxylation with urinary elimination.
NOTE: Significant hepatic and/or renal
dysfunction has the potential to increase drug toxicity.
AEs of Relaxin?
Additive CNS depression with other depressant drugs, and alcohol.
Common side effects include drowsiness, dizziness, lightheadedness, blurred vision, N/V, headache and irritability.