Fibromyalgia, Muscle Relaxers, Spasticity Drugs

Question 1

Duloxetine

Answer 1

Inhibits uptake of SER > NE.

CYP metabolism, esp. CYP2D6.

Question 2

Milnacipran

Answer 2

Inhibits uptake of NE > SER (3x)

Question 3

Side effects of duloxetine & milnacipran

Answer 3

↑ HR & BP
Contraindicated with uncontrolled closed-angle glaucoma & in conjunction with MAOIs.
SIADH, BBW for suicidal ideation.

Question 4

Pregabalin

Answer 4

Inhibits the presynaptic alpha2delta subunit of L-type calcium channels → inhibit excitatory transmission by glutamate.

Question 5

Side effects of pregabalin

Answer 5

Rebound after withdrawal, can cause dependence.
Additive sedation, worsening depression/suicidal ideation.
Dizziness, sedation, blurred vision, xerostomia, esp in elderly.

Question 6

Drugs for fibromyalgia

Answer 6

Duloxetine, milnacipran, pregabalin

Amitriptyline (TCA) & fluoxetine (SSRI) & cyclobenzaprine (muscle relaxer)

Question 7

Carisoprodol

Answer 7

Central CNS action in reticular activating system & spinal cord → sedation and ↓ perception of pain. No direct effect on neuronal conduction.

Question 8

Side effects of Carisoprodol

Answer 8

CYP2C19 metabolism

Drowsiness, dizziness, agitation, insomnia, vertigo, ataxia, asthenia, mydriasis, orthostatic hypotension.

Question 9

Monitoring with pregabalin

Answer 9

serum creatinine

Question 10

Monitoring with carisoprodol

Answer 10

serum creatinine/BUN

Question 11

Cyclobenzaprine

Answer 11

Similar to amitriptyline. Central action, maybe at brain stem.
For muscle spasm & fibromyalgia.

Question 12

Side effects of cyclobenzaprine

Answer 12

CYP3A4, CYP1A2, CYP2D6 metabolism.
Significant anticholinergic action.
Additive CNS depression & anticholinergic activity. GI problems most significant.
Can prolong QT interval.

Question 13

Methocarbamol

Answer 13

Oral, IM, or IV.
Generalized sedative action, altered pain perception.
For muscle spasm & tetanus.

Question 14

Side effects of methocarbamol

Answer 14

Additive CNS depression. Drowsiness, dizziness, lightheadedness, blurred vision, HA, irritability.

Question 15

Tizanidine

Answer 15

Agonist on presynaptic alpha2 receptor → decreased activation of polysynaptic spinal cord motor neurons and reduction in muscle tone.
For MS, spasticity, spinal cord trauma.

Question 16

Side effects of tizanidine

Answer 16

Caution in elderly and renal dz pts.
Hepatocellular toxicity.
Rebound hypertonicity, tachycardia, & HTN after cessation.
Additive CNS depression & hypotension (w/centrally acting agents).

Question 17

Monitoring with tizanidine

Answer 17

LFTs

Question 18

Baclofen

Answer 18

GABAb agonist in spinal cord → inhibition of excitatory pathways. Inhibition of substance P → pain relief. Higher doses → sedation.
For MS, muscle spasm, spasticity, spinal cord trauma.

Question 19

Side effects of baclofen

Answer 19

BBW: rebound neural activity → seizures, confusion, hallucinations, psychiatric disturbances, spasticity. Taper over 2 weeks. 
Additive CNS depression & hypotension.
↑ blood glucose.
Drowsiness, asthenia, confusion, HA.
CNS toxicity in renal failure.

Question 20

Dantrolene

Answer 20

Directly interferes with the ryanodine receptor and calcium release from SR to decrease striated muscle contraction. Uncouples the excitation-contraction process.
For malignant hyperthermia, MS, neuroleptic malignant syndrome, spasticity.

Question 21

Side effects of dantrolene

Answer 21

Can cross placenta → floppy child syndrome if used during C-section. 
Maybe hepatic toxicity.
Additive CNS depression.
IV + CCB can cause Vfib & CV collapse.
Muscle weakness.

Question 22

Monitoring of dantrolene

Answer 22

LFTs

Question 23

Drugs used for spasticity

Answer 23

Baclofen, botulinum toxin, dantrolene, tizanidine

Question 24

Muscle relaxants

Answer 24

Carisoprodol, cyclobenzaprine, methocarbamol, tizanidine

Question 25

Isoquinoline derivative non-depolarizing agents

Answer 25

Atracurium, cisatracurium, D-tubocurarine

Question 26

Steroid derivative non-depolarizing agents

Answer 26

pancuronium, rocuronium, vecurionium

Question 27

Depolarizing NMB drug

Answer 27

succinylcholine

Question 28

NMB drug reversal agents & their anticholinergic

Answer 28

Neostigmine - Glycopyrrolate Edrophonium - atropine Pyridostigmine - glycopyrrolate