Muscle Relaxants

Question 1

Muscle relaxants

Answer 1

• used for severe muscle spasms with pain
• can be habit forming
• sedating
• should be used short term

Question 2

Baclofen

MOA

Answer 2

• inhibits transmission by both monosynaptic and polysynaptic reflexes at the spinal cord level, possibly by hyperpolarization of primary afferent fiber terminals, which results in relief of muscle spasticity

Question 3

Baclofen

Caution and Contraindications

Answer 3

• caution in renal impairment
• caution in elderly patients (CNS depression)
• caution with seizure disorder
• avoid in pregnancy
• caution in lactation

Question 4

Baclofen

Adverse Drug Effects

Answer 4

• drowsiness, confusion, headache, n/v, hypotension, seizures

Question 5

Cyclobenzaprine (Flexeril)

MOA

Answer 5

• act on the monosynaptic and polysynaptic spinal reflexes; inhibiting the synaptic reflex arcs affects the messages that are producing and maintaining the skeletal muscle spasm

Question 6

Cyclobenzaprine (Flexeril)

Caution and Contraindications

Answer 6

• avoid in hyperthyroidism, heart failure, heart block, or conduction disturbances and acute recovery phase of MI
• caution in patients with urinary retention, angle closure glaucoma, increased ocular pressure
• caution in hepatic impairment
• caution in elderly patients
• approved in pediatrics older than 12 years old
• limited data in pregnancy and lactation
• should not be used for more than 3 weeks

Question 7

Cyclobenzaprine (Flexeril)

Adverse Drug Effects

Answer 7

• dry mouth, drowsiness, fatigue, n/v, constipation, hallucinations, blurred vision
• serotonin syndrome (rare)

Question 8

Tizanidine

MOA

Answer 8

• centrally acting alpha-2 adrenergic agonist that reduces muscle spasticity by presynaptic inhibition of motor neurons
• check drug-drug interactions

Question 9

Tizanidine

Caution and Contraindications

Answer 9

• avoid in hepatic impairment
• caution in renal impairment
• avoid alcohol use
• do not abruptly stop
• caution in elderly patients
• avoid in pregnancy and lactation
• should only be used by specialists in pediatrics

Question 10

Tizanidine

Adverse Drug Effects

Answer 10

• dry mouth, weakness, fatigue, constipation, hypotension, bradycardia
• hepatotoxicity (rare), anaphylaxis and angioedema (rare)