Week 12 - Muscle Relaxants

Question 1

Baclofen: MOA

Answer 1

Inhibits the transmission of both monosynaptic and polysynaptic reflexes at the spinal cord level

• Possibly by hyperpolarization of primary afferent fiber terminals –> relief of muscle spasticity

Question 2

Baclofen: caution and contraindications

Answer 2

• Caution in renal impairment
• Caution in seizure disorder
• Avoid in pregnancy and lactation
• Caution in elderly

Question 3

Cyclobenzaprine (Flexeril): MOA

Answer 3

Acts on the monosynaptic and polysynaptic spinal reflexes

• Inhibits the synaptic reflex arcs –> affects the messages that are producing and maintaining the skeletal muscle spasm

Question 4

Cyclobenzaprine (Flexeril): ADR

Answer 4

Dry mouth, drowsiness, fatigue, N/V, constipation, hallucinations, blurred vision

Question 5

Cyclobenzaprine (Flexeril): caution and contraindication

Answer 5

• Avoid in hyperthyroidism, HF, arrhythmias, heart block or conduction disturbances, acute recovery phase of MI
• Caution in patients w/ urinary retention, angle closure glaucoma, increased ocular pressure
• Caution in hepatic impairment
• Avoid in pregnancy

Approved in pediatrics >12 years

Question 6

Tizanidine: MOA

Answer 6

Centrally acting alpha-2 adrenergic agonist that reduces muscle spasticity by presynaptic inhibition of motor neurons

Question 7

Tizanidine: ADR

Answer 7

Dry mouth, weakness, fatigue, constipation, hypotension, bradycardia

Rare: hepatotoxicity, anaphylaxis, angioedema

Question 8

Tizanidine: caution and contraindications

Answer 8

• Avoid in hepatic and renal impairment
• Avoid w/ alcohol use
• Do not abruptly stop
• Caution in elderly

Avoid in pregnancy and lacation

Should only be used by specialist in pediatrics

Question 9

General centrally acting muscle relaxants ADRs

Answer 9

CNS sedation, respiratory depression

Question 10

Centrally acting muscle relaxants: drug interactions

Answer 10

Additive sedation w/ CNS depressants