Spasticity

Question 0

Contraindications to baclofen

Answer 0

Lowers the seizure threshold

can cause weakness insomnia confusion sedation

Question 1

What is the mechanism baclofen?

Answer 1

• Oral GABA-mimetic agents which acts as a GABA agonist at GABA-b receptors (GABA analogue)
• provides inhibitory effect in monosynaptic and to a lesser extent in polysynaptic reflex pathways.
• activation of GABA-b receptors reduces CALCIUM influx suppressing the release of excitatory neurotransmitters from the PREsynaptic axon.
• ACTIVATION OF THE POSTSYNAPTIC GABA-b RECEPTORS INCREASES POTASSIUM Egress, MAINTAINIng MEMBRANE POLARIZATION. MAKES IT MORE DIFFICULT TO DEPOLARIZE POSTSYNAPTIC CELL AND DAMPENS EFFECTS OF EXCITATORY NEUROTRANSMITTERS FROM PRESYNAPTIC AND AXONS. THIS REDUCES gamma MOTOR NEURON EXCITABILITY.

Question 2

Where does baclofen work the best?

Answer 2

Lower extremities over upper extremities.

Question 3

Mechanism for diazepam/Valium.

Answer 3

• Facilitates GABA’s effects on GABA-A’s receptor subtype. Overall effect results in membrane hyperpolarization and decreased neuronal firing.
• not the fact is increased presynaptic inhibition and reduced the mono and polysynaptic reflexes.
• Acts diffusely through neuronal axis.

Question 4

Side effects of diazepam

Answer 4

Sedation, memory impairment, and decreased REM sleep

Question 5

Mechanism of dantrolene.

Answer 5

Unique mechanism with peripheral sites of action.
- acts peripherally in striated muscle by blocking the release of calcium from sarcoplasmic reticulum.
- reduces extrafusal muscle fiber contraction strength and muscle spindle sensitivity.
-Fast twitch motor units are more sensitive than slow twitch.
.-Minor effects on smooth or cardiac muscle.

Question 6

Side effects of tizanidine

Answer 6

• Liver toxicity in 1% of patients
• highest risk and females over 30 years old on high doses (greater than 300 mg) for greater than two months
• risk of hepatonecrosis.
• Drowsiness
• weakness fatigue paresthesias diarrhea nausea vomiting

Question 7

Other uses for dantrolene.

Answer 7

Malignant hyperthermia

neuroleptic malignant syndrome, and hyperthermia due to baclofen withdrawal

Question 8

How does clonidine (Catapres) work as an anti-spasmodic?

Answer 8

Central acting alpha two adronergic agonist with effects in the Locus ceruleus. In the spinal cord, provides presynaptic inhibition of sensory afferents.
- commonly used as transdermal patch oral also available

Question 9

Common side effects of clonidine

Answer 9

Hypotension-syncope-nausea

-sedation-depression-dry mouth-ankle edema

Question 10

Strange diabetes related side effect of clonidine.

Answer 10

May impair hypoglycemia induced tachycardia in diabetics, thus delaying the diagnosis of clinically significant hypoglycemia in this population

Question 11

Mechanism for tizanidine (Zanaflex)

Answer 11

Centrally acting alpha-2 adronergic agonist (chemically related to clonidine).

• Binds to alpha-2 receptors both spinally and super spinally
• thought to act by enhancing presynaptic inhibitory modulation of spinal reflexes this effect is especially noted in polysynaptic reflexes. Less potent than clonidine in regards to blood pressure less issues with hypotension.

Question 12

When is tizanidine contraindicated?

Answer 12

Contra indicated in use with concurrent IV ciprofloxacin due to inhibition of cytochrome P4 50.
-Recommended LFT monitoring