Clin med 2

Question 1

General classes of drugs based on therapeutic use Those used to reduce muscle excitability
Spasticity Muscle spasm

Answer 1

Skeletal muscle relaxants

Question 2

what is the goal of skeletal muscle relaxants?

Answer 2

Goal is to decrease muscle excitability without limiting muscle function

Question 3

Spasticity
(Hypertone) is ?

Answer 3

Occurs after a CNS injury or disease
Due to an exaggerated muscle stretch reflex
Is velocity dependent
Usually in antigravity muscles (biceps)

Question 4

a Spasms?

Answer 4

-Increased muscle tension following injury and inflammation
-Due to an orthopedic injury
-Myogenic, does have a neuro component/time
-Continuous, tonic

Question 5

Hypertone develops when there is:

Answer 5

-↓ in inhibition from cortex and inhibitory sp cord interneurons
-Following an Upper Motor Neuron lesion
-Spasticity – velocity dep hypertone, on the against gravity mm side of a joint

Question 6

Muscle Spasm develops due to:

Answer 6

Electrolyte imbalance
Dehydration
Mm overuse
Mm strain

Has both a neurogenic and myogenic components when prolonged

Question 7

what are the Muscle Relaxants for Hypertonicity OR Spasms

Answer 7

Baclofen – primarily used for hypertone
Tizanidine – poly synaptic inhibitor (within spinal cord)
Diazepam- poly synaptic inhibitor AND central acting
Dantrolene – acts directly on the muscle
Botox – acts at the NMJ

Question 8

Muscle Tone Management

Answer 8

Mo = Motor neuron in Sp Cord
Ii = Inhibitory interneuron
Ie = Excitatory interneuron
NMJ = Neuromuscular Junction

Question 9

Muscle Relaxant Agents –Polysynaptic inhibitors

Answer 9

-Polysynaptic inhibitors
Centrally acting
Mechanism of action is poorly understood
Can cause a general reduction in CNS activity
This may be the reason why the muscles tend to relax
-Commonly used agents
Diazepam
Carisoprodol, chlorphenesin carbamate, chlorzoxazone, cyclobenzaprine, metaxalone,
Methocarbamol, orphenadrine citrate

Question 10

Muscle Tone Management - Baclofen

Answer 10

GABA-B agonist
+ hyperpolarization
↓s release of excitatory NT
↑neuronal inhibition

Question 11

Baclofen
“Intrathecal Administration”

The Programmer

Answer 11

-Externally programmed via computer software

-Instructions transmitted through a “wand” by radio telemetry to the infusion pump

-Can be programmed for a continuous dose over 24 hours up to 12 specific dosages throughout the day
*Simple continuous
*Periodic Bolus
*Complex-Continuous

Average doses – 300- 1000mcg
Refill every 4 – 12 weeks

Question 12

Baclofen
“Intrathecal Administration”

The Pump

Answer 12

*Surgically implanted SC in abdomen
*Stores & releases prescribed amounts of drug
*Holds 18 ml (3.5 teaspoons)
*Refilled q 1-5 months depending on pump size, concentration, and dose

Question 13

Baclofen
“Intrathecal Administration”

The Catheter

Answer 13

*Small diameter, silicone rubber tube
*Travels from pump, under skin, to delivery site in spinal cord
*Catheter introduced below L3, advanced to T8-10

Question 14

disadvantages of Intrathecal Pump

Answer 14

*Requires surgery to implant the pump
*Expensive
*Tubing can become disconnected or kinked
*Risks
-Infection
-Baclofen overdose
-Pump dysfunction
-Symptoms of withdrawal

Question 15

Advantages of Intrathecal Pump

Answer 15

*Medicine is sent directly to the nerve cells
*Medicine dosage can be adjusted
*Less medication is needed, which reduces side effects.
*Reservoir can be easily refilled when needed
*Surgery is reversible

Question 16

what are S&S of Intrathecal Pump
over dose

Answer 16

Somnolence
Drowsiness
Seizures
Respiratory Depression
Hypertonia
Loss of consciousness

Question 17

Intrathecal Baclofen Candidates

Answer 17

*Moderate to severe hypertonicity
*Potential to be more independent with ADL’s
*Non-ambulatory with tone interfering with caregiving
*Pain or at risk for skeletal deformity
*Committed support system
*Over 4 y/o
*Respond to intrathecal test dose < 100 micrograms
*One year post TBI

Question 18

Muscle Tone Management- Diazepam

Answer 18

↑s GABA’s central
inhib effect @ Ii
CNS depressant

Question 19

Muscle Tone Management – Dantrolene (Dantrium

Answer 19

*Acts directly on mm
*An antagonist of the ryanodine receptor (Ca channel receptor in SR of skeletal mm)

Question 20

Muscle Tone Management – Zanaflex (Tizanidine)

Answer 20

Central acting -2 agonist
↑inhib effects of Ii

Question 21

Muscle Tone Management – Botulinum Toxin

Answer 21

*Prevents release of acetylcholine vesicles from presynaptic axon @ NMJ
-Toxin binds to presynaptic axon terminal
-Internalization of toxin
-Inhibition of NT release
*Administered IM in specific muscles
*Chemical denervation within days – lasts approx 3 months

Question 22

Anti-Muscle Spasm Agents

Answer 22

Drug
Onset of action (min)
Duration of action (hrs)
*Carisoprodol (Soma)
onset 30 mins
duration 4 - 6hrs

*Chlorzoxazone (Paraflex, Parafon Forte)
onset Within 60 mins
duration 3 - 4hrs

*Cyclobenzaprine (Flexeril)
onset Within 60
duration 12 - 24 hrs

*Diazepam (Valium)
onset 15-45 min
variable

*Metaxalone (Skelaxin)
onset 60 min
duration 4 - 6 hrs

*Methocarbamol (Carbacot, Robaxin)
onset Within 30
duration 24 hrs

*Orphenadrine citrate (Antiflex, Norflex)
onset-Within 60
duration 12hrs

Question 23

Clinical Implications – Muscle Relaxants
adverse reactions

Answer 23

*Generalized muscle weakness
*Decreased muscle tone
*Sedation
*Dizziness
*Ataxia

Question 24

Clinical Implications – Muscle Relaxants
Effects interfering with rehabilitation

Answer 24

*Motor control problems
*Functional decline
*Decreased alertness
*Weakness
*Tolerance and physical dependence

Question 25

What are side effects

Answer 25

constipation
dizziness
low blood pressure
dry mouth
allergic reactions
impaired thinking
heart problem