Presented by: Dr. Sandra Joiner
Primarily used for:
Back pain
Muscle spasms
Cramps
Centrally Acting Skeletal Muscle Relaxants:
Baclofen (Lioresal)
Carisoprodol (Soma)
Chlorzoxazone (Paraflex)
Cyclobenzaprine (Flexeril)
Methocarbamol (Robaxin)
Orphenadrine (Banflex, Flexoject)
Tizanidine (Zanaflex)
Direct Acting Skeletal Muscle Relaxants:
Botulinum toxin type A (Botox)
Botulinum toxin type B (Myobloc)
Dantrolene (Dantrium)
Incobotulinumtoxin A (Xeomin)
Definition: A disturbance in the CNS caused by diseases, infections, toxins, or injuries.
Results in involuntary muscle contractions due to:
Overstretching
Joint wrenching
Tendon or ligament tearing
Pain mechanism:
Accumulation of lactic acid from reduced blood flow during contractions.
Treatment: Antispasmodic agents are used for musculoskeletal pain.
Definition: Occurs with damaged neurons in the CNS, leading to permanent abnormalities.
Results in:
Hypertonia: Excessive muscle stimulation
Loss of coordinated muscle activity
Conditions treated: Chronic conditions like Cerebral Palsy and Upper Motor Neuron disorders.
Carisoprodol:
Schedule: IV, high abuse potential
Action: Blocks interneural activity; depresses neuronal transmission.
Adverse Effects (AEs): Sedation, dizziness, headache, GI discomfort.
Cyclobenzaprine (Flexeril):
1st line therapy for skeletal muscle relaxation; economical.
Mechanism: Structurally related to TCA; acts as 5HT3 antagonist.
Effects: Sedation; potentiates norepinephrine, may increase HR.
Cautions: Avoid MAO-I within 14 days; enhances effects of alcohol and other depressants.
Metaxolone (Skelaxin):
Minimal side effects; low sedation potential.
Use: Adjunct to physical therapy; monitor hepatic and renal function.
Methocarbamol (Robaxin):
Indicated for acute, painful musculoskeletal conditions.
Also treats tetanus in children (not 1st line).
AEs: Anaphylaxis, seizures, leukopenia.
Baclofen:
Agonist at GABA receptors in CNS.
Used for upper motor neuron spasticity.
Effective with fewer sedative effects compared to Diazepam.
Administration: Oral or intrathecal (with black box warning).
CIs: Diabetes mellitus, preexisting psychiatric conditions.
Dantrolene:
Directly acts without affecting neuromuscular transmission.
Mechanism: Blocks ryanodine receptors; no Ca++ release.
Uses: Upper Motor Neuron disorders; malignant hyperthermia.
AEs: Sedation, malaise, lightheadedness, hepatotoxicity.
Children:
Safety and efficacy are not established.
Baclofen is used for cerebral palsy; Methocarbamol for tetanus.
Adults:
Use caution in activities requiring alertness; diazepam can be used for anxiety-related spasms.
Pregnant/lactating women should use alternatives.
Older Adults:
Higher risk of AEs; Carisoprodol is preferred for those with hepatic or renal impairment.
Tizanidine (Zanaflex):
Treats muscle spasms and spasticity; not 1st line for neck/back pain.
AEs: Urinary retention; hypotension risks.
Diazepam (Valium):
Treats pain from spasms; has multiple CNS actions.
Botulinum toxin (OnabotulinumtoxinA):
Acetylcholine release inhibitor; treats various spastic conditions.
AEs: Risks of anaphylactic reactions.
Centrally Acting Muscle Relaxant for Tetanus in Children?
Options: Botulinum Toxin type B, Dantrium, Baclofen, Methocarbamol
Baclofen Taper Duration to Prevent Psychosis?
Options: 12-21 days, 1-10 days, 7-14 days, 7-21 days
Patient with Botulinum Toxin A Complains of Headache?
Options: Provide comfort/measure safety, Assess for possible anaphylactic reactions.