Dosing and uses of Myobloc (rimabotulinumtoxinB)
Adult dosage forms and strengths
injectable solution
- 5000 unit/mL
Cervical Dystonia
Prior botulinum toxin injection: 2500-5000 units IM, divided among affected muscles
No prior botulinum toxin injection: Administer lower dose for initial treatment
Repeat dose: Adjust dose based on response and administer no sooner than 12-16 weeks
Sialorrhea (Off-label)
Second-line agent for drooling associated with ALS or Parkinson disease if inadequate response to anticholinergics
2500 units injected into bilateral parotid and submandibular glands
Other Indications & Uses
Off-label: spasticity associated with cerebral palsy, chronic anal fissure; sialorrhea associated with ALS or Parkinson disease
Pediatric dosage forms and strengths
Safety/efficacy not established
Geriatric dosage forms and strengths
Cervical Dystonia
Prior botulinum toxin injection: 2500-5000 units IM, divided among affected muscles
No prior botulinum toxin injection: Administer lower dose for initial treatment
Repeat dose: Adjust dose based on response and administer no sooner than 12-16 weeks
Sialorrhea (Off-label)
Second-line agent for drooling associated with ALS or Parkinson disease if inadequate response to anticholinergics
2500 units injected into bilateral parotid and submandibular glands
Myobloc (rimabotulinumtoxinB) adverse (side) effects
Frequency not defined
Headache
Dry mouth
Dysphagia
Dyspepsia
Injection site pain
Flu-like symptoms
Warnings
Black box warnings
Effects of all botulinum toxin products may spread from the area of injection to produce symptoms consistent with botulinum toxin effects
These symptoms may include asthenia, generalized muscle weakness, diplopia, blurred vision, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence, and breathing difficulties
These symptoms have been reported hours to weeks after injection
Swallowing and breathing difficulties can be life threatening, and death have been reported
The risk of symptoms is probably greatest in children treated for spasticity, but symptoms can also occur in adults treated for spasticity and other conditions, particularly in those patients who have underlying conditions that would predispose them to these symptoms
In unapproved uses, including spasticity in children and adults, and in approved indications, cases of spread of effect have been reported at doses comparable to those used to treat cervical dystonia and at lower doses
Contraindications
Hypersensitivity
For IM administration only
Cautions
Peripheral motor neuropathic diseases (eg, ALS, motor neuropathy)
Neuromuscular junctional disorders (eg, myasthenia gravis, Lambert-Eaton syndrome)
Increased risk for severe dysphagia and respiratory compromise in pts with neuromuscular disorders
Risk of respiratory compromise & death esp in children treated off-label for cerebral palsy-associated spasticity
Contains human albumin
Pregnancy and lactation
Pregnancy category: C
Lactation: Not known if excreted in breast milk; effect on nursing infant not known
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Myobloc (rimabotulinumtoxinB)
Mechanism of action
Neurotoxin from Clostridium botulinum; blocks cholinergic transmission at the neuromuscular junction by inhibiting acetylcholine release from the peripheral cholinergic nerve endings
Pharmacokinetics
Duration: 12-16 weeks
Absorption: Minimal levels in circulation after IM injection
Administration
IM Information
Preparation
- May dilute with 0.9% NaCl
- Once diluted, use within 4 hr (does not contain preservative)
Storage
- Refrigeration at 2-8C
