Postmarketing reports indicate that the effects of rimabotulinumtoxinB and all botulinum toxin products may spread from the area of injection to produce symptoms consistent with botulinum toxin effects. These 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 there have been reports of death. 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 occurred at doses comparable to those used to treat cervical dystonia and at lower doses.
Cervical dystonia: IM: Initial: 2,500 to 5,000 units divided among the affected muscles in patients previously treated with botulinum toxin; initial dose in previously untreated patients should be lower. Subsequent dosing should be optimized according to patient's response.
Sialorrhea (drooling): Intraglandular: 1,500 to 3,500 units divided among the parotid (500 to 1,500 units/gland) and submandibular (250 units/gland) glands. Subsequent dosing should be optimized according to patient’s response and should generally be repeated no sooner than every 12 weeks.
No dosage adjustment provided in manufacturer’s labeling.
No dosage adjustment provided in manufacturer’s labeling.
Refer to adult dosing.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Intramuscular [preservative free]:
Myobloc: 2500 units/0.5 mL (0.5 mL); 5000 units/mL (1 mL); 10,000 units/2 mL (2 mL) [contains albumin human]
No
An FDA-approved patient medication guide, which is available with the product information and at https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/103846s5195lbl.pdf#page=17, must be dispensed with this medication.
IM: Cervical dystonia: Use an appropriately sized gauge needle to administer intramuscularly. Simultaneous electromyography (EMG) guided application may be helpful in locating active muscle not identified by physical examination alone (Chinnapongse 2010). Incidence of dysphagia may be reduced by administering sternocleidomastoid injections into the upper third of the muscle, increasing the concentration of the toxin, or by reducing the dose per muscle when administering bilateral sternocleidomastoid and hyoid muscle injections (Albanese 2015).
Intraglandular: Sialorrhea (drooling): Use a 30-gauge, 0.5 inch sterile needle. Locate salivary glands using ultrasound imaging or surface anatomical landmarks (refer to manufacturer's labeling).
Cervical dystonia: Treatment of cervical dystonia (spasmodic torticollis)
Sialorrhea: Treatment of chronic sialorrhea in adults
Upper limb spasticity
Botulinum products are not interchangeable; potency differences may exist between the products.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%:
Gastrointestinal: Dysphagia (4% to 25%; severe: 3%), xerostomia (12% to 39%; severe: 6%)
Immunologic: Antibody development (20% to 50%; neutralizing: 10% to 18%)
Local: Pain at injection site (12% to 16%)
Nervous system: Headache (10% to 16%), pain (13%)
1% to 10%:
Cardiovascular: Chest pain (≥2%), edema (≥2%), vasodilation (≥2%)
Dermatologic: Ecchymoses (≥2%), pruritus (≥2%)
Gastrointestinal: Dental caries (5% to 7%), dyspepsia (10%), gastrointestinal disease (≥2%), hernia of abdominal cavity (≥2%)
Genitourinary: Cystitis (≥2%), urinary tract infection (≥2%)
Infection: Abscess (≥2%), viral infection (≥2%)
Nervous system: Anxiety (≥2%), chills (≥2%), dizziness (3% to 6%), hyperesthesia (≥2%), malaise (≥2%), migraine (≥2%), vertigo (≥2%)
Neuromuscular & skeletal: Arthralgia (7%), asthenia (6%), back pain (4% to 7%)
Ophthalmic: Amblyopia (≥2%), visual disturbance (≥2%)
Respiratory: Dyspnea (≥2%), flu-like symptoms (6% to 9%), increased cough (6% to 7%), pneumonia (≥2%)
Miscellaneous: Cyst (≥2%)
Postmarketing:
Dermatologic: Skin rash, urticaria
Gastrointestinal: Constipation
Hypersensitivity: Anaphylaxis, angioedema, hypersensitivity reaction (including severe hypersensitivity reactions), serum sickness
Ophthalmic: Accommodation disturbance, xerophthalmia
Respiratory: Respiratory failure
Hypersensitivity to botulinum toxin or any component of the formulation; infection at the injection site(s)
Concerns related to adverse effects:
• Anaphylaxis/hypersensitivity reactions: Serious hypersensitivity (eg, serum sickness, urticaria, soft tissue edema, dyspnea) and anaphylactic reactions may occur; discontinue therapy immediately with signs/symptoms of hypersensitivity. Immediate medical treatment should be available.
• Antibody formation: Higher doses or more frequent administration may result in neutralizing antibody formation and loss of efficacy.
• Cardiovascular events: Rarely, arrhythmia and myocardial infarction have been reported with use of onabotulinumtoxinA (another botulinum toxin formulation), sometimes in patients with preexisting cardiovascular disease.
• Dysphagia: Common when used for cervical dystonia and may persist for several months after administration. In severe cases, patients may require alternative feeding methods. Risk factors include smaller neck muscle mass, bilateral injections into the sternocleidomastoid muscle, or injections into the levator scapulae.
• Systemic toxicity: [US Boxed Warning]: Distant spread of botulinum toxin beyond the site of injection has been reported; dysphagia and breathing difficulties have occurred and may be life threatening; other symptoms reported include blurred vision, diplopia, dysarthria, dysphonia, generalized muscle weakness, ptosis, and urinary incontinence which may develop within hours or weeks following injection. Risk likely greatest in children treated for the unapproved use of spasticity. Systemic effects have occurred following use in approved and unapproved uses, including low doses. Immediate medical attention required if respiratory, speech, or swallowing difficulties appear
Disease-related concerns:
• Neuromuscular disease: Avoid use in patients with myasthenia gravis (AAN [Narayanaswami 2021]). Use with caution in patients with peripheral motor neuropathic disease, amyotrophic lateral sclerosis, or neuromuscular junction disorders (eg, Lambert-Eaton syndrome).
• Respiratory disease: Use extreme caution in patients with pre-existing respiratory disease; treatment of cervical dystonia using botulinum toxin may weaken accessory muscles that are necessary for these patients to maintain adequate ventilation. Risk of aspiration resulting from severe dysphagia is increased in patients with decreased respiratory function.
Concurrent drug therapy issues:
• Neuromuscular transmission: Use with extreme caution in patients receiving other agents that may interfere with neuromuscular transmission (eg, aminoglycosides, neuromuscular-blocking agents)
Dosage form specific issues:
• Albumin: Product contains albumin and may carry a remote risk of virus transmission and variant Creutzfeldt-Jakob disease (vCJD). There also is a theoretical risk for transmission of CJD.
• Product interchangeability: Botulinum products (abobotulinumtoxinA, onabotulinumtoxinA, rimabotulinumtoxinB) are not interchangeable; potency units are specific to each preparation and cannot be compared or converted to any other botulinum product.
Other warnings/precautions:
• Appropriate use: Concurrent use of onabotulinumtoxinA (or abobotulinumtoxinA) or use within <4 months of rimabotulinumtoxinB is not recommended.
• Chronic therapy: Long-term effects of chronic therapy unknown.
• Injection site: Use with caution if there is inflammation, excessive weakness, or atrophy at the proposed injection site(s).
The U.S. Food and Drug Administration (FDA) and Health Canada have issued respective communications to health care professionals alerting them of serious adverse events (including fatalities) in association with the use of onabotulinumtoxinA (Botox, Botox Cosmetic) and rimabotulinumtoxinB (Myobloc). Events reported are suggestive of botulism, indicating systemic spread of the botulinum toxin beyond the site of injection. Reactions were observed in both adult and pediatric patients treated for a variety of conditions with varying doses; however, the most serious outcomes, including respiratory failure and death, were associated with the use in children for cerebral palsy limb spasticity. The FDA has evaluated postmarketing cases and now reports that systemic and potentially fatal toxicity may result from local injection of the botulinum toxins in the treatment of other underlying conditions, such as cerebral palsy associated with limb spasticity. Monitor patients closely for signs/symptoms of systemic toxic effects (possibly occurring 1 day to several weeks after treatment) and instruct patients to seek immediate medical attention with worsening symptoms or dysphagia, dyspnea, muscle weakness, or difficulty speaking.
None known.
Aminoglycosides: May enhance the neuromuscular-blocking effect of Botulinum Toxin-Containing Products. Risk C: Monitor therapy
Anticholinergic Agents: Botulinum Toxin-Containing Products may enhance the anticholinergic effect of Anticholinergic Agents. Risk C: Monitor therapy
Botulinum Toxin-Containing Products: May enhance the neuromuscular-blocking effect of other Botulinum Toxin-Containing Products. Risk C: Monitor therapy
Muscle Relaxants (Centrally Acting): May enhance the adverse/toxic effect of Botulinum Toxin-Containing Products. Specifically, the risk for increased muscle weakness may be enhanced. Risk C: Monitor therapy
Neuromuscular-Blocking Agents: Botulinum Toxin-Containing Products may enhance the neuromuscular-blocking effect of Neuromuscular-Blocking Agents. Risk C: Monitor therapy
Animal reproduction studies have not been conducted.
It is not known if rimabotulinumtoxinB is excreted in breast milk. The manufacturer recommends that caution be exercised when administering rimabotulinumtoxinB to nursing women.
RimabotulinumtoxinB (previously known as botulinum toxin type B) is a neurotoxin produced by Clostridium botulinum, spore-forming anaerobic bacillus. It cleaves synaptic Vesicle Association Membrane Protein (VAMP; synaptobrevin) which is a component of the protein complex responsible for docking and fusion of the synaptic vesicle to the presynaptic membrane. By blocking neurotransmitter release, rimabotulinumtoxinB paralyzes the muscle.
Onset of action: Sialorrhea: ~1 week (Isaacson 2020).
Duration: 12 to 16 weeks.
Absorption: Not expected to be present in peripheral blood at recommended doses.
Solution (Myobloc Intramuscular)
2500 units/0.5 mL (per 0.5 mL): $348.60
5000 units/mL (per mL): $697.20
10000 units/2 mL (per mL): $697.20
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