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Medically reviewed by Last updated on Jul 1, 2019.


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Index Terms

  • Botulinum Toxin Type B

Dosage Forms

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]

Brand Names: U.S.

  • Myobloc

Pharmacologic Category

  • Neuromuscular Blocker Agent, Toxin


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.


Not expected to be present in peripheral blood at recommended doses

Duration of Action

12-16 weeks

Use: Labeled Indications

Cervical dystonia: Treatment of cervical dystonia (spasmodic torticollis)

Sialorrhea: Treatment of chronic sialorrhea in adults

Off Label Uses

Upper limb spasticity

Based on the American Academy of Neurology practice guidelines on the use of botulinum neurotoxin, rimabotulinumtoxinB may be considered as a treatment option for focal manifestations of adult upper limb spasticity.


Hypersensitivity to botulinum toxin or any component of the formulation; infection at the injection site(s)

Dosing: Adult

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.

Dosing: Geriatric

Refer to adult dosing.


May be diluted with normal saline. Do not shake.


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).


Store vials under refrigeration at 2°C to 8°C (36°F to 46°F). Protect from light. Once diluted, use within 4 hours. Does not contain preservative. Single use vial. Do not freeze.

Drug Interactions

Aminoglycosides: May enhance the neuromuscular-blocking effect of Botulinum Toxin-Containing Products. Monitor therapy

Anticholinergic Agents: Botulinum Toxin-Containing Products may enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

Botulinum Toxin-Containing Products: May enhance the neuromuscular-blocking effect of other Botulinum Toxin-Containing Products. 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. Monitor therapy

Neuromuscular-Blocking Agents: Botulinum Toxin-Containing Products may enhance the neuromuscular-blocking effect of Neuromuscular-Blocking Agents. Monitor therapy

Adverse Reactions


Central nervous system: Headache (10% to 16%), pain (≤13%)

Gastrointestinal: Dysphagia (10% to 25%; severe dysphagia: 3%), xerostomia (3% to 34%; severe xerostomia: 6%)

Local: Injection site pain (12% to 16%)

Neuromuscular & skeletal: Neck pain (≤17%)

Miscellaneous: Infection (≤19%), antibody formation (~10% to 18%, at 12 and 18 months, respectively)

1% to 10%:

Cardiovascular: Chest pain, edema, peripheral edema, vasolidation

Central nervous system: Dizziness (3% to 6%), anxiety, chills, confusion, fever, hyperesthesia, malaise, migraine, somnolence, tremor, vertigo

Dermatologic: Pruritus, bruising

Endocrine & metabolic: Hypercholesterolemia

Gastrointestinal: Nausea (≤10%), dyspepsia (≤10%,) glossitis, stomatitis, taste perversion, vomiting

Genitourinary: Cystitis, urinary tract infection, vaginal moniliasis

Hematologic: Serum neutralizing activity

Neuromuscular & skeletal: Torticollis (≤8%), arthralgia (≤7%), back pain (≤7%), myasthenia (≤6%), weakness (≤6%), arthritis, hernia

Ocular: Amblyopia, vision abnormal

Otic: Otitis media, tinnitus

Respiratory: Cough (3% to 7%; placebo 3%), dyspnea, pneumonia

Miscellaneous: Flu-like syndrome (6% to 9%), abscess, allergic reaction, cyst, neoplasm, viral infection

<1%, postmarketing, and/or case reports: Constipation

ALERT: U.S. Boxed Warning

Distant spread of toxin effect:

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.


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: Use with caution in patients with neuromuscular diseases (eg, myasthenia gravis, Eaton-Lambert syndrome) and neuropathic disorders (eg, amyotrophic lateral sclerosis).

• 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).

Pregnancy Considerations

Animal reproduction studies have not been conducted.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience injection site pain, headache, dry mouth, nausea, flu-like signs, joint pain, back pain, dizziness, or neck pain. Have patient report immediately to prescriber signs of infection, blurred vision, change in voice, droopy eyelids, loss of strength and energy, difficulty breathing, difficulty swallowing, difficulty speaking, muscle pain, muscle weakness, vision changes, eye pain, severe eye irritation, urinary incontinence, or diplopia (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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