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myobloc

Myobloc (Botulinum Toxin Type B) is a medication used to treat Sialorrhea, Torticollis, Dystonia, Neck Pain.

Botulinum Toxin Type B · by Elan Pharm

Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Active ingredient
Botulinum Toxin Type B
Form
Injectable
Strength
Botulinum Toxin Type B 5000IU/VIAL
Type
Prescription (Rx)
Brand or generic
Brand-name
Manufacturer
Elan Pharm
FDA application
BLA103846

What is Myobloc?

From the FDA label:RimabotulinumtoxinB is an acetylcholine release inhibitor. RimabotulinumtoxinB is a 700 kDA botulinum toxin type B complex produced from fermentation of the bacterium Clostridium botulinum type B (Bean strain) and exists in noncovalent association with hemagglutinin and nonhemagglutinin proteins as a neurotoxin complex. The neurotoxin complex is recovered from the fermentation process and purified through a series of precipitation and chromatography steps. MYOBLOC (rimabotulinumtoxinB) injection is a sterile, preservative-free, clear and colorless to light-yellow solution in a single-dose vial for intramuscular or intraglandular use. Each vial contains 2,500 Units/0.5 mL; 5,000 units/mL; or 10,000 Units/2 mL of rimabotulinumtoxinB at a concentration of 5,000 Units/mL at approximately pH 5.6. Each 2,500 Units/0.5 mL vial of MYOBLOC contains 2,500 Units rimabotulinumtoxinB, 0.235 mg albumin human, 2.9 mg sodium chloride and 1.35 mg sodium succinate. Each 5,000 Units/mL vial of MYOBLOC contains 5,000 Units rimabotulinumtoxinB, 0.47 mg albumin human, 5.8 mg sodium chloride and 2.7 mg sodium succinate. Each 10,000 Units/2 mL vial of MYOBLOC contains 10,000 Units rimabotulinumtoxinB, 0.94 mg albumin human, 11.6 mg sodium chloride and 5.4 mg sodium succinate. One unit of MYOBLOC corresponds to the calculated median lethal intraperitoneal dose (LD50) in mice. The method for performing…

How to use

Cervical Dystonia: for patients with demonstrated tolerance of botulinum toxin injection, recommended total dosage is 2,500 Units to 5,000 Units divided among effected muscles ( 2.2 ) Chronic Sialorrhea: recommended dosage is 1,500 Units to 3,500 Units; 500 Units to 1,500 Units per parotid gland and 250 Units per submandibular gland; no more frequent than every 12 weeks ( 2.3 ) 2.1 Instructions for Safe Use The potency units of MYOBLOC are specific to the preparation and assay method utilized. They are not interchangeable with other preparations of botulinum toxin products and cannot be compared to or converted into units of any other botulinum toxin products [see Warnings and Precautions (5.2) , Description (11) ] . Each single-dose vial should only be used during one session and only for one patient. Discard any remaining solution in the vial. MYOBLOC is ready to use; no reconstitution required. MYOBLOC may be diluted with 0.9% Sodium Chloride Injection. Once diluted, the product must be used within 4 hours as the formulation does not contain a preservative. 2.2 Dosing for Cervical Dystonia The recommended initial dosage of MYOBLOC for cervical dystonia patients with a prior history of tolerating botulinum toxin injections is 2,500 Units to 5,000 Units divided among affected muscles [see Clinical Studies (14.1) ] . Patients without a prior history of tolerating botulinum…

Side effects

The following clinically significant adverse reactions to MYOBLOC are discussed in greater detail in other sections of the labeling: Spread of Toxin Effect [see Warnings and Precautions (5.1) ] Lack of Interchangeability Between Botulinum Toxin Products [see Warnings and Precautions (5.2) ] Hypersensitivity Reactions [see Warnings and Precautions (5.3) ] Dysphagia and Breathing Difficulties [see Warnings and Precautions (5.4) ] Human Albumin and Transmission of Viral Diseases [see Warnings and Precautions (5.5) ] The most common adverse reactions (>5% of MYOBLOC-treated patients at any dose and >5% more common than placebo) include: Cervical Dystonia: dry mouth, dysphagia, injection site pain, and headache ( 6.1 ) Chronic Sialorrhea: dry mouth and dysphagia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Solstice Neurosciences at 1-888-461-2255 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in clinical trials of another drug and may not reflect the rates observed in practice. Cervical Dystonia In the treatment of cervical dystonia, MYOBLOC was studied in both placebo-controlled single treatment studies and open-label repeated treatment studies; most treatment…

FDA Boxed Warning (the FDA’s most serious warning)

Boxed (black-box) warning — from the FDA label

Postmarketing reports indicate that the effects of MYOBLOC 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 [see Warnings and Precautions (5.1) ]. WARNING: DISTANT SPREAD OF TOXIN EFFECT See full prescribing information for complete boxed warning. The effects of MYOBLOC and all botulinum toxin products may spread from the area of injection to produce symptoms consistent with botulinum toxin effects. 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, particularly in those patients who have an underlying condition that would predispose them to these symptoms ( 5.1 ).

Warnings

Important safety information

Spread of toxin effects; swallowing and breathing difficulties can lead to death. Seek immediate medical attention if respiratory, speech or swallowing difficulties occur ( 5.1 , 5.4 ) MYOBLOC potency units cannot be compared to or converted into units of other botulinum toxins ( 5.2 ) Patients with neuromuscular disorders should be monitored closely for swallowing/breathing difficulty ( 5.4 ) 5.1 Spread of Toxin Effect Postmarketing safety data from MYOBLOC and other approved botulinum toxins suggest that botulinum toxin effects may, in some cases, be observed beyond the site of local injection. The symptoms are consistent with the mechanism of action of botulinum toxin and 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 related to spread of toxin effects. 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, and 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, symptoms consistent with spread of toxin effect have been reported at doses comparable to or lower than doses used to treat cervical dystonia. 5.2 Lack of Interchangeability between Botulinum Toxin Products The potency units of MYOBLOC are specific to the preparation and biological activity assay method utilized. Due to differences in the aspects of this assay such as the vehicle, dilution scheme, and laboratory protocols for various potency assays, potency units are not interchangeable with other preparations of botulinum toxin products and, therefore, units of biological activity of MYOBLOC cannot be compared to or converted into units of any other botulinum toxin products assessed with any other specific assay method [see Description (11) ] . 5.3 Hypersensitivity Reactions Serious hypersensitivity reactions have been reported with botulinum toxin products. Angioedema, urticaria, and rash have occurred with MYOBLOC treatment [see Adverse Reactions (6.3) ]. Hypersensitivity reactions can also include anaphylaxis, serum sickness, soft tissue edema, and dyspnea. If serious and/or immediate hypersensitivity reactions occur, discontinue further injection of MYOBLOC and institute appropriate medical therapy immediately. The use of MYOBLOC in patients with a known hypersensitivity to any botulinum neurotoxin or to any of the excipients (human albumin, sucrose), could lead to a life-threatening allergic reaction [see Contraindications (4) , Adverse Reactions (6.3) ]. 5.4 Dysphagia and Breathing Difficulties Treatment with MYOBLOC and other botulinum toxin products can result in swallowing or breathing difficulties. Patients with pre-existing swallowing or breathing difficulties may be more susceptible to these complications. In most cases, this is a consequence of weakening of muscles in the area of injection that are involved in breathing or swallowing. When distant effects occur, additional respiratory muscles may be involved. Deaths as a complication of severe dysphagia have been reported after treatment with botulinum toxin. Dysphagia may persist for several months and require use of a feeding tube to maintain adequate nutrition and hydration. Aspiration may result from severe dysphagia and is a particular risk when treating patients in whom swallowing or respiratory function is already compromised. Treatment of cervical dystonia with botulinum toxins may weaken neck muscles that serve as accessory muscles of ventilation. This may result in a critical loss of breathing capacity in patients with respiratory disorders who may have become dependent upon these accessory muscles. There have been postmarketing reports of serious breathing difficulties, including respiratory failure, in cervical dystonia patients. Patients treated with botulinum toxin may require immediate medical attention should they develop problems with swallowing, speech or respiratory disorders. These reactions can occur within hours to weeks after injection with botulinum toxin [see Adverse Reactions (6.1) ] . Individuals with peripheral motor neuropathic diseases, amyotrophic lateral sclerosis, or neuromuscular junctional disorders (e.g., myasthenia gravis or Lambert-Eaton syndrome) should be monitored particularly closely when given botulinum toxin. Patients with neuromuscular disorders may be at increased risk of clinically significant effects including severe dysphagia and respiratory compromise from typical doses of MYOBLOC [see Adverse Reactions (6.1) ] . 5.5 Human Albumin and Transmission of Viral Diseases This product contains albumin, a derivative of human blood. Based on effective donor screening and product manufacturing processes, it carries an extremely remote risk for transmission of viral diseases and variant Creutzfeldt-Jakob disease (vCJD). There is a theoretical risk for transmission of Creutzfeldt-Jakob disease (CJD), but if that risk actually exists, the risk of transmission would be considered extremely remote. No cases of transmission of viral diseases, CJD, or vCJD have ever been identified for licensed albumin or albumin contained in other licensed products.

Who should not take Myobloc

MYOBLOC is contraindicated in patients with: A known hypersensitivity to any botulinum toxin product or to any of the components in the formulation [see Warnings and Precautions (5.3) , Description (11) ] Infection at the proposed injection site(s) MYOBLOC is contraindicated in patients with: Known hypersensitivity to any botulinum toxin preparation or to any of the components in the formulation ( 4 , 5.3 ) Infection at the proposed injection site(s) ( 4 )

Overdose — what happens if you take too much

Excessive doses of MYOBLOC may be expected to produce neuromuscular weakness with a variety of symptoms. Respiratory support may be required where excessive doses cause paralysis of respiratory muscles. In the event of overdose, the patient should be medically monitored for symptoms of excessive muscle weakness or muscle paralysis [see Warnings and Precautions (5.1 , 5.4) ] . Symptomatic treatment may be necessary. Symptoms of overdose are likely not to be present immediately following injection. Should accidental injection or oral ingestion occur, the person should be medically supervised for several weeks for signs and symptoms of excessive muscle weakness or muscle paralysis. In the event of overdose, antitoxin raised against botulinum toxin is available from the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. However, the antitoxin will not reverse any botulinum toxin-induced effects already apparent by the time of antitoxin administration. In the event of suspected or actual cases of botulinum toxin poisoning, please contact your local or state Health Department to process a request for antitoxin through the CDC. If you do not receive a response within 30 minutes, please contact the CDC directly at 770-488-7100. More information can be obtained at http://cdc.gov/ncidod/srp/drugs/drug-service.html.

U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.

Interactions

Co-administration with aminoglycosides or other agents interfering with neuromuscular transmission may potentiate effects of MYOBLOC ( 7.1 ) Co-administration or overlapping of botulinum toxin serotypes (within 4 months) may potentiate neuromuscular paralysis ( 7.3 ) 7.1 Aminoglycosides and Other Agents Interfering with Neuromuscular Transmission Co-administration of MYOBLOC and aminoglycosides or other agents interfering with neuromuscular transmission (e.g., curare-like compounds) should only be performed with caution as the effect of the toxin may be potentiated. 7.2 Anticholinergic Drugs Use of anticholinergic drugs after administration of MYOBLOC may potentiate systemic anticholinergic effects. 7.3 Other Botulinum Neurotoxin Products The effect of administering different botulinum toxin products at the same time or within several months of each other is unknown. Excessive neuromuscular weakness may be exacerbated by administration of another botulinum toxin prior to the resolution of the effects of a previously administered botulinum toxin. 7.4 Muscle Relaxants Excessive weakness may also be exaggerated by administration of a muscle relaxant before or after administration of MYOBLOC.

May treat (source: NIH RxClass)

Dosage forms

Injectable

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

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Frequently asked questions

What does Myobloc treat?
Myobloc (Botulinum Toxin Type B) may be used to treat sialorrhea, torticollis, dystonia, neck pain, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
Is there a coupon or discount for Myobloc?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Myobloc. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Myobloc?
Myobloc is marketed by Elan Pharm. You can see Elan Pharm's full profile, rating, and other products on pharmaranks.
Is Myobloc a brand-name or generic drug?
Myobloc is a brand-name product with the active ingredient Botulinum Toxin Type B.
Is Myobloc available over the counter?
No. Myobloc is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Myobloc come in?
Myobloc is currently marketed as injectable, per the FDA's National Drug Code Directory.
Is Myobloc FDA-registered?
Myobloc is on record with the U.S. FDA under application number BLA103846. You can verify this on its official FDA label.
Is Myobloc safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Myobloc. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Myobloc?
Myobloc's side effects are taken directly from its FDA label. From the label: The following clinically significant adverse reactions to MYOBLOC are discussed in greater detail in other sections of the labeling: Spread of Toxin Effect [see Warnings and Precautions (5.1) ] Lack of Interchangeability Between Botulinum Toxin Products [see Warnings and Precautions (5.2) ] Hypersen… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

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