Last reviewed 2026-05-19 · How we verify

Myobloc (RIMABOTULINUMTOXINB)

Myobloc (generic name: RIMABOTULINUMTOXINB) is a Acetylcholine Release Inhibitor [EPC] Recombinant protein drug developed by Elan Pharm. It is currently FDA-approved (first approved 2009) for Cervical Dystonia, Chronic Sialorrhea.

Myobloc works by blocking the release of acetylcholine, a chemical messenger that signals muscles to contract.

Myobloc is a botulinum toxin type B that inhibits the protein vesicle-associated membrane protein 2. It is used to treat various conditions, including hyperhidrosis, spasmodic torticollis, and sialorrhea, among others.

At a glance

Mechanism of action

MYOBLOC blocks cholinergic transmission at the neuromuscular and salivary neuroglandular junction by inhibiting the release of acetylcholine from peripheral cholinergic nerved terminals. This inhibition occurs according to the following sequence: neurotoxin binding to cholinergic nerve terminals, internalization of the neurotoxin into the nerve terminal, translocation of the light-chain part of the molecule into the cytosol of the nerve terminal, and enzymatic cleavage of synaptic Vesicle Associated Membrane Protein (VAMP, also known as synaptobrevin), a presynaptic target protein essential for the release of acetylcholine. In both muscles and glands, impulse transmission is re-established by the formation of new nerve endings.

Approved indications

• Cervical Dystonia
• Chronic Sialorrhea

Boxed warnings

• WARNING: DISTANT SPREAD OF TOXIN EFFECT 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 ).

Common side effects

• Dry mouth
• Dysphagia
• Injection site pain
• Headache
• Dyspepsia
• Flu Syndrome
• Arthralgia
• Back Pain
• Cough Increased
• Asthenia
• Dizziness
• Dental caries

Drug interactions

• Aminoglycosides
• Other agents interfering with neuromuscular transmission
• Anticholinergic drugs
• Other botulinum toxin products
• Muscle relaxants

Key clinical trials

• Efficacy and Safety Study of MYOBLOC in the Treatment of Sialorrhea in Pediatric Subjects (PHASE3)
• Efficacy and Safety Study of MYOBLOC® in the Treatment of Adult Lower Limb Spasticity (PHASE2,PHASE3)
• Efficacy and Safety Study of MYOBLOC® in the Treatment of Adult Upper Limb Spasticity (PHASE2,PHASE3)
• Open-Label and Single-Arm Study of MYOBLOC® in the Treatment of Troublesome Sialorrhea in Adults (PHASE3)
• Efficacy and Safety Study of MYOBLOC® Followed by Open-Label Multiple-Treatment With MYOBLOC® in the Treatment of Troublesome Sialorrhea in Adult Subjects (PHASE3)
• Effect and Safety of Local Injection of Botulinum Toxin Type B Against Digital Ulcer in Systemic Sclerosis (PHASE2)
• Post-marketing Surveillance of Administration of Botulinum Toxin Type B(NerBloc)-Investigation of the Clinical Condition and Safety in Patients With Cervical Dystonia
• An Open Label Safety and Immunogenicity Study of MYOBLOC (Neurobloc; Botulinum Toxin Type B) Injectable Solution in Patients With Cervical Dystonia (PHASE4)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Myobloc CI brief — competitive landscape report
• Myobloc updates RSS · CI watch RSS
• Elan Pharm portfolio CI

Frequently asked questions about Myobloc

Related

• Drug class: All Acetylcholine Release Inhibitor [EPC] drugs
• Manufacturer: Elan Pharm — full pipeline
• Therapeutic area: All drugs in Neuroscience
• Indication: Drugs for Cervical Dystonia
• Indication: Drugs for Chronic Sialorrhea

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing