OnabotulinumtoxinA

Reviewed on 4/22/2022

What Is OnabotulinumtoxinA and How Does It Work?

OnabotulinumtoxinA is a prescription medication used to treat the symptoms of muscle spasms or stiffness, severe underarm sweating, overactive bladder, incontinence, and migraine prevention.

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What Are Dosages of OnabotulinumtoxinA?

Adult and pediatric dosage

Injectable, powder for reconstitution

  • 50 units/vial (Botox, Botox Cosmetic)
  • 100 units/vial (Botox, Botox Cosmetic)
  • 200 units/vial (Botox)

Blepharospasm and Strabismus

Adult dosage

  • Blepharospasm
    • 1.25-2.5 units injected into medial and lateral pretarsal orbicularis oculi of the upper lid and lateral pretarsal orbicularis oculi of the lower lid; not to exceed 200 units in 30 days
    • May increase dose 2-fold if the response to initial treatment dose does not last longer than 2 months
    • The little benefit obtained from injecting above 5 units per site
  • Strabismus
    • 1.25-5 units IM; less than 25 units per injection
    • Vertical muscles, and horizontal strabismus of less than 20 prism diopters: 1.25-2.5 units in any one muscle
    • Persistent VI nerve palsy of above 1 month of duration: 1.25-2.5 units in the medial rectus muscle
    • Horizontal strabismus of 20-50 prism diopters: 2.5-5 units in any one muscle
    • Incomplete paralysis of target muscle: May increase dose 2-fold if patient experience incomplete paralysis of the target

Pediatric dosage

  • Blepharospasm
    • Children below 12 years: Safety and efficacy not established
    • Children above 12 years:1.25-2.5 units IM; less than  200 units in 30 days
    • May increase dose 2-fold if the response to initial treatment dose does not last longer than 2 months
    • The little benefit obtained from injecting above 5 units per site
  • Strabismus
    • Children below 12 years: Safety and efficacy not established
    • Children above 12 years: 1.25-5 units IM; less than 25 units per injection
    • Vertical muscles, and horizontal strabismus of less than 20 prism diopters: 1.25-2.5 units in any one muscle
    • Persistent VI nerve palsy of above 1 month of duration: 1.25-2.5 units in the medial rectus muscle
    • Horizontal strabismus of 20-50 prism diopters: 2.5-5 units in any one muscle
    • Incomplete paralysis of target muscle: May increase dose 2-fold if the response to initial treatment dose

Primary Axillary Hyperhidrosis

Adult dosage

  • 50 units injected intradermally to each axilla evenly distributed in multiple sites approximately 1-2 cm apart

Cervical Dystonia

Adult dosage

  • Not to exceed 50 units per site

Spasticity

Adult dosage

  • Do not exceed a cumulative dose of 400 units in the 3-month interval when treating adults for 1 or more indications
  • Upper limb
    • In clinical trials, doses ranging from 75-400 units were divided among selected muscles to treat upper limb spasticity at a given treatment session
    • Dosage per muscle
    • Biceps brachii: 60-200 units divided into 2-4 sites
    • Brachioradialis: 45-75 units divided into 1-2 sites
    • Brachialis: 30-50 units divided into 1-2 sites
    • Pronator teres: 15-25 units in 1 site
    • Pronator quadratus: 10-50 units in 1 site
    • Flexor carpi radialis: 12.5-50 units in 1 site
    • Flexor carpi ulnaris: 12.5-50 units in 1 site
    • Flexor digitorum profundus: 30-50 units in 1 site
    • Flexor digitorum superficialis: 30-50 units in 1 site
    • Lumbricals/interossei: 5-10 units in 1 site
    • Adductor pollicis: 20 units in 1 site
    • Flexor pollicis longus: 20 units in 1 site
    • Flexor pollicis brevis/opponens pollicis: 5-25 units in 1 site
  • Lower limb
    • 300-400 units divided among 5 muscles (gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, and flexor digitorum longus)
    • Dosage per muscle
      • Gastrocnemius medial head: 75 units divided into 3 sites
      • Gastrocnemius lateral head: 75 units divided into 3 sites
      • Soleus: 75 units divided into 3 sites
      • Tibialis Posterior: 75 units divided into 3 sites
      • Flexor hallucis longus: 50 units divided into 2 sites
      • Flexor digitorum longus: 50 units divided into 2 sites

Pediatric dosage

Upper limb

  • 3-6 units/kg divided among affected muscles
  • The maximum total dose per treatment session: 6 units/kg or 200 units, whichever is lower
  • Dosage range per muscle
    • Biceps brachii: 1.5-3 units/kg divided into 4 injection sites
    • Brachialis: 1-2 units/kg divided into 2 injection sites
    • Brachioradialis: 0.5-1 units/kg divided in 2 injection sites
    • Flexor carpi radialis: 1-2 units/kg divided into 2 injection sites
    • Flexor carpi ulnaris: 1-2 units/kg divided in 2 injection sites
    • Flexor digitorum profundus: 0.5-1 unit/kg divided into 2 injection sites
    • Flexor digitorum superficialis: 0.5-1 unit/kg divided into 2 injection sites
  • Lower limb
    • 4-8 units/kg divided among affected muscles
    • The maximum total dose per treatment session: 8 units/kg or 300 units, whichever is lower
    • Dosage range per muscle
      • Gastrocnemius medial head: 1-2 units/kg divided into 2 injection sites
      • Gastrocnemius lateral head: 1-2 units/kg divided into 2 injection sites
      • Soleus: 1-2 units/kg divided into 2 injection sites
      • Tibialis posterior: 1-2 units/kg divided into 2 injection sites

Chronic Migraine

Adult Dosage

  • Recommended total dose 155 units, as 0.1 mL (5 units) IM injections per each site divided across 7 head/neck muscles every 12 weeks
  • The recommended dose per muscle site (totaling 155 units)
  • Frontalis: 20 units divided into 4 sites
  • Corrugator: 10 units divided into 2 sites
  • Procerus: 5 units in 1 site
  • Occipitalis: 30 units divided into 6 sites
  • Temporalis: 40 untied divided into 8 sites
  • Trapezius: 30 units divided into 6 sites
  • Cervical paraspinal muscle group: 20 units divided into 4 sites

Detrusor Overactivity

Adult dosage

  • 200 units (divided into 30 intradetrusor injections) administered using cystoscopy

Detrusor Overactivity Associated With a Neurologic Condition

Pediatric dosage

Children above 5 years

  • Administer doses as 0.5-mL injections across 20 sites into the detrusor (total volume: 10 mL) via cystoscopy
  • Consider reinjection when clinical effect diminishes (median time to qualify for re-treatment was 207 days [30 weeks] for Botox 200 units), but no sooner than 12 weeks from prior bladder injection
  • Weighing below 34 kg: 6 units/kg per treatment session
  • Weighing above 34 kg: 200 units per treatment session

Overactive Bladder

Adult dosage

  • 100 units (divided into 20 intradetrusor injections of 5 units each) administered using cystoscopy

Cosmetic Uses

Adult dosage

  • Glabellar lines: Inject 4 units (0.1 mL) into each of 5 sites, 2 in each corrugator muscle and 1 in procerus muscle for a total dose of 20 units
  • Lateral canthal lines: Inject 4 units (0.1 mL) into 3 sites per side (6 total injection points) in the lateral orbicularis oculi muscle for a total of 24 units/0.6 mL (12 units per side)
  • Forehead lines: Inject 4 units (0.1 mL) into each of 5 forehead line sites (20 units); treat in conjunction with glabellar lines with 0.1 mL (4 units) into each of 5 glabellar line sites (20 units), for a recommended total of 40 units

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using OnabotulinumtoxinA?

Common side effects of OnabotulinumtoxinA include:

  • puffy eyelids,
  • dry eyes,
  • dropping eyebrows,
  • dry mouth,
  • headache,
  • tiredness,
  • increased sweating in areas other than underarms, and
  • bruising, bleeding, pain, redness, or swelling at the injection site.

Serious side effects of OnabotulinumtoxinA include:

  • unusual or severe muscle weakness,
  • trouble breathing,
  • difficulty talking or swallowing,
  • loss of bladder control,
  • hoarse voice,
  • drooping eyelids,
  • vision changes,
  • eye pain,
  • severely dry or irritated eyes,
  • light sensitivity,
  • chest pain,
  • pain spreading to the jaw or shoulder,
  • irregular heartbeat,
  • pain or burning when urinating,
  • trouble emptying the bladder,
  • sore throat,
  • cough,
  • chest tightness,
  • shortness of breath,
  • swelling of the eyelids, and
  • crusting or drainage from the eyes.

Rare side effects of OnabotulinumtoxinA include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with OnabotulinumtoxinA?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for OnabotulinumtoxinA?

Contraindications

  • Hypersensitivity
  • Neuromuscular disease
  • Infection at the proposed injection site
  • Intradetrusor injection: Urinary tract infection or urinary retention (post-void residual above 200 mL, who are not routinely performing clean intermittent self-catheterization who are not routinely performing clean intermittent self-catheterization)

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using OnabotulinumtoxinA?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using OnabotulinumtoxinA?”

Cautions

  • Avoid injections near the levator palpebrae superioris to minimize the risk of ptosis, especially in individuals with larger brow-depressor complexes
  • Risk of respiratory compromise & death esp in children treated for cerebral palsy-associated spasticity
  • Effects of the botulinum toxin may spread from the area of injection to other areas of the body, causing symptoms similar to those of botulism - watch for dyspnea, dysphagia, or speech impairment
  • The different botulinum toxin products are not interchangeable
  • Patients with pre-existing neuromuscular disorders should be monitored when given botulinum toxin; patients with known or unrecognized neuromuscular disorders or neuromuscular junction disorders may be at increased risk of clinically significant effects including generalized muscle weakness, diplopia, ptosis, dysphonia, dysarthria, severe dysphagia and respiratory compromise from therapeutic doses
  • Only consider for treatment of urinary incontinence for patients willing and able to initiate catheterization post-treatment, if required (due to risk of urinary retention); patients with diabetes mellitus are more likely to develop urinary retention than non-diabetics
  • Increased risk for UTI; do not use for the treatment of urinary incontinence with present UTI, routine catheterization, or if the patient is unable to empty the bladder without assistance
  • Use with caution in patients with compromised respiratory function
  • Corneal exposure and ulceration due to reduced blinking may occur when treating blepharospasm
  • Retrobulbar hemorrhages and compromised retinal circulation may occur when treating strabismus
  • Bronchitis and upper respiratory tract infections in patients treated for upper limb spasticity reported
  • Serious adverse reactions, including excessive weakness, dysphagia, and aspiration pneumonia, with some adverse reactions associated with fatal outcomes, were reported in patients who received injections for unapproved uses
  • Tailor dosing in initial and sequential treatment sessions to the individual based on the size, number, and location of muscles involved, severity of spasticity, presence of local muscle weakness, patient’s response to previous treatment, or adverse event history with this therapy
  • 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); risk for transmission of CJD is theoretical; no cases of transmission of viral diseases, CJD or vCJD have ever been identified for licensed albumin or albumin contained in other licensed products
  • Patients with known or unrecognized neuromuscular disorders or neuromuscular disorders may be at increased risk of clinically significant effects including generalized muscle weakness, diplopia, ptosis, dysphonia, dysarthria, severe dysphagia, and respiratory compromise from therapy
  • Adverse events involving the cardiovascular system, including arrhythmia and myocardial infarction, some with fatal outcomes reported; risk factors including pre-existing cardiovascular disease may increase risk; use caution when administering to patients with pre-existing cardiovascular disease
  • Autonomic dysreflexia associated with intradetrusor injections could occur in patients treated for detrusor overactivity associated with a neurologic condition; may require prompt medical therapy
  • Use for the treatment of overactive bladder in patients taking antibiotics chronically due to recurrent UTIs and in patients with multiple recurrent UTIs during treatment should only be considered when the benefit is likely to outweigh the potential risk
  • Drug interactions overview
    • Coadministration of abobotulinumtoxin A and aminoglycosides or other agents interfering with neuromuscular transmission (eg, curare-like compounds) should only be performed with caution as the effect of the toxin may be potentiated
    • Anticholinergic drugs: Use of anticholinergic drugs after abobotulinumtoxin A administration may potentiate systemic anticholinergic effects
    • Administration of different botulinum neurotoxin products concomitantly or within several months of each other is unknown; excessive neuromuscular weakness may be exacerbated by administration of another botulinum toxin before the resolution of the effects of a previously administered botulinum toxin
    • Muscle Relaxants: Excessive weakness may also be exaggerated by administration of a muscle relaxant before or after administration of abobotulinumtoxin A

Pregnancy and Lactation

  • There are no adequate data from postmarketing surveillance on the developmental risk associated with use in pregnant women
  • In animal studies, administrations during pregnancy resulted in adverse effects on fetal growth (decreased fetal body weight and skeletal ossification) at clinically relevant doses, which were associated with maternal toxicity
  • Lactation
    • Not known if excreted in breast milk; effect on nursing infant not known
References
Medscape. OnabotulinumtoxinA.

https://reference.medscape.com/drug/botox-cosmetic-onabotulinumtoxina-999222#6

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