Botulinum Toxin Type A And Type B: The Difference

botulinum toxin a vs b image comparison

Botulinum toxin type A and type B are the only two serotypes approved for cosmetic purposes. As you may know, botulinum toxin is a biological agent that has been isolated from the Hall strain of Clostridium bacterium and adapted for cosmetic and clinical use. In addition to their composition, botulinum toxin types A and B differ in the way they are prepared for use, injection procedure, their particular mechanism of action, durability, treatment cost, and other factors.

The Main Differences Between Botulinum Toxin Type A And B

This article covers some of the most important differences in a quick, easy-to-read format. If you are running short on time, jump to a simplified table summarizing all information on this article by clicking here.

Brands

Botulinum toxin type A is used by such brands as Botox Cosmetic®, Dysport®, Xeomin®, and Jeuveau®.

Botulinum toxin type B is used by such brands as Myobloc®.

Preparation

Botulinum toxin type A (Botox) comes in a sterile, vacuum-dried purified form consisting of several accessory proteins supplied in a single-use vial. The reconstituted solution must be clear, colorless, and free of particulates. Botox is available in 50, 100, and 200 units per vial formulation.

Botulinum toxin type B is manufactured as a purified solution in a ready-to-use vial injected as an intact complex. Dosing is different from other BT preparations, with a concentration of 5,000 units/ml. The equivalent conversion ratio to BT type A is a wide range of 1:125.35.

Injection procedure

Botulinum toxin type A. Draw 2.5ml of 0.9% sterile saline without preservative using a 21G needle and appropriately sized syringe. Slowly inject it into the Botox vial at a 45° angle. Gently rotate the vial and record the time and date of reconstitution. For glabellar facial lines, inject a dose of 0.1ml into each of the 5 sites using a 30G needle for a total dose of 20 units. Refer to the product pamphlet for other indications.

Botulinum toxin type B. Patients with prior history of tolerating BT therapy must start with an initial dose of 2,500–5,000 units divided among the affected muscles. Myobloc comes in a ready-to-use vial and does not require dilution. It can still be diluted with normal saline, and the reconstituted solution must be used within 4 hours. Dilution for BT type B is 0.01cc–50 units.

Action mechanism

Botulinum toxin type A. Type A products block neuromuscular transmission by attaching to the receptor sites on motor neuron terminals and inhibiting the release of acetylcholine. The inhibition is initiated when the neurotoxin cleaves SNAP-25 — a protein essential for the successful release of acetylcholine.

Botulinum toxin type B. Just like type A, neurotoxin type inhibits the release of acetylcholine at the neuromuscular junction. But type B inhibition occurs by cleaving synaptobrevin or synaptic vesicle-associated membrane proteins (VAMP) — an important component of the protein complex that facilitates neurotransmitter release.

Durability

Botulinum toxin type A. The effects of BT type A products are often felt within a few days and may last up to 4 months. Patients who want to maintain the positive results from Botox will need to undergo repeat sessions every 3 to 4 months.

Botulinum toxin type B. A double-blind, randomized study in 2003 showed that BT type B is comparable to type A in rapidly and satisfactory reducing fine lines in the perioral area but has a shorter duration of effects. When used for treating glabellar wrinkles, Myobloc (BT type B) was reported to be safe and effective at a dose of 1,800 units, but the longevity only lasts for eight weeks. Higher doses tend to result in a longer duration of effect.

Price

Botulinum toxin type A. The cost for BT type A injections ranges from $300 to $1,200 in the US.

Botulinum toxin type B. The average cost for BT type B injection at 5000 units/mL is around $312.

Side effects

Adverse events from Type A and Type B injections are almost similar, but studies confirmed that type B is associated with slightly more discomfort despite having a quicker onset of action. Animal studies show Botox to have a better safety margin than Dysport and BT type B. Refer to the chart below for a non-exhaustive list of side effects for both types.

Treating Botulinum Toxin Immunity

Sometimes, patients may become unresponsive to treatments after repeated injections. An antibody test can determine if an individual has developed antibodies against the neurotoxin. Patients who have developed resistance to BT type A may experience efficacious results from BT type B injections but may soon develop resistance to it as well. Neutralizing antibodies can inhibit the biological activity of botulinum toxin. The immunogenicity of BT products is assessed by the following tests:

  • EDB (extensor digitorum brevis) assay;
  • FTAT (frontalis antibody test);
  • UBI (unilateral brow injection);
  • ELISA assay;
  • MNA (mouse neutralization assay).

Conclusion

Botulinum toxin therapy is a simple and effective modality for upper and lower face wrinkles. It is a cost-effective and non-invasive alternative to surgical procedures. With new studies emerging regularly, the market is hoping to develop products with longer duration and increased efficacy. Research and development of these products is an exciting and promising frontier in the cosmetic industry.

Type A

Type B

Other names

OnabotulinumtoxinA, AbobotulinumtoxinA, IncobotulinumtoxinA

RimabotulinumtoxinB

Molecular weight

150-900 kD

700 kD

Brands

Botox, Dysport, Xeomin

Myobloc

Indications

Moderate to severe glabellar lines, crow’s feet, blepharospasm, cervical dystonia

Cervical dystonia

Dilution

0.9% saline without preservatives

Ready to use. No reconstitution required.

Composition

Botulinum toxin type A, human serum albumin, and NaCl. Additional lactose and trace cow’s milk protein for Dysport; sucrose for Xeomin

Botulinum toxin type B, human serum albumin, NaCl, and sodium succinate

Preparation

50, 100, 200, 300, 500 units/vial

2,500, 5,000, or 10,000 units/vial

Mechanism of Action

Cleaves with SNAP 25

Cleaves with VAMP

Duration

Up to 4 months

12 to 16 weeks

Side Effects

-Localized pain, swelling or bruising

-Headache

-Dryness of the eyes

-Drooping eyelids and brows

-Crooked smile

-Localized pain or muscle weakness

-Dry mouth or nausea

-Upset stomach

-Headache or joint and back pain

-Drowsiness

-Drooping eyelids

-Stiff neck

FDA Approval Status

Approved

Approved

Cost

$300–$1,200

$312


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