Medications and Drugs

Pharmacy Author: Omudhome Ogbru, Pharm.D.
Medical Editor: Jay Marks, M.D.

GENERIC NAME: botulinum toxin type A

BRAND NAME: Botox, Botox Cosmetic

DRUG CLASS AND MECHANISM: Botulinum toxin type A is an injectable neuro-toxin, that is, a toxin that blocks the ability of nerves to make muscles contract. It paralyzes muscles.

To cause muscles to contract, nerves release a chemical, acetylcholine, where they meet muscle cells. The acetylcholine attaches to receptors on the muscle cells and causes the muscle cells to contract or shorten. Botulinum toxin prevents the release of acetylcholine and thereby prevents contraction of the muscle cells. In order to affect the release of acetylcholine, botulinum toxin must be injected into the muscle. Botulinum toxin type A was approved by the FDA in December, 1989.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Vial: Powder, 100 units

STORAGE: Unopened vials of botulinum toxin should be refrigerated at 2-8°C . Reconstituted toxin should be used within 4 hours.

PRESCRIBED FOR: Botulinum toxin is used for the treatment of cervical dystonia (spasm of the muscles of the neck) to reduce abnormal head position and neck pain caused by the muscular spasm. It also is injected into the muscles that control the eyeball for treating strabismus (misaligned or lazy eyes) and the muscles of the eyelid for treating blepharospasm (uncontrollable blinking) associated with a condition called dystonia. Botox cosmetic is used for reducing glabellar lines (frown lines) in adults 65 years of age or younger.

DOSING: Botulinum toxin is giving by injection. Dosing should be individualized, and the lowest effective dose should be used. In a study that investigated the use of botulinum toxin in treating cervical dystonia the median total dose was 236 U divided between the affected muscles.

For the treatment of blepharospasm the recommended initial dose is 1.25 to 2.5 U injected into the medial and lateral pre-tarsal orbicularis oculi, the muscle of the upper and lower eyelid. Effects are seen within three days and peak within one to two weeks. Effects may last up to three months after which the treatment may be repeated. If the initial response is inadequate, the dose may be increased two-fold. Injecting more than 5 U is not increasingly beneficial.

In the treatment of strabismus, the initial dose is 1.25-5 U depending on the severity of the strabismus. Muscle paralysis may occur within one to two days after the injection and may last for 2-6 weeks. Treatment should be assessed every 7-14 days after an injection, and, if there is an adequate response, the same dose can be continued. If the response is not adequate, the dose can be increased two-fold.

The total treatment dose for glabellar lines is 20 units. The lowest effective dose should be used, and treatment should not be more frequent than every three months.

DRUG INTERACTIONS: Administration of botulinum toxin with other agents (e.g. aminoglycosides, curare) that affect neuromuscular function may increase the effect of botulinum toxin.

PREGNANCY: There are no adequate studies of botulinum toxin in pregnant women.

NURSING MOTHERS: Botulinum toxin has not been evaluated in nursing mothers.

SIDE EFFECTS: Side effects of botulinum toxin include allergic reactions, rash, itching, headache, neck pain, difficulty swallowing, shortness of breath, nausea and weakness. Patients also complain of pain and tenderness at the injection site. Patients treated for blepharospasm may experience drooping of the eyelid (ptosis), inflammation of the cornea (keratitis), eye dryness, double vision, tearing and sensitivity to light.

Reference: FDA Prescribing Information

Last Editorial Review: 8/8/2004 12:38:23 PM

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