onabotulinumtoxinA, Botox, Botox Cosmetic

GENERIC NAME: onabotulinumtoxinA

BRAND NAME: Botox, Botox Cosmetic

DRUG CLASS AND MECHANISM: OnabotulinumtoxinA is an injectable neuro-toxin, that is, a toxic chemical 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. OnabotulinumtoxinA prevents the release of acetylcholine and thereby prevents contraction of the muscle cells. In order to affect the release of acetylcholine, onabotulinumtoxinA must be injected into the muscle. OnabotulinumtoxinA was approved by the FDA in December 1989.
PRESCRIPTION: Yes
GENERIC AVAILABLE: No
PREPARATIONS: Powder for Injection: 50, 100 or 200 units
STORAGE: Unopened vials or reconstituted onabotulinumtoxinA should be refrigerated at 35.6 to 46.4 F (2 to 8 C). Reconstituted toxin should be used within 24 hours.
PRESCRIBED FOR: OnabotulinumtoxinA is used for the treatment of chronic migraine, axillary hyperhidrosis (excessive armpit sweating), and upper limb spasticity. It is also used for treating cervical dystonia (spasm of the muscles of the neck) to reduce abnormal head position and neck pain caused by the muscular spasm. It 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: OnabotulinumtoxinA is giving by intramuscular injection. Dosing should be individualized, and the lowest effective dose should be used. OnabotulinumtoxinA is not interchangeable with other preparations of botulinum toxin.

• Chronic Migraine: 155 units divided amongst 31 sites and injected every 12 weeks
• Upper limb spasticity: 75-360 units divided among selected sites. No more than 50 units injected per site; may repeat when effect diminishes but no sooner than every 12 weeks.
• Cervical dystonia: 189-300 units divided among affected muscles. No more than 50 units injected per site.
• Axillary hyperhidrosis: 50 units per arm pit; repeat when effect diminishes.
• Blepharospasm: Initial dose is 1.25-2.5 units. Increase if response is not adequate. There appears to be no benefit in injecting more than 5 units.
• Strabismus: Initial dose is 1.25 to 5 units per muscle; may increase subsequent doses by up to two-fold; maximum dose for each muscle is 25 units.

DRUG INTERACTIONS: Administration of onabotulinumtoxinA with other agents (for example, aminoglycosides, curare) that affect neuromuscular function may increase the effect of onabotulinumtoxinA. Use of muscle relaxants may increase the occurrence of weakness.
PREGNANCY: There are no adequate studies of onabotulinumtoxinA in pregnant women.
NURSING MOTHERS: OnabotulinumtoxinA has not been evaluated in nursing mothers.
SIDE EFFECTS: Side effects of onabotulinumtoxinA include allergic reactions, rash, itching, headache, neck pain, difficulty swallowing, shortness of breath, nausea and weakness, and dry mouth. 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.