Mechanism of Action
Botulinum Toxin A is being used frequently in cosmetic surgical practices to inhibit the function of the muscles of facial expression. Botulinum Toxin is an endotoxin produced by the bacterium Clostridium botulinum, a gram positive anaerobic organism. The primary effect of botulinum toxin is receptor-mediated endocytosis of the toxin in the area of neuromuscular synapse with selective proteolysis of the vesicular protein SNAP (synaptonal associated protein). The Botox molecule binds to the neuromuscular endplate and blocks the release of acetylcholine. Botulinum toxin does not affect the binding of acetylcholine, and has no effect on norepinephrine release or binding.
Dosage and Administration
- Botox Cosmetic is administered by intramuscular injection
- Glabellar Lines Administration: 0.1 mL (4 Units) into each of 5 sites, for a total dose of 20 Units (2.3)
- Lateral Canthal Lines Administration: 0.1 mL (4 Units) into each of 3 sites per side (6 total injection points), for a total of 24 Units (2.3)
- Forehead Lines Administration: 0.1 mL (4 Units) into each of 5 forehead line sites (20 Units) with 0.1 mL (4 Units) into each of 5 glabellar line sites (20 Units), for a recommended total of 40 Units (2.3)
Manufacturer Dilution Instrucitons
| Diluent Added to 50 Unit Vial | Diluent Added to 100Unit Vial | Resulting Dose Units per 0.1 mL |
|---|---|---|
| 1.25 mL | 2.5 mL | 4 units |
Glabellar Lines
- Glabellar facial lines arise from the activity of the corrugator and orbicularis oculi muscles. These muscles move the brow medially,
and the procerus and depressor supercilii pull the brow inferiorly. This creates a frown or “furrowed brow”. The location, size, and use of the muscles vary markedly among individuals. Lines induced by facial expression occur perpendicular to the direction of action of contracting facial muscles. An effective dose for facial lines is determined by gross observation of the patient’s ability to activate the superficial muscles injected. - In order to reduce the complication of ptosis the following steps should be taken:
- Avoid injection near the levator palpebrae superioris, particularly in patients with larger brow depressor complexes.
- Lateral corrugator injections should be placed at least 1 cm above the bony supraorbital ridge.
- Ensure the injected volume/dose is a ccurate and where feasible kept to a minimum.
- Do not inject toxin closer than 1 cm above the central eyebrow.
- Inject 4 Units(0.1 mL) of reconstituted BOTOX Cosmetic intramuscularly into each of 5 sites, 2 in each corrugator muscle and 1 in the procerus muscle for a total dose of 20 Units. Typically the initial doses of reconstituted BOTOX Cosmetic induce
chemical denervation of the injected muscles one to two days after injection, increasing in intensity during the first week.
Forehead Lines
- Forehead lines arise largely from the activity of the frontalis muscles. This muscle moves the brow superiorly, interacting with the procerus, orbicularis, corrugator, and depressor supercilli. Frontalis contraction causes brow elevation. The location, size, and use of the muscles vary markedly among individuals.
- Treat forehead lines in conjunction with glabellar lines (see Glabellar Lines Administration and Figure 1) to minimize the pot ential for brow ptosis. The recommended total dose for treatment of forehead lines (20 Units [0.5 mL]) in conjunction with glabellar lines (20 Units[0.5 mL]) is 40 Units(1mL).
- When identifying the location of the appropriate injection sites in the frontalis muscle, assess the overall relationship between the size
of the subject’s forehead, and the distribution of frontalis muscle activity. Locate the following horizontal treatment rows by light palpation of the forehead at rest and maximum eyebrow elevation:- Superior Margin of Frontalis Activity: approximately 1 cm above the most superior forehead crease
- Lower Treatment Row: midway between the superior margin of frontalis activity and the eyebrow, at least 2 cm above the
eyebrow - Upper Treatment Row: midway between the superior margin of frontalis activity and lower treatment row
- Inject 4 Units(0.1 mL) of reconstituted BOTOX Cosmetic into 5 sites in the frontalis muscle, for a total of 20 Units (0.5 mL). Place
the 5 injections at the intersection of the horizontal treatment rows with the following vertical landmarks:- On the lower treatment row at the midline of the face, and 0.5 – 1.5 cm medial to the palpated temporal fusion line (temporal crest); repeat for the other side.
- On the uppertreatment row,midway between the lateral and medial sites on the lower treatment row; repeat for the other side.
Lateral Canthal Lines
- Lateral canthal lines arise largely from the activity of the orbicularis oculi muscles around the eye responsible for blinking and eyelid closure. Forceful contraction of the orbicularis oculi results in lateral and radially oriented folds (crow’s feet lines) which originate from the lateral canthus. The distribution of these radial lines differs among patients.
- Injections should be given with the needle bevel tip up and oriented away from the eye. Inject 4 Units/0.1 mL of reconstituted BOTOX Cosmetic 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). The first injection (A) should be approximately 1.5-2.0cm temporal to the lateral canthus and just temporal to the orbital rim. If the lines in the lateral canthal region are above and below the lateral canthus, inject per diagram. Alternatively, if the lines in the lateral canthal region are primarily below the lateral canthus, inject per diagram.
