Clinical indications and use

Abstract

Botulinum toxin is used for cosmetic (45%) and noncosmetic (55%) indications. It is effective as a skeletal muscle relaxant, an antispasticity agent, for essential tremor and for trigeminal neuralgia. Botulinum toxin acts at the autonomic junctions to treat hyperhidrosis and reduce sialorrhoea. It works on involuntary muscle contraction and is effective for internal organ spasticity. It modifies the effect of pain mediators and is effective in chronic migraine.

Cosmetic indications include elimination of wrinkles around the eyes (crow’s feet), forehead lines, vertical glabellar (frown) wrinkles, perioral lines, neck rhytids and lip lines. The concentration of the preparation of botulinum toxin is directly related to the desired degree of diffusion of effect and the desired duration of effect. The different serotypes are assessed with different unit assays, and 100 BOTOX units are equivalent to 400 AZZALURE/Dysport units. Various concentrations may be used to reduce or extend the duration of effect. The author recommends using a constant concentration of botulinum toxin whilst varying the volume injected to develop the intuitive art of choosing the correct degree of diffusion over underlying muscles and glands.

Keywords

Botox, Dysport, Azzalure, Xeomin, diffusion, dose, concentration

The cosmetic indications for botulinum toxin have not changed since the first edition of this book and are listed in Box 3.1 , but the noncosmetic indications now represent 55% of all botulinum toxin use. In the author’s oculofacial practice, botulinum toxin is an essential first-line treatment for hemifacial and blepharospasm, post–facial nerve palsy synkinesis, chronic migraine, frontal ‘trigeminal’ headaches and hyperhidrosis. Table 3.1 provides a list of other uses at the time of press.

BOX 3.1 ■

Cosmetic Indications For Botulinum Toxin

Crow’s feet (periocular rhytids)
Vertical (glabellar) frown
Horizontal (frontalis) frown
Wrinkles on nose
Upper lip rhytids
Vermilion border
Angle of mouth
Pebbly chin
Nasolabial folds
Jaw line (platysma)
Venus rings (horizontal neck rhytids)
Turkey neck (vertical platysma bands)
Décolleté
Scar management

TABLE 3.1 ■

Noncosmetic Indications for Botulinum Toxin

Movement Disorders	Internal Organs	Other
Focal dystonias	Detrusor muscle	Hyperhidrosis
Essential tremor	Bladder spasm pain	Chronic migraine
Parkinsonism	Urinary retention	Tension headaches
Spasticity	Hyperactive/overactive	Trigeminal neuralgia
Post-stroke spasticity	Pelvic floor pain	Temporomandibular pain
Traumatic spasticity	Anal fissures	Spinal muscle pain
Multiple sclerosis	Benign prostate hyperplasia	Frey’s syndrome
Eye movement disorders		Sialorrhoea

Much has been published on the differences between the different products, and the reader is referred to an excellent 2018 review on the same by Dr. Richard Glogau.

USER TIP

DIFFUSION is influenced by concentration, by product and by the concentration of receptors on the muscle being injected. More receptors mean less diffusion per volume injected.

Concentrations

Botulinum toxin is the most potent toxin known to mankind. It functions at very low concentrations and so can be assessed accurately only in terms of lethal dose unit per Swiss-Webster mouse. (Research is ongoing in to cell-based potency assay.) Different serotype A brands are shown in Table 3.2 . One mouse unit (mu) is the median intraperitoneal dose required to kill 50% (LD ₅₀ ) of a batch of 18- to 20-g female Swiss-Webster mice over 3 to 4 days.

TABLE 3.2 ■

Botulinum Toxin Serotype Type A

Onabotulinumtoxin A	Abobotulinumtoxin A	Incobotulinumtoxin A
BOTOX/visabel	Dysport/Azzalure	Xeomin/Bocouture
900-kDa complex	<900 kDa	150 kDa
Vacuum-dried powder	Freeze-dried powder	Freeze-dried powder
2–8°	2–8°	Room temperature
HSA 500 μg NaCl (900 μg/vial	HSA 125 μg Lactose (2.5 mg/vial)	HSA 1000 μg Sucrose (4.7 mg/vial)
BOTOX: 100-U or 200-U vial Vistabel: 50 U	Dysport: 300 U or 500 U Azzalure: 125 U	Xeomin: 100 U or 200 U Bocouture: 50 U
5 ng/100 U	4.35 ng/500 U	0.44 ng/100 U