What are the Cosmetic Uses of Botulinum Toxin?
Clostridium botulinum A exotoxin, commonly known as botulinum toxin (BTX), is a treatment method that has become quite popular in recent years in combating the signs of aging on the skin and especially dynamic wrinkles on the face. This substance, which is a powerful neurotoxin, has gained an important place in the field of cosmetic dermatology due to its ease of application and effective results. The effects of the application usually appear within a few days, the procedure time is short, the complication rate is low and the side effects are usually mild.

Although the use of botulinum toxin is becoming increasingly widespread among dermatologists, application protocols are still the subject of some debate. For example, there is no full consensus yet on which solution and at what rate the toxin should be diluted, the unit amount to be used per injection and how long it can maintain its effectiveness after dilution. In this section, the methods frequently used by the experienced author in botulinum toxin applications are explained. It is recommended that clinicians who are new to this treatment adopt the techniques successfully applied by experienced experts at the beginning.

Mechanism of Action
BTX binds to proteins required for the release of acetylcholine (Ach), causing chemical denervation in striated muscles. The proteins it binds to vary depending on the serotype used. It causes temporary paralysis in the injected muscles, and this effect can last for approximately 3-5 months. There are seven known serotypes of BTX (A-G). Type A is the most potent of these and was the first serotype to enter medical use in the United States.

Botox (Allergan Inc.) and Dysport (Ipsen Products) are derived from serotype A and are agents that disrupt the SNAP-25 protein, a component of the SNARE complex. Vesicles carrying Ach fuse with the synaptic membrane via the SNARE complex (synaptobrevin, SNAP-25, syntaxin) and release acetylcholine into the neuromuscular junction. BTX disrupts this cycle and stops the release of acetylcholine.

BTX-B is marketed as Myobloc in the United States and similarly blocks the release of Ach by targeting the protein synaptobrevin.

Clinical Indications
In the 1970s, Dr. Alan Scott first used BTX-A in monkeys to treat strabismus (strabismus) and published the first human study in 1977. Ophthalmologists then began using this toxin for conditions such as nystagmus and blepharospasm.

The first cosmetic use of BTX was reported in 1990. Since then, BTX has become the second most commonly performed cosmetic procedure in the United States for the treatment of wrinkles (the first is chemical peels). Botox applications increased by 216% in 1999. Although the FDA did not approve BTX for cosmetic use at that time, the practice has continued to be widespread.

Today, the indications for the use of botulinum toxin for cosmetic purposes are as follows:

Treatment of dynamic wrinkles (caused by facial muscles)

Excessive sweating (hyperhidrosis)

Neck lines associated with the platysma muscle (turkey neck appearance)

Reduction of sagging and signs of aging in the lower face area

Reduction of migraine attacks in some patients treated with BTX

In line with these effects, the areas of use of botulinum toxin are expected to expand further in the future.

Dysport
Dysport is offered in vials containing 500 units of BTX-A. It is not approved in the USA. It has a different protein structure compared to Botox, and roughly 1 unit of Botox is equivalent to ≈ 3-4 units of Dysport. In addition, the lactose in Dysport may cause allergic reactions (fixed drug rash) in some individuals.

Dilution and Storage
There is no consensus among physicians on how much saline solution to dilute BTX with and how long it retains its effectiveness after dilution. The commonly used method is to add 2.5 mL of 0.9% preservative-free saline solution to 100 units of BTX. This also corresponds to the dilution approved by the FDA. Dilutions ranging from 1 mL to 10 mL can be used in the literature.

Points to consider during the dilution process:

Saline should be injected slowly to prevent foaming and bubble formation.

The bottle should not be shaken beforehand and rapid saline entry should be prevented by vacuum effect.

It is recommended to use the prepared solution within 48 hours, but some experts state that it remains stable for up to four weeks in the refrigerator.

Prepared BTX should not be refrozen because ice crystals denature the toxin.

Botox
Botox was first used for cosmetic purposes in 1981. Although it is not FDA approved, it continues to be widely applied. During production, Clostridium botulinum cultures are fermented, then the toxin is released by autolysis. These 900 kDa toxin complexes are stabilized with human serum albumin and dried in vials.

Botox begins to lose its effectiveness over time after being diluted with saline. The best end