Some of the best selling and widely known technologies that became available in the mid-1990s to treat photodamaged skin are injectable agents. One of these is an injectable form of the neurotoxin associated with botulism, Botulinum toxin. Commercially known as Botox, this protein-based toxin is injected in the areas around the eyes and forehead to treat fine lines and wrinkles (particularly in the furrow area between the eyes); the effect is a relaxation of the skin due to absence of muscle tension, and thereby relieving the appearance of fine lines and wrinkles. Mechanistically, this occurs by temporarily preventing muscle contractions by blocking the release of acetylcholine over a four-step process that involves internalization of the large subunit (Fig. 15.4). Part of the popularity of this procedure is that the effects are noticed immediately and can last between two and three months, albeit sometimes it can go up to six months in some extreme cases.
Some of the limitations of this procedure include the fact that the effect is localized to the injection area and more distal skin areas with fine lines or texture imperfections are not affected. In addition, there are potential side issues such as relaxation of neighboring tissue, including eyelids, as well as loss of sensation. The procedure is viewed as minimal in its invasiveness, and can be administered outside of the professional’s offices.
Blokade
of Veside
Fusion
Figure 15.4 Description of the various steps in which Botox reduces neuromuscular activity. Binding of the neurotoxin dichain near the nerve synaptic region allows for internalization and subsequent blocking by the light chain domain to acetylcholine vesicles [66].
Clinically, the results can be dramatic and, appear rapidly after treatment to the patient, with no significant downtime which is an important fact for the patient. In addition to the treatment of glabellar frown lines [40], other benefits have also been reported for other skin-aging symptoms including frown lines [41] and treatment of the neck area for sagging skin [42]. The effects can last up to six months, with some patients noticing the reappearance of wrinkles after two to three months. While a re-treatment will have an immediate effect as before, it is not clear what longer-term side effects can occur from repeated treatments on muscle and skin integrity.
In contrast to the mechanistic action of Botox on temporarily impacting muscle contractions, another injection procedure that is very popular is the usage of dermal fillers to temporarily efface fine lines and wrinkles. In this case, the wrinkled area of the patient’s skin is injected with a sterile solution comprised of collagen and hyaluronic acid, or a combination of both. The material is deposited in the dermal area around the injection site and it serves as a physical filler that pushes out from underneath to minimize the appearance of fine lines and wrinkles. Effects can be seen rapidly, but side effects include temporary pain discomfort to the patient, as well as bruising and swelling.