Injectables - Plastic Surgery Internal

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of Zyderm and Zyplast. They contained purified human-derived collagen produced from human fibroblast cells; skin testing was therefore not required with use of these products. They were FDA-approved in 2003 for the correction of soft-tissue contour deficiencies, such as wrinkles and acne scars, and overcorrection by up to 150% of the desired results was recommended. 77 • Evolence (Ortho Dermatologies, Skillmann, NJ), was a 35 mg/mL type I collagen extracted from porcine tendons and cross-linked with ribose. It was approved in 2008 for correction of moderate to deep facial wrinkles and folds, such as nasolabial folds. Porcine collagen is thought to be less immunogenic than bovine collagen. Shoshani et al. 78 calculated the hypersensitivity of Evolence to be 0.58%, lower than that of bovine and human collagen. Considering that hypersensitivity to this product was rare, skin testing was not required before treatment. It was recommended that defects not be overcorrected. The clinical effects of Evolence could be seen for up to 1 year. 79 It was recommended that Evolence not be injected into the lips because of the high incidence of nodule formation. 80 The manufacturer has discontinued the production of Evolence. Long-lasting Injectables HA HA is a glycosaminoglycan biopolymer that is a part of all connective tissue in living organisms. It is chemically the same for all species and has reduced risk for allergic reactions, so skin testing is not required with this product. 81 HA is hydrophilic and provides a structural matrix to retain moisture within the dermis, where collagen can develop. SRPS • Volume 10 • Issue 28 • 2010 One gram of HA can bind up to 6 L of water. 82 HA products were developed as an alternative to collagen because of their longer duration of effect, generally 6 to 9 months, and lower potential for hypersensitivity reactions, 0.6% to 0.8%. 83,84 Animal-based HA fillers derived from rooster combs and non-animal based HA fillers produced from bacterial fermentation by Streptococcus species are available for use. 83,85 Hyaluronic gels, known as hylans, are crosslinked HA at varying degrees to improve stability and increase longevity. Naturally occurring HA has a half-life of approximately 20 h. Hyaluronic gels are 95% water by weight. 86 Dynamic viscosity, a unique attribute of hyaluronic gels, refers to decreasing viscosity as shear rate increases. At the time of injection, high-shear-rate hyaluronic gels pass through needles more easily. At the time of removal of shearing forces, the viscosity increases and the gel thickens at its implanted site, minimizing migration. 87 Another unique property of hyaluronic gels is isovolemic degradation. As the product degrades, the remaining HA binds more water, such that the overall volume remains the same. This process can maintain 95% of the initial filling volume until all of the material is resorbed. 87 Animal-Based HA Injectables—Hylaform (Allergan), was the first hyaluronic gel. It was approved in 2004 for injection into the mid to deep dermis for the correction of moderate to severe facial wrinkles and folds, such as nasolabial folds. 77 HA from the dermis of rooster combs is extracted to a concentration of 5.5 mg/mL and 20% cross-linked with divinyl sulfone to create a non-water-soluble gel, making the molecule less susceptible to degradation. It is contraindicated in patients with known history of hypersensitivity to avian proteins. Hylaform Plus (Allergan) has a particle size larger than that of than Hylaform, 750 compared with 500 mm. Hylaform Plus is intended for deeper implantation because it has an increased gel hardness and is more resistant to shear forces, making it more capable of deforming surrounding tissues to correct contour defects. When compared 11
SRPS • Volume 10 • Issue 28 • 2010 with non-animal-based HA fillers, the animalbased fillers have less gel hardness, making them more suitable for areas requiring augmentation in the superficial dermis, such as the wet vermilion of the lips. 85 Non-animal-based HA Injectables— Restylane (Medicis Aesthetics) was the first HA filler to receive FDA approval for use in the United States, in 2003, for the correction of moderate to severe facial wrinkles and folds, such as nasolabial folds. It is produced from bacterial fermentation of Streptococcus equi at a concentration of 20 mg/ mL, with a uniform particle size of 400 mm. It is 1% cross-linked with epoxides, which is less crosslinking than that of other HA injectables. The stabilized cross-linking possibly is attributed to the prolonged efficacy by stimulating collagen synthesis and inhibiting collagen breakdown. 88 When compared with Hylaform, Restylane is more viscous and less elastic. The Restylane products, Fine Lines and Perlane, are designed for different depths with different size particles. 89 Narins et al. 90 found that improvements persisted for up to 18 months with retreatment. In 2006, Matarasso et al. 89 provided detailed consensus recommendations for Restylane use to optimize patient outcomes. Juvederm (Allergan) has a higher concentration of HA, 24 mg/mL, when compared with Restylane, with more cross-linking in an attempt to increase longevity. It was approved by the FDA in 2006 for injection into the mid to deep dermis for correction of moderate to severe facial wrinkles and folds, such as nasolabial folds. Juvederm is produced from S. equi bacterial fermentation. The particles are non-uniformly shaped for a smoother gel consistency. It is available in Ultra and Ultra Plus with variable cross-linking and particle sizes, and its effects have been reported to last up to 12 months. 13 The XC formulations add 0.3% lidocaine and have been found to be associated with less procedural pain in 93% of patients. 91 Hydrelle, formally Elevess, (Anika, Bedford, MA) is cross-linked HA produced from S. equi 12 bacterial fermentation and suspended in a buffer solution of 0.3% lidocaine. It is approved for injection into the mid to deep dermis for the correction of moderate to severe facial wrinkles and folds, such as nasolabial folds. Elevess was the first FDA-approved soft-tissue injectable to combine HA and lidocaine. Prevelle Silk (Mentor, Santa Barbara, CA) is bacterial-derived HA with 0.3% lidocaine. Its crosslinking makes Prevelle softer than most products. The results of this product, which was approved in 2008, are reported to last approximately 4 months. Poly-l-lactic Acid (PLLA) PLLA is a biodegradable, nontoxic, synthetic, and inactive material derived from corn starch in the alpha hydroxy acid family. It has been used in suture material, stents, and other biomedical implants. Sculptra (sanofi-aventis U.S., LLC, Bridgewater, NJ), known as New-Fill in Europe, was FDA-approved in 2004 for restoration and/ or correction of the signs of lipoatrophy (facial fat loss) in people with or receiving treatment for human immunodeficiency virus. The lipoatrophy is thought to result from the use of highly active antiretroviral therapy. In 2009, Sculptra Aesthetic received FDA approval for the correction of shallow to deep nasolabial fold contour deficiencies and other facial wrinkles in which deep dermal grid pattern (cross-hatch) injection technique is appropriate. It contains PLLA microspheres in a powdered form. PLLA is metabolized to carbon dioxide, glucose, and water for several weeks after injection. The long-term soft-tissue augmentation is caused by the stimulation of fibroblasts and growth of type I collagen into areas of accumulated PLLA microspheres. It is best used as a three-dimensional volumetric filler, as opposed to a superficial line filler. 92 Sculptra often requires a series of injections to achieve adequate correction. The clinical effects can be seen for 18 to 24 months. 13 Semi-permanent Injectables Calcium Hydroxylapatite (CaHA) CaHA is found naturally in the body as the mineral
Page 1 and 2: SRPS SELECTED READINGS IN PLASTIC S
Page 3 and 4: Editor-in-Chief Editor Emeritus Con
Page 5 and 6: SRPS • Volume 10 • Issue 28 •
Page 13: SRPS • Volume 10 • Issue 28 •
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Injectables - Plastic Surgery Internal

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