Boston — Although, for many patients, hyaluronic acid (HA) fillers have become the treatment of choice in the United States, Gary D. Monheit, M.D., says many questions remain: Can Hylaform (Inamed), Restylane (Q-Med) and Juvederm (LEA Derm) be improved to achieve more than a three- to six-month longevity? How will the fillers compare after more extensive head-to-head testing? And where will HA products ultimately fit in an armamentarium ranging from bovine collagen to polylactic acid?
"Looking toward the future, I think the full family of HA products - Restylane, Hylaform and Juvederm - will give us the necessary tools we need for lunchtime filling," he says.
HA vs. collagen
"The HA molecule is hydroscopic," he says, "and its ability to bind water gives it a viscoelastic feel. After injection, the product will swell, adding more volume. This is in contrast to collagen, which loses water suspension after injection."
Even after the cosmetic benefit dissipates, a substantial amount of hyaluronic acid remains in the skin for up to a year. Thus, a follow-up treatment will often induce a larger and longer-lasting benefit than the first.
On the other hand, the HA generation lacks some of collagen's advantages. Hylaform, Restylane and Juvederm inhibit the clotting cascade and are formulated without lidocaine.
"It's a good idea to use very fine needles, like the 30-gauge MaxFlo (Richard James Inc.), to minimize trauma, bruising, bleeding and discomfort," Dr. Monheit says.
Distinguishing among HA products "Both Hylaform and Restylane, which have FDA (U.S. Food and Drug Administration) approval, are particles of HA bonded together and suspended in a gel," Dr. Monheit says. "Juvederm, which is in the clinical trial phase, is a homogeneous gel-based HA."
Thus, when compared to Juvederm, Hylaform and Restylane have increased surface area exposure with increased susceptibility to enzymatic degradation. There is also more friction upon injection and increased exposure to free radicals. Approved for correction of soft tissue contour deficiencies, such as wrinkles or acne scars, Hylaform binds to water up to 1,000 times its volume, resists degradation, feels natural and does not clump. Hylaform Fine Line, Hylaform and Hylaform Ultra correlate to superficial, mid, and deep levels of dermal filling.
Dr. Monheit often uses Hylaform in combination with Cosmoplast (Inamed). The collagen provides structure, while the HA adds volume. The combination (achieved either by mixing the products or by injecting Cosmoplast first) also causes less pain and bruising than Hylaform alone.
Produced via a bacterial fermentation process, the Restylane family line tailors particle size to tissue matrix. Restylane Fine Lines (reformulated in January 2004) is designed for treatment of smile lines and superficial lines and wrinkles around the eyes and on the forehead. Restylane, on the other hand, is made for treatment of moderate lines, wrinkles and folds, and lips, while Perlane targets deep tissue improvements, such as enhancement of lips, chin and cheeks.
According to Dr. Monheit, Restylane products should be used as superficially as possible within the recommended tissue depth. Techniques include serial puncturing, linear threading, fanning and cross-hatching.
Also manufactured via bacterial fermentation, Juvederm is distributed as Hydrafil in Europe. As a single-phase gel without particles, it is homogenous, more resistant to in situ degradation, pliable and viseoelastic, and less inflammatory than its FDA-approved counterparts.