Restylane (Q-Med) was introduced in 1994 as the first nonanimal stabilized hyaluronic acid (NASHA) filler and quickly became widely used around the world. In spite of intense competition from other, newer hyaluronic acid (HA) products, Restylane remains the best-selling product today. It was the first HA product to receive Food and Drug Administration (FDA) approval, in December 2003, and is distributed in the United States by Medicis Aesthetics Inc.
Restylane is a partially (single) cross-linked HA manufactured from Streptococcus bacterial fermentation. It is a moderately viscous clear particulated gel (biphasic gel) that can be injected through a 30-gauge needle. Restylane, like other HA products, binds water very well. In fact, as, over time, it loses cross-linkage as it undergoes enzymatic degradation, its volume can actually increase as more water becomes bound to the exposed HA.
For this type of product, the manufacturing process can determine the gel particle size, which, at equal concentrations of HA, determines viscosity of the gel. Outside the United States, a variety of Restylane products are available, which are of variable particle size and thus of variable numbers of particles per milliliter. The number of particles per milliliter is inversely proportional to the particle size. The larger the particle size, the greater the viscosity.
Four Restylane products are available in Canada and Europe (Table 8.1). They are, in order of particle size, Restylane Fine Lines, Restylane, Perlane, and Restylane SubQ. In the United States, only Restylane and Perlane are FDA approved.