1. Q. Is Hymovis® a drug or a medical device?
A. Hymovis® is a medical device (Class III, Dir 93/42/EEC)
2. Q. How can a product based on medium-low molecular weight hyaluronic acid be highly viscous?
A. The selectively controlled chemical modification makes the polysaccharide partially hydrophobic, and the peculiar molecular arrangement that ensues in aqueous solution enables the conversion of Hymovis® into a highly viscous hydrogel.
3. Q. Is a highly viscous, hydrogel formulation difficult to inject?
A. No, the viscoelasticity of Hymovis® is comparable to that of other commercially available products, that can be easily injected, with a similar use. Moreover, its rheological characteristics make the product less viscous during flow through the syringe needle.
4. Q. What is MObile REticulum?
A. This is the name given to the peculiar molecular arrangement of Hymovis® in aqueous solution; that is, a sort of reticulum, stabilized by hydrophilic and hydrophobic interactions, that can disrupt and recover its structure indefinitely. The so-called “MO.RE.® Technology” is the groundbreaking technique underlying this arrangement. Moreover, the term “mobile” refers to the hydrogel’s dynamic capacity to recover its structure after a destabilization.
5. Q. What does “structural recovery capacity” mean?
A. It is the ability of the Hymovis® mobile reticulum to recover its three-dimensional configuration after a destabilization. From a rheological point of view, this property enables Hymovis® hydrogel to restore completely and rapidly its original viscoelasticity, even after repeated mechanical shocks.
6. Q. What is the importance of the linear structure?
A. The linear structure of Hymovis® is very similar to unmodified hyaluronic acid, which means it is not intercepted by the immune system. As reported in scientific literature, systemic adverse effects have been associated with cross-linked derivatives, either due to the formation of immuno-complexes or in any case, to the activation of the immune system.
7. Q. What is the benefit of Hymovis® over cross-linked hyaluronic acid?
A. The advantage of a product based on linear hyaluronic acid with comparable – if not superior – mechanical properties, over products based on cross-linked hyaluronic acid, is its higher biocompatibility. Both the scientific and clinical evidence have attributed a lower safety profile to cross-linked hyaluronic acid, with respect to unmodified hyaluronic acid.
8. Q. What does MO.RE.® (MObile REticulum) Technology imply?
A. The shock absorbing properties of the synovial fluid relate to the rheological properties of hyaluronic acid and its turnover rate, mediated by the biosynthetic capacities of the synovial fluid and the joint cartilage. When the cartilage is damaged as in osteoarthritis, synovial fluid turnover is completely or partially lacking. The Hymovis® mobile reticulum absorbs the energy generated by mechanical stress, recovering its original structure and thereby compensating for the reduced turnover of the natural polymer.
9. Q. Can Hymovis® be administered during inflammation?
A. Tests have shown that HYADD®4 is resistant to hyaluronidase, a ubiquitous enzyme found in the body and a marker of inflammation.
It is ALWAYS advisable to inject “cool” joints, since inflammation not only activates hyaluronidase, but also other enzymatic activities of various kinds, which could considerably affect the product’s activity in the joint.
10. Q. What is the metabolic fate of Hymovis®?
A. It is not known, but it can be assumed that the initial metabolic degradation affects the linear chain, with more or less extensive depolymerization.
Given the resistance to hyaluronidase, said depolymerization reaction is likely to occur over relatively long periods of times. Low molecular weight fragments escape through the interstitial drainage pores in the synovial lining and are conveyed to the liver through the bloodstream (and lymphatic circulation). In the liver, enzymes known as amidases break the amide bond and remove the hexadecyl residue. The oligosaccharide fragments are then conveyed into the pathways of carbohydrate metabolism.
11. Q. What cross-linked viscosupplement can Hymovis® be compared with?
A. The MO.RE.® Technology provides Hymovis® with equal or superior biomechanical characteristics compared to cross-linked derivatives, while maintaining the biocompatibility of the natural polymer. Hymovis® can be considered the forerunner of the next generation viscosupplements, characterized primarily by an innovative rheological profile and, moreover, by the ability to act on the inflammatory parameters that characterize osteoarthritis (OLIVIERO et al. 2013).