Starpharma Holdings Ltd has filed a patent application for the use of SPL7013, the active ingredient in VivaGel, to inhibit hyaluronidase activity in the treatment or prevention of a number of diseases. The inhibitory activity was discovered during studies on the contraceptive activity of SPL7013, in which effects on hyaluronidase were examined due to the enzyme's involvement in the fertilization process.

The inhibitory action of SPL7013 has potential application in the treatment of diseases and conditions associated with excess activity of the enzyme hyaluronidase, such as rheumatoid arthritis and osteoarthritis, as well as a dermatological agent. Hyaluronidase breaks down a macromolecule called hyaluronic acid, which is widely distributed in the body. The functions of hyaluronic acid include its lubrication and cushioning of joints and retention of moisture in skin. By inhibiting the enzyme that breaks down hyaluronic acid, SPL7013 would be expected to extend and enhance the therapeutic effect of hyaluronic acid products marketed for the treatment of rheumatoid arthritis and osteoarthritis.

The potency of SPL7013 as an inhibitor is equivalent to the most potent inhibitors reported in the literature, including those patented by major pharmaceutical companies. An inhibitor of hyaluronidase may also have potential as a cosmetic treatment to improve the aesthetic appearance of skin. With VivaGel already in clinical development under IND as a topical microbicide for the prevention of HIV infection and genital herpes, Starpharma has an extensive clinical and non-clinical dossier for the topical use of SPL7013.

"The results of recent studies on the mechanism of the contraceptive action of SPL7013 have two benefits - additional commercial opportunities related to the inhibition of hyaluronidase that Starpharma will explore both internally and with interested third parties, and importantly, support for Starpharma's plans to advance to a phase II study for the contraceptive effect of VivaGel in women," said Dr Jackie Fairley, CEO.

The inhibitory effect of SPL7013 on hyaluronidase activity was discovered from studies on the contraceptive mechanism of VivaGel. To fertilize an egg, sperm must penetrate the egg, a process that depends on the release of two enzymes, hyaluronidase and acrosin, which help create a passage for the sperm through the outer layers of the egg. SPL7013 was found to inhibit both of these enzymes, as well as to have other effects that could impart contraceptive activity.