New hyaluroran derivative with prolonged half-life for ophthalmogical formulation

Two new hyaluronan derivatives containing phosphate or cystamine groups have been synthesised to obtain tear drops with improved rheological properties and prolonged half-life. Rheological analysis, in terms of apparent viscosity, pointed out that phosphorylated hyaluronan showed promising characteristics for the foreseen application. The presence of phosphate groups along the chains, confirmed by infrared analysis, induced a strengthening in hyaluronan hydrogen bond capability thus modifying its thermal behaviour and prolonging its resistance against hyaluronidase attack. Finally, in vitro cytoxicity tests excluded any adverse effect of the developed hyaluronan derivative.