Decongestant activity of a new formulation of xylometazoline nasal spray: a double-blind, randomized versus placebo and reference drugs controlled, dose-effect study.

Xylometazoline hydrochloride is an imidazoline derivative commonly used in topical application to relieve nasal congestion associated with acute or chronic rhinitis, common cold, sinusitis and hay fever or other allergies. To reduce the negative effects on the mucosal defensive mechanism, a new formulation of xylometazoline (Rhinostop) with inactive preservatives and hyaluronic acid (HA) was studied. The most appropriate concentration of xylometazoline and its decongestant activity in the new formulation were investigated in a double-blind, dose-effect study. The new formulation at three different concentrations of xylometazoline (0.025%, 0.05% and 0.1%) was compared with a placebo formulation, three equivalent aqueous solutions containing xylometazoline (without HA) and a reference formulation, containing benzalkonium chloride as preservative. The drugs' efficacy in reducing airflow resistance was also evaluated. The effects of xylometazoline on inspiratory and expiratory nasal resistance were found to be concentration-dependent. Indeed, the new formulation at a concentration of 0.05% was more effective than the new formulation at a concentration of 0.025%, but was statistically equivalent to the new formulation at a concentration of 0.1%; therefore, the 0.05% concentration of xylometazoline seemed to achieve maximal decongestant activity. These findings were confirmed by the observation that the efficacy of the new formulation at a concentration of 0.05% was also statistically comparable to that of the reference formulation and the aqueous solution of xylometazoline 0.1%. HA seems to act as an enhancer/carrier of the active principle, xylometazoline, as already demonstrated for other drugs. The new formulation at a concentration of 0.05% was therefore selected for further clinical development.