Abstract: The invention relates to a nasal dispenser for atomizing pharmaceutical substances which is of elongate form and is traversed by a longitudinal channel having an open end for housing the free end of the stem of a pump or dispensing valve, its other end being intercepted by a wall provided with a hole through which the substance is dispensed. The channel has a stepped cross-section which is a minimum in proximity to said wall. The channel houses an elongate element the cross-sections of which are smaller than their surrounding cross-sections of the channel into which the element is inserted. The length of the portion of smaller cross-section of the profiled element is greater than the length of the minimum cross-section portion of said channel to define an expansion chamber within it.

Abstract: The pump comprises a chamber divided into a lower cavity occupied by the fluid and an upper cavity at atmospheric pressure. A flexible ring piston sealingly runs in the chamber and is inserted in a slidable way on a stem valve, with which it co-operates to enable or interrupt the outward flow of the fluid. The piston has a tapered section at its lower end, which engages by friction in a corresponding tapered groove of the stem valve to allow delivering of a fine mist with a very low delivery pressure also.