Patent attributes
A hand-held dispenser for dispensing a pharmaceutical product is disclosed. The dispenser has a housing providing a duct. A frangible membrane is provided in the duct. A probe with a piercing tip is mounted in the duct and arranged such that, in use the piercing tip pierces the frangible membrane. An air compression device is provided to compress air for expelling a pharmaceutical product through the probe and a channel is provided to substantially equalise the pressure in the air compression device and the pressure above the frangible membrane. The ability to substantially equalise the pressure in the bellows and the pressure above the frangible membrane on the sheath provides for a mote consistent release of pharmaceutical product when the frangible membrane is pierced. This is because the compressed air from the bellows which expels the pharmaceutical product through the probe does not encounter a sudden change in pressure as it passes the pierced frangible membrane with the entrained pharmaceutical product. In use, when compressed air is used to expel a pharmaceutical product through the probe, the air path through the probe has a lower resistance than the channel to substantially equalise the pressure in the air compression device and the pressure above the frangible membrane. This ensures that the majority of the compressed air is used to expel the pharmaceutical product. The piercing tip preferably comprises a generally annular cutting edge on an end portion of the probe with an interruption in the generally annular cutting edge.
