Powder inhaler having a multi-positioned metering cup

#This is a continuation of PCT application No. PCT/GB91/01147, filed Jul. 11, 1991.

#This invention relates to an inhaler, namely a device for use in delivering a dose of medicament or other substance for inhaling into the lungs.

#The most common form of inhaler propels the dose of medicament in pressurised gas from an aerosol. However, this form of inhaler is becoming less popular because of environmental and other considerations. The delivery of some drugs in a dry, finely divided form has been shown to have certain medical advantages over other forms of delivery.

#The invention is exemplified in the accompanying drawings, in which:

#FIG. 1 is a general perspective view of an inhaler of the invention;

#FIG. 2 is a side view of the inhaler in use;

#As shown in the external views of FIGS. 1 and 2, the inhaler comprises a housing 1 which is provided with an air intake 2. A tubular mouthpiece 3 projects from the housing.

#Referring to FIGS. 3 to 6, the housing contains an internal body 4 which, on its side remote from the mouthpiece 3, contains a recess 5 that provides a seat for a metering member 6 which is rotatable about its axis in the recess. The metering member includes a portion having a frusto-conical metering surface 7 which includes a series of circumferentially arranged cup-like metering depressions 8. The recess 5 provides a seat of corresponding frusto-conical shape, the angular tolerance and circumferential form of the metering surface and of the seat being carefully monitored in manufacture to ensure a close sliding contact between the two mating faces.

#The opposite side of the body 4 includes a storage chamber 10 for a drug in the form of a micronised powder, the chamber 10 being arranged to register with one of the depressions 8. A second, outer chamber 11 surrounds the storage chamber 10 for containing a moisture absorbing material such as silica gel granules. The second chamber 11 is open to the depressions 8 on both sides of the depression which is currently in register with the storage chamber 10, but the silica gel is prevented from migrating into the depressions by a shaped filter membrane 12. The same side of the body 4 further contains an inhalation passage 15 and a waste chamber 16, both of which register with one of the depressions 8. The inhalation passage 15 has a smooth internal contour and registers with both the air inlet 2 and the mouthpiece 3. The air inlet 2 contains a filter membrane 17 for removing any contaminating particles that may be drawn into the inlet. The waste chamber 16 contains a brush, a piece of sponge rubber or other flexible wiping element 18 which projects into the corresponding depression 8 to make wiping contact with the walls of the depression.