This small device is similar to a metered dose inhaler (MDI), but the drug is in powder form. The patient exhales out a full breath, places the lips around the mouthpiece, then quickly breathes in the powder. Note that the technique is different than for MDIs -- dry powder inhalers do not require the timing and coordination that are necessary with MDIs. There are other important differences, so make sure that you always know the proper technique for the method you are using.
Dry powder inhalers are becoming more common, in part because they do not use the "CFC" propellant that used to be in all MDIs. (CFCs damage the ozone and have been removed from MDIs.) Dry powder inhalers are as effective as MDIs -- in fact, some may prove to be slightly more effective.
Naturally, there are several disadvantages. If the patient exhales directly toward the device, the powder can be blown out. Also, much of the powder ends up in the mouth, which can cause unwanted side effects -- this is similar to what happens when a patient puts an MDI directly into their mouth. As with MDIs, it is recommended that you wash your mouth after administering the drug.