The present invention provides in part dry powder inhaler (DPI) devices for dispensing dry powder and methods for using the same. The DPI devices feature exchangeable cartridges having drum mechanisms that prepare metered doses of dry powder, and are able to direct air in a turbulent manner sufficient to entrain and deagglomerate a dose of dry powder for delivery into a user's lungs. The DPI devices feature a reservoir of dry powder advanced by a plunger, as well as a gauge that advances with the plunger to indicate the amount of dry powder remaining in the reservoir.