Dry powder inhalers with a multi-dose dry powder package for dispensing pharmaceutical grade formulations of inhalable dry powder, include: (a) a blister package comprising a plurality of spaced apart sealed blisters thereon, each blister having a projecting ceiling and a floor defining a blister channel therebetween, the blister channel comprising a dry powder therein; (b) a movable blade cartridge holding a blade at a forward portion thereof; and (c) an extendable mouthpiece attached to the movable blade cartridge. In operation, a user pulls the mouthpiece outward and then pushes the mouthpiece inward to cause the blister package to advance to position a blister in a selected dispensing position in the inhaler and to cause the blade cartridge to move the blade across a blister ceiling held in the dispensing position in the inhaler to thereby open the blister held in the dispensing position.