Described are capsules to contain a drug for use in an inhaler. The capsules may be two-part capsules where each half has apertures which may correspond to apertures in the other half. The first half fits snugly within the second half and the two halves may be rotated around their longitudinal axes with respect to each other to produce unlocked and locked positions. In the unlocked position, at least one aperture in the first half aligns with at least one aperture in the second half, which permits introduction of a medicament. In the locked position, at least two apertures in the first half align with at least two apertures in the second half, allowing air to pass through the capsule, releasing the medicament contained therein. Each capsule may have a unique key on each half that only fits with a particular inhaler or identifies the medicament contained therein.