In order to improve the security and reliability of administration of powdered pharmaceuticals through dry powder inhalers, the invention proposes an inhaler (1) for powdered medicaments, comprising an activating device (4) for manual engagement by the patient for repeatedly metering a dose of medicament to be administered to the patient, and further comprising an advancing mechanism (25) for advancing a counter or indexing means (8) each time the activating device (4) has been engaged by the patient so that a dose of medicament has been released for administration to the patient, wherein the counter or indexing means (8) comprises an index (9), the index (9) being detectable by a detection means (10) of the inhaler, and the detection means (10) being coupled to a locking mechanism (12), the locking mechanism (12) blocking the activating device (4) and/or any transportation mechanism (5) of the inhaler (1) delayed by a predetermined number of metering cycles since detection of the index (9), and a cartridge (3).