From the November 2006 issue

We received a report about a dosage counter for an inhaler that may not work as intended.  An asthma patient called his pharmacy to ask how long his inhaler “is supposed to be good for.” He stated that he had been using the product for months now, yet the window of the ASMANEX TWISTHALER (mometasone furoate), a steroid inhalation powder available in 14, 30, 60 or 120 metered dose sizes, read over 180 puffs. When the patient brought the Twisthaler in for inspection, the pharmacist verified that the dosage counter indeed read 182.

The Asmanex Twisthaler (see photo) is designed to work by “cap activation technology.” To prepare for dosage administration, the white cap is twisted in a counter-clockwise direction and removed. As the cap is lifted, the dosage counter goes down by one and the inhalation powder is loaded in the device and ready to be inhaled. After the dose is inhaled, the cap is replaced by turning it clockwise until hearing a clicking sound, the signal that it is fully closed and ready to load the next dose. When the dosage counter reaches “00”, the Twisthaler is supposed to automatically lock to prevent patients from using an empty device. The pharmacist who reported this error took an Asmanex Twisthaler placebo demonstration inhaler and attempted to reproduce the situation. The pharmacist found that when she set the dosage counter to “00” and applied enough force while twisting the inhaler cap, the counter reset to 199, a number that is not even available as a package size. We have alerted Schering-Plough, the manufacturer of this product, to this problem. They admitted that if a patient “forcefully” attempts to remove the cap once the dosage counter reaches “00” there is a potential for the counter to reset. They have agreed to further investigate the issue.