Metered dose inhaler add-on device, observance improvement system and method for improving observance of use in metered dose inhalers

Metered dose inhaler observance add-on device adapted to be removably mountable onto an exterior surface of a metered dose inhaler, said add-on device comprising:

• an observance system housing component comprising an observance system with at least one pressure sensor;
• a mouthpiece component having a wall defining a channel and an inhaler opening, said wall is configured to fit, surround and removably engage with an exterior surface of a mouthpiece outlet provided on the metered dose inhaler such that at least a portion of said wall is insertable into a mouth of a user and such that medication flow from the mouthpiece outlet of the metered dose inhaler is inhaled through the inhaler opening;
• wherein
• said observance system housing component is configured to fit and removably engage with said mouthpiece component;
• and
• said mouthpiece component is specifically adapted such that an interior surface of the wall of the mouthpiece component elastically engages with and rests on the exterior surface of the mouthpiece outlet of the metered dose inhaler without obstructing delivery of a dose of drug through said mouthpiece outlet;
• and wherein the add-on device does not create any supplemental chamber through which the drug would have to pass, in addition to a chamber already provided by the metered dose inhaler.