Metered dose inhalers: a need for dose counters.

Objectives: This study investigated the ability of patients to assess when a metered dose inhaler (MDI) is empty.

Methodology: A total of 17 patients assessed, by shaking, the number of doses remaining in a salbutamol MDI that had been partially emptied. Another 100 patients were asked to collect all salbutamol MDIs they considered to be empty and would have thrown away.