Inhaler devices - from theory to practice.

This brief overview of the factors determining lung deposition of aerosols provides background information required by health care providers when instructing patients to use their prescribed inhalers. We discuss differences in the optimal inhalation manoeuvres for each type of aerosol generator and the difficulties patients face. Provision of short, clear instructions with demonstration of critical steps and checking technique during later clinical visits are necessary if these aerosolised medications are to be fully beneficial.