Survey of pharmacists’ attitudes towards interchangeable use of dry powder inhalers

Background It is a common cost-containment practice in some countries to dispense a cheaper, generic version of a prescribed medication. This presents few problems for most medications. However, dry powder inhalers used in asthma and COPD vary markedly in design and method of operation, so generic substitution may not be acceptable to patients or healthcare professionals. Patients dispensed an unfamiliar device in which they have received no training, risk poor inhalation technique with the potential for inadequate dosing and loss of disease control.
Objective To assess the views of pharmacists towards interchangeable use of dry powder inhalers.
Setting Community pharmacists in Australia, Canada, France, Germany, and the UK.
Method Following exploration of the key issues with international opinion leaders in respiratory management, a structured web questionnaire was developed for use in computer assisted web interviews. Fieldwork was carried out in March and April 2005. Main outcome measure: Responses to the web questionnaire were analysed by percentage of respondents or by mean or median score, as appropriate to the question.
Results A total of 254 pharmacists were included in the study. Just 6% of pharmacists considered that dry powder inhalers are interchangeable, with a high level of concern shown about interchangeable use (median score of 6 on a scale of 1, not at all concerned, to 7, extremely concerned). Patient confusion was the main concern, expressed by 77% of respondents. Pharmacists also envisaged substitution having an adverse impact on pharmacy stock levels (72%), patient device handling (70%), pharmacist workload (63%), patient compliance (56%) and outcomes for the patient (51%), with pharmacists in Germany having a particularly negative view and those in France generally the most positive. Despite the generally negative view of pharmacists about interchangeable use of dry powder inhalers, overall only 22% would contact the prescribing physician often/very often for approval of the substitution.
Conclusion The study showed that only a small minority of pharmacists believe that dry powder inhalers can be used interchangeably, with the majority concerned about generic substitution of these products. Pharmacists in Germany were particularly negative about the interchangeable use of dry powder inhalers.