International journal of clinical practice. Supplement
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Int J Clin Pract Suppl · Dec 2005
ReviewDo all dry powder inhalers show the same pharmaceutical performance?
Important measures of pharmaceutical performance of dry powder inhalers include total emitted dose (TED, the quantity of drug emitted from the device when used at a fixed flow rate, typically 60 l/min or the flow rate achieved at a pressure drop of 4 kPa) and fine particle mass (FPM, the quantity of drug with small particles, typically with an aerodynamic diameter of less than 5 microns emitted from the device at a fixed flow rate). There is a wide range of dry powder inhalers available. ⋯ It is not surprising therefore that evidence from in vitro studies shows considerable variation in pharmaceutical performance of dry powder inhalers. Although neither TED nor FPM can accurately predict in vivo performance, it may be expected that highly variable or inhalation flow sensitive in vitro behaviour will be reflected in variable performance when used by patients.
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Int J Clin Pract Suppl · Dec 2005
ReviewCould interchangeable use of dry powder inhalers affect patients?
The aim of asthma treatment is optimal disease control. Poor asthma control results in considerable patient morbidity, as well as contributing to the considerable burden placed by the disease on healthcare budgets. There is a need for costs to be carefully scrutinised, with the switching of patients to inhaler devices with lower acquisition costs likely to be increasingly considered. ⋯ Furthermore, clinical trials to assess equivalence may not take into account factors in patient behaviour or variations in patient inhaler technique that may affect use of devices in real-life situations. When assessing the consequences of interchangeable use of dry powder inhalers on healthcare costs, it is important to ensure that the acquisition cost of the devices is not the only cost considered. Other costs that should be considered include the cost of time spent demonstrating to the patient how to use the new device, the cost of additional physician visits to address patient concerns and the management costs if disease control is adversely affected.
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Int J Clin Pract Suppl · Dec 2005
ReviewDo healthcare professionals think that dry powder inhalers can be used interchangeably?
It is important to assess the attitudes of healthcare professionals to the interchangeable use of dry powder inhalers, as there is the potential for this to occur more frequently in the future. A survey of healthcare professionals in the UK found that 87% were concerned about potential problems arising from prescriptions that do not specify the device to be dispensed, and 46% were aware of actual incidents in which patients received an unfamiliar inhaler, including patient confusion, ineffective inhaler technique and the need to reissue prescriptions. In another survey conducted among 427 primary and secondary care physicians in Germany, Netherlands, UK and USA, one third of the physicians considered the device before considering the chemical entity within a class of treatments and over half the respondents reported problems with the device as one of the main reasons for switching inhaled therapy. ⋯ In conclusion, a number of surveys among healthcare professionals have shown that they believe patient involvement in treatment choice to be essential for adherence to therapy. Dry powder inhalers were perceived as different and not interchangeable, with physicians opposed to substitution of one dry powder inhaler by another without consultation with the patient or physician. Consequently, physicians are in favour of official recognition that dry powder inhalers are not interchangeable, with any cost benefits likely to be outweighed by the need for additional consultations and prescriptions.
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If patients are unable to use their inhaler, drug delivery may be unsatisfactory and the patients may fail to benefit from the prescribed medication. It is important to consider whether patients can use all dry powder inhalers equally well. Changing a patient from a dry powder inhaler used well to one that the patient is unable to operate effectively could compromise asthma control. ⋯ The method for operation of dry powder inhalers varies. Ease of use is seen as an important consideration when selecting an inhaler device, which should be evaluated in real-life studies using unselected patient populations. In conclusion, the evidence suggests that patients cannot use all dry powder inhalers equally well.