A Government recommendation to switch stable patients using pressurised metered dose inhalers (pMDI) to more environmentally friendly dry powder inhalers risks harming patients, warn respiratory experts.
Making inhaler choices with only emotive environmental issues in mind could set back decades of efforts to improve respiratory disease control, asthma outcomes, and patient self-management, they say in a Lancet Respiratory Medicine, editorial.
The authors are GP Dr Duncan Keeley, Respiratory Nurse Consultant Jane Scullion, both senior PCRS members, and Dr Omar Usmani, Reader and Consultant Physician at the National Heart and Lung Institute, Imperial College London & Royal Brompton Hospital.
Their concerns arise from a recent directive of the Environmental Audit Committee of the UK Parliament that by 2022 at least 50% of prescribed inhalers should have a low impact on global warming.
They argue the recommendation is a mistake because:
- Stable patients with asthma initiated on pMDIs have better health outcomes compared with the same drug prescribed as a dry powder inhaler.
- It would limit physicians’ ability to tailor treatment to patients.
- Deteriorating asthma control would result in increased primary care consultations, rescue symptom prescriptions, emergency room visits, hospital admissions, and mortality.
- pMDIs constitute only around 6% of hydrofluoroalkane propellant use and therefore make only a small contribution to global warming
- Inhaler recycling schemes, research into more environmentally friendly propellants and novel inhaler devices and better education of healthcare professionals and patients in inhaler use would all result in effective and less wasteful use of inhalers.
- The Committee’s assumption that switching one inhaler device to another on the basis that pharmaceutical drug dose equivalence achieves comparable clinical effectiveness is factually incorrect. Aerosol research has shown that both the engineering characteristics and formulation properties of an inhaler determine the actual drug dose reaching the lungs, and the lung dose varies between every device in daily clinical practice. Both the drug and device together determine the clinically effective lung dose. Inhaler device choice and inhaler technique training also have an impact on patient outcomes.
Duncan Keeley said: “We should consider how to minimise the environmental impact of respiratory treatments but care is needed to avoid adversely affecting outcomes. pMDIs remain vital for treating young children and the elderly, and for the most effective management of exacerbations and work is under way to develop new pMDI propellants of low global warming potential.”
Jane Scullion said: “With the main workload of asthma care and inhaler prescribing taking place in primary care it is important that there is a strong voice from here when well intentioned decisions could have disastrous unintended consequences.”