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Overlooked opportunities for nebulizers in inhalation product development An introduction to nebulized therapy The popularity of the nebulizer as a means of delivering aerosolized medication has varied in the 150 years since its inception. Before the advent of the pressurized metered dose inhaler (pMDI) and dry powder inhaler (DPI), the nebulizer was the main method of administering aerosolized drug to the lungs. But the increased portability and convenience that pMDIs and DPIs provided has resulted in reduced popularity for nebulizers in recent decades. Nevertheless, the ability to deliver therapeutic doses of drug to patients utilizing their normal tidal breathing is a fundamental attribute that has given the nebulizer universal applicability in the delivery of aerosolized medication to all groups and types of respira- tory patient. It avoids undesirable situations, such as that of very young children unable to understand instructions to inhale upon command, or that of older or physiologi- cally impaired patients not able to perform the fast/slow/deep breathing maneuver required by inhaler devices such as DPIs and pMDIs. This may also explain the enduring popularity of nebulizers in emergency departments, where the treatment of asthma exacerba- tions has been shown to be equally achievable with a pMDI and an add-on valved holding chamber, 1 but where the use of nebulizers has remained widespread. 2, 3 Use in a hospital setting may create a perception in the patient mind that nebulized treatment is the most effec- tive since it helps them recover when they are feeling at their worst. This also may give them additional confi- dence to persist with this form of treatment when they return home. 4, 5 Other advantages of treatment via nebu- lizer include the obvious indications that the device is gen- erating aerosol and that drug administration is complete. Nebulized therapies are typically prescribed for young children with asthma and for elderly and very sick patients with asthma and chronic obstructive pulmonary disease (COPD). Thus, the most commonly prescribed drugs are short-acting β-agonists or anti-muscarinics, alone or in combination, together with corticosteroids in pediatric asthma. Other nebulized drugs include antibi- otics, saline and DNase for treatment of cystic fibrosis and prostacyclin for pulmonary arterial hypertension. Corticosteroids, particularly budesonide, are the largest- selling class of nebulized drug by value, comprising over 50% of the total nebulized drug market in the United States. 6 Indeed, nebulized budesonide generates the most revenue of any inhaled drug in China, including drugs administered via pMDI or DPI; however, this reflects the price per dose. By number of prescriptions, short-acting bronchodilators dominate, accounting for over 80% of prescriptions for nebulized medication in the US. It has been estimated that, in 2015, approximately 7% of inhaled doses were taken by nebulizer, and that between 2011 and 2015, the number of nebulized doses used were growing faster than either that of pMDIs or DPIs. 7 This may not be surprising, considering the increases in global life expectancy (an increase of 5 years between 2000 and 2015) and the associated rise in prevalence of COPD. 8, 9 That prevalence is particularly relevant to nebulizer use as, among the three principal types of aerosol delivery devices (nebulizers, DPIs and pMDIs), the nebulizer is the device most suited to deliv- ery of aerosol to the more severe COPD patient. Such patients may be elderly and have degraded fine motor skills, dexterity and hand muscle strength, which can inhibit the correct use of inhalers. 10 Therefore, it is not unexpected that 50% of patients discharged from a hos- pital after an COPD acute exacerbation are prescribed nebulized drugs, 11 most commonly a combination of short-acting β-agonist and muscarinic drugs. Despite this, the large majority of new treatments recently brought to market have been developed in portable inhalers. 12 Yet recent developments in nebulizer technology, along with the relative ease with which solu- Nebulized medication use is growing faster than that of inhalers, yet most companies focus on bringing new inhalers to market. What opportunities might they be missing? John N. Pritchard, PhD Respironics Respiratory Drug Delivery Inhalation JUNE2017 9

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