A new report claims that despite an “impressive list of benefits, several drawbacks remain” for inhaled medicines, notably the devices used to deliver the medicines.

A Datamonitor-authored study notes that respiratory diseases like asthma and chronic obstructive pulmonary disease are mostly treated with inhaled drugs in order to relieve bronchoconstriction and target inflammation in the lungs. There are several advantages to taking the inhaled route compared to oral therapy – faster onset of action, lower drug doses and a better efficacy-to-safety ratio – and it is also painless and more convenient than injectable drugs.

However, says Datamonitor respiratory analyst Lisette Oversteegen, “one of the biggest problems relates to the inhaler device through which the drug is delivered”. She notes that since there are so many different types of inhalers available, “it can be difficult for the patient to learn and remember the correct use for each one of them”.

There are two main types – metered dose inhalers (MDIs), including pressurised MDIs (pMDIs) and breath-activated MDIs (BAIs); and dry powder inhalers (DPIs). However, among the BAIs and DPIs especially, there is a wide variation in design, “making it impossible to learn only one technique to use them correctly”, the report says.

The standard pMDI is the oldest and most often-used inhaler since it is cheap and available containing many different molecules. Nonetheless, a large proportion of patients cannot use them correctly. One of the most common problems is a failure to co-ordinate inhalation with actuation of the device, and BAIs help to overcome this. However, the major drawback of BAIs is that there are only a few drugs available in these devices due to the high cost involved in developing them, Ms Oversteegen says.

She also notes that while the inhalation technique for pMDIs is generally the same, the wide variety of DPIs available means that instructions can be very different. “Furthermore, to ensure that most of the drug emitted from a dry powder inhaler reaches the lungs, it is necessary for the patient to inhale deep and fast enough. A number of asthma and COPD patients are unable to do so, especially the elderly, children and people with severe airflow limitation”, the analyst notes.

The ultimate goal is to have a range of molecules delivered in the same type of device, thus minimalising errors in inhalation technique, Ms Oversteegen says. “This would also lead to increased convenience for the patient, as only one technique needs to be learnt and remembered.

She concludes by saying that some companies do market one type of inhaler device with different molecules across drug classes, covering all the needs of a standard asthma patient. However, “these are all generic molecules and the newer treatments are not available in the same range, leaving many asthma and COPD patients struggling”.