An asthma inhaler may look like a straightforward device – but the technology behind it is minutely researched; and changes to the way the inhalers are designed can make a huge difference to the daily lives of asthma sufferers.
That’s the message that comes across from Andy Dundon, head of device engineering at GSK. He’s one of the country’s leading experts on inhaler technology, which has been around a surprisingly long time. It was back in 1778 that an English doctor named John Mudge first used the method of delivering medication via a vapour. Mudge used a pewter tankard to dispense opium as a gas to treat coughs. His invention became the prototype for the creation of ceramic pots that were used through the 1800s to do a similar job; and around the same time, doctors in France began to create nebulisers, using perfume atomiser-type devices to spray the drug.
The principle, Dundon says, is as relevant today as hundreds of years ago. “For asthma, a disease of the lungs, delivering the drug to the site of the disease has significant advantages, including how quickly the drug works, which is important when a patient is having an asthma attack, for example. Inhaled drug delivery may not be as convenient as a tablet you ingest, but a tablet takes a while to get into the bloodstream and the site of the disease. Comparing the two, you can see the patient benefit of inhaling the drug.”
The crucial starting point in devising any sort of inhaler, says Dundon, is this: the particle sizes must be less than 5 microns to be absorbed by the lungs; but if the particles are too tiny, less than 1 micron, they will be breathed out again. “You have to be in control of the particle size, not just when you make the product but right through its life cycle,” he explains.
The game-changing moment in the history of asthma control came 50 years ago in 1969 with the launch of salbutamol, a drug that opens up the airways in the lungs and provides immediate relief from a frightening and potentially life-threatening asthma attack. It was delivered via a pressurised metered-dose inhaler (MDI) that had been invented by a US doctor called George Maison in the 1950s to help his daughter, who was struggling to take her medication. With one push on the device, the MDI delivered the drug to exactly where it was needed – the lungs.
The MDI made treating asthma much easier – it was small, handheld, portable, and it contained a month’s supply of the drug. But some patients found it a challenge to use. “They had to remember to shake the MDI before use, and they also had to learn to coordinate the actions of pressing the machine, and breathing in,” explains Dundon.
One answer was the development of the spacer device, a plastic chamber into which the drug could be pushed, and where patients could breathe it in at their own convenience. But what it gained in ease of use, the spacer lost in portability – and what’s clear from research, says Dundon, is that patients value a discreet device from which to take medication.
During the 1980s another problem became urgent: MDIs used propellants that were dependent on chlorofluorocarbons (CFCs), and they were found to contribute to ozone depletion in the atmosphere. In 1987, the international Montreal protocol on substances that deplete the ozone layer was agreed, and GSK became one of the first companies to launch an MDI that used a new family of propellants called hydrofluoroalkanes, which are far less environmentally damaging. Later, in 2004, the company refined its MDI further as it produced an inhaler that enabled patients to see how many doses remained.
Alongside MDIs, GSK has also been improving the other main type of asthma inhaler, the dry-powder inhaler (DPI). It uses a dry-powder form of a drug, which originally was loaded into an earlier version of the DPI device via a capsule. The patient would twist the inhaler before breathing in the medicine when they were ready. But the benefits of this system were offset by the fact that the MDI held one month’s worth of medicine, and the DPI used a single-dose capsule. As the design of the device was improved, the next version could hold four doses at a time, and then in 1994, a new DPI was created that could hold 60 doses, which equated to one month’s worth of medicine taken twice a day. For patients who found coordinated breathing difficult when using the MDIs, this new design was a good solution and by 2008 a billion of them had been sold and distributed. DPIs are also more environmentally friendly than MDIs, as MDIs release greenhouse gases during use.
One important thing to realise, says Dundon, is that development of devices goes hand in hand with the development of drugs – the drug needs a user-friendly device, and the device needs the most efficient and effective drugs. So, Dundon and his team refined their devices. Improvements were based on the feedback provided by patients, healthcare professionals, pharmacists and payers, to simplify how the device operated, how it was stored, and how it was manufactured. GSK, as well as other companies, have also subsequently produced combination therapies (allowing two or more medicines to be inhaled in the same breath).
Since 2011, GSK has been running a scheme to recycle inhalers, called Complete the Cycle; it was the first scheme of its kind for the UK – and given that 73m inhalers are prescribed here each year, it has the potential to make a significant ecological difference.
What, then, of the future? The buzzword in inhaler technology, as in so many other areas of life today, is digital; but, says Dundon, the best approach is not solution-focused, but issue-focused. Smart inhalers, apps and digital technology may have their place, and could for example offer prompts to take medication, or record the use of medication – even, in time, gauge the need for medication. “The important thing to concentrate on is, what is the problem?” he says. “Solutions are the easy bit. What I worry about is people falling in love with the technology and then trying to get it to be a solution. Good design is always about understanding the problem first, and coming up with the solution second.”
