Drug delivery
Nélio Drumond believes the design of the device used to administer an inhaled drug can play a significant role in patient acceptability and medication compliance.
of the covid vaccines, which are now being repurposed and looked at for inhaled applications.” This is certainly reflected in the vaccine marketplace, with two nasal Covid-19 vaccines given approval in 2022, one in China, the other in India, and many more in clinical trials seeking approval in different regions. “There are also some potential novel applications that have been proposed,” says Forbes. “Here, you could improve the mucosal barrier function of the lung, to almost trap and remove infection or negate either bacterial or viral infection before it actually engages through its entry point to the body mechanisms.” At the more ambitious end of the research and development spectrum, there are teams looking at the potential for inhalable therapies that can potentially correct innate disease-causing errors of genes, bringing new hope to those suffering from respiratory diseases like cystic fibrosis.
A promising development
The promise of inhalation as a route for drug delivery is significant, but all of it begs the question: Why are the lungs a potentially effective route for drug delivery? “You get instantaneous deposition to the mucosal surface, where you have a huge surface area, relatively low pre-systemic metabolism and extremely high blood flow,” explains Forbes. “It is also one of the few organs in the body, maybe the only organ in the body, that receives the entire cardiac output, and it has an extremely thin air to blood barrier because of its physiological function – which is to oxygenate the blood as it passes.” In layman’s terms, all of this means that inhaled drugs get absorbed into the bloodstream quicker, and because they avoid the GI tract, they aren’t broken down by enzymes that reduce the amount of active pharmaceutical ingredient that reaches its target.
“If you go via the oral route, you are going via an environment that is designed to digest peptides, proteins, carbohydrates and anything else, so going via the lungs, you can avoid that degradation and you can start to achieve better bioavailability,” explains Forbes. It’s not all advantages though, and there’s a reason the market hasn’t been flooded with inhalable options for therapeutic drugs. “They are much more expensive than a tablet,” says Forbes. “It is the cost
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of developing something quite so complex and the cost of producing something that has got multiple parts. It has a device and it has a specially formulated medication that requires a particular fine particle size, that is reproducible. Additionally, the drugs themselves can be expensive.”
On the formulation side, another obstacle is the use of excipients – components included in drug formulations to assist in their stability or shelf life, as well as producing immune reactions that can make them work more effectively inside the body. Unlike with parenteral delivery, only a small number of excipients are approved for inhaled drugs. Outside of formulation, Forbes says the barriers are more to do with how environmentally friendly devices are – unsurprising when you’re talking about propelling a gas. “We have already had one reformulation of all the metred-dose inhalers to replace propellants with lower global warming potential alternatives, and that is starting to happen again with even more environmentally friendly options,” he explains. “But there are new devices coming along and new technologies so things will probably change there.”
What the customer wants One of the most important factors in drug delivery, and something pharmaceutical companies are appreciating more and more, is how the end-user – the patient – interacts with their products. Nélio Drumond, associate director of manufacturing sciences at Takeda, is a frequent keynote speaker on patient-centric drug product design, and he stresses the importance of making things easy for patients. “We should ensure that when we are developing and designing devices, like inhalers, we are thinking about the patient in the very end,” he says. “You need to build a holistic perspective and understand that the device you are engineering must fit the specific needs of the target patient population. Inhaler devices are particularly challenging, because you must consider the whole spectrum of patients, from young children to the very old and frail.” Both of these patient populations share individual needs that will be distinct from those of healthy adults, and Drumond believes those developing inhalable drugs need to increase their efforts to understand patient language by asking the following questions: “How do
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