Advantages & Limitations of Dry Powder Inhalers

When you think of an inhaler, you probably think of the conventional metered-dose inhaler (MDI). MDIs are one of the most popular inhaler types for a reason - it was the first truly portable and convenient inhaler to deliver medicine to the lungs effectively. Since its introduction in the 1950s, there have been multiple types of portable inhalers developed, giving people a wider range of options when it comes to choosing an inhaler. Dry powder inhalers (DPIs) are one of these newer types of inhalers, which became available commercially in the 1970s and become significantly more popular since then. Let’s learn more about dry powder inhalers and what makes them different.

What are Dry Powder Inhalers?

Dry powder inhalers are so called because they deliver the medicine in the form of a dry powder rather than the aerosol that is sprayed from MDIs. There are many different types of DPI models that vary both in how they look and how the medicine is loaded into them. For some unit-dose and multiple unit-dose DPIs, you can load a capsule or series of capsules which you can then inhale for a single dose or multiple doses. There’s also another type of DPI, reservoir devices, that contains a storage unit that contains the powdered medicine, a particular amount of which is released when it’s used. Dry powder inhalers are used for respiratory diseases like asthma and COPD. They can deliver both bronchodilators (medicines that relax the muscles of the airways) and anti-inflammatories (medicines that reduce swelling of the airways).

Advantages of Dry Powder Inhalers

1. DPIs are portable

Portability is an important factor in inhalers, especially when it comes to inhalers that are required to be used daily. Just like MDIs, DPIs are also portable and some are even more compact. You can carry the DPI around with you through the day so you can use it as prescribed by your doctor.

2. DPIs are easy to use

MDIs may look like simple devices but they can be complex to use. They require coordination between inhaling and pressing to spray the medicine. DPIs, on the other hand, are much easier to use. They are breath-actuated, which means that the medicine is released when you inhale so no coordination is required.

3. DPIs are convenient

Most DPIs come with a dose counter that makes them convenient to use. Some multi-dose DPIs can hold up to 200 doses so you can use them for a longer period of time before replacing them. They also don’t require a spacer attached to it to be able to use it properly, unlike MDIs where a spacer might sometimes be necessary.

4. DPIs are propellant-free

MDIs require propellants to create the aerosolized spray of medicine. This is an added advantage as propellants have been known to be harmful to the environment as they contribute to global warming. For eco-conscious patients, DPIs can be a greener choice.

5. DPIs effectively deliver the medicine

DPI deposit the medicine in the lungs at a much higher rate than MDIs. This makes them more efficient and effective as they can provide a higher quantity of medicine with a single dose.

Limitations of Dry Powder Inhalers

While there are many advantages of dry powder inhalers, it also has some limitations. Since they contain dry powder, it’s necessary that they are kept in dry conditions and away from humidity. Depending on where you stay, DPI might not a good enough shelf stability for long-term use.

They also deliver medicine based on how forcefully you breathe in and some contain a minimum amount of force required which might not be possible for all. Because they can’t be used with a spacer, it’s also been questioned whether it can effectively be used for those who need a high volume of medicine.

Some DPIs also contain lactose which doesn’t usually have negative effects since it’s in a very small quantity but it can be an issue for those with severe milk allergies.

Conclusion

Dry powder inhalers can be a great option for those with asthma or COPD. You can ask your doctor if DPIs can work for you as they do have many advantages and the limitations might not be an obstacle for you.

References:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5278812/

https://www.liebertpub.com/doi/10.1089/jam.1991.4.151

https://www.sciencedirect.com/topics/medicine-and-dentistry/dry-powder-inhaler

https://www.aarc.org/wp-content/uploads/2018/03/aersol-guides-for-hcp.pdf

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