Is an asthma inhaler (MDI) an example of vaporization?

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SUMMARY

The discussion centers on the classification of asthma inhalers, specifically metered dose inhalers (MDIs), in relation to vaporization. Participants clarify that MDIs dispense aerosols rather than vapors, despite some sources inaccurately labeling them as vaporization devices. The consensus suggests that while the process of evaporation occurs within MDIs, they do not fit the strict definition of vaporization. The conversation also explores the broader context of vaporization in pharmaceutical delivery, emphasizing the need for clarity in academic literature reviews.

PREREQUISITES
  • Understanding of aerosol science and its distinctions from vaporization
  • Familiarity with the mechanics of metered dose inhalers (MDIs)
  • Knowledge of pharmaceutical delivery methods, particularly for pulmonary applications
  • Basic principles of phase transitions, including evaporation and condensation
NEXT STEPS
  • Research the differences between aerosols and vapors in pharmaceutical contexts
  • Explore the mechanics of nasal inhalers and their role in vaporization
  • Investigate other medical devices that utilize vaporization for drug delivery
  • Study "The Mechanics of Inhaled Pharmaceutical Aerosols: An Introduction" for deeper insights into aerosol generation
USEFUL FOR

Medical researchers, pharmaceutical scientists, and students in healthcare fields seeking clarity on vaporization methods and their applications in drug delivery systems.

urb-nurd
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I am trying to give some context to medical vaporizers in a literature review I am composing and initially decided to give asthma inhalers and nasal inhalers as examples.
I realized however, that some sources on-line were referring to these metered dose inhalers as vaporization devices when they are in fact dispensing an aerosol rather than a vapour.

I understand the nasal inhaler to be a good example of evaporation and therefore vaporization.Though the label of a vaporizer applied to an MDI inhaler still seems problematic.

This quote (from The Mechanics of Inhaled Pharmaceutical Aerosols: An Introduction, but taken from Wikipedia) implied it may be somewhat accurate to propose that an asthma inhaler is using the process of vaporization for drug delivery : "Breakup of the volatile propellant into droplets, followed by rapid evaporation of these droplets, results in the generation of an aerosol consisting of micrometer-sized medication particles that are then inhaled"

The quote suggests that the evaporation of the atomized droplets is generating an aerosol.
I am struggling to understand how the inhaler is not a vaporization device - as it produces an aerosol, but this aerosol is produced from the evaporation of droplets of propellant and is therefore a device used for the transformation of phase from liquid to gas i.e a vaporizer.

What is the general consensus on this?

I will likely avoid the inclusion of the asthma inhaler as an example of a common vaporization device in my lit review if this level of confusion will be present in the mind of the examiners marking it.

I have discussed anaesthetic vaporizers then moved onto explain that vaporization as a method of pharmaceutical delivery is more common than it first appears, thus the context of my question is my attempt to show the viability and popularity of vaporization for pulmonary delivery of medicines.
Also I would be interested if anybody could suggest any other common, but not necessarily obvious examples of vaporization devices used for medical purposes or other favourable applications (by favourable, i mean... not cannabis vaporizers - my institution of academia seems to frown heavily on that particular application).

Thanks for reading, any input or information is greatly appreciated.
 
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urb-nurd said:
What is the general consensus on this?
"Solids, liquids, and gases" --- plus sols, gels, emulsions --- ta-da, ta-da, ta-da. Three phases at equilibrium. The rest of the "gray" area are non-equilibrium situations, meta-stable states, whatever you will. An aerosol is not a vapor, and it's not a liquid, nor is it at equilibrium. You might dig around in Adamson's Physical Chemistry of Surfaces for some sense of what is and is not happening. Probably a good item to have in a review.
 
http://en.wikipedia.org/wiki/Aerosol_spray

If aerosol cans were simply filled with compressed gas, it would either need to be at a dangerously high pressure and require special pressure vessel design (like in gas cylinders), or the amount of gas in the can would be small, and would rapidly deplete. Usually the gas is the vapor of a liquid with boiling point slightly lower than room temperature. This means that inside the pressurized can, the vapor can exist in equilibrium with its bulk liquid at a pressure that is higher than atmospheric pressure (and able to expel the payload), but not dangerously high. As gas escapes, it is immediately replaced by evaporating liquid.

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