Dry Powder Inhalers (DPIs) Are Generally Better Than Metered-Dose Inhalers (MDIs)
Dry powder inhalers (DPIs) are superior to metered-dose inhalers (MDIs) for most patients due to easier technique, better medication delivery, and lower environmental impact.
Advantages of Dry Powder Inhalers
Ease of Use
- DPIs are breath-activated, eliminating the need for hand-breath coordination that MDIs require 1
- Studies show that DPIs are generally easier to use than MDIs and cause fewer irritant effects 2
- Unlike MDIs, few patients develop poor inhalation technique with continued use of DPIs 2
- The majority of patients with severe acute asthma can achieve sufficient inspiratory flow for effective DPI use 2
Environmental Benefits
- DPIs have a significantly lower carbon footprint compared to MDIs 1, 3
- MDIs contain hydrofluoroalkane propellants that are potent greenhouse gases 3
- Environmental impact should be a consideration when selecting otherwise equivalent inhaler options 3
Clinical Effectiveness
- Multidose DPIs achieve similar bronchodilation to MDIs 2
- DPIs have more consistent dose emission regardless of patient's inhalation flow 4
- Better asthma control is observed among correct users of inhalers, and DPIs have advantages for many patients 5
Comparing Specific Devices
Device Preferences
- In comparative studies, patients often prefer certain DPIs (like Turbuhaler) over other devices 2, 6
- Multidose DPIs (Accuhaler, Turbuhaler) are preferred over single-dose DPIs (Aerolizer, Handihaler) 6
- Fatal errors that would result in no drug delivery are significantly more common with single-dose devices than multidose DPIs 6
Technique Considerations
- The most common technique error with DPIs is failure to "exhale to residual volume" before inhalation 5
- MDIs require precise coordination between actuation and inhalation, resulting in only 20-30% of medication being deposited in the lungs 1
- MDIs with spacers can improve drug delivery but add complexity and maintenance requirements 1
Patient-Specific Factors to Consider
When to Choose DPIs:
- For patients with adequate inspiratory flow (>30 L/min) 1
- For adolescents and adults who struggle with MDI coordination 1
- For environmentally-conscious patients 3
- For patients requiring combination therapies in a single device 1
When to Choose MDIs:
- For very young children or elderly patients with insufficient inspiratory flow
- When used with spacers for patients with very poor coordination 1
- When cost is a significant barrier (though this varies by region)
Improving Inhaler Technique
- Repetitive training (at least 3 times) significantly improves correct inhaler technique 5
- Regular technique assessment should be part of follow-up visits 1
- Patients whose mothers have lower educational status may need additional training and support 5
Conclusion
While both inhaler types have their place in therapy, DPIs offer significant advantages in terms of ease of use, environmental impact, and consistent drug delivery for most patients. The evidence suggests that for patients capable of generating sufficient inspiratory flow, DPIs should be the preferred choice over MDIs.