3c. Dry Powered Inhaler

Question 1

What is a DPI?

Answer 1

It’s a breath actuated system with no propellant, to administer dry-powder formulations to the lungs

Question 2

How does DPI generate aerosol?

Answer 2

The patient creates the aerosol by drawing air though a dose of finely milled drug powder with sufficient force to disperse and suspend the powder in the air

Question 3

What’s the Inspiratory Flow Rate required for DPI?

Answer 3

Inspiratory Flow Rate per Egans is 40-60LPM minimum. But >60LPM is preferred for efficient drug delivery.

Question 4

Advantages of DPIs (5)

Answer 4

‣ Doesn't require hand-breath coordination
‣ Breath activated 
‣ Can provide accurate dose count
‣ Breathe holding not required
‣ No propellants

Question 5

Disadvantages of DPIs (3)

Answer 5

‣ Dependence on Patient’s Inspiratory Flow
‣ High oropharyngeal deposition
‣ Difficult to deliver high doses

Question 6

What is required for effective lung deposition?

Answer 6

With a high inspiratory flow rate, there should be a creation of Turbulent Flow to disperse the powder into respirable particles

Question 7

What are the 3 categories of DPIs?

Answer 7

Single Dose, Multiple Unit-Dose, and Multiple-Dose

Question 8

How does a Single Unit Dose Work, and what are examples (4)?

Answer 8

Single Unit Dose (ex. Aerolizer, HandiHaler, TOBI Podhaler, Neohaler)
Dispenses individual doses of drug from punctured gelatin capsule

Question 9

How does Multiple Unit-Dose work? and what is an example?

Answer 9

Multiple Unit-Dose (ex. Diskhaler), contains a case of 4-8 blister packets of medication. Each blister is mechanically punctured when the cover is lifted

Question 10

How does the Multiple Dose work? and what are examples?

Answer 10

Multiple Dose (ex. Twisthaler, Flexhaler, Diskus, Respiclick, Ellipta, Pressair).
Preloaded with quantity of pure drug sufficient for dispensing 30-120 doses depending on medication

Question 11

Factors that affect DPI performance (3)

Answer 11

‣ Intrinsic Resistance and Inspiratory Flow Rate
‣ Exposure to Humidity and Moisture
‣ Patient’s Inspiratory Flow Ability

Question 12

Why is the exposure to humidity and moisture a factor that will affect DPI performance?

Answer 12

If there’s moisture, for example when you breathe into the device, the moisture will cause the medication to clump up.

Question 13

Which patients can’t use DPI? (3)

Answer 13

Patients who are unable to follow instructions, Infants, and patients with severe airway obstruction, because they can’t develop a high inspiratory flow rate

Question 14

What are the particle size range for dry powder?

Answer 14

1-3 um for the drug. But the lactose or glucose particles can range from approx 20-65um.

Question 15

What’s the proper technique to use a DPI (Step by step)?

Answer 15

1. Assemble the apparatus
2. Load the dose and keep it upright
3. Exhale slowly to FRC (keeping the device away to prevent exhaled moisture inside)
4. Seal lips around the mouthpiece
5. Inhale deeply and forcefully >60LPM. Breath holding is encouraged but not essential.
6. Repeat process until unit dose is complete
7. Monitor adverse reactions and beneficial effects

Question 16

Multiple-Dose DPI: What’s the drug container and the doses for Diskus, Flexhaler, and Twisthaler?

Answer 16

Diskus ➔ Blister Strip ➔ 60
Flexhaler ➔ Reservoir ➔ 60 or 120
Twisthaler ➔ Reservoir ➔ 30