Dry powder inhalers

Question 1

DPIs are driven by what?

Answer 1

Flow inspiration

Question 2

What creates the energy required for fluidisation and entrainment of the formulation and deaggregation of the drug for delivery?

Answer 2

The patient’s forced inspiratory action

Question 3

No co-ordination skill is required for pMDIs or DPIs?

Answer 3

DPIs

Question 4

Patients need to generate what to produce the energy required to deliver the dose?

Answer 4

a minimum inhalation flow (Qmin)

Question 5

The energy is created by the pressure drop(ΔP) that results from what?

Answer 5

The inhalation flow (Q) and the internal resistance of the device (R)

Question 6

Internal resistance of the device affects what?

Answer 6

Speed and acceleration of airflow through the device

Question 7

Speed of inhalation affects what?

Answer 7

How much drug is deposited in the lung

Question 8

Can generic inhaled formulations be approved if they have in-vitro similarity?

Answer 8

Yes

Question 9

What ways are there of approving a generic inhaled formulation?

Answer 9

In vitro similarity
Lung deposition equivalent and systemic PK similarity
Efficacy pharmacodynamics and systemic PK similarity
Lung deposition equivalent and safety pharmacodynamics equivalence

Question 10

Delivery of respirable dose is dependent on what 3 factors?

Answer 10

Powder formulation
Inhalation device
Patient inspiratory flow

Question 11

Particle interactions are primarily dictates by what?

Answer 11

Van der waals forces
Eelectrostatic forces
Capillary forces

Question 12

What is the dominant force at low humidity in the absence of electrostatic forces?

Answer 12

Van der waals

Question 13

Is van der waals a short rang or long range force?

Answer 13

Short

Question 14

What are capillary forces?

Answer 14

Condensation of water vapour between contiguous bodies which forms a liquid bridge

Question 15

The magnitude of capillary force directly relates to what?

Answer 15

Relative humidity and hydrophobicity

Question 16

What is the dominant force under ambient conditions?

Answer 16

capillary forces

Question 17

What are electrostatic forces caused by?

Answer 17

Frictional contact (triboelectrification) between dissimilar materials

Question 18

Are electrostatic forces long or short range forces?

Answer 18

Long

Question 19

What interactions are to be controlled and modified?

Answer 19

Drug-drug interactions (cohesion)
Drug-excipient interactions (adhesion)
Drug-device interactions (segregation)

Question 20

What formulation strategies are there for DPIs?

Answer 20

Carrier-based systems

Agglomerated systems

Question 21

What is an example of a carrier based excipient?

Answer 21

a-lactose monohydrate

Question 22

What are the advantages of carrier based formulations?

Answer 22

Allows accurate metering of small quantities of potent drug

Improves processing of formulation

Question 23

Modified lactose gives a what fold increase in therapeutic dose of salbutamol sulphate?

Answer 23

2.5

Question 24

Fine particle lactose blending gives a what fold in therapeutic dose of salbutamol sulphate?

Answer 24

2

Question 25

What are agglomerated powder systems used for?

Answer 25

High dose drugs, whereby formulation as carrier-based systems is not feasible

Question 26

How are free flowing macroscopic agglomerates produced?

Answer 26

Via cohesive bond formation

Question 27

What needs to happen to agglomerated powder systems before the drug is presented to the lungs as discrete particles?

Answer 27

Deaggregation