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Pharmacy Stage 2 > Inhaled Route of Delivery: DPI > Flashcards

Inhaled Route of Delivery: DPI Flashcards

1
Q

two types of actions from inhaled drug therapy?

A

local action and systemic action

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2
Q

where is the drug absorbed from to get into the systemic circulation?

A

the alveoli

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3
Q

what three stages do particles go through in the airways?

A
  1. deposition
  2. dissolution
  3. absorption
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4
Q

three devices used to deliver tiny pdrug particles by inhalation?

A
  1. pMDI
  2. DPI
  3. Nebulisers
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5
Q

you can either have the drug alone or the drug with carrier particles in the inhaler. What are the benefits of having the carrier particles with it?

A
  1. enhances flow
  2. reduces aggregation
  3. aids dispersion
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6
Q

two ways the drug is administered in the inhaler?

A
  1. preloaded in the inhaler

2. filled in a hard gelatin capsule or foil blister disc which are loaded into the device prior to use

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7
Q

what is the suitable size of drug powders?

A

2-5 micrometers

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8
Q

what are the issues with having small(micronized) powders?

A
  1. poor flowability
  2. rough particle surfaces
  3. powders nor completely homogenous
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9
Q

physical properties that affect powder flowability?

A
  1. particle size and shape
  2. density
  3. surface roughness
  4. hardness
  5. moisture content
  6. bulk density
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10
Q

what factors should you consider when formulating dry powder inhalers?

A
  1. crystallinity (powders crystalize as it’s a lower energy state form)
  2. size (affect deposition)
  3. hygroscopicity (measure of capacity to absorb or release water vapour)
  4. aerodynamic diameter (particle size based on idealised spherical particle structure)
  5. polydispersity (range of particle sizes around the mode)
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11
Q

what substance can be used as a carrier particle in DPI’s due to being inert?

A

lactose

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12
Q

what can be used to modify adhesion properties between drug and carrier?

A

magnesium stearate

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13
Q

what factors predict the drug deposition site?

A
  1. drug particle dispersion

2. drug particle size distribution

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14
Q

what is the issue with the carrier particles having a rough surface?

A

-they would hold the micronized drug too strongly during storage and cause the drug to be trapped in the rough areas hence the inhaled dose would be low.

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15
Q

what is the issue with using a carrier that has a smooth surface?

A

they may not stay mixed together during inhaler filling and dosing.

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16
Q

what is the benefit of mixing the rough surfaced carrier particles with micronized carriers before mixing with the micronized drug?

A

the micronized drug is free to detach from the micronized carrier whenever leaving the micronized carrier trapped in the rough carrier-particle.

17
Q

what are the formulation steps for making dry powder inhalers?

A
  1. API prep
  2. API formulation
  3. Excipients
  4. Formulation with excipients
  5. Particle Porosity
  6. Agglomerates
  7. Processing
  8. Filling
  9. Storage
18
Q

what limits the liberation of drug powders from the inhaler device?

A

the patient’s ability to inhale (breath activated)

19
Q

what are the pros and cons of a rapid airflow (fast inspiration) when using a DPI?

A

pro: increases particle deagglomeration
con: increases oropharyngeal deposition hence reducing the dose delivered to the lungs.

20
Q

what is inertial impaction?

A

high speed particles collide with airways instead of following its curvature

21
Q

what is sedimentation?

A
  • when particles are deposited due to the force of gravity and the point of sedimentation depends on the terminal velocity of the particles and their density.
  • enhanced by holding breath or slow steady breaths in spacer.
22
Q

what part of the respiratory tract does inertial impaction occur?

A

the upper respiratory tract

23
Q

what part of the respiratory tract does gravitational sedimentation occur?

A

the lower respiratory tract

24
Q

how does a unit-dose device work?

A
  • each dose is contained in a hard gelatin capsule and placed individually prior to use
  • capsule is pierced by two needles on either side
  • inhalation causes turbulence flow as the rotor rotates rapidly
  • powder disperses out into the inspired air through the perforations
25
Q

three types of unit-dose devices?

A
  1. spinhaler
  2. handihaler
  3. aerolizer
26
Q

how does a multi-dose: ‘foil in blister’ device work?

A

-drugs in a multi-dose foil blister disc
-loaded by patient
-blisters are pierced by needle in the lid
-patient inhales, drug flows out
(use until they’ve pierced all blister packs then swap)

27
Q

advantage of using a multi-dose device over a unit-dose device?

A

more convenient as no individual dosing

28
Q

give an example of a multi-dose: ‘foil in blister’ device?

A

Serevent diskhaler

29
Q

explain how a preloaded multi-haler works and give an example of one?

A
  • the drug is already loaded into the device containing 60 doses.
  • each dose is packed separately and only exposed prior to dosing
  • an example is the seretide accuhaler
30
Q

explain how a preloaded multi-haler with a reservoir works and give an example of one?

A
  • drug-lactose blend is stored in reservoir
  • metering cups filled by gravity from reservoir and delivered to an inhalation passage ready for administration
  • shake inhale before using (holds up to 200 doses)
  • example: salbutamol clickhaler
31
Q

how does a symbicort turbohaler work?

A
  • Contains 200 doses of undiluted, loosely aggregated micronized drug in a reservoir
  • Drug flows on to a rotating disc in the dosing unit with excess removed by scrapers as the rotating disc is turned.
  • no carrier needed
  • requires higher inspiratory effort than a diskhaler as has higher resistance
  • more sensitive to humidity than accuhaler.
32
Q

what is the advantage of using breath assisted device over a inhalation device?

A
  • they reduce/eliminate the reliance on patient’s inhalation effort to disperse the drug.
  • e.g. spiros was a breath assisted device which used batteries to help aerosolize the drug powder making it easier to administer.
33
Q

4 DPI classifications used in asthma and COPD?

A
  1. SABA (e.g. salbutamol, terbutaline)
  2. LABA (e.g. salmeterol, formeterol)
  3. LAMA (e.g. tiotropium)
  4. ICS (e.g. budesonide, beclometasone, fluticasone)
34
Q

pros and cons of DPI’s?

A 
Pros:
1. environmentally friendly
2. stable formulation as 1 phase
3. easy to use
cons:
1. deposition related to inspiratory flow rate
2. dexterity issues 
3. dose uniformity of powders
4. complex manufacture so expensive

Pharmacy Stage 2 (85 decks)

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