W11 Routes Of Administration- Inhalation

Question 1

What is meant by an Emergency supply of salbutamol?

Answer 1

In an emergency, as a pharmacist working in a registered retail pharmacy, you can supply prescription-only medicines (POMs) without a prescription at the request of a relevant prescriber or a patient.

Question 2

Steps of How to use a salbutamol inhaler:(pMDI)

Answer 2

1. Remove cap (some must be squeezed at the sides to release)
2. Check dose counter (if device has one)
3. Hold inhaler upright and shake well
4. Breathe out gently (away from inhaler)
5. Put mouthpiece between teeth (without biting) and close lips to form good seal
6. Start to breathe in slowly through mouth and at the same time press down firmly on canister
7. Continue to breathe in slowly and deeply
8. Hold breath for about 5 – 10 seconds or as long as comfortable
9. While holding breath, remove inhaler from mouth
10. Breathe out gently (away from inhaler)
11. If more than one dose is needed, repeat all steps starting from step 3
12. Replace cap

Question 3

What is a pMDI?

Answer 3

Pressurised metered-dose inhaler

Question 4

Pulmonary drug delivery- Two routes and conditions they treat

Answer 4

Local or topical drug administration:
* Asthma
* COPD
* Cystic fibrosis
* Pulmonary hypertension
* Lung infections?

Systemic application via the lung:
* CNS stimulation
* Anaesthetics
* Diabetes
* Pain and migraine
* Appetite suppression

Question 5

Systemic: Inhaled insulin
What was the issue?

Answer 5

Because of the route of administration, many
respiratory adverse effects were reported,
including increased risks of respiratory infection, cough, pharyngitis, and rhinitis.

Question 6

How do we deliver drugs to or via the lungs?

Answer 6

• Solid in gas: Solid particles suspended in air, e.g. smoke
• Liquid in gas: Liquid particles suspended in air, e.g. mist
• Gases

Question 7

How does Branching of the lungs impact airflow?

Answer 7

• Halving the radius produces 1600% increase
  in airflow resistance
• 1% decrease in diameter = 4% increase in
  resistance

Airflow decreases with increasing branching

Question 8

Airflow in the lung is affected by which
diseases?

Answer 8

Obstructive lung disease:
* Asthma
* COPD
* Cystic fibrosis

Restrictive lung disease:
* Interstitial lung disease, such as idiopathic pulmonary fibrosis
* Obesity

Question 9

What problem can occur in drug delivery to the lungs?

Answer 9

Particles entering the respiratory tract are prevented from reaching the terminal bronchioles and alveoli by mechanisms which cause them to be caught by the mucous sheath lining the tubules.

Question 10

What is inertial impaction?

Answer 10

-Inertial impaction tends to occur in the upper airways when the velocity and mass of the particles cause them to impact the airway surface

Question 11

Aerodynamic diameter

Answer 11

d_ae = Aerodynamic diameter
* Diameter of a sphere with the same terminal
velocity in air or some other relevant fluid as the
particle

• Aerodynamic diameter (dae) is dependent on the geometric diameter (dg), shape factor (1 for spheres) and density (ρ) of the particle

Question 12

Factors Influencing lung deposition (6)

Answer 12

• Particle size
• Particle size distribution
• Particle density
• Particle shape
• Particle hygroscopicity- ability to absorb moisture
• Propellants

Question 13

What are the function of Cilia?

Answer 13

Wafts drug away so reduces drug absorption

Question 14

Inhaler types

Answer 14

• Pressurized metered-dose inhaler + (spacer)
• Accuhaler / Diskus
• Handihaler
• Respimat
• Turbohaler
• (Nebuliser)

Question 15

Things to consider in manufacturing of an inhaler-quality control

Answer 15

• Deposition of emitted dose
• Content uniformity
• Aerodynamic particle size distribution
• Spray pattern

Question 16

What are the advantages of pulmonary drug delivery?

Answer 16

Advantages:
* Drug delivered directly to target organ
* Lower doses may be required for optimal effect
* Rapid onset of action
* Fewer systemic side effects
* Non-invasive delivery

Question 17

What are the disadvantages of pulmonary drug delivery?

Answer 17

• Low efficiency of delivery
• Difficulty in breath coordination, manual handling of device, or breathing through the device
• Corticosteroid use can suppress immune response
• Throat irritation is possible

Question 18

Advantages of systemic delivery of drugs via the lungs

Answer 18

• Very rapid onset of action
• Circumvents first pass effect
• Non-invasive delivery route
• Good for biopharmaceuticals

Question 19

Disadvantages of systemic delivery of drugs via the lungs

Answer 19

• Low efficiency of delivery
• Some patients may have difficulty using some devices (handling
  and coordination)
• Some patients may have difficulty breathing (through the device)
• May need very low or very exact doses or special devices
• Expensive compared with oral therapies

Question 20

What are the reasons as to why the OTC ‘Inhalator’ is NOT an inhaler:

Answer 20

Doesn’t deliver drug to the lungs like an inhaler
* When a patient draws air into the mouth through the
mouthpiece, nicotine is vaporised and absorbed by the buccal mucosa into the bloodstream

Question 21

How to use a Nicorette inhalator?

Answer 21

• Line up the markers and pull each end in the opposite direction
• Insert the cartridge into the mouthpiece and twist to close securely
• When you have a craving take a shallow puff about every 4 seconds or take 2 deep puffs every minute. Each cartridge lasts for approximately 40 minutes of frequent puffing

Question 22

Anatomy of the mouth, throat and lung

Answer 22

Upper airways:
- Spheroidal
- Sinus
- Middle
- turbinateInferior
- turbinateNasopharynx
- Oropharynx
- Larynx

Central/conducting airways:
Trachea
Main bronchus
Large
subsegmental
bronchus
Small
bronchus
Bronchiole

Respiratory/peripheral/pulmonary airways:
Terminal Bronchiole
Respiratory
bronchiole
Alveolar ducts and sacs

Question 23

Drug delivery to the lungs:

How are particles entering the respiratory tract hindered?

Answer 23

Particles entering the respiratory tract are prevented from reaching the terminal bronchioles and alveoli by mechanisms which cause them to be caught by the mucous sheath lining the tubules

Question 24

Where does Inertial impaction occur?
What does it depend upon?
(for info)

Answer 24

In the upper airways when the velocity and mass of the particles cause them to impact the airway surface.

Whether impaction occurs depends upon:
- The particle’s momentum (dependent upon size)
- The position of the particle in the airstream of the parent branch
- The angle of bifurcation (°θ)

• Inertial impaction can be influenced to some degree by
  hyperventilation
• Impaction is of significance for the largest particles moving at the highest speed in the respiratory tract
• 10 μm particle has a 50% chance of impaction
• 5 μm – 20%
• 3 μm – 10%
• 1 μm – 1%

Question 25

Sedimentation (for info)

Answer 25

• Particles suspended in a gas are subject to the vertical
  gravitational force
• Sedimentation is the dominant mechanism for particles
  depositing in the lower/peripheral airways
• Tends to be influenced by breath-holding, which allows more
  time for gravity to have an effect
• Important for particles 0.5 μm < daero < 5μm
• 2 μm – 55%
• 1 μm – 29%
• 0.5 μm – 10%

Question 26

Diffusion (for info)

Answer 26

• Diffusion = dominant mechanism for particles < 0.5 μm
• The smaller the particles, the more they deposit via diffusion in the peripheral lung and alveolar space

Minor mechanisms of deposition:
* Interception for elongated particles
* Charge reflection for charged particles

Question 27

What is inertial impaction?

Answer 27

-Inertial impaction tends to occur in the upper airways when the velocity and mass of the particles cause them to impact the airway surface

Inertial impaction is a mechanism by which particles suspended in air can be deposited in the lungs. When air carrying these particles flows through the airways of the lungs, the particles tend to continue moving in a straight line due to their inertia. As a result, they can collide with the walls of the airways and become deposited there.

This mechanism is particularly effective for particles that are larger than about 2.5 micrometers in diameter, such as pollen, dust, and some types of pollution. These particles are too large to follow the normal airflow patterns in the lungs and are instead affected more by their inertia.

Inertial impaction is one of several mechanisms by which particles can be deposited in the lungs, along with sedimentation, diffusion, and electrostatic attraction. The deposition of particles in the lungs can have negative health effects, as they can cause inflammation and other respiratory problems.