Routes of Administration - Inhalation Flashcards
Can you prescribe inhaler as a pharmacists?
You need to be an IP
How to council patient to use an inhalier?
- Remove cap (some must be squeezed at the sides to release)
- Check dose counter (if device has one)
- Hold inhaler upright and shake well
- Breathe out gently (away frominhaler)
- Put mouthpiece between teeth (without biting) and close lips to form good seal
- Start to breathe in slowly through mouth and at the same timepress down firmly on canister
- Continue to breathe in slowly and deeply
8.Hold breath for about 5 – 10 seconds or as long as comfortable - While holding breath, remove inhaler from mouth
- Breathe out gently (away from inhaler)
- If more than onedose is needed, repeat all steps starting fromstep 3
- Replace cap
Emergency supply of salbutamol
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
What is pulmonary drug delivery?
provides a noninvasive, alternative method to subcutaneous injection, and also intravenous injection
Pulmonary drug delivery; two routes
Local or topical drug administration
1] Asthma
COPD
Cystic fibrosis
Pulmonary hypertension
Lung infections?
2] Systemic application via the lung
CNS stimulation
Anaesthetics
Diabetes?
Pain and migraine?
Appetite suppression?
Systemic: Inhaled insulin
Because of the route of administration, many respiratory adverse effects were reported, including increased risks of respiratory infection, cough, pharyngitis, and rhinitis
How do we deliver drugs to or via the lungs?
Solid in gas: Solid particles suspended in air, e.g. smoke
Liquid in gas: Liquid particles suspended in air, e.g. mist
Gases
But how do the solids/liquids/gases really get to where we want them to go?
It’s about engineering
Anatomy of the mouth, throat and lung
a) Upper airways
b) Central/conducting airways
c) Respiratory/peripheral/pulmonary airways
Upper airways
- Spheroidal sinus
- Middle turbinate
- Inferior turbinate
- Nasopharynx
- Oropharynx
- Larynx
Central/conducting airways
- Trachea
- Main bronchus
- Large sub-segmental bronchus
- Small bronchus
- Bronchiole
Respiratory/peripheral/pulmonary airways
- Terminal bronchiole
- Respiratory bronchiole
- Alveolar ducts and sacs
Revise the structure of lungs
Label the lungs
Branching of the lungs
Halving the radius produces 1600% increase in airflow resistance
- 1% decrease in diameter = 4% increase in resistance
Airflow ________ with _______ branching.
decreases
increasing
Difference between healthy adults and adults with diseases;
> healthy airway (clear diameter)
asthmatic airway - tight, shorter diameter, lining of the airways becomes swollen and inflamed
COPD airway - bronchial tubes become inflamed and narrowed and your lungs produce more mucus, which can further block the narrowed tubes
> healthy alveoli - effective for the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out
Alveoli with emphysema - the walls of the alveoli are partially destroyed
> Healthy airway - clear
Cystic fibrosis airway - filled with thick, sticky mucus, making it difficult to breathe
Airflow in the lung is affected by the disease
- Obstructive lung disease
Asthma
COPD
Cystic fibrosis - Restrictive lung disease
Interstitial lung disease, such asidiopathic pulmonary fibrosis
Obesity
What is the Drug delivery to the lungs?
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
Inertial impaction
Inertial impaction tends to occur 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)
What is inertial impaction influenced by?
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%
Sedimentation meaning;
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
How is sedimentation influenced>]?
Breath-holding, allows more time for gravity to have an effect
Important for particles 0.5 μm < daero < 5 μm
2 μm – 55%
1 μm – 29%
0.5 μm – 10%
DIFFUSION
Which particles?
Minor mechanisms?
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
Aerodynamic diameter
Equation - what each letter means?
dae = dg (ρ0.5)
Aerodynamic diameter (dae) is dependent on the geometric diameter (dg), shape factor (1 for spheres) and density (ρ) of the particle
dae = Aerodynamic diameter
Diameter of a sphere with the same terminal velocity in air or some other relevant fluid as the particle
Factors Influencing lung deposition
Particle size
Particle size distribution
Particle density
Particle shape
Particle hygroscopicity
Deposition —> Absorption [upper airways]
Mucociliary escalator
(local drug concentration ↓ )
Drug dissolution
(local drug concentration ↑ )
Deposition —> Absorption [alveolar region]
Macrophage clearance
(local drug concentration ↓ )
Translocation/efflux
(local drug concentration ↓ )
Deposition —> Absorption [summary]
Dissolution > Clearance > Mucus direction > Phagocytosis > Translocation > To cells, blood 7 lymph
Formulation Selection - Step by step
Beclomethasone dipropionate metered dose inhaler
1) Released (60%)
2) Deposited (20%)
3) Permeated (2%)
4) Efficacy (0.24%)
Factors influencing lung deposition
Particle size
Particle density
Particle shape
Particle hygroscopicity
Propellants
Inhaler types
metered-dose inhaler + (spacer)
Accuhaler / Diskus
Handihaler
Respimat
Turbohaler
(Nebuliser)
Quality control
Deposition of emitted dose
Content uniformity
Aerodynamic particle size distribution
Spray pattern
Advantages of local delivery of drugs to the lungs
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
Disadvantages of local delivery of drugs to the lungs
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
Advantages of systemic delivery of drugs via the lungs
Very rapid onset of action
Circumvents first pass effect
Non-invasive delivery route
Good for biopharmaceuticals
Disadvantages of systemic delivery of drugs via the lungs
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
OTC inhalator
When a patient draws air into the mouth through the mouthpiece, nicotine is vaporised and absorbed by the buccal mucosa into the bloodstream
How to use Nicorette inhalator?
1) Line up the markers and pull each end in the opposite direction
2) Insert the cartridge into the mouthpiece and twist to close securely
3) 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
