Pulmonary drug delivery

Question 1

pulmonary drug delivery is the same as nasal drug delivery, true or false

Answer 1

false

Question 2

the pathway of drugs after inhalation

Answer 2

deposited in the lungs, then it’s absorbed from the lungs into systemic circulation

10-20% of the inhaled drug remains in the lungs

Question 3

the lungs are the most exposed organs to the enmvironment, true or false

Answer 3

true

Question 4

which side of the lung is slightly larger than the other and why

how many lobes does each side of the lung have

Answer 4

left lung larger, as 2/3 of the heart located on the left side of the body

3 for right
2 for left

Question 5

anatomically the respiratory tract is divided into?

Answer 5

**1. Upper respiratory tract
2. Lower respiratory tract
**

Question 6

upper respiratory tract consists of the?

lower?

Answer 6

nose
sinuses
mouth
pharynx
larynx

trachea
bronchi
bronchioles
lungs

Question 7

functionally the respiratory tract is divided in two zones, what are they

Answer 7

conducting zone (carries air to the site of gas exchange )

respiratory zone(site of gas exchange)

Question 8

describe the tracheobronchial tree

Answer 8

The tracheobronchial tree is a branching system of airways, starting with the trachea and continuing through the bronchi and bronchioles, that transports air to the lungs for gas exchange.

Every branching of the TBT produces a new generation of airways

i.e (larynx and trachea = generation 0)
from respiratory bronchioles (generation 17) to alveolar sacs (generation 23).

Question 9

the higher the TBT generation, the larger the diameter of the airway, true or false

Answer 9

false
the highern the generation the smaller the diameter

Question 10

name of cells lining the aveoli in the lungs

Answer 10

pneumocytes

2 types, type 1 and 2

95% of alveoli lined with type 1

Question 11

typen 1 pneumocytes function
type 2 function

Answer 11

Primarily responsible for gas exchange (oxygen and carbon dioxide) between the air in the alveoli and the blood in the capillaries.

Where surfactant is secreted and prevents aveoli from collapsing.

type 1 are thin and squamous, type 2 are cuboidal

Question 12

clara cells

Answer 12

Clara cells are** non-ciliated, secretory epithelial cells** found in the respiratory bronchioles,

Question 13

mucus and cilia are present in the aveolar region of the lungs, true or false

Answer 13

false

unless there is an abnormality

Question 14

function of alveolar macrophages

Answer 14

they engulf and digest particles deposited in the alveoli, thereby clearing it

Question 15

how does alveolar clearance occur

Answer 15

alveolar macrophages engulf and digest particles

The engulfed material may be (1) taken to the ciliated TBT region where mucociliary escalator takes charge of clearance

or the material is taken via the lymphatic system to the lymph nodes and then to the blood circulation. Finally, the material might be cleared by the kidneys

The ciliated mucus that extends from the terminal
bronchioles to the upper airways is known as the
mucociliary escalator.

Question 16

what happens tp particles in the pulmonary system after they have been inhaled

Answer 16

they could be coughed out(large partivcles mostly)

mucus may act as a barrier preventing them from geeting into the lower respiratory tract, mainly the aveoli

mucocilliary clearance

alveolar clearance

the viscosity of the pulmonary mucus slows down drug dissolution rate, esp for DPIs

Question 17

advantages of pulmonary drug delivery

Answer 17

Large SA, increased permeability, appropriate vascularity for systemic drug absorption

rapid onset of action

lower therapeutic doses (as no first pass metabolism. gets to lungs directly)

lower systemic side effects if any at all

no GI side effects

targeted delivery…etc

Question 18

disadvantages of pulmonary drug delivery

Answer 18

Local SEs (drug deposition in the upper respiratory tract).

Techniques differ between device categories.

Correct use / training.

Irreproducibility.

The mucus layer: physical absorption barrier.

Mucociliary clearance.

may be Less convenient than oral drug
administration for certain ppl

Question 19

the three main types of devices used to generate aerosols for inhalation

Answer 19

Pressurised metered-dose inhalers (pMDIs).
Dry powder inhalers (DPIs).
Medical nebulisers

these aim to produce an aerosol from the drug solution or solid particles

An aerosol is a suspension of fine solid particles or liquid droplets in a gas, typically air.

Question 20

the main constituents of a pMDI

Answer 20

A container (canister) – chemically inert towards the formulation.

2. A propellant in which the drug is dissolved or suspended.
3. A metering valve – designed to release a fixed dose on actuation.
4. An actuator – contains an orifice through which the aerosol is released

Question 21

name the propellant class used in pMDIs and which previous propellant it replaced

Answer 21

**HFA (hydrofluoroalkane) propellants **are low-boiling liquids used in metered-dose inhalers (MDIs) to deliver medication, replacing chlorofluorocarbons (CFCs) which damage the ozone layer.

Question 22

do we always have to offer spacers with pMDIs

Answer 22

no, but it is recommended, to help with delivery of the drug to it’s target(lung)

Question 23

disadvantages of pMDIs

Answer 23

hand-breath coordination required
ineffective sometimes in poorly ventilated patients
Oropharyngeal deposition and local side effects

Question 24

DPIs are passive and patient driven, true or false

Answer 24

true

note this makes them more suitable for patients with good inhalation capacities

Question 25

DPI devices can be low-resistant and up to high resistant devices, what does this mean? and how does the level of resistance of a DPI associate to it's inspiratory flow?

Answer 25

how much the device "slows down" or "restricts" your inhaled airflow. for low resistance devices, it is Very easy to suck air through → But needs fast, forceful inhalation to break powder(higher inspiratory flow required ) for high resistance devices, Harder to suck air through making it easier to create turbulence → But device uses turbulence to break down the powder → works even at slower inhalation(lower inspiratory flow required )

Question 26

in DPIs, what is the dispersion of the powder into respirable drug particles dependent on

Answer 26

it is dependent on the creation of a turbulent flow in the inhaler. this turbulent flow happens based on the patient's inspiratory flow rate, and the devices level of resistance. ## Footnote i.e the higher the resistance of the device, the less inspiratory power/ inspiratory flow rate is required to create tubulence in the device, which causes the dispersion of the powder

Question 27

most DPIs require the use a carrier substance. what are some examples of carrier substances that could be used

Answer 27

lactose and glucose these allow the powder to flow more readily out of the device

Question 28

the three types of medical nebuliser are ?

Answer 28

Air-jet nebulisers Ultrasonic nebulisers Vibrating-mesh nebulisers(can be passive or active) ## Footnote A nebulizer is a medical device that transforms liquid medication into a fine mist, allowing for easy inhalation into the lungs

Question 29

the three main mechanisms of particle deposition in the lungs

Answer 29

Inertial impaction. Sedimentation. Brownian diffusion. ## Footnote Brownian diffusion, also known as Brownian motion, describes the random movement of particles suspended in a fluid (liquid or gas) due to the constant bombardment of surrounding molecules

Question 30

what size must an aerosol be to be coonsidered therapeutically useful and why

Answer 30

less than 5 micrometers. because such particles are more likely to be deposited in the deep lung. ## Footnote **Deep lung= peripheral airways=lower respiratory tract** basically the smaller the particle size, the higher the systemic absoprtion. if greater than 5um, the drug may only be deposited in the mouth or oesophagus, and may be swallowed(G.I).

Question 31

what name is given the fraction of drug that deposits into the peripheral airways(aka lower respiratory tract)

Answer 31

The fraction of drug that deposits in the peripheral airways is called **“fine particle fraction (FPF)”, or “respirable fraction”**