PR2154 IC6 inhalation devices

What are the three types of inhalation devices we need to know?

Metered dose inhaler

Dry powder inhaler

Nebulizer

What are the advantages of using a metered dose inhaler?

cheap

portable

easy to use in critical situations

high sealability (prevent microbial contamination)

What are the disadvantages of using a metered dose inhaler?

high spray velocity → cold freon sensation at the back of the throat (that’s why we use spacer)

Need to coordinate inhalation (special population needs to be considered)

What is the basic formulation structure in Metered dose inhaler?

Drug substance (active ingredient)

Propellant

Surfactant

Lubricant

Co-solvent

How does the drug exit the MDI?

drug encapsulated in a droplet made of propellant, which evaporates and forms a spray plume

What is the vapour pressure keps at in the metal canister of MDI?

3-5 bar (atm is 1 bar)

What is the volume delivery of metering valve?

20-100microL

20-5000micro grams of drug

What are some of the requirements for propellants?

Toxicologically safe

nonflammable

chemically inert

appropriate boiling points and densities

Why is propellant kept as liquefied compressed gas?

It provides the driving force and energy source for atomization of the formulation upon actuation

What are some common propellants used?

Chlorofluorocarbon (CFC)

Hydrofluoroalkane (HFA)

Why do we need to shake the canister before using?

the propellant has a different density

What are the common used CFC propellants?

Trichlorofluoromethane CFC11 → 3 Cl 1 F

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Dichlorodifluoromethane CFC12 (most popular) → 2 Cl 2 F

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Dichlorotetrafluoromethane CFC114 → 1 Cl 2 F C-C

What are some advantages of using CFC as propellant?

Good solvent

Low flammability

Low toxicity

What are some disadvantages of using CFC as propellant?

Destroy ozone layer

a significant greenhouse gas→ climate change

CFC114 worse global warming potential ATM life 200 years

what are some commonly used hydrofluoroalkane HFA?

Tetrafluoroethane (HFA 134a)

Heptafluoropropaone (HFA 227)

What are some advantages of using HFA as propellant?

Good solvent

Low flammability

Low toxicity

Does not destroy ozone layer

What are some disadvantages of using HFA as propellant?

Greenhouse gas→ climate change (less severe than CFC)

What are the considerations in choosing a propellant?

Global warming potential

Vapour pressure (we want high pressure to liquify the propellant 5 bar

Boiling point

How does vapour pressure affect propellant?

it determines the speed and rate of evaporation

It affects the aerosol droplet size → affecting the efficiency of deposition within the lung

\
higer VP→ more rapid propellant evaporation → smaller droplets

How does boiling point affect propellant?

impacts on the method of filling the canister

CFC 11 → prepatration of hte formulation as liquid at room temp.

What is the target apparent solubility of HFA 134a?

2-5% at least.

50% is very good

what is the best Solvent to be used for HFAs?

Plutonic 10-R5

What are the three types of nebuliser?

Jet

Ultrasonic

Mesh

What are the advantages of nebuliser as compared to MDI and DPI?

Do not need patient coordination between inhalong and actuating → Special population (pediatric, elderly, un-conscious)

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Larger doses (longer administration duration)

What is the role of carrier powder in a powder formulation im DPI?

to prevent agglomeration of powder