Patches, injections and inhalers

Question 1

Which two methods is transdermal drug delivery achieved by?

Answer 1

matrix

rate limiting membrane

Question 2

The adhesive layer on a transdermal patch creates a _______ gradient and adheres to the skin

Answer 2

diffusion

Question 3

What are the advantages of transdermal drug delivery?

Answer 3

bypass first pass metabolism
Systemic effects
controlled constant rate of delivery
long duration of action - up to 7 days

Question 4

What are the disadvantages of transdermal drug delivery?

Answer 4

Can cause skin sensitisation
patch may fall off
not suitable for all drugs
appearance
hairy areas of skin

Question 5

Injections may be freeze dried for reconstitution with water for injection. True or false?

Answer 5

True

Question 6

Are intravenous injections o/w or w/o?

Answer 6

o/w

Question 7

In an emulsion injection, what happens if the globule size is too large?

Answer 7

may cause an embolism

Question 8

Are intramuscular injections o/w or w/o?

Answer 8

w/o

Question 9

What are the advantages of injections?

Answer 9

Can be used for local or systemic effects
Bypass GIT and therefore first pass metabolism
Can be used if oral route not available
Rapid onset of action or prolong release

Question 10

What are the disadvantages of injections?

Answer 10

Invasive/painful
Difficult to administer in some patients
Patients fear of needle
Risk of infection/embolism

Question 11

In inhalers, the smaller the particle size the further down the respiratory tract the drug will penetrate. True or false?

Answer 11

True

Question 12

What happens if the particle size of a drug in the inhaler is less than 1um?

Answer 12

The particle will be exhaled

Question 13

What happens if the particle size of a drug in the inhaler is more than 10um?

Answer 13

Particle will remain in the oropharynx

Question 14

What is the optimum size for drug particles in inhalers?

Answer 14

3-5um

Question 15

In MDIs, actuation results in the _______ of propellent to form droplets to be inhaled into the lung

Answer 15

evaporation

Question 16

What must a patient do to disperse the propellant and drug?

Answer 16

Shake the aerosol

Question 17

What type of inhalers are spacers used with?

Answer 17

MDIs only

Question 18

What are spacers used for?

Answer 18

Remove the need for coordination - children and infants must always be prescribed spacers with MDI

Question 19

How do breath actuated inhalers work?

Answer 19

Inhalation triggers actuation of the device

Question 20

What are the excipients for MDIs?

Answer 20

Propellant - gases at room temp are maintained as liquids under pressure in metal aerosol canister
Surfactants
Co-solvents

Question 21

What are surfactants used for in MDIs?

Answer 21

To aid wetting of the suspension

Question 22

What are co-solvents used for in MDIs?

Answer 22

To aid dissolution

Question 23

Are propellants required in dry powder inhalers?

Answer 23

No

Question 24

What are the excipients for DPIs?

Answer 24

Carrier for the drug e.g. lactose

Pure drug

Question 25

MDIs are more stable than DPIs. True or false?

Answer 25

True - because of packaging, DPIs are susceptible to moisture degradation

Question 26

What are the advantages of inhalers?

Answer 26

Can use small doses
Reduced systemic side effects
Fast onset of action
Can use drugs with poor oral bioavailability 
MDIs are cheap

Question 27

What are the disadvantages of inhalers?

Answer 27

Difficult technique
Not suitable for all drugs
Only 20% of drug reaches the lungs
Inflammation can reduce the size of the airways
Cost of DPI