Drug Delivery Systems

Question 1

What are the three main factors considered when making up a dosage regime?

Answer 1

o The dose of the drug to be given
o The frequency of administration
o The timing of administration

Question 2

What is the rate-limiting step in absorption of oral tablets?

Answer 2

Dissolution or tablet break down is the rate limiting step in absorption

Question 3

What are the advantaged of giving drugs as pills or tablets?

Answer 3

o	Convenience
o	Accuracy of dose
o	Reproducibility
o	Drug stability
o	Ease of mass production

Question 4

What are enteric coated capsules?

Answer 4

Enteric coating delays disintegration of the tablet by gastric acid until it reaches the small intestine

Question 5

Why are drugs enteric coated?

Answer 5

o Protect the drug from stomach acid

o Protect the stomach from the drug

Question 6

Why are prolonged release formulations useful?

Answer 6

o Most disorders required prolonged therapy
o Maintains drug levels within a therapeutic range
o Reduces the need for frequent dosing
o Compliance is improved
o Improved nursing and doctor compliance

Question 7

What are pro-drugs?

Answer 7

Pro-drugs are synthesised inactive derivatives of an active drug which requires to be metabolically activated after administration

Question 8

What are the advantages of pro-drugs?

Answer 8

o Prolongation of duration of action

o Avoidance of degradation of the drug in the gut

Question 9

Why are buccal and sublingual drugs useful?

Answer 9

Ideal method for drugs which have extensive pre-systemic or first pass metabolism

Question 10

When would rectal suppositories, creams and solutions be useful?

Answer 10

Useful in the young or old
Patients unable to swallow
To treat local conditions such as proctitis
To achieve systemic absorption (indomethacin)
Bypass pre-systemic metabolism

Question 11

Whats the benefit of injection based drug administration?

Answer 11

• Provide fast systemic effects bypassing first-pass metabolism
• Drugs can be administered in unconscious or comatose patients
• Drugs having short half-life can be infused continuously

Question 12

What are the three methods of injection based drug administration?

Answer 12

• Intramuscular
• Intradermal
• Subcutaneous

Question 13

When are drugs given intravenously?

Answer 13

o A rapid onset of action is required
o Careful control of plasma levels is required
o A drug has a short half-life

Question 14

When are intramuscular injections usually used?

Answer 14

• Allows a more sustained duration of action up to months
• Depot injections of contraceptives and neuroleptics

Never if they have an issue with clotting!

Question 15

What are the benefits of subcutaneous injection?

Answer 15

Easy to use and bypasses need for venous access

Question 16

What are the benefits of transdermal delivery?

Answer 16

Bypasses first-pass hepatic inactivation
Easy to use
Good patient compliance

Question 17

Describe the advantages of drug inhalation

Answer 17

o	Drug delivered directly to site of action
o	Rapid effect
o	Small doses used
o	Little systemic absorption
o	Reduced adverse effects

Question 18

What are the disadvantages of drug inhalation?

Answer 18

Patient education is essential

Question 19

What are liposomes?

Answer 19

Liposomes are self-assembling closed colloidal structures composed of lipid bilayers and have a spherical shape in which an outer lipid bilayer surrounds a central aqueous space. Synthesised from cholesterol and can be used as drug delivery systems

Question 20

What are the benefits of nanoparticle based drug delivery?

Answer 20

More specific drug targeting and delivery, which also reduces side effects and toxicity