drug absorption

Question 1

List the 4 main absorption routes via. the GI tract

Answer 1

Oral (most common
Buccal
Sublingual
Rectal

Question 2

List forms of oral absortption

Answer 2

Solutions + suspensions
Tablets + capsules
Enteric coated tablet

Question 3

Describe advantages of solutions and supsensions

Answer 3

Useful for the elderly, young and patients with swallowing difficulties
Extremely rapid absorption (small intestine most rapid)

Question 4

What is a suspension

Answer 4

Coarse drugs in the liquid phase - good for unpalatable drugs

Question 5

Give advantages of tablets and capsules

Answer 5

Convenient
Stable
Accurate dose
Reproducable
Mass production

Question 6

Describe enteric coated drugs

Answer 6

Delayed disintegration of tablet until it reaches the small intestine
Can protect drug from the stomach acid OR protect stomach from drug eg aspirin

Question 7

Describe and give advantages of the buccal/ sublingual routes

Answer 7

Ideal for drugs with extensive first pass metabolism

Dissolve slowly under tounge or buccal cavity eg. GTN for angina

Question 8

Give advantages of the rectal route (suppository)

Answer 8

Useful in youg, old and those with difficulties swallowing
Treat local conditions
Achieve systemic absorption
Bypass first pass metabolism

Question 9

Give advantages of injection based administration (IV, IM, subcutaneous)

Answer 9

Provide fast, systemic effects by passing first pass metabolism
Can be administered to the unconscious
Short half life so can be infused continuously

Question 10

Give advantage and disadvantages of IV routes

Answer 10

Rapid onset
100% absorption
Can be toxic (give slowly, monitor plasma level)
Narrow therapeutic index

Question 11

Describe Intramuscular administartion

Answer 11

Injection is given into muscle mass
Allows more sustained duration of action
NEVER use if abnormal clotting

Question 12

Give advantages of subcutaneous injections

Answer 12

Easy for patient to use
No need for venous access
eg. insulin, heparin

Question 13

Describe transdermal routes of adminstration

Answer 13

Adhesive pathways allow drug to cross skin surface by diffusion and go into systemic circulation by precutaneous absorption

Question 14

Give examples of precutaneous routes

Answer 14

creams, ointments, patches

achieve local effects

Question 15

What is the main advantage of skin patches

Answer 15

Controlled, sustained blood levels

eg. nicotine, contraception

Question 16

Give advantages of inhalation administration

Answer 16

Drug delivered directly to action site (lung)
Rapid effect
Reduced adverse affects
However, patients must be educated.

Question 17

Define prodrugs

Answer 17

Synthesised inactive derivatives of an active drug which is then activated metabolically after administartion

Question 18

Give advantages of prodrugs

Answer 18

Prolongation of duration
Avoid degradation in the gut
Unpalatable drugs are made tasteless

Question 19

Discuss the use of prolonged release drugs

Answer 19

Most disorders require prolonged therapy
This maintains drug levels within the therapeutic range and reduces need fro frequent dosing - patients comply & save staff time

Question 20

How do prolonged release drugs work

Answer 20

Reduce rate of absorption of the drug - slower but sustained

Can use a more active form of the drug