Routes of Administration

Question 1

Oral

Answer 1

Taken through mouth

Question 2

Intramuscular

Answer 2

Injection directly into muscle

Question 3

Subcutaneous

Answer 3

Injection into tissue layer between skin and muscle (fat layer)

Question 4

Intravenous

Answer 4

Delivers substance directly into vein, full dose enters systemic system and has effect

Question 5

Buccal

Answer 5

Under tongue to dissolve and absorb into blood

Question 6

Transdermal

Answer 6

Delivered across skin (path/ointment) for systemic distribution

Question 7

Inhalational

Answer 7

Inhalation through mouth - must be smaller droplets than inhalation through nose so drugs can pass through windpipe into lungs

Question 8

Intrathecal

Answer 8

Injection into CSF, used in chemo and pain management

Question 9

Epidural

Answer 9

Injection into epidural space around spinal cord

Question 10

Topical

Answer 10

Applied to particular place on/in body (normally application to body surfaces such as skin/mucous membranes)

Question 11

What routes of administration bypass 1st pass metabolism?

Answer 11

Intravenous, buccal, transdermal

Question 12

What is 1st pass metabolism?

Answer 12

First visit via the hepatic portal vein to the liver (anything we ingest orally always goes via the hepatic portal vein and liver to begin with, before it is absorbed into systemic circulation)

Question 13

What are modified-release dosages?

Answer 13

Delivers drug with a delay after its administration or for a prolonged period of time (release in a modified way)

Question 14

Advantages of modified doses?

Answer 14

1. Less frequent administrations
2. Reduces incidence and severity of GI tract effects
3. Control over therapeutic plasma concs
4. Improved treatment of chronic conditions in which steady plasma conc is required
5. Maintenance of therapeutic action overnight
6. Minimise adverse affects associated with high plasma conc

Question 15

How do modified doses reduce incidence of GI tract effects?

Answer 15

Release over longer period

Question 16

Disadvantages of modified doses?

Answer 16

1. Cost more per unit
2. Possibility of unsafe over dose
3. Rate of transit through GI tract limits max period for which therapeutic response can be maintained
4. Variability in physiological factors influence drug bioavailability (GI tract, pH, enzymes, food)

Question 17

Disadvantages of oral route?

Answer 17

Cannot be used for drugs that are inactivated by 1st pass metabolism or that irritate gut

Question 18

Define bioavailability

Answer 18

Proportion of drug which enters circulation when introduced into the body and so is able to have an active effect