principles of pharmacology

Question 1

pharmacokinetics

Answer 1

what the body does to the drug

Question 2

4 stages of pharmacokinetics

Answer 2

• absorption
• distribution
• metabolism
• excretion

Question 3

what determines type of drug administration

Answer 3

• desired duration of action
• desired plasma concentration
• drug type
• infection location

Question 4

enteral administration

Answer 4

entry of drug through GI tract
- oral
- rectal
- sublingual

Question 5

oral (PO) administration

Answer 5

into mouth and swallowed
- absorbed in stomach/small intestine
- absorption < 100%
- most common (cheap and convenient)

Question 6

absorption depends on:

Answer 6

• disintegration/solubility
• acidity of GI tract
• stability of drug (proteins destroyed by digestive enzymes)
• GI blood flow
• gastric emptying & motility

Question 7

oral benefits

Answer 7

• easiest, safest, cheapest
• drug doesn’t need to be sterile/pure

Question 8

oral drawbacks

Answer 8

• acid-sensitive and protein drugs unstable
• variable absorption and bioavailability
• possible upper GI tract irritation

Question 9

first pass metabolism

Answer 9

orally administered drugs go to liver before systemic circulation (hepatic portal vein) and liver cells can metabolize drug so concentration drops

• changes based on person and liver health (no liver enzymes means dose is higher)

Question 10

rectal (pr) administration

Answer 10

absorption through rectal mucosa

Question 11

rectal benefits

Answer 11

• rapid absorption
• cheap and easy
• useful when patients can’t/won’t swallow
• less first pass effect

Question 12

rectal drawbacks

Answer 12

• absorption often incomplete
• irritation of mucosal lining

Question 13

sublingual (sl) administration

Answer 13

drug under tongue dissolves and absorbs through sublingual mucosa
- most similar to parenteral administration

Question 14

sublingual benefits

Answer 14

• fast absorption
• no first pass effect
• good for acid sensitive drugs
• fast easy cheap

Question 15

sublingual drawbacks

Answer 15

drugs taste bad

Question 16

parenteral administration

Answer 16

• injection
• IM, SC, IV
• break. barrier to outside world: increased infection risk, drug must be sterile
• know how much enters body (high bioavailability)

Question 17

subcutaneous injection (SC)

Answer 17

drug injected under skin

Question 18

SC advantages

Answer 18

• rapid effect via general circulation
• good for local drug delivery
• easy-self administration

Question 19

SC disadvantages

Answer 19

-need sterile drug
- absorption efefcted by blood flow and injection volume
- injections

Question 20

intramuscular injection (IM)

Answer 20

drug injected into skeletal muscle

Question 21

IM advantages

Answer 21

• can go into large muscle mass
• self-administration
• absorption into systemic circulation can be controlled (oil slower absorption - depot bolus)

Question 22

IM disadvantages

Answer 22

pain

Question 23

intravenous (IV) administration

Answer 23

drug injected directly into vein
- no absorption

Question 24

IV advantages

Answer 24

• 100% bioavailability
• quick distribution and onset of action
• large drug volumes

Question 25

IV disadvantages

Answer 25

• need skilled administration and close monitoring
• sterility needed
• costly
• pain
• infection risk

Question 26

inhaled administration

Answer 26

advantages: no first pass effect, good for local action (bronchodilators)

disadvantages: limited absorption of large proteins, possible irritation of lung lining

Question 27

topical administration

Answer 27

• local use
• not exposing whole body to drug
• transdermal: absorption through skin to general circulation

Question 28

topical advantages

Answer 28

• cheap and easy
• simple local administration
• no first pass effect

Question 29

topical drawbacks

Answer 29

• not suitable for many drugs
• slow delivery
• absorption affected by skin hydration

Question 30

what is absorption

Answer 30

entry of drug to circulatory system (concentration gradient)

Question 31

bioavailability

Answer 31

% of drug administered that enters systemic circulation