Pharmacodynamics

Question 1

Pharmacodynamics definition

Answer 1

Study of effect of drugs and their mechanism of action in the body

Question 2

Targets for drug action

Answer 2

• Physical interaction

- Biological interaction

Question 3

Physical interactions have _______ effects

Answer 3

Non- Specific

Question 4

Three examples of physical interaction

Answer 4

• Osmotic diuretics
• Antacids
• Radioactive iodine

Question 5

Osmotic diuretics

Answer 5

Ex- Mannitol (sugar molecule)

a hyperosmolar agent that moves through the body and attracts fluid with it until excreted in urine

Question 6

Antacids

Answer 6

Act by direct neutralization of acids in the GI tract

Ex- calcium carbonate tablets

Question 7

Radioactive iodine

Answer 7

1-31 radiations will destroy all tissue within 2-3 mm

– use in older cats with thyroid issues

Question 8

Biological interactions

Answer 8

• Non-receptors

- receptors

Question 9

Non- Receptor interactions

Answer 9

• Ion channels
• Enzymes
• Carrier protein

Question 10

Ion channels in NRI

Answer 10

-voltage gates channels
- blocking ion channels by physically obstructing the channel
–ex- lidocaine ( blocked Na+channels)
Modulation of opening and closing the channel
– ex -Amlodipine

Question 11

Endogenous neurotransmitter

Answer 11

Binds to more than one type of receptor

Question 12

Receptor up regulation

Answer 12

Increase the number of receptors and drug effect

Question 13

Receptor down- regulation

Answer 13

Decrease in the number of receptors and effect

Question 14

Tolerance

Answer 14

Gradual decreasing in responsiveness to a drug when given repeatedly over days to months

Question 15

Tachyphylaxis

Answer 15

Acute tolerance developing over a short period of time, sometimes involves depletions of stored mediators

Question 16

Ligand

Answer 16

Anything that binds to a recognition site

Question 17

Agonist

Answer 17

Mimics the effect of an endogenous ligand
-positive response causing action to occur
Affinity and efficacy
– ex: Fentanyl

Question 18

Full agonist

Answer 18

• Spare receptors (receptor reserve)
• Titrational effect
• -ex: Morphine

Question 19

Partial agonist

Answer 19

• binds to receptor but does NOT cause much effect as a full agonist
• still blocks that receptor from full agonist binding
• • ceiling effect
• -ex: buprenorphine

Question 20

Antagonist

Answer 20

• Binds to the same receptor and prevents an agonist from

- inhibits the effects of the receptor

Question 21

Competitive antagonism

Answer 21

• -most common
• reversible
• concentration dependent binding

Question 22

Non-competitive antagonism

Answer 22

• -less common
• Irreversible
• prevents actions of the agonist at any concentration

Question 23

Inverse Agonist

Answer 23

Binds to the same receptor site and produces the opposite effect as agonist
— ex: carboline

Question 24

Mixed Agonist- Antagonist

Answer 24

Acts as a agonist on one type of receptor and as an antagonist on other type of receptors
–Ex: butorphanol

Question 25

Potency

Answer 25

- Concentration of a drug needed to produce the effect - dose will account for the potency of drug - -- more potent ( smaller dose)

Question 26

Maximal effect (ceiling)

Answer 26

Point at which increasing concentration does not yield greater response

Question 27

Efficacy

Answer 27

- the minimal effect of a drug can have | * partial agonist may never achieve full efficacy

Question 28

Effective concentration (EC50)

Answer 28

50% of maximal response in vitro | - relates to the concentration of the drug at the site

Question 29

Effective dose (ED50)

Answer 29

Desired effect in 50% of the population | - relates to the dose given to individuals and observed effect

Question 30

Therapeutic index (TI)

Answer 30

A ratio used to evaluate the safety of a drug - narrow therapeutic index - wide therapeutic index

Question 31

Narrow therapeutic index

Answer 31

- small number, close to 1 | - dose required to cause death is close to the dose required to have a therapeutic effect

Question 32

Wide therapeutic index

Answer 32

Does required to cause death is much higher than the dose required to have a therapeutic effect

Question 33

Onset of action

Answer 33

Time required after drug administration for a response to be observed (latent period)

Question 34

Duration of action

Answer 34

Length of time that a drug is effective (from onset of action until termination of action)