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Flashcards in Pharmacology Deck (56)
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1

What is the difference between pharmacodynamics and pharmacokinetics?

  • Pharmacodynamics - what the drug does to the body
  • Pharmacokinetics - what the body does to the drug

2

Drugs which act on receptors can be either _________ or ______________

Agonists

Antagonists

3

What is affinity?

The strength at which a ligand will bind to its receptor

4

What is efficacy?

The ability of an agonist to evoke a cellular response

5

What is EC50?

The concentration of agonist that elicits half maximal response

This is the Michaelis-Menten constant

6

What is competitive antagonism?

The antagonist and agonist compete for the same binding site

7

What is non-competitive antagonism?

The agonist binds to the orthosteric site and the antagonist bings to a separate allosteric site

Activation cannot occur when the antagonist is bound

8

What is potency?

The effectiveness of a drug at a given concentration

9

How do competitive antagonists affect the concentration response curve?

Competitive antagonists cause a parallel rightward shift of the agonist concentration response curve with no depression of the maximal respons

10

How do non-competitive antagonists affect the concentration response curve?

Non-competitive antagonists depress the slope and maximum of the concentration response curve, but do not cause a rightward shift

11

Label A, B and C on the concentration response graph

12

What is the therapeutic window?

Any concentration of drug between the minimum effective concentration (MEC) and maximum tolerated concentration (MTC)

13

How is the therapuetic ratio calculated?

TR - MTC/MEC

14

Drugs with ____ therapeutic ratios are unsafe

Low

15

When a drug is given by IV, how is the initial concentration calculated?

C0 = D/Vd

  • D - dose (mg)
  • Vd = volume of body plasma

16

The drop in concentration of a drug in the body over time depends on what?

The rate of removal or elimination (Kel)

17

What is first order kinetics?

Most drugs express this

It is when the rate of elimination is directly proportional to drug concentration

18

What is "clearance"?

This is the volume of plasma filtered clear of the drug in unit time

19

How is rate of elimination calculated?

Rate = Cl x Cp

  • Cl - clearance
  • Cp - plasma concentration

Rate of elimination is measured in l/hr

20

At a stead state the rate of drug administration will equal what?

The rate of elimination

(drug concentration remains constant)

21

Changing the rate of drug administration does not change the time to reach a steady state, it will change what instead?

It will change the concentration of the steady state

22

How many half lives does it take to reach a steady state?

5

23

What is a loading dose?

An initially higher administered dose given at the beginning f treatment.

It accelerates the time at which a steady state can be reached and when plasma concentration becomes adequate

24

How does a larger Vd affect half life?

It increases it

25

How can half life be shortened?

If Cl is reduced

26

What is zero order kinetics?

This describes drugs that are eliminated at a constant rate, regardless of their concentration

An increase in drug concentration will have no effect on the rate of elimination

(at very low concentrations some drugs may initially function at first order kinetics because concentration is the limiting factor)

27

What is the reason for some drugs functioning at zero order kinetics?

The enzyme that breaks them down has a Km that is lower than the concentration of the drug in the body

28

What is a ganglion?

A group of cells at which a synpase is present

29

Why is the sympathetic innervation of the adrenal gland unusual?

It is innervated by a preganglionic neurone

Acetylcholine is released

The adrenal gland acts as the postganglionic neurone, by releasing adrenaline

30

Where does the sympathetic outflow originate?

The sympathetic chain (thoracolumbar outflow)

Between the levels of T1 and L2