Pharmacology Flashcards Preview

Principles > Pharmacology > Flashcards

Flashcards in Pharmacology Deck (33)
Loading flashcards...
1

What is the difference between pharmacodynamics and pharmacokinetics?

- pharmacodynamics - what the drug does to the body
- pharmacokinetics- what the body does to the drugs

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 binds 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 response

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

What is the therapeutic window?

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

12

How is the therapeutic ratio calculated?

TR= MTC/MEC

13

Drugs with ____ therapeutic ratios are unsafe

Low

14

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

C0= D/Vd

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

15

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

The rate of removal or elimination (Kel)

16

What is first order kinetics?

Most drugs express this
It is when the rate of elimination is directly proportional to drug concentration

17

What is "clearance"?

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

18

How is the rate of elimination calculated?

Rate = Cl x Cp

Cl= clearance
Cp= plasma concentration

Rate of elimination is measured in l/hr

19

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

The rate of elimination
(drug concentration remains constant)

20

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

21

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

5

22

What is a loading dose?

An initially higher administration interred dose given at the beginning of treatment.
It accelerates the time at which a steady state can be reached and when plasma concentration becomes adequate

23

How does a larger Vd affect half life?

It increases it

24

How can half life be shortened?

If Cl is reduced

25

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)

26

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

27

What is a ganglion?

A group of cells at which a synapse is present

28

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

29

Where does the sympathetic outflow originate?

The sympathetic chain (thoracolumbar outflow)
Between the levels of T1 and L2

30

Where does parasympathetic outflow originate?

- Cranial nerves III, VII, IX, X
- Cranio-sacral outflow
- Thoracolumbar outflow
- Sacral spinal nerves