Karens Cards On Pharmocodynamics

Question 1

What is pharmacodynamics?

Answer 1

• What drugs do to the body
• How is works

Question 2

What are Zwitterions?

Answer 2

Amino acids and proteins are Zwitterions. They can be both positively and negatively charged or nothing/neutral

Question 3

What does an amino acid look like?

Answer 3

NH2 (nitrogen, hydrogen) - R- COOH (carbon, oxygen, hydrogen)

Amino group = N terminal
Carboxyl group = C terminal

Question 4

1) What are positively charged ions known as?

2) What are negatively charged ions known as?

Answer 4

1) positively charged ions = cations
2) negatively charged ions = anions

Opposites attract:

Rods - positive = anode and negatives = cathode

Question 5

What are the 4 functions of proteins in a cell membrane?

Answer 5

1) Transporters (form channels)
2) Linkers (form adhesion molecules, structure - can unlink and travel)
3) Receptors (carry messages)
4) Enzymes (spread up chemical reaction)

Question 6

What is the electrical charge inside a cell?

Answer 6

Inside a cell is always negative charge
Outside a cell is always positive charge

Question 7

What are the targets for drug actions?

Answer 7

RICE

R - receptors
I - ion channels
C - carrier molecules
E - Enzymes

Question 8

There are 4 main types of receptors (superfamilies). What are they?

Answer 8

1) Inotropic - Ligand gated channels
2) Metabotropic - G protein coupled
3) Kinase linked
4) Nuclear

Question 9

Describe characteristics of ligand gated channel receptors? (3)

Answer 9

1) Inotropic
2) Directly coupled to an ion channel
3) fastest (nerve/cardiac tissue)

Question 10

Describe characteristics of G protein coupled receptor (4)

Answer 10

1) metabotropic
2) signalling cascade
3) second messenger system
4) fast - seconds

Question 11

Describe characteristics of kinase linked receptors (2)

Answer 11

1) Enzyme amplifier
2) hours

Example - insulin

Question 12

Describe characteristics of nuclear receptors (3)

Answer 12

1) within the cell (intracellular)
2) turns nucleus off
3) hours/days

Example - steroids

Question 13

1) what is an agonist?

2) what is an antagonist?

Answer 13

1) an agonist activates, initiates a response, a natural response

2) an antagonist blocks receptors by preventing access to the site by the natural agonist

Question 14

1) What is a competitive receptor?

2) What is a non competitive receptor?

Answer 14

1) Competitive = catipiller - concentration dependent

2) non competitive = Wedge/tap - doesn’t matter about concentration

Question 15

What is Tachyphylaxis?

Answer 15

Desensitisation - rapidly decreasing response to a drug

Causes:

• change in receptors
• loss of receptors
• hiding receptors

Question 16

What is an ion channel and what are the 4 main types of ion channels?

Answer 16

Ion channels exist in open and closed form (open allowing movement, closed preventing movement or inactive)

1) Ligand gated (intracellular)
2) Ligand gated (extracellular)
3) voltage gated
4) mechanically gated

Question 17

Describe how the below ion channels are activated:

A) Ligand gated ion channels?
B) voltage gated ion channels?
C) mechanically gated ion channels?

Answer 17

A) Activated by the binding of endogenous ligands to a specific receptor which forms part of the ion channel

B) Activated following a change in voltage

C) Activated by the weight or force of a molecule hitting it open

Question 18

Consider 5 features of ion channels

Answer 18

1) Over 100 types
2) Important for systems that require a rapid response (NS, renal, CVS)
3) Drugs either block (directly block the ion channel preventing movement) or modulate (indirect- the binding of a drug to the site of an associated receptor can either increase or decrease the likelihood of a channel being open)
4) Ions need the help of proteins to cross cell membrane (such as ion channels)
5) Ion channels don’t bind but form a channel through the membrane (they let in water and small ions pass)

Question 19

What are the 4 characteristics of carrier molecules?

Answer 19

1) Transport a substance across a cell membrane
2) Carrier molecules can be ion, glucose or amino acids
3) They carry a specific molecule/shape
4) Some drugs target these carriers and block transport - common by inhibiting an enzyme ATP that provides the energy to drive them

Question 20

Drugs can act to modulate the function of carrier molecules directly or indirectly….explain

Answer 20

Direct - Binds completely to the carrier preventing the binding of endogenous ligands

Indirect - Allosteric (binds to a separate site on the carrier and alters the 3D shape, preventing the binding of endogenous ligands

Allosteric = change in shape or activity
Endogenous = existing

Question 21

What are the 2 main types of carrier molecules?

Answer 21

1) Energy dependent:

• can work across a concentrated gradient
• requires energy (usually ATP)

2) Energy independent:

• Transporters (single molecule in one direction)
• Symporters (2 different molecules in the same direction)
• Antiporters (2 molecules in opposite directions?

(Can only work down a concentrated gradient)

Question 22

What are Enzymes? (2)

Answer 22

1) Enzymes are biological catalysts that speed up a chemical reaction

2) Enzymes have an active or catalytic site that binds substrates specifically (substrate fits shape like a key in a lock)

• chemical reaction
• then substrate forms into products

Question 23

What does a substrate analogue do and how does it work? (2)

Answer 23

1) Mimic the substrate or feature of the substrate

2) Can act as a competitive inhibitor or a non competitive inhibitor

Question 24

What are the characteristics of a competitive inhibitor? (4)

Substrate analogue

Answer 24

1) have a similar chemical structure (shape) and slows down a reaction rate

2) The inhibitor competes with the substrate to slow down the reaction

3 Binds at the active site

4) reversible

(Drugs help prevent harmful products or growth of foreign cells. Penicillin inhibits an enzyme which help bacteria grow)

Question 25

What are the characteristics of a non competitive inhibitor? (4)

(Substrate analogue)

Answer 25

1) Bind to the enzyme but not at the active site

2) Still inhibit the reaction

3) Work by changing the enzyme shape, thus making it inactive

4) non reversible

(Aspirin)

Question 26

What are the characteristics of a false substrate? (3)

Answer 26

1) Transformed by an enzyme to produce an abnormal non functioning product

2) Target a specific point in a pathway and often have less side effects as it’s more targeted

3) Fools the enzyme into thinking it’s metabolising

Question 27

What are the characteristics of conversion of pro drugs? (3)

Answer 27

1) Most oral drugs are in the inactive form

2) They rely on conversion by enzymes (usually in the liver) to activate the drug

3) Pro drug is an active metabolite

Example - codeine - morphine

Question 28

Drugs are either reversible or irreversible inhibitors….explain

Answer 28

Reversible - temporarily binds to the catalytic site

Irreversible- binds permanently to the enzyme making it terminally inactive. These require the production of new enzymes to re start activity

Aspirin - irreversible inhibitor
Penicillin - reversible inhibitor