1.1 general principles of drug action

Question 1

Define pharmacodynamics

2) What does in involve?

3) What does studying allow us to do:

Answer 1

The effects of a drug on the body

2) a) Molecular interactions by which drugs exert effects and ..
b) influence of drug concentration on the magnitude of response
3) a) Determine the appropriate dose range for patients
b) Compare the effectiveness and safety of one drug to another

Question 2

Define pharmacokinetics

2) what 4 things does this encompass?

Answer 2

what the drug does to the body
2) a) Absorption
(From site of administration into the blood)
b)Distribution
(Drug can reversibly leave the bloodstream and distribute into the interstitial and intracellular fluids of tissues)
c) Metabolism
(Body inactivates the drug through enzymatic modification)
d) Excretion
(Drug is eliminated from the body in urine, bile or faeces)

Question 3

Explain what determines how drugs interact with their targets

Answer 3

1. shape (the ability of the drug to bind “lock and key” mechanism)
   and
2. charge distribution (types of bonds that form)
   EXTRA (but still important) Hydrophobicity

Ionisation of drug (pKa)

Conformation of target

Stereochemistry of drug molecule

Question 4

Define the four main targets for drug action

Answer 4

1. receptors
2. enzymes
3. ion channels
4. carrier molecules

Question 5

Describe the receptor-effector mechanisms activated by agonists

Answer 5

when binds to ligand promotes a positive response

Question 6

Can you give me an example of a naturally occurring drug:

Answer 6

e.g. Taxanes (anti-cancer agents) from yew tree bark

Question 7

1) What are the 2 subtypes of synthetic drugs?

2) give examples for each:

Answer 7

1) totally synthetic and Identical/derived from natural compounds
2) e.g. Insulin (identical)
Codeine (derived)

Question 8

1) What are the 2 subtypes of synthetic drugs?

2) give examples for each:

Answer 8

1) totally synthetic and Identical/derived from natural compounds
2) e.g. Insulin (identical)
Codeine (derived)

Question 9

What differerent interactions can occur due to differences in charge distribution between a drug and receptor: (in order from least to most strong)

Answer 9

1. van der waals
2. Hydrogen
3. Ionic
4. Covalent

Question 10

Define van der waals

Answer 10

Shifting electron density in a molecule results in generation of transient positive or negative charges. These react with transient areas of opposite charge on another molecule

Question 11

Define hydrogen bonding:

Answer 11

Hydrogen atoms bound to oxygen or nitrogen become more positively polarised. These bond with more negatively polarised atoms (e.g. oxygen)

Question 12

Define ionic bonding:

Answer 12

Atoms with an excess of electrons (negatively charged) are attracted to atoms with a deficiency of electrons (positively charged)

Question 13

Define covalent bonding:

Answer 13

Two bonding atoms share electrons

Question 14

Give an example of an antidote which works by virtue of its physico-chemical properties:

Answer 14

e.g. acetylcysteine to treat poisoning with Paracetamol (overdose)

Question 15

Give an example of an antacids which works by virtue of its physico-chemical properties:

Answer 15

aluminium hydroxide

Question 16

Give an example of an laxatives which works by virtue of its physico-chemical properties:

Answer 16

lactulose (osmotic laxatice)