Lecture 2

Question 1

How do dugs act?

Answer 1

Receptors are molecular targets for most drugs

Drug + Receptor ——> drug - receptor complex which leads to the physiological response

Question 2

Name physiological responses

Answer 2

Increase in temp
Decrease in blood pressure
Contraction of muscle
Secretion of hormone
Growth
Increase in sugar levels
Heart rate

Question 3

What can drug action be?

Answer 3

Specific and non specific

Question 4

Name the different protein targets

Answer 4

Receptors
Ion channels
Enzymes
Carrier proteins
DNA for cancer therapeutics

Question 5

Give some information about the cell membrane and receptors

Answer 5

Most common site for receptors are on the cell membrane or on the nucleus. Receptors for steroids are located inside the cell.

Question 6

Give some information about asthma patients

Answer 6

In asthma the air pipes are narrower and breathing is constricted. Contraction of the smooth muscles means that medication is needed to open up the airways. For example salbutamol, an inhaler is taken and the airways open up and muscles relax so it is easier to breathe. The blue inhaler is a reliever and should be taken as soon as you feel a tight feeling in the chest or breathlessness. The brown inhaler is a steroid inhaler and should be taken every day, it is important not to miss this dose because it takes longer to work as the receptors are inside the cell so takes longer to work.

Question 7

What are receptors?

Answer 7

Receptors are transducers capable of converting the energy from environmental stimulus into nerve impulses

Question 8

Name the 5 receptor classifications

Answer 8

Selective agonists 
Selective antagonists
Ligand binding
Transduction pathways
Molecular structure

Question 9

What is an agonist?

Answer 9

An agonist is a drug which is capable of interacting with a receptor and binding to it and activating it to cause a response

Question 10

What is an antagonist?

Answer 10

An antagonist is a drug capable of binding to receptors, but not activating it and then blocking the action of the agonist

Question 11

What is histamine?

Answer 11

A naturally occurring chemical in the body which is released by the body during an allergic reaction or inflammation

Question 12

Give the example of hay fever

Answer 12

Hay fever is an allergic response to pollen which causes a runny nose, itchy eyes and a cough. Antihistamines are used to combat the symptoms which reduces the allergic response. The antihistamine binds to the histamine receptors. The antihistamines are antagonists for the histamine receptor.

Question 13

What is the h1 receptor?

Answer 13

Blocked by the antihistamine to reduce allergic response and inflammation

Question 14

What is the h2 receptor?

Answer 14

Blocked by the antihistamine to treat peptic ulcer

Question 15

Explain ion channels

Answer 15

Pores on the cell membrane can open/close to allow or prevent the passage of ions down the conc gradient

Question 16

Name three drugs which act on ion channels

Answer 16

Benzodiazepines, verapamil and lignocaine

Question 17

What does benzodiazepine do?

Answer 17

It is an anti anxiety and anti convulsant agent. It increases the conductance of chloride ions by increasing the frequency of chloride channel opening. This means the inside of the cell is more positive than the outside of the cell which means the cells are less likely to be excitable and the anxiety symptoms are reduced.

Question 18

How does verapamil work?

Answer 18

It is a calcium channel blocker used for patients with heart problems. Calcium is important in the contraction if muscle. Typically used in patients with angina or Arrhythmias. They inhibit the entry of calcium into cardiac and muscle cells which leads to a reduction in contraction.

Question 19

Lignocaine

Answer 19

Local anaesthetics exert action by blocking the sodium channel

Question 20

Where are cattier proteins located?

Answer 20

Located on the cell membrane or intracellular organelles and they transfer materials against their conc gradient using active transport and ATP

Question 21

What are examples of carrier proteins?

Answer 21

Sodium pump - pumps out Na+ and K+ into cells by using ATP. The action of the pup can be inhibited by cardiac glycosides

Sodium chloride co-transporters in kidney can be inhibited by thiazide diuretics and loop diuretics

Question 22

What are enzymes?

Answer 22

Enzymes are molecular proteins which catalyse or speed up the rate of a chemical reaction in the organism

Question 23

How do enzymes and drugs work?

Answer 23

Drugs can bind to enzymes and inhibit or interfere with their action

Question 24

Give the example of aspirin?

Answer 24

Aspirin is used for pain relief, thinning blood and anti-inflammatory action. It effects the enzymes that is responsible for inducing inflammation mediators (prostaglandins) in the body, inhibits the COX enzyme

Question 25

Specific action of drugs on dna

Answer 25

Drugs may bind to DNA and modify their replication in cell division process for example cisplatin the anti cancer drug

Question 26

What do drugs of non specific action have?

Answer 26

Poor structural relationship

They are needed in much higher concentrations

Question 27

What is a beneficial or therapeutic effect?

Answer 27

Binding of a drug to sites with a high affinity

Question 28

Explain adverse effects

Answer 28

Effects which are never wanted as the drug binds to sites that are not desired

Question 29

What is the therapeutic index?

Answer 29

Comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxic effects

Question 30

What is the ratio for the TI?

Answer 30

Toxic dose divided by the therapeutic dose (effective)

Question 31

Which TI is preferred?

Answer 31

A high therapeutic index is preferred to a low one, this means it would take a higher amount of a drug to do harm than the amount taken to do good. The narrower this margin means the drug is more likely to produce unwanted effects.

Question 32

Give examples of drugs with a narrow TI?

Answer 32

Digoxin, dimercapol, theophylline, lithium carbonate and some antibiotics e.g. gentamicin, amphotericin B