Pharmacology of the Nervous System

Question 1

What is pharmacology

Answer 1

A chemical substance that interacts with a specific target within a biological system to produce a physiologic effect

Question 2

3 qus to ask about each drug

Answer 2

Where is the effect produced
What is the target for the drug
What is the response after interaction with this target

Question 3

What is the response after interaction with the target ? ( heroin)

Answer 3

Euphoria as it stimulates the reward pathway
Analgesia ( pain relief)
Cough suppression

Question 4

Where is the effect of heroin produced ?

Answer 4

Analgesia is produced in the per - aqueduct all grey region
Euphoria is produced in the ventral tegmental area
Cough suppression is produced in the solitary nucleus

Question 5

What is the target for heroin

Answer 5

Opioid receptors- this recognise drugs such as heroin and morphine ( exogenous products ) and also recognise endorphins which is produced by the body ( endogenous product)

Since heroin has many effects ( pain relief , euphoria etc) the opioid receptors must be present in many different areas of the brain - peri- aqueductal grey region , ventral tegmental area and solitary nucleus

Question 6

Majority of drug targets are proteins - 4 main classes

Answer 6

Receptors
Enzymes
Transport proteins
Ion channels

Question 7

Drug : atorvastatin

Answer 7

Target ; enzyme - HmG CoA reductase

Question 8

Drug : Amlodipine

Answer 8

Ion channel - calcium channel and useful for hypertension , blocking the ion channel and causes vasodilation which reduces BP

Question 9

Salbutamol

Answer 9

Affects receptors and binds to B2 adronergic receptor in lungs which then bronchodilates. The blue inhalers are for asthma

Question 10

Citalopram

Answer 10

Anti depressant and the drug target is a transport protein as it blocks serotonin reputable protein.

Question 11

Drugs can act on targets to ….

Answer 11

Enhance activation and stimulate an effect or prevent activation ( block an effect from being produced)

Question 12

Drug selectivity

Answer 12

Lock and key model : to be an effective therapeutic agent, a drug must show a high degree of selectivity for a particular drug target

Question 13

3 structurally similar CNS neurotransmitters

Answer 13

Dopamine, noradrenaline and serotonin

Question 14

Why might selectivity be more important for drugs than endogenous compounds like dopamine

Answer 14

Dopamine is released by dooamanergic nerve into synapse to be given to dopamine receptor. Neurotransmitters are very specifically delivered to drug target, so these neurotransmitters would be released from nerves that would be specifically released into synapse that would go to drug target. But with drugs usually administered orally so drugs need to go via blood stream and then released to relevant tissue, but problem is that as they have already entered bloodstream, they can go to any tissue

Question 15

What is a side effect

Answer 15

An effect produced by the drug that is secondary to the intended effect

Question 16

What is an adverse effect

Answer 16

If the side effect has negative health consequences

Question 17

Therapeutic effect

Answer 17

Effect that you want to produce

Question 18

What happens in terms of side effects and adverse effects as you increase the dose of a drug ?

Take for example pramipexole ( dopamine receptor agonist) - mimics effect of dopamine

Answer 18

At low dose, pramipexole will bind to dopamine receptor and therapeutic effects kick in ( so dopamine like effects) But as you increase the dose, you might see serotonin side effects as pramipexole can bind to serotonin receptor and produce Serotonin , eventually same happens with noradrenaline

Question 19

Side effects can be …

Answer 19

Off target or effects in the same target

Question 20

As dose increase, selectivity ……

Answer 20

Decreases and you start to see side effects that you do not want

Question 21

Dopaminerguc pathways

Answer 21

Many diff dopaminergic pathways in Brian so if you take drug that is a dopamine receptor agonist so will have to assume that the drug that has effect on all pathways in the brain. Many dopamine receptors in the body like eyes, vessels, heart, adrenals , kidney and gut . So can get constipation as pramipexole would be accessing dopaminergic receptors in the gut

Question 22

Off target effects tend to kick in as drug …

Answer 22

Increases

Question 23

What constitutes as the ‘safest’ drugs

Answer 23

Where there is a large difference between the dose required to induce the desired effect and the dose required to induce side effects / adverse effects .

Drugs where there isn’t a large enough margin probably needs to be administered in hospitals where the side effects can be monitored