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Molecular Pharmacology > Basic Principles > Flashcards

Basic Principles Flashcards

1
Q

What is pharmacology?

A

the study of the effects of drugs on the function of living systems

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2
Q

What is a drug?

A

a substance of known chemical structure which when administered to a living organism produces a biological effect

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3
Q

What is pharmacodynamics?

A

the study of how drugs work

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4
Q

What is the general principle of a drug?

A

A drug will not work unless it is bound

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5
Q

What can drugs target?

A

receptors, enzymes, ion channels, transporters and other miscellaneous targets i.e. DNA

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6
Q

How might a drug target a receptor?

A

It may be an agonist - which initiates a biological response

It may be an antagonist - which has no effect but blocks the endogenous modulator

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7
Q

How might an agonist work on a receptor?

A

Directly or Indirectly

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8
Q

How might an agonist work directly on a receptor?

A

Ligand binding ion channels

Enzyme activation or inactivation

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9
Q

How might an agonist work indirectly on a receptor?

A

Through transduction mechanisms
Through ion channel modulation
DNA transcription

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10
Q

How might a drug target an ion channel?

A

Blockers- blocking the ion channel

Modulators - increasing or decreasing the permeability of an ion - i.e. NMDA receptor is blocked by MK-801

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11
Q

How might a drug target enzymes?

A

Inhibition - inhibiting the normal reaction
False substrate - causing an abnormal metabolite to be produced
Pro-drug - drug is administered in an inactive form and the active form is produced by the enzyme

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12
Q

Give an example of a drug which targets an enzyme

A

Monoamine Oxidase Inhibitor B - Selegine
MAOs metabolise monoamines such as dopamine, serotonin and noradrenaline
MAO-B Inhibitor is used in the treatment of Parkinson’s to prevent the metabolism of dopamine and phenylethylamine

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13
Q

How might a drug target transporters?

A

Inhibitors can attack the same site or an allosteric site blocking transport

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14
Q

Give an example how a transporter might be blocked and how it might be used

A

Uptake 1 inhibitors - the re-uptake of neurotransmitter is known as uptake 1 and may be blocked, such as in anti-depressants to maintain higher levels of neurotransmitter in the synapse

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15
Q

What is a receptor?

A

Any cellular assembly (target molecule) that a drug molecule binds to in order to elicit a specific response

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16
Q

What is the difference between affinity and efficacy?

A

Affinity is the ability of the drug to bind to a receptor

Efficacy is the ability of the drug to elicit a biological response once bound - agonists only

17
Q

What is a full agonist?

A

A full agonist has maximal effects and high efficacy

18
Q

What is a partial agonist?

A

A partial agonist has sub maximal effects and medium efficacy

19
Q

What is an antagonist?

A

Antagonists have no efficacy and do not exert an effect on the receptor other than to block it

20
Q

What is agonist potency?

A

How strongly an agonist can exert its effects can be used in comparison to other agonists when choosing drugs

21
Q

What kind of antagonists are there?

A

competitive - binds to same site as agonist
non-competitive - binds to an allosteric site
reversible - binds non-covalently
irreversible - binds covalently

22
Q

Give an example of a reversible competitive antagonist and its actions

A

Propanolol (decreases BP, B-blocker) is an antagonist of isoproterenol (increases HR and works on B-adrenoceptors)
The maximum response is not changed however there is a shift right in the dose-response curve as more agonist is needed.

23
Q

Give an example of an irreversible competitive antagonist and its actions

A

Naloxone is used in opioid overdose

The EC50 is not affected however the maximal effects are as an increase in agonist will not overcome this.

24
Q

Give an example of a reversible, non-competitive antagonist and its actions

A

Ketamine is an antagonist to NMDA by blocking the ion channel of the glutamate receptor
The maximum response is reduced but there is no change in the EC50

25
Q

Give an example of a irreversible non-competitive antagonist and its actions

A

Phenoxybenzamine blocks the effects of noradrenaline on a-adrenoceptors on vascular sm. muscle

26
Q

What are the other methods of antagonism?

A

Physiological - two drugs producing opposing effects i.e. NA and adrenaline
Chemical - drug reduces concentration of an agonist by forming a chemical complex i.e. protamine sulphate(+ve) binder to heparin(an anticoagulant)(-ve) preventing heparin from working
Pharmacokinetic - one drug affects the absorption, metabolism or elimination of another i.e. phenobarbital-induced enzyme induction increases the metabolism of the anticoagulant coumadin

27
Q

What kind of receptor families do you get?

A

Ion Channels
GPCRs
Tyrosine Kinase
Nuclear Hormone Receptors

28
Q

How might drugs affect ion channels?

A

agonist binding results in a conformational change in the receptor and may cause the ion channel to open

29
Q

How might drugs affect GPCRs?

A

activation results in a stimulation of a second messenger signalling cascade

30
Q

How might drugs affect tyrosine kinase receptors?

A

these receptors mediate the first steps in transduction of signals by insulin and growth factors

31
Q

How might drugs affect Nuclear hormone receptors?

A

they may cause transcriptional changes in the DNA and hence change gene expression

32
Q

What is the pathway of drugs in the body?

A

absorption > distribution > metabolism > excretion

33
Q

How might the absorption of drugs be influenced?

A

Route of administration - how quickly it reaches the bloodstream and its bioavailability
If to be absorbed in the GI tract it must be lipid soluble and able to cope with changes in pH - stomach is acidic and intestines are alkaline

34
Q

How might drug dissolution be affected?

A

The presence of food, the availability of HCl and the availablility of pancreatic/intestinal secretions

35
Q

What is the first-pass effect?

A

Where the liver is able to metabolise and inactivate drugs before they are distributed about the body i.e. heroin can be converted to morphine

36
Q

What may affect drug metabolism?

A

Liver metabolising enzymes may be induced or inhibited by other drugs - drug-drug interactions

37
Q

What are bioassays designed to do?

A

To see how one drug works against a standard on a dose response curve

38
Q

What are the parameters against which drugs are checked?

A

IC50 - antagonists - how well they can block agonists and enzymes at a 50% of max effect
EC50 - 50% of the maximum effect of an agonist
ED50 - the minimum dose required to show effect in 50% of the tested population
LD50 - the dose required to kill 50% of the population after x time
The therapeutic index - LD50/ED50

39
Q

How many phases of drug trials are there and what happens during them?

A

Phase I - hospital, v.controlled, safety checking
Phase II - checking for efficacy and how well it works
Phase III - confirm the findings in large populations
Phase IV - testing the long term safety 2-3 years

Molecular Pharmacology (5 decks)

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