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Pharmacology > General principles of pharmacology (L1&2) > Flashcards

General principles of pharmacology (L1&2) Flashcards

1
Q

what is pharmacodynamics?

A

the effects of a drug on the body

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2
Q

what is pharmacokinetics?

A

what the body does to the drug

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3
Q

what are the principles of pharmacodynamics?

A

molecular interactions by which drugs exert their effects

influence of drug concentration on the magnitude of response

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4
Q

what does the study of pharmacodynamics allow us to do?

A

determine the appropriate dose range for patients

compare the effectiveness and safety of one drug to another

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5
Q

what is the journey of the drug? (pharmacokinetics)

A

absorption
distribution
metabolism
excretion

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6
Q

what does the study of pharmacokinetics allow us to do?

A

design and optimise treatment regimes for individuals

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7
Q

what are the sources of drugs?

A

naturally occurring

synthetic

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8
Q

what is biologics?

A

new source of drug development - allows us to manufacture naturally derived products

can genetically modify them

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9
Q

how does a drug interact with its target?

A

a drug will not work unless its bound

due to:

1) shape
2) charge distribution

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10
Q

what does the shape of a drug determine?

A

the ability of the drug to bind

lock and key mechanism

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11
Q

what does the charge distribution of the drug determine?

A

the type of bonds that hold the drug to the target

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12
Q

what are the type of bonds from weakest to strongest?

A

van der waals
hydrogen
ionic
covalent

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13
Q

what are van der waals forces?

A

shifting of electron density in a molecule results in the generation of transient positive and negative charges.
these react with transient areas of opposite charges on other molecules

bond strength = +

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14
Q

what are hydrogen bonds?

A

H atoms bound to O or N become more positively polarised
these bond with more negatively polarised atoms

bond strength = ++

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15
Q

what are ionic bonds?

A

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

bond strength = +++

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16
Q

what are covalent bonds?

A

2 bonding atoms share electrons

bond strength = ++++

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17
Q

what are the further considerations to drug binding?

A

hydrophobicity

ionisation of drug (pKa)

conformation of target

stereochemistry of drug molecule

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18
Q

what are the targets for drug action?

A

receptors
enzymes
ion channels
carrier molecules

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19
Q

what are receptors?

A

targets for endogenous transmitters

eg. hormones and neurotransmitters

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20
Q

what are enzymes?

A

biological catalysts which facilitate biochemical reactions

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21
Q

what are ion channels?

A

pores which span the membranes to allow the selective passage of ions

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22
Q

what are carrier molecules?

A

transport ions and small organic molecules across cell membranes

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23
Q

what drugs act by virtue of their physiology-chemical properties?

A

antidotes

antiacids

laxatives

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24
Q

what do drugs do to receptors?

A

agonists activate the receptor

antagonists block the action of agonists

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25
Q

what do drugs do to ion channels?

A

either block or modulate the opening and closing

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26
Q

what do drugs do to enzymes?

A

either inhibit them or act as a false substrate

27
Q

what do drugs do to carrier molecules?

A

either transported in the place of endogenous substrate or inhibit transport

28
Q

how does the allosteric action of benzodiazepines (BZ) have on the GABAa receptor?

A

decrease excitability of the channel by stopping Cl- moving through

BZ binds allosterically to the GABA binding site (orthosteric)
doesn’t change Cl- activity without the GABA

enhances the effect of GABA

29
Q

what are NSAIDs?

A

non steroidal inflammatory drugs

e.g. ibuprofen and aspirin

inhibit cyclooxygenase preventing prostaglandins being released

30
Q

what are prostaglandins?

A

inflammatory mediators

lead to inflammation, pain and fever

31
Q

what are agonists?

A

a ligand that combines with receptors to elicit a cellular response

32
Q

what is an antagonist?

A

a drug which blocks the response of the agonist

33
Q

what are receptor subtypes?

A

receptors within a given family generally occur in several molecular varieties

often have similar structures but significant differences in their pharmacological responses

34
Q

how are receptor subtypes identified?

A

on the basis of selectivity of agonists and/or antagonists

or

by cloning techniques

35
Q

what are the types of receptor signal transduction?

A

ligand gated ion channels
GPCR
enzyme (kinase) linked receptors
intracellular receptors

36
Q

what is the fastest signal transduction?

A

ligand gated ion channels

37
Q

what are the 2 types of channel linked (inotropic) receptors?

A

ligand gated

voltage gated

38
Q

how do ligand gated ion channels work?

A

they require an agonist to open the channel

eg. nicotinic acetylcholine receptor
acetylcholine causes skeletal muscle to contract by opening ligand-gated ion channels

39
Q

how do voltage gated ion channels work?

A

are not linked to receptors
they require a change in electrical charge across a membrane to open/close

e.g. Na+ channels in nerve cell membranes
local anaesthetics work by blocking VG Na+ channels

40
Q

how do nicotinic acetylcholine receptors work?

A

pentameric structure

inward kink - allows ion channels to stay shut: stops ions flowing through ion channel in resting state

on extracellular binding we get a twist to open so the inward kink falls out - allows passage of cations

inside of channel is negatively charged so only cations can flow through

41
Q

what are used as muscle relaxants?

A

nicotinic ACh receptor antagonists

42
Q

what are GPCR?

A 
largest family of receptors 
7 transmembrane helices 
consists of 3 subunits:
• alpha 
• beta 
• gamma
43
Q

examples of drugs that GPCRs?

A

endogenous agonists

α/β adrenoceptors – epinephrine (natural)
β2 adrenoceptors – salbutamol (drug based)

44
Q

how is specificity achieved in GPCRs?

A

molecular variation in alpha subunits

different subunits have different signalling systems

45
Q

what are the different subunits in GPCRs?

A

Gs, Gi, Gq, G0

46
Q

whats the action of Gs?

A

stimulatory

activates adenylyl cyclase
activates Ca++ channels

47
Q

whats the action of Gi?

A

inhibitory

inhibits adenylyl cyclase
activates K+ channels

48
Q

whats the action of Gq?

A

activates phospholipase C

49
Q

whats the action of Go?

A

doesn’t work on the alpha subunit

uses beta and gamma subunits to bring about transduction

50
Q

how does Gs protein signalling transduction work?

A

1) unoccupied receptor does not interact with the Gs protein
2) hormone/neurotransmitter binds to the receptor
3) occupied receptor changes shape and interacts with the Gs protein
4) Gs protein releases GDP and binds GTP
5) adenylyl cyclase catalyses formation of cAMP
6) when hormone or drug is no longer present, the receptor reverts to its resting state. GTP I hydrolysis and adenylyl cyclase is deactivated

51
Q

what does atenolol do to GPCR?

A

it is a B1 receptor antagonist

52
Q

what does salbutamol do to GPCR?

A

it is a B2 receptor agonist

53
Q

what are enzyme liked receptors?

A

large extracellular ligand-binding domain connected to intracellular domain by single membrane-spanning helix

ligand binding –> dimerisation –> autophosphorylation

54
Q

examples of drugs that target enzyme linked receptors?

A

endogenous agonists

insulin receptor – insulin
tyrosine kinase – imatinib

55
Q

how do insulin receptors work?

A

1) insulin binding activates receptor tyrosine kinase activity in the intracellular domain of the beta subunit of the insulin receptor
2) tyrosine residues of the beta subunit are auto-phosphorylated
3) receptor tyrosine kinase phosphorylates other proteins, eg. insulin receptor substrates (IRS)
4) phosphorylates IRSs promote activation of other protein kinases & phosphatases, leading to biologic actions of insulin – lowered blood glucose levels
5) can take hours – longer timeframe

56
Q

how do intracellular receptors work?

A

no extracellular binding site
drug has to get into the nucleus

family of 48 soluble receptors

important for expression of cholesterol and hormones

57
Q

examples of drugs that target intracellular receptors

A

Estrogen receptors – estradiol & tamoxifen

58
Q

what are the 2 major classes of intracellular receptors?

A

class 1 - located in the cytoplasm, form homodimers, ligands are endocrine - class 1 binds to class 1 only

class 2 - present in nucleus, form heterodimers, ligands are lipids (fatty acids)

59
Q

how does class 1 nuclear receptor signal transduction work?

A

1) unoccupied receptor does not provide intracellular signal
2) lipid-soluble drug diffuses across the cell membrane
3) drug binds to receptor – occupied receptor changes shape & is activated
4) activated receptor moves to nucleus
5) the drug-receptor complex binds to chromatin, activating the transcription of specific genes
6) mRNA is translated into specific proteins that result in a specific biological response

60
Q

how many binding sites do drugs have?

A

most have multiple

binding at 1 site will alter the binding at another site - positively or negatively

61
Q

what binds at allosteric sites?

A

allosteric antagonists - positive or negative

62
Q

what binds at orthosteric sites?

A

full and partial agonists

inverse agonists

reversible competitive antagonists

irreversible competitive antagonists

63
Q

what binds at effector region?

A

non competitive antagonists

channel activators

Pharmacology (24 decks)

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