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(Physio) Health Sciences > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

How do ion channels ensure only the target ion passes through

A

Molecular selectivity filter – specific substrates

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2
Q

Define antagonist

A

Antagonist: blocks or reduces agonist mediated responses

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3
Q

Define placebo

A

Any intentionally ineffective medical treatment, such as a sugar pill, used to replace medication.

Still gives a physiological as well as psychological response

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4
Q

Describe the effect of ‘induction’ i.e. brussel sprouts

A

Induction = shortens action of drugs

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5
Q

Define therapeutics

A

use of drugs to diagnose, prevent and treat illness (and/or pregnancy) i.e. the medical use of drugs

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6
Q

Define drug

A

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

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7
Q

What is the relationship between the systemic circulation and the tissue called?

i.e.

Circulation – high conc = Greater movement to tissue

As tissue concentration increased = Movement back to blood

A

dynamic equilibrium

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8
Q

What are the 4 common protein target types

A

Enzymes Carrier molecules (transporters / pumps) Ion channels Receptors

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9
Q

Describe orthosteric binding

A

A different substance to the intended ligand competes for the target binding site by binding orthosterically via the same binding site. This blocks access for the intended ligand.

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10
Q

Described how a Ca2+ channel blocker would work (and overall effect)

A

Physically blocks the channel to prevent the ions from passing through e.g. Vasodilator – smooth muscle Reduced myocardial contraction force Slows SA node Slows AV node conduction

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11
Q

Describe phase 2 of metabolism

A
  • Adding of endogenous substance- (covalent bonding)
  • Making it water soluble
  • Inactivates pharmacologically
  • Converting the drug/toxin by covalently joining to other molecules
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12
Q

Finish the sentence:

Basic drugs e.g. propranolol

———- ionised in basic solutions (high pH)

———- ionised in acidic solutions (low pH)

A

Basic drugs e.g. propranolol

Less ionised in basic solutions (high pH)

Become ionised in acidic solutions (low pH)

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13
Q

What are the 4 basic principles of pharmokinetics

A
  1. Absorption
  2. Distribution
  3. Metabolism
  4. Excretion
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14
Q

In the duodenum (pH 8.5) could an acidic drug pass into the blood plasma?

A

Acidic drug = ionised so NO

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15
Q

define enzyme

A

A protein (or protein-based molecule) that acts as a catalyst to speed up a chemical reaction. Acts on specific substances known as substrates

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16
Q

Does this illustrate well, or poorly perfused tissues?

A

Well perfused tissues

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17
Q

Which one of the 3 injection site types is generally the best, and why?

A

Intravenous (I.V.)

–most direct, bypasses absorption barriers

–rapid, high concentrations

–bioavailability ~100%

–avoids 1st pass metabolism

Intramuscular (I.M) –dependant on blood flow

Subcutaneous (S.C.) –more slowly absorbed, again dependant on blood flow

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18
Q

In the duodenum (pH 8.5) could a basic drug pass into the blood plasma?

A

Yes, as unionised

Basic drug becomes unionised –> Less lipophilic –> Becomes partitioned (trapped)

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19
Q

State 4 Transepithelial routes: AKA enteral routes of drug absorption

A
  1. Oral
  2. Buccal
  3. Inhalation
  4. Rectal Suppository
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20
Q

How does drug ionisation affect their permeability?

A

Affects drug permeation i.e. their solubility by changing lipophillicity, as Ionised molecules cant diffuse across membranes

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21
Q

True or False: Drugs have complete specificity for their actions

A

No drug acts with complete specificity

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22
Q

What does this graph infer

A

The Atenolol is a ‘selective’ β1 receptor antagonist

As reduced potency

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23
Q

Define pharmacokinetics

A

The way the body effects the drug- How the drug is handled.

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24
Q

What are the 3 major types of membrane protein

A

transporter enzyme receptor

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25
Q

Define affinity

A

the relative attraction of a drug molecule to the target receptor

(which may or may not produce a response i.e. antagonist)

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26
Q

What is an EC50

A

The effective concentration of the drug in question- Concentration needed to give 50% maximal response

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27
Q

State 3 factors that can affect distribution

A
  1. Protein binding
  2. Blood flow
  3. Membrane permeation \ Tissue solubility
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28
Q

describe the Quaternary protein structure

A

2 or more polypeptides combine to form functional protein

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29
Q

Why can protein binding be dangerous in terms of pharmacology?

A

Drugs can compete at plasma protein binding site

may displace each other →drug-drug interaction

e.g. warfarin & aspirin have same binding site of serum albumin and could lead to uncontrollable bleeding if both taken together

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30
Q

Broadly, how does a drug produce an effect

A

the drug molecule binds to a target molecule, changing the properties to either activate, deactivate or modulate the target molecule to produce an effect

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31
Q

Why is drug ionisation an issue?

And how does this occur?

A

Affects the way the drug behaves i.e. its actions

Due to pH changes in the body

i.e. propanolol in +ve state, and aspirin in -ve state

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32
Q

What are the beneficial affects of having poorly perfused tissues?

A
  • Slower increase
  • But- acts as a ‘sink’, effectively removing drug for circulation
  • Until equilibrium point is reached
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33
Q

What is important to consider in biliary excretion?

A

Gut bacteria can convert drug to original form via metabolising enzymes.

Drug can be resorbed across intestinal wall and re- circulate in blood.

Then can be metabolised in liver again and re-secreted into bile

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34
Q

Define pharmacodynamics

A

Effect(s) of a drug on the body- How it works!

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35
Q

Define allosteric

A

Allosteric: binds to different region but still affects the binding site

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36
Q

Define ligand

A

Ligand: a molecule that binds to the receptor e.g. ACh

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37
Q

describe the tertiary protein structure

A

α-helices and β-sheets re-folded to form a globular molecule.

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38
Q

Would ions move up or down the electrochemical gradient preferentially

A

Down

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39
Q

Give an example of an instrinsic situation of poor perfusion

A

The blood brain barrier

L-DOPA can’t cross BBB due to its charge, so transported with L Amino Acid Transporter instead

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40
Q

What does the rate of absorption of drugs depend on?

A
  • Route of administration
  • Permeation ability
41
Q

What are the three different names for a drug

A

The chemical name The generic name The proprietary name

42
Q

Which organ is the principle site of drug metabolism?

A

The liver

43
Q

Define efficacy

A

The ability to produce maximal response

44
Q

Describe the principle excretory route of billary excretion

A
  1. hepatocyte uptake
  2. bile
  3. duodenum
  4. excreted in faeces
45
Q

State 2 causes of tachyphylaxis

A
  • Change in receptors
    • e.g. GPCRs - phosphorylation by kinases
  • Known as desensitisation – loss of affinity for ligand
  • Loss of receptors
    • e.g. internalisation
  • Exhaustion of mediators
    • e.g. loss of downstream transmitters
  • Physiological adaptation
    • e.g. other systems adjust / homeostasis
  • Increased metabolic degradation
    • e. g. Enzyme upregulation
46
Q

What is the difference between full and partial agonists

A

Full agonists give an increase in response with increase in concentration until maximum tissue response is reached

Partial agonists give an increase in response with increased concentration but cannot produce maximal possible response

47
Q

What is an EMax

A

maximum response a drug can produce point at which receptors are saturated

48
Q

Describe the principle of lipophillicity in relation to membrane permeation

A

oCharged molecules, ions, ionised molecule diffuse less efficiently

oUncharged, non-ionised drugs have better access to membrane bound compartments

49
Q

What is first pass metabolism

A

the rapid uptake and metabolism of an agent into inactive compounds by the liver, immediately after enteric absorption and before it reaches the systemic circulation.

Nutrient rich blood from the gut passes directly to the liver

50
Q

Describe the effect of ‘inhibition’ i.e. grapefruit

A
51
Q

What is the key function of metabolism

A

Conversion from lipid-soluble compound to more water-soluble one

Lipid soluble drugs can freely return to plasma from filtered urine and / or faeces

52
Q

Define medicine

A

‘usually, but not necessarily, contains one or more drugs which is administered with the intention of producing a therapeutic effect.’

53
Q

State one enzyme type which is involved first pass metabolism in each of the:

Liver, intestine, and lungs

A
  • Liver- cytochrome p450
  • Intestine- proteases or amino acid converting enzymes
  • Lungs- oxidising enzymes
54
Q

Define bioavaliability

A

proportion of active drug that reaches the systemic circulation

55
Q

What organs display the most first pass metabolism

A

Liver, intestine, skin and lungs

56
Q

Define orthosteric

A

Orthosteric: ‘competes’ for the same binding site

57
Q

what is a false substrate analogue

A

Similar molecular shape to normal substrate Drug behaves like normal substrate Target enzyme produce an abnormal product Disruption the normal pathway i.e. signalling or metabolic i.e. methyldopa reducing production of norepinephrine by binding to dopamine hydroxylase

58
Q

Define agonist

A

Agonist: a molecule that ‘activates’ a receptor

59
Q

State 3 factors affecting oral absorption

A
  • Disintegration of dosage form
  • Chemical stability of drug
  • Stability of drug to enzymes
  • Presence and type of food
  • Passage across GI tract wall
60
Q

What is an excipient

A

substances ‘formulated’ along side a drug

61
Q

In the gut lumen, could a basic drug pass into the blood plasma?

A

Basic drug (ionised) so NO

Ionised = more lipophillic

62
Q

State 3 methods of transporting things in the body (via carrier proteins)

A

Active transport Facilitated diffusion Osmosis Passive transport

63
Q

What are the benefits of having well perfused tissues?

A
  • Rapid increase in bioavailable drug
  • Rapid decrease –drug partitions to poorly perfused tissues
  • Plasma concentration falls so- Drug re-partitions back to plasma

(Well perfused tissue ‘feeds’ uptake in poor)

64
Q

Which drug is more potent? Red or Green?

A

Green as it has a higher EC50 at a lower concentration

65
Q

Define potency

A

Concentration of a drug necessary to produce a given response

66
Q

Define tachyphylaxis

A
  • rapidly decreasing response to drug
  • repeated or continuous administration
67
Q

What are the 3 injection site types of drugs?

A
  • Intravenous
  • Intramuscular
  • Subcutaneous
68
Q

What is this schematic indicating?

A

first pass metabolism occuring

69
Q

What is the major benefit of topical administration of drugs (absorption)

A

virtually insignificant first pass metabolism

70
Q

define pro-drug

A

inactive/ partially active drug metabolically transformed in the body to an active form

71
Q

What is a drug formulation

A

how the drug is ‘packaged’

72
Q

Finish the sentence:

Acidic drugs e.g. Aspirin

———- ionised in acidic solutions (low pH)

———- ionised in basic solutions (high pH)

A

Acidic drugs e.g. Aspirin

Less ionised in acidic solutions (low pH)

Become/more ionised in basic solutions (high pH)

73
Q

What are the two phases of metabolism

A

Phase 1- oxidation, reduction and hydrolysis etc

Phase 2- covalently joining of metabolite to other molecule

  • Phase 1 may produce toxic metabolites
  • Phase 2 converts to soluble metabolites for excretion
74
Q

In urine, can acidic drugs pass into the blood plasma

A

Acid drug > tend to become non-ionised –> Looses it’s net charge = Become lipophilic

SO freely diffuses

****Acid drug –> mostly ionised –> remains in plasma

75
Q

Describe the primary protein structure

A

Amino acids in a polypeptide chain Polar side groups

76
Q

what are the three key drug/enzyme interactions

A
  1. Substrate analogues 2. False substrates 3. Conversion of pro-drugs
77
Q

State 2 types of ion channels

A

Ligand-gated Voltage-gated Leak Background

78
Q

what is an enzymatic substrate analogue

A

Similar molecular shape to normal substrate Usually work via ‘competitive’ inhibition of enzyme i.e. neostigmine (ACh inhibitor) for myasthenia gravis which binds to AChE resulting in more ACh at the NMJ

79
Q

Describe protein binding in the context of drug distribution

A
  • Partly bound to plasma protein and partly in plasma water
  • Binding is reversible
  • Only the UNBOUND fraction becomes avaliable and can cross membranes or bind to receptors
80
Q

State 2 characteristics on an ideal drug

A

have a desirable pharmacological action with acceptable side effects (or none) reach it target in the right concentration at the right time remain at the site of action for sufficient time (in sufficient concentration) be rapidly and completely removed from the body when no longer needed

81
Q

In the gut lumen (pH 1-2), could an acidic drug pass into the blood plasma?

A

Acid drug (unionised), so YES

Acid drug becomes ionised –> Less lipophilic –> Becomes partitioned (trapped)

82
Q

Broadly, what is EC50 used to measure

A

The drugs potency

83
Q

describe the secondary protein structure

A

Chains ‘fold’ or ‘coil’ α-helix: linkage within polypeptide chain β-sheet: linkage within or between chains

84
Q

Describe why a pro-drug might be useful

A

If the drug isn’t metabolically activated until a specific target area it would minimise side effects, and increase the drug efficacy by having a stronger dose at the intended site.

85
Q

Give an example of an endogenous ligand

A

Acetylcholine GABA Glutamate

86
Q

Fick’s law states the rate of permeation depends on what 3 things?

A
  1. Surface area
  2. Concentration gradients
  3. Thickness of barrier
87
Q

In the kidney, what are the 3 main mechanisms of excretion

A
  1. Glomerular Filtration

Only unbound drugs

  1. Secretion

Proximal convoluted tubule cells

  1. Reabsorption

Lipophilic drugs resorbed throughout nephron

88
Q

Describe phase 1 of metabolism

A

Phase I – oxidation, reduction, hydrolysis

  • oxidation (losing electrons)
  • reduction (gaining electrons)
  • hydrolysis (adding H2O)
  • Polarization of the substance
  • Increase water solubility
  • Reduce pharmacological activity
  • BUT may activate prodrugs
  • Other enzymes often involved- (oxidases, hydrolases, reductase)
89
Q

What is the implication of first pass metabolism

A

Reduced bioavaliabilty of the drug where it is needed in the body

90
Q

Where are these protein targets found in the cell

A

in the cell membrane

91
Q

Give an example of an exogenous ligand

A

Neostigmine Aspirin Methyldopa Acetylcholine etc. (manufactured)

92
Q

Does this illustrate well, or poorly perfused tissues?

A

Poorly perfused tissues

93
Q

What can our metabolic rate determine

A

•Metabolic rate can determine the duration of drug action and affects the rate of repeat dosing (Related to half-life)

94
Q

Give 3 way drugs can be excreted

A
  • Fluids- Urine / Sweat / Tears / Breast milk
  • Solids- Faeces / hair
  • Gases- Expelled air
95
Q

State 4 main receptor superfamilies

A

Ionotropic (ligand-gated channels) Metabotropic (G-protein coupled) Kinase-linked Nuclear

96
Q

True or False-

the two phases of metabolism are mutally dependent

A

Not mutually dependent-

One or other or both

May be required…

phase II can precede phase I

phase II can occur in the absence of phase I

97
Q

What are the 4 major transportational processes of drug absorption?

A

oAqueous diffusion

oPassive diffusion

oCarrier-mediated diffusion

oActive transport

(pinocytosis with high molecular weight drugs)

98
Q

Define drug distribution

A

Drugs transferred from circulation into tissue

99
Q

State 3 sources of individual variation in drug response

A

Genetic variables Physiological variables Drug interactions Age Sex Weight Kidney & liver functions - elimination of drug

(Physio) Health Sciences (10 decks)

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