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Pharmacology Flashcards

1
Q

Define Pharmacodynamics

A

Biological effects of drugs and mechanisms of action of a drug (what a drug does to the body)

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2
Q

Define Pharmacokinectics

A

Effect the body has on a drug (including; absorption, distribution, metabolism, elimination)

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3
Q

Define Efficacy

A

They ability of an agonist to evoke a response

Higher efficacy = larger response) (calculated by ß/a

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4
Q

Define Affinity

A

The strength of association between ligand and its receptor (it is determined by the chemical bonds between the two)

Greater affinity = greater duration of binding

Calculated by K+1/K-1

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5
Q

Define EC50

A

The concentration of agonist that results in a half maximal response (i.e. 50% of receptors are occupied)

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6
Q

If agonist A requires 0.01 concentration to elicit a response and agonist B requires 0.05 concentration to elicit a response.
Agonist A is more ____ than agonist B.

A

Potent

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7
Q

In the presence of a competitive antagonist, EC50 is unchanged. True/False?

A

False - EC50 increases

Increased concentration of agonist required to elicit same response

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8
Q

Both the ionised and unionised forms of a drug readily diffuse across the lipid bilayer. True/False?

A

False

Unionised form diffuses across more readily

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9
Q

Define pKa

A

The pH at which 50% of a drug is ionised and 50% is unionised

Therefore, when pH=pKa then 50% of drug is ionised and 50% is unionised

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10
Q

List 3 variations of the Henderson Hasselbach Equation

A

For weak acids:
pKa = pH + log[AH]/[A-]
pH - pKa = log[A-]/[AH]
10^(pKa-pH) = [AH]/[A-]

(For weak bases substitute AH for BH+ and A- for B)

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11
Q

Increasing the pH of an acidic drug causes it to become less ionised. True/False?

A

False

It becomes more ionised (acid drugs are less ionised in an acid environment)

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12
Q

Which administration routes by-pass first pass metabolism?

A

Sublingual, rectal, intravenous and intramuscular

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13
Q

Define the apparent volume of distribution (Vd)

How is it calculated?

A

Describes the extent to which a drug partitions between plasm and tissue compartments

Vd = Dose / [Drug]plasma

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14
Q

An apparent volume of distribution (Vd) closer to total body volume of water (~41L) suggests…

A

Drug is hydrophilic and contained within vascular compartment

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15
Q

An apparent volume of distribution (Vd) much greater than total body volume of water (~1000L) suggests…

A

Drug is lipophilic and can enter body tissue easily

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16
Q

Sympathetic preganglionic NT is?

A

Acetylcholine (cholinergic)

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17
Q

Sympathetic postganglionic NT is?

A

Noradrenline (adrenergic)

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18
Q

Parasympathetic pre and post ganglionic NT is acetylcholine. True/False?

A

True

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19
Q

Preganglionic neurone of sympathetic chain is long. True/False?

A

False - Preganglionic neurone of sympathetic chain is short

Note: preganglionic neurone of parasympathetic chain is long as ganglions are usually embedded in the target organ

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20
Q

Parasympathetic stimulation decreases force of heart contraction. True/False?

A

False

Has no effect on force of ventricular contraction, but does decrease heart rate

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21
Q

Components of a G-protein

A

α (contains guanine nucleotide binding site for GDP/GTP) and β + γ complex

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22
Q

M1 GPCR

Type: G_

Action: ___ acid secretion in stomach

A

Gq

  • Increased acid secretion in stomach
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23
Q

M2 GPCR

Type: G_

Action: ___ heart rate

A

Gi

  • Decreased heart rate (and heart force in atria only)

Remember: M2 is a presynaptic autoreceptor that modulates ACh release

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24
Q

M3 GPCR

Type: G_

Action: ___ of airways; ___ of specific vasculature; ____ mucus production; _____ intestinal motility and secretions; ____ bladder wall; ____ erection

A

Gq

  • Contraction of airways smooth muscle
  • Relaxation of vascular smooth muscle (in penis, salivary glands & pancreas)
  • Stimulates mucus production
  • Increases intestinal motility and secretions
  • Contracts bladder wall
  • Stimulates erection
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25
Regarding the adrenergic transmission - NA Uptake 1 is located on the?
Post-ganglionic neurone
26
Regarding the adrenergic transmission - NA Uptake 2 is located on the?
Effector cell
27
NA taken up by U1 is broken down by which enzyme?
Monoamine Oxidase - MAO - in the post-ganglionic neurone | N.B. MAO is a target of some anti-depressant drugs
28
NA taken up by U2 is broken down by which enzyme?
Catechol-O-methyltransferase - COMT - in the effector cell
29
ß1 GPCR Type: G_ Action: ____ heart rate and force
Gs Increased heart rate and force (in both atria and ventricles)
30
ß2 GPCR Type: G_ Action: ___ of airways and vasculature
Gs Relaxation of airway and vascular smooth muscle
31
α1 GPCR Type: G_ Action: ____ of vasculature
Gq Contraction of vascular smooth muscle
32
α2 GPCR Type: G_ Action: ____ NA release
Gi Decreased NA release Remember: α2 is a presynaptic autoreceptor that modulates release of NA
33
ACh binding to post-ganglionic M2 receptor causes ____ Ca2+ entry, which results in ___ NT release
Reduced, less Remember: M2 is a presynaptic autoreceptor that modulates ACh release
34
NA binding to post-ganglionic α2 receptor causes increased Ca2+ entry, resulting in more NT release. True/False?
False Decreased Ca2+ entry, resulting in less NT release Remember: α2 is a presynaptic autoreceptor that modulates release of NA
35
Cocaine blocks U_, causing an ___ in NA in the synaptic cleft What effect does cocaine have via α1 and ß1 GPCRs?
Cocaine blocks U1, causing an increase in NA in the synaptic cleft Overstimulation - α1 - increases vasoconstriction Overstimulation - ß1 - arrhythmia (increased heart rate)
36
Amphetamine enters the postganglionic neurone via ___ and inhibits the enzyme ___, resulting in ___ in NA in the cytoplasm. It also displaces ___ from _____ to cytoplasm which then exits via ___.
Amphetamine enters the postganglionic neurone via U1 and inhibits the enzyme MAO, resulting in increase in NA in the cytoplasm. It also displaces NA from vesicles to cytoplasm which then exits via U1
37
Which subunits form the PNS ganglionic nicotinic receptors?
3 x B4 | 2 x α3
38
What term is given to the concentration that a drug must reach in the plasma to achieve an effect?
Minimum effective concentration
39
Define the maximum tolerated concentration as...
The drug concentration in the plasma which must not be exceeded to prevent toxic effects
40
Therapeutic ratio/index is given by...
MTC/MEC ``` MTC = maximum tolerated concentration MEC = minimum effective concentration ```
41
How can drug plasma concentration be calculated?
Dose/Vd
42
What is first order kinetics in terms of elimination?
Rate of elimination is proportional to drug concentration
43
How is drug half life calculated?
0.693*Vd/CL CL= rate of clearance
44
For drugs exhibiting 1st order kinetics, the dose administered changes __ directly, but has no effect upon __ or __
Plasma concentration, half-life, rate of elimination
45
Plasma clearance is given by...
Vd x rate of elimination or Rate of elimination / [Drug] plasma
46
Rate of 1st order kinetic drug elimination is given by...
Cp x Clp
47
Css (steady state concentration) is normally achieved after _ half lives
5
48
The time to reach Css is determined by the infusion rate but not the half life. True/False?
False Css is determined by the half life, not infusion rate
49
Depolarisation is when the membrane potential becomes more negative. True/False?
False More positive
50
Resting membrane potential, Vm, is normally approx...
-70mV
51
Activation of Na+ channels and subsequent Na+ channels is an example of ____ feedback
Positive
52
Refractory period of the AP describes...
The inactivated state of sodium channels, ultimately causing repolarisation to closed state
53
In the relative refractory period, a strong enough stimulus can elicit the generation of a new AP. True/False?
True
54
What is the function of Schwann cells?
Wrap around axons in a "myelin sheath" to provide insulation and speed up electrical conduction
55
Saltatory conduction describes...
APs jumping between gaps between adjacent nodes of Ranvier
56
Where does reversible competitive antagonism occur?
Orthosteric site
57
Where does reversible non-competitive antagonism occur?
Allosteric site
58
Define oral availability
Fraction of drug reaching systemic circulation after orl ingestion
59
Define systemic availability
Fraction of drug reaching systemic circulation after absorption
60
Define Drug Clearance
Volume of blood removed (or cleared) of drug per unit of time
61
Define Steady state
When the rate of drug administration is equal to the rate of elimination
62
What is the shape of the agonist -receptor saturation curve?
Hyperbolic relationship
63
What is the shape of the agonist -receptor saturation curve in a semi-logarithmic plot?
Sigmoidal
64
How does the addition of a competitive antagonist effect the agonist -receptor saturation curve in a semi-logarithmic plot?
Shift of sigmoidal curve to the right Equal efficacy to agonist alone, however agonist alone is more potent (lower EC50)
65
How does the addition of a non-competitive antagonist effect the agonist -receptor saturation curve in a semi-logarithmic plot?
Small curve in same position Same potency as agonist alone, however less efficacy
66
What is the difference between autocrine and paracine chemical signalling?
Autocrine - cells release chemical signals that affect itself Paracrine - cells release chemical signals that affect neighbouring cells
67
What is the difference between speed of transmission of ligand-gated ion channels, GPCR, Kinase-linked receptors and nuclear receptors?
LGIC - miliseconds GPCR - seconds Kinase-linked - hours Nuclear - hours/days
68
List typical ligands for ionotropic LGIC receptors
ACh, AAs, rarely amines
69
List typical ligands for metabotropic GPCR receptors
ACh, AAs, amines, peptides and adrenaline
70
List typical ligands for kinase-linked receptors
Insulin, Growth factors immune signals
71
List typical ligands for nuclear receptors
steroid hormones and thyroid hormones
72
Which type of receptor is targeted by hydrophobic signalling molecules?
Nuclear receptors
73
Which types of receptor are targeted by hydrophilic signalling molecules?
LGICs, GPCRs, Kinase-linked receptors
74
Describe the action of insulin kinase-linked receptors
Insulin causes autophosphorlyation of intracellular tyrosine residues which recruits proteins i.e. insulin receptor substrate 1
75
Describe the action of nuclear receptors
Lipophilic steroid hormone diffuses across plasma membrane then combines with intracellular receptor (causing dissociation of HSP). Receptor-steroid complex travels to nucleus and forms a dimer which binds DNA to switch on/off genes.
76
How is the GPCR signal turned off?
Alpha subunit hydrolyses GTP to GDP
77
What are the steps involved in GPCR activation?
Agonist binds transmembrane receptor causing conformational change which in turn causes alpha subunit to release GDP and pick up GTP. Activated alpha subunit separates from the beta-gamma dimer and combines with effector channel
78
How do Gs type GPCRs work?
Stimulates AC ⮕ upregulates cAMP ⮕increased PKA ⮕ Phosphorylation
79
How do Gi type GPCRs work?
Inhibits AC ⮕ downregulates cAMP ⮕ decreased PKA ⮕ inhibited phosphorylation
80
How do Gq type GPCRs work?
Stimulates PLC ⮕ upregulates the conversion of PIP2 to IP3 and DAG ⮕ IP3 binds receptor (causing calcium influx from ER) and DAG causes phosphorylation
81
Where do drugs that are weak bases accumulate?
In compartments with low pH (acidic)
82
Where do drugs that are weak acids accumulate?
In compartments with high pH (basic)
83
Where does most drugs get absorbed regardless of pH?
Small intestine - due to large surface area
84
How can volume of distribution be calculated when giving IV fluids?
Dose = Vd
85
What is the most abundant plasma protein?
Albumin
86
How does plasma protein binding affect drug availability for diffusion to target organ?
Reduced
87
Describe the therapeutic window of a safe dug
High therapeutic ratio = large therapeutic window
88
Where are the drug-metabolising enzymes in hepatocytes found?
Bound to SER
89
Describe Phase 1 Drug Metabolism
Change drug via catabolic reactions (i.e. oxidation, reduction or hydrolysis) - Oxidation via CYP450 produces more chemically active (or toxic) metabolites by introducing a reactive species
90
Describe Phase 2 Drug Metabolism
Anabolic reactions involving conjugation to form a water soluble metabolite, usually result in inactive products - Conjugated species are usually readily excreted via kidneys
91
What types of metabolites are readily excreted by the kidneys?
Charged metabolites
92
How are unbound drugs filtered by the kidneys?
Passive glomerular filtration
93
How are acidic drugs filtered by the kidneys?
Active OAT
94
How are basic drugs filtered by the kidneys?
Active OCT
95
Describe zero-order elimination kinetics
When Vmax is reached and rate of elimination is constant
96
How can the rate of drug elimination be calculated?
Rate = (Vmax x [Drug]plasma) / (Km + [Drug] plasma)
97
Does changing rate of administration change the time to steady state?
No, but it does alter the [ss]
98
How can steady state dosage be calculated?
Dosage rate = [Drug]plasma x Clearance rate
99
What does a loading does do?
Decreases time to steady state
100
How can Loading doses be calculates?
IV: LD = Vd x target [plasma] PO: LD = (Vd x target [plasma]) x F (where F = oral bioavailability)
101
``` What effect does; - ageing, - obesity, - pathological fluid ...have on drug half life? ```
- decreases - increases - increases
102
Name factors that effect the volume of distribution
Ageing and obesity
103
Name factors that effect clearance rate
CYP450 concentration, renal failure, cardiac failure and hepatic failure
104
``` What effect does; - increased CYP450, - decreased CYP450, - renal failure, - cardiac failure, - hepatic failure, ...have on drug half life? ```
- decreased - increased - increased - increased - increased
105
Which NTs modulate activity in the sympathetic nervous system?
Main: NA | Additional modulators: ATP and NPY
106
Which NTs modulate activity in the parasympathetic nervous system?
Main: ACh | Additional modulators: NO and VIP
107
Which subunits form the PNS skeletal muscle nicotinic receptors?
(alpha1) x2 Beta1 Gamma Epsilon
108
Which subunits form the CNS nicotinic receptors?
(alpha7) x5 or (alpha4) x2 (beta2) x3
109
What is the effect of prazosin on alpha1 ADRs?
Antagonist - causing vasodilation Therefore, used as an anti-hypertensive
110
What is the effect of atenolol on ß1 ADRs?
Antagonist Used as an anti-anginal and anfti-hypertensive
111
What is the effect of atropine on M1-3 GPCRs?
Widespread parasympathetic blockade Used in decreasing heart rate following MI and also used in acetylycholinesterase poisoning

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