Pharmacology Flashcards
1
Q
pharmacodynamics
A
effect drug has on body
2
Q
pharmacokinetics
A
effect body has on drug
3
Q
agonist possesses
A
efficacy and affinity
4
Q
antagonist possesses
A
only affinity
5
Q
define affinity
A
strength of association between ligand and receptor
6
Q
define efficacy
A
ability of agonist to evoke cellular response
7
Q
what axis is potency on
A
x axis, increasing potency from right to left
8
Q
what axis is efficacy on
A
y axis, increasing efficacy from bottom to top
9
Q
competitive antagonism has what effect on graph
A
parallel shift to right
10
Q
non-competitive antagonism has what effect on graph
A
depresses curve as binds to different site
11
Q
define absorption
A
process when drug enters body
12
Q
define distribution
A
process when drug leaves circulation and enters tissues
13
Q
define metabolism
A
process when drug converted to more polar form for excretion
14
Q
define excretion
A
process when drug leaves body
15
Q
factors controlling drug absorption
A
solubility, chemical stability, lipid-to-water partition coefficient, degree of ionisation
16
Q
lower pKa or higher Ka means what type of acid
A
stronger acid
17
Q
define oral availability
A
fraction of drug that reaches systemic circulation after oral ingestion
18
Q
define systemic availability
A
fraction of drug that reaches systemic circulation after absorption
19
Q
enteral routes of administration
A
oral, sublingual, rectal
20
Q
parenteral routes of administration
A
IV, IM, inhalation, topical
21
Q
advantages of sublingual
A
rapid absorption
22
Q
advantages and disadvantages of inhalation
A
large surface area but requires dexterity (skills)
23
Q
where are drugs distributed
A
one or more body fluid compartments, not evenly distributed around body
24
Q
what are the body fluid compartments?
A
intracellular water, extracellular water (interstitial, plasma, transcellular)
25
define volume distribution
apparent volume in which drug is dissolved
26
for IV what does Vd = ?
for IV, Vd = dose / plasma concentration
27
what does Vd < 10L mean
drug mainly retained in vascular compartment
28
what does Vd 10-30L mean
drug mainly in extracellular water
29
what does Vd > 30L mean
drug distributed throughout whole body or accumulated in certain tissues
30
what does MEC stand for
minimum effective concentration
31
what does MTC stand for
maximum tolerated concentration
32
Therapeutic ratio = ?
Therapeutic ratio = MTC/MEC. Higher ratio, safer the drug
33
what is first order kinetics
rate of elimination is directly proportional to drug concentration
34
what is the clearance of a drug
volume of plasma cleared of drug in unit time
35
Rate of elimination = ?
rate of elimination = Clearance x Plasma concentration
36
when is dosing to a steady state reached
after 5 half lives
37
for drug dosing orally what happens to plasma concentration
plasma concentration fluctuates about an average steady state value
38
what is the loading dose
initial dose higher before stepping down to lower maintenance dose. Employed to decrease time to steady state for drugs with longer half-lives
39
define half life
time for concentration of drug in plasma to half
40
what is zero order kinetics
initially eliminated at constant rate
41
how can drug metabolism happen
convert drug to more polar metabolites not readily absorbed or convert drug to metabolites less pharmacologically active than parent compound
42
what are the 2 phases of drug metabolism
```
phase 1 (rhs of liver): oxidation, reduction and hydrolysis to make drug more polar.
phase 2 (lhs of liver): Conjugation, when endogenous compounds added to increase polarity
```
43
example of phase 1 and phase 2 drug metabolism reactions
CYP450 monooxygenase cycle
44
3 phases of drug excretion
1. glomerular filtration
2. active tubular secretion
3. passive reabsorption
45
what does glomerular filtration achieve
removes unbound drugs
46
what does active tubular secretion achieve
can secrete highly bound drugs. Organic anion transporter handles acidic drugs and Organic cation transporter handles basic drugs like morphine
47
what does passive reabsorption rely on
urine concentration, factors influencing reabsorption include polarity, urinary pH and urinary flow rate
48
what is depolarisation and hyperpolarisation
```
depolarisation = membrane potential becomes less negative.
repolarisation = membrane potential becomes more negative
```
49
Sodium channels
Na flows down conc. gradient INTO cell. but still negative anions outside so NA+ flow down electrical gradient OUT of cell. When conc gradient = electrical gradient then Ena= +61mV
50
Potassium channels
K+ flow down concentration gradient OUT of cell. but still negative anions inside cell to K+ flow down electrical gradient INTO cell.
Ek = -90mV
51
which channels are depolarising
Na channels = depolarising so move membrane potential towards Ena.
K+ channels = repolarising s more Em towards Ek.
52
define action potential
a brief electrical signal at which the polarity of the membrane is momentarily reversed
53
why is the membrane potential -70mV, thus closer to Ek of -90mV
at resting potential the membrane is 100x more permeable to K= ions than Na, but there's a slight difference due to slight inward leak of Na ions
54
What are the Nernst and Goldman- Hodgkin-Katz equations for
```
Nernst = calculates membrane potential for single ion
Goldman = calculates overall membrane potential
```
55
how do voltage activated Na and K channels work
depolarisation causes Na channels to open. Depolarisation is maintained by positive feedback which causes Na channels to enter inactivated state. K+ channels then open to cause repolarisation which causes Na channels to enter closed state
56
define absolute refractory period and relative refractory period
```
Absolute = no stimulus, cannot elicit a second action potential.
Relative = stronger than normal stimulus may elicit a second AP
```
57
why don't passive signals spread far from their site of origin
'leaky' nerve cell membrane. To increase conductance then increase axon diameter, or coat in conductive layer of myelin. Oligodendrocytes produce myelin in CNS. Schwann cells for PNS
58
Sympathetic ANS
flight or fight.
preganglionic neurotransmitter is ACh.
postganglionic neurotransmitter is noradrenaline.
Thoraco-lumbar outflow (T1-L2)
59
Effects of sympathetic stimulation
- increases HR, force of contraction
- relaxes bronchi, decrease mucus production
- vasoconstriction but relax skeletal muscle
- ejaculation
60
Parasympathetic ANS
- coordinates body's basic homeostatic functions
- preganglionic and postganglionic are ACh
- cranial nerves 3,7,9,10
61
Effects of parasympathetic stimulation
- decrease HR
- bronchconstriction, stimulates mucus production
- no effect on blood vessels
- erection
62
t1/2 half life =
0.69/kel
63
what is EC50
The conc. of agonist that results in a half maximal response (i.e. 50% of receptors are occupied)
64
What are the lengths of the ganglions in para and sympathetic ANS
```
Sympathetic = short preganglion, long post ganglion
Parasympathetic = long preganglion and short post ganglion
```
65
what happens in neurochemical transmission
- AP from CNS
- Travels to presynaptic terminal of preganglion which triggers calcium entry and ACh release.
- synthesis and storage of ACh opens ligandgated channels in postganglion neurone
- causes depolarisation of AP, calcium entry and then release of noradrenaline or ACh
- Noradrenaline activates adrenocrptors
- ACh activates Muscarinic ACh receptors
66
how are ANS signals terminated
degradation of ACh to choline and acetate by AChE terminates transmission.
- reuptake and reuse of choline
67
structure of nicotinic ligand gated ACh receptors
5 glycoprotein subunits forming a central, cation conducting channel
68
G protein structure and activation
- receptor =7 transmembrane spans, 3 extracellular loops.
- G p = 3 subunits (a,b,y)
- Agonist activates receptor so it couples with G protein
- GDP dissociates and GTP binds to alpha subunit
- alpha subunit dissociates with GTP attached, these are signalling molecules
- turned off by alpha hydrolysing GTP > GDP and re-joining with subunits
69
M1 receptor coupled to Gq does what
stimulates phospholipase C, increases stomach acid secretion
70
M2 receptor coupled to Gi does what
inhibits adenylyl cyclase and decreases HR
71
M3 receptor coupled to Gq does what
stimulates phospholipase C, increases saliva secretion and bronchoconstriction
72
B1 adrenoceptor in heart does what
stimulates adenylyl cyclase, increases HR/force
73
B2 adrenoceptor in airways does what
stimulates adenylyl cyclase, bronchodilation
74
A1 adrenoceptor coupled to Gq does what
stimulates phospholipase C, bronchoconstriction
75
A2 adrenoceptor coupled to Gi does what
inhibits adenylyl cyclase, inhibits noradrenaline release
