Pharmacology Flashcards
1
Q
Pentazocine mode of action
A
Agonist at κ-opioid receptors antagonizing μ-opioid receptors
2
Q
Clozapine mode of action
A
Atypical antipsychotic. Partial agonist at D2 and antagonist at 5-HT2A
3
Q
Competitive antagonist dose response curve action
A
Shift curve to right. CMax unaltered
4
Q
Antagonists may also act as agonists - true/false
A
Yes, if mixed antagonist/agonist e.g. pentazocine
5
Q
What is ED50
A
Effective concentration 50 - refers to dose of the drug. Dose required to produce an effect in 50% of the population that take it
6
Q
Therapeutic index calculation
A
Lethal dose / ED50
7
Q
Wrt log-dose response curve - how do you assess potency
A
Position of ED50
8
Q
G-protein CR subunits
A
alpha, beta, gamma subunits
9
Q
Insulin receptor - Mode of Action
A
Via tyrosine kinase - NOT GPCR
10
Q
Mixed antagonist/agonist drugs
A
Opioids (Pentazocine, Nalbuphine and Buprenorphine), Mirtazepine, Pindolol and Xameterol
11
Q
Xameterol MoA
A
Mixed beta agonist/antagonist
12
Q
Pindolol MoA
A
Non-selective Beta-blocker with partial beta-agonist activity. It also has partial agonist / antagonist activity at the 5-HT1A recepto
13
Q
Time constants vs Half life
A
An exponential process is said to be complete after 3 time constants, as opposed to 5 half-lives thus TC is longer
14
Q
Time constant definition
A
Time taken for expontential process to fall by 37% or 1/e its previous value
15
Q
ACh subunits
A
2 alpha, 1 beta, 1 delta and epsilon (replaced by gamma in foetus)
16
Q
Loop diuretic effects
A
Hypomagnesium, kalaemia and natraemia
Metabolic alkalosis
17
Q
Cimetidine - enzyme inducer or inhibitor
A
Inhibitor
18
Q
Csf constituents
A
Magnesium higher Glucose lower Potassium lower Chloride higher Sodium marginally lower
19
Q
Svr calculation
A
Svr = (map-cvp) / co
20
Q
Vaporiser output calculation
A
(Carrier gas flow x svp) / ambient pressure - svp
21
Q
MET O2 consumption
A
3.5ml O2 / kg / min = 1 met
22
Q
Adenosine diphosphate effect
A
Conformational change in fibrinogen receptor which secures platelet plug
23
Q
Endothelin effect
A
Most potent vasoconstrictior
24
Q
Disinfection
A
Cleans everything but bacterial spores
25
Sterilization
Cleans everything including bacterial spores
26
From thick ascending limb of loop of Henle - what is absorbed via secondary active transport?
K and Cl cotransported
| H countertransported
27
Sodium movement in DCT
Via specific sodium channel AND cotransport with Cl
28
H2O resorption
70% PCT, 25% DCT
29
K resorption
90% in PCT
30
What is urinary concentration of K dependent on
Secretion in DCT/collecting ducts
| Passive secretion via channels and K/Cl cotransport and active transport via Na/K ATPase
31
Plasma conc. for renal threshold of glucose
11 mmol/L
32
Potassium resorption
55% PCT
| 30% Loop of Henle
33
Do ADH and Angiotensin II suppress renin?
Yes
34
Angiotensin II effects
Stimulate thirst
Constrict afferent and efferent arterial (Efferent > afferent, thus increasing GFR)
Aldosterone release
ADH release
Act directly on Na/H antiporters in PCT to cause Na and H2O retention
35
ANP renal effects
Afferent arteriolar dilation and efferent arteriolar constriction, thus increasing net filtration pressure
36
Renal clearance equation
Clearance = (urinary concentration x urinary flow rate) aka renal excretion / plasma concentration of substance
37
Renal blood flow equation
Renal blood flow = renal plasma flow / (1-HCT)
38
Critical temperature of O2
-118 deg C
39
Temp in VIE
-160 to -180 deg C
40
Nitrous critical temp
36.4 degrees
41
What are medical gas cylinders made of?
Molybdenum steel
42
What do the plastic neck rings around gas cylinders signify?
Date of last safety check (Every 5 hrs)
43
Inspiratory limb within expiratory limb breathing system
Bain (Coaxial mapleson D)
44
Expiratory limb within inspiratory limb
Lack (CoAxial mapleson A)
45
Fresh gas runs in inner tube of this coaxial system
Bain
46
Fresh gas flow in outer tube of this coaxial variant
Lack
47
Soda lime equations
1. CO2 + H2O → H2CO3 (slow, rate-limiting step)
2. H2CO3 + 2 NaOH →2 H2O + Na2CO3
3. Na2CO3 + Ca(OH)2 →2 NaOH + CaCO3
4. H2CO3 + Ca(Oh) 2 - - > CaCO3 + 2H2O
48
What is the Pethick check
Checks for inner tube defect in Bain system
49
Euler's number
2.718
50
Time constant definition
1. It is the time required for a process to complete if it continued at its initial rate of fall, i.e. it is the tangent to the graph at time = 0
2. The graph (Fig 1) shows that it is the time taken for the magnitude of the variable to fall to 37% of its initial value
3. The time to fall to 1/e or 1/eth of its original value.
51
Relationship between tau and k
τ = 1/k
52
1/2 life and t relationship
t½ = τ x 0.693
53
Clearance equation
Clearance = drug infusion rate/blood concentration
The relationships between clearance and the rate and time constants can be expressed mathematically as:
Cl = k x Vd
or
Cl = Vd/τ
54
adrenaline low dose effects
Increased beta effects
55
adrenaline high dose effects
increased alpha effects
56
What sympathomimetic may cause diastolic to fall due to B2 linked peripheral vasodilation
Adrenaline
57
D1 receptor activation
Vasodilation of renal and mesenteric beds
58
Dopamine effects
It increases atrio-ventricular conduction
Can cause tachycardia at higher doses particularly with inadequate preload
It stimulates noradrenaline release
59
Dobutamine site of action
Mainly B1 with some B2 and a1 effects
60
Similar structure to isoprenaline
dobutamine
61
Dobutamine effect on peripheral vessels
Decreases left ventricular end diastolic pressure (LVEDP, see Starling’s law) via its action on peripheral β2-receptors. β2 linked peripheral vasodilatation reduces venous return and systemic vascular resistance
62
Dopexamine mode of action
Dopamine analogue. Mainly b2 action with some D1 action. no A1 action
Inotropic via B1
Reduces SVR and afterload via B2
63
Levosimendan mechanism
Increases myocyte sensitivity to Ca2+ by binding to Trop C without increasing intracellular Ca2+
Relaxes vascular smooth muscle by opening ATP-sensitive K channels causing peripheral vasodilation
64
Methyldopa MoA
```
a2 agonist (+ minimal a1)
S/E - Positive direct coombs test 10-20% of cases
```
65
Clonidine MoA
a2 agonist (+ minimal a1).
Also inhibits ADH + inhibits insulin release
Rebound HTN following acute cessation
66
Guanethidine MoA
Enters adrenergic neurone via neuronal reuptake and displaces norad thus prevent further norad release
Leads to decreases a1 stimulation
S/E - diarrhoea and postural hypotension
Commonly used now to manage chronic pain
67
Trimetaphan
Ganglion blocking agent - non depolarizing competitive antagonist at ganglion type nicotinic receptors of autonomic ganglia
S/E - assoc histamine release
side effects mainly to parasympathetic NS
68
Sodium nitroprusside side effects
Reacts with OxyHb to form cyanide, NO, and methaem. 5 cyanide molecules per SNP
Broken down in light, so syringes covered in foil
69
Sodium nitroprusside MoA
Given only parenterally
Rapid onset and offset
Acts on arterioles and venules
Increases ICP but autoregulation maintained
Activates renin/angiotensin system and increases plasma catecholamines which can cause rebound hypertension if treatment is stopped abruptly
Hypoxic pulmonary vasoconstriction can be inhibited causing shunt
70
Magnesium anti hypertensive effect
Direct action on vascular smooth muscle
71
ACE inhibitor subgroups
Active drug, metabolized to active metabolites – Captopril
Pro drugs activated in liver – Ramipril
Active drugs excreted unchanged in urine – Lisinopril
72
Phentolamine
Short acting competitive antagonist for a1 and a2
| A1 >>> A2
73
Phenoxybenzamine
Non selective alpha antagonist. More selective for alpha 1
| Irreversible blockade of alpha receptors + inhibit catecholamine uptake
74
Can induce AF due to decreased atrial refractory period - which antiarrhythmic/drug used in SVT
adenosine
75
Raises risk of dig toxicity
```
HypoK
HypoMag
HyperNa
HyperCa
Hypoxia
Renal failure
Other drugs - amiod, verapamil, diazepam
```
76
Fentanyl metabolism - where, to what and active or not
Hepatic, norfentanyl, inactive metabolite
77
Efficacy Definition
Measure of maximal effect of agonist + describes ability to produce a therapeutic effect
78
Term pregnancy respiratory chances
Lower frc + rv, Lower chest compliance, lower airway resistance
Higher minute ventilate due to higher tidal volume and RR (TV > RR
79
Cerebral autiregulation
60-140mmhg
80
Cytochrome isoform responsible for metabolism of opiates/benzos
CYP3A4
81
Cytochrome isoform responsible for metabolism of sevo/iso/halothane
CYP2E1
82
Does sevo inhibit pulmonary vasoconstriction
true
83
Vapour that sensitises heart to catecholamines
halothane
84
Esmolol - selective or non selective?
Non selective
85
Beta blockers metabolised by kidney mainly:
| propranolol, sotalol, labetalol, atenolol, metoprolol
atenolol, sotalol
86
Labetalol
| Effect
Beta > alpha
3:1 oral and 7:1 IV
Retrograde ejaculation due to alpha blocking action
Significant intrinsic sympathomimetic activity
Significant postural hypotension
87
Dopexamine
| MoA + effect on splanchnic blood flow
```
Analogue of dopamine
No alpha activity
Mainly beta + on D1/2
Inhibits uptake-1
Powerful splanchnic vasodilator, thus reducing afterload
```
88
Etomidate moa
Enhances GabaA
| Lower ceberal blood flow and icp
89
Etomidate isomer
Stereoisomer
Two enantiomers
Only R is biologically active
90
Nernst equation
Proportional to RT (universal gas constant + absolute temp on kelvin)
Inversely proportional to zF (ionic valency and Faraday constant)
91
Kinetic energy
1/2mv^2
92
BP changes in pregnancy
SVR fall
SBP fall by 10% by 20 weeks, then back to normal by term
DBP fall by 25% by 20 weeks, then back to normal by term
93
RBCs and pregnancy
Red blood cell volume falls during the first 8 weeks, rises to non-pregnant levels by 16 weeks and rises to 30% above non-pregnant levels by term
94
Respiratory changes in pregnancy
Respiratory changes in pregnancy are as follows (Fig 1):
Alveolar ventilation ↑ by 70% at term
Tidal volume ↑ by 45% at term
Respiratory rate ↑ by 10%
Minute ventilation ↑ by 50% due to larger tidal volumes
95
Synthetic catecholamines
Isoprenaline, dobutamine
96
Rate limiing step in catecholamine synthesis
L-Tyrosine --> DOPA via tyrosine hydroxylase
97
Nitrous effects
Direct myocardial depressent, but also increases sympathetic tone
Increase cerebral blood flow
Inhibits NMDA receptors, stimulates alpha adrenoreceptors + dopaminergic receptors
Oxidies cobalt ion in B12
Avoid first trimester of pregnancy
Directly activates opioid receptors + stimulates endogenous opioid release
98
force
kg/ms^2
99
pressure
kg/m/s^2
100
Joule
kgm^2/s^2
101
power
m^2kg/s^3
102
Defibs
AC charges defib
DC delivered to patient. Rectifier converts AC to DC
Capacitor stores charge before discharge
Current produced during shock is about 35 A
103
Normal PT
12-16s
104
Normal APTT
23-31s
105
TT
13-15s
106
Bleeding time
3-9 mins
107
MRI + atom aligning + MoA
The magnetic field of an MRI scanner aligns atoms with an odd number of protons plus neutrons
Bursts of radiofrequency energy are then applied ,which are taken up by hydrogen nuclei in water and knocked out of alignment
The energy is subsequently released again as the hydrogen ions 'relax' and is picked up by an external radiofrequency coil.
108
Strength of an MRI
less than 2 Tesla
109
Initial concentration equation
initial concentration = Dose/Vd
110
Atracurium metabolism
Ester hydrolysis (60%) to laudanosine, quaternary alcohol and quaternary acid
Sped up by acididy
Hoffman degradation, slowed by acidity and hypothermia, to laudanosine and quaternary monoacrylate
111
Cisatracurium metabolism
Hoffman degradation to mono quaternary acrylate
112
Ketamine metabolism
De methylated in liver
| Active metabolite - norketamine
113
the context sensitive half time is proportional to the duration of an infusion - True/False
False - CSHT is always constant. Also is equal to the half life
114
rate of elimination = clearance multiplied by drug concentration
true
115
Surrogate measure of LVEDP
Wedge pressure
| Will also equal capillary pressure, left atrial pressure + pulmonay artery pressure
116
Cerebral autoregulation MAP
50-140mmHg
117
Vd, dose, plasma concentration equation
Vd = dose/plasma concentration.
118
Clearance = dose / auc
As above
