ACEM Pharmacology Flashcards
(372 cards)
1
Q
Mechanism of action of atropine
A
a competitive reversible muscuranic ACh receptor antgonist
Anticholinergic activity
equally powerful at M1 M2 M3 receptors
minimal effect of nicotinic receptors
2
Q
Pharmacokinetics of atropine
A
Administration: IV oral topical nebulized/inhaled
Distribution: wide Vd including into CNS
Metabolism and excretion: Half life is 2 hours, 60% is excreted unchanged via kidneys. 40% undergoes phase I and phase II metabolism and then renally excreted
3
Q
Organ effects of atropine
A
Eye - mydriasis and cycloplegia
CNS delerium decreased tremor in parkinsons
CVS tachycardia
Resp bronchodilation and decreased secretions
GIT decreased saliva decreased gastric acid secretion decreased mucin production delayed gastric emptying decreased gut motility
Urinary relaxes ureteric and bladder wall smooth muscle urine retention
Skin decreased sweating
4
Q
Clinical use of atropine
A
Treatment of symptomatic bradycardia or bradyarrhythmias
in opthalmology for mydriasis (dilate pupils)
occasionally used in RSI in paediatrics
drying of secretions in palliative patients
travellers diarrhoea
5
Q
Atropine toxicity effects
A
Agitation, delirium
raised temperature
blurred vision, mydriasis
flushed skin
dry mouth
tachycardia
(mad as a hatter, blind as bat, red as a beet, dry as a bone)
6
Q
What is the mechanism of action of indirectly acting cholinomimetics
A
(acetylcholinesterase inhibitors)
inhibit acetylcholinesterase enzyme
increasing concentration of Ach in the vicinity of cholinoreceptors
action on both nicotinic and musarinic receptors
7
Q
what type of indirectly acting cholinomimetics (acetylcholinesterase inhibitors) are there ?
A
Reversible - neostigmine, physostigmine, pyridostigmine
Irreversible - organophosphates and insecticides
8
Q
Cardiovascular effects of Indirectly acting cholinomimetics (acetylcholinesterase inhibitors)
A
Both sympathetic and parasympathetic ganglia can be activated
Parasympathetic effects generally predominate -
bradycardia, decreased CO, decreased contractility
OVerdose may cause tachycardia and hypotension
9
Q
Pharmacokinetics of Adrenaline?
A
Administration; IV, IM, subcut, nebulised. Poor oral absorption
Distribution: Crosses the placenta, does not cross blood brain barrier. 50% protein bound. Onset within seconds, duration 2 mins
Metabolism: terminated by metabolism in sympathetic nerve terminals by COMT and MAO. Circulating adrenaline metabolised by COMT
Elimination: metabolites excreted in urine
10
Q
Pharmacodynamics of adrenaline?
A
Equal effects on alpha and beta receptors
Alpha - vasoconstriction
Beta1 - positive inotropic and chronotropic effects
Beta2 - smooth muscle relaxation in airways and skeletal muscle
11
Q
Effects of adrenaline on other organs?
A
Respiratory - bronchodilation
Eyes - pupil dilation, decreased IOP and production of aqueous humour
Gastric smooth muscle - relaxation
Genitourinary - bladder smooth muscle relaxation
Liver - enhanced glycolysis
Increased production of sweat at apocrine glands
12
Q
What receptors does noradrenaline act on ?
A
Predominantly alpha 1 - vascular smooth muscle constriction
some alpha 2 beta 1 and beta 2
13
Q
How does noradenaline increase blood pressure?
A
Increase in both systolic and diastolic blood pressure
Alpha 1 activity - vasoconstriciton, increased peripheral resistance = increased diastolic pressure
Beta 1 activity - increased myocardial contractility = increased systolic BP
14
Q
What effect does noradrenaline have on heart rate ?
A
Minimal change
Beta 1 increases heart rate
however,
compensatory baroreceptor reflex causes decrease in HR
15
Q
Mechanism of action metaraminol ?
A
Direct alpha 1 agonist - vascular smooth muscle constriction
16
Q
Classes of local anaesthetics
A
Aminoamides - Lignocaine, Bupivocaine, prilocaine
Aminoesters - procaine, benzocaine, tetracaine
17
Q
Mechanism of action of lignocaine
A
Sodium channel blocker
Class 1B antiarrhytmic
Local anaesthetic
Blocks voltage gated sodium channels without altering the resting membrane potential
18
Q
Toxic effects of Lignocaine
A
CNS; perioral or tongue numbness, metallic taste > nystagmus, tinnitus, muscle twitching, nausea, vomiting > seizures, sedation
CVS; arrhythmias, hypotension, worsening CCF
GIT; vomiting anorexia nausea
Haem; methaemoglobinaemia (increase in MetHb, become blue), most often with prilocaine
19
Q
Mechanism of action of nitrous
A
Modulates GABA-A recetpors
Increased dynorphin release
NMDA agonist
low solubilty in the blood so reaches arterial tension rapidly, rapid equilibrium in the brain, fast onset and fast recovery
20
Q
Organ effects of nitrous
A
CNS; analgesia amnesia increased cerebral blood flow
Renal; decrease GFR increased renal vascular resistance
CVS; dose dependent mycardial depression
Resp; reduced response to CO2 and hypoxia
GI; nausea, vomiting
21
Q
Pharmacokinetics of propofol
A
Administration; IV only
Distribution; rapid onset and recover is driven by redistribution of the drug from the brain to other areas. Half life 2-4 minutes, elimination half life up to 25 mins
Metabolism; rapidly metabolised in the liver
Elimination; Excreted in the urine as inactive metabolites
22
Q
Usual induction dose of propofol
A
1-2.5mg/kg in adults
2.5-3.5mg/kg in paediatrics
23
Q
Clinical effects of propofol
A
Anaesthesia/sedation
no analgesia
Transient apnoea
Decreased BP
anti-emetic properties
24
Q
Adverse effects of Propofol
A
Hypotension
Apnoea
pain on injection
allergy/anaphylaxis
propofol infusion syndrome (a metabolic acidosis)
25
Pharmacodynamics of Ketamine
NMDA receptor antagonist
Inhibits reuptake of serotonin and catecholamines
Potent short acting sedative
26
Pharmacokinetics of Ketamine
Absorption; Highly lipid soluble so rapid onset
Distribution; Effect is terminated by redistribution to inactive tissue sites. Low protein binding
Metabolism; Metabolised in the liver via the P450 enzymes to inactive metabolites
Elimination; metabolites are excreted in the urine
27
System effects of Ketamine
CNS; dissociative anaesthesia, profound analgesia, Cerebral vasodilation. Potential anticonvulsant properties
CVS; haemodynamically stable, increase HR, BP, CO and myocardial oxygen consumption
Respiratory; Maintains airway reflexes, minimal respiratory depression, bronchodilator effects. Can cause lacrimation and laryngospasm in children
Ocular; nystagmus
28
Adverse effects of ketamine
CNS - emergence phenomenon, dysphoria, hallucinations
GI - nausea, vomiting
Respiratory - latyngospasm, increased salivation
29
Pharmacokinetics of Thiopentone
Administration IV
Absorption
Acts in one arm-brain circulation time and lasts 5-15 mins after bolus – accumulates with repeated administration
Distribution
Vd ~2 L/kg
~80% protein bound in the plasma, predominantly albumin
pKa of 7.6 with 60% unionised at pH 7.4 –> where only 12% free drug is immediately available
Distribution half-life: T1/2 (alpha) fast: 8 min // T1/2 (alpha) slow: 60 min
Rapid onset due to:
High blood flow to the brain
Lipophilicity
Low % ionised
Metabolism
Hepatic
Saturable pathway –> first order –> Zero order kinetics
Liver oxidation (CYP450) –> pentobarbital (active metabolite)
Elimination
Predominantly in the urine, 0.5% unchanged
Clearance is 2.7-4.1 mL/kg/min
Elimination half-life:
T 1/2 (beta): 11 hoursAdministration; IV bolus
Rapidly crosses BBB, highly lipid soluble, redistributes to muscle and fat
metabolised in the liver
excreted by the kidney
30
Advantages of Thiopentone
rapid onset
amnesic
reduction in ICP
anitconvulsant
31
Adverse effects of thiopentone
hypotension
reduced stroke volume and cardiac output
apnoea
32
Mechanism of Action of Suxamethonium
Deploarizing neuromuscular blocker
2 acetylcholine molecules linked end to end
2 phases;
1. depolarising
- reacts with nicotinic receptor to open channel
- depolarises the motor endplate which spread to adjacent membranes
- causes fasiculations
2. desensitising
- continued repeat exposure to sux
end plate depolarisation increases
membrane repolarizes but cannot depolarise
unresponsive to subsequent impulses
causes a flaccid paralysis
33
Pharmacokinetics of suxamethonium
Administration; IV
Distribution; rapid onset 30-60 seconds, short duration 2-8 minutes
Metabolism - Hydrolysed rapidly by plasma pseudocholinesterase
34
Adverse effects of suxamethonium
Muscle pain and fasiculations
Bradycardia
release of potassium - especially in burns and trauma
raised IOP and raised ICP
risk of malignant hyperthermia
risk of prolonged paralysis in cases of reduced or abnormal cholinesterase
35
Mechanism of action of Rocuronium
A non deploarizing neuromuscular blocker
a competitive inhibitor of acetylcholine at the nicotinic receptors
In large doses it can enter the pore of the ion channel and cause a stronger block
36
Pharmacokinetics of Rocuronium
Administered; IV bolus 1.2mg/kg onset 40/60 seconds
Distribution ; Rapid, highly ionized, small Vd. Duration of 20-75 minutes
metabolised in the liver, short half life
Eliminated the urine
37
How does suxemethonium differ from rocuronium?
Duration of suxamethonium is shorter - 5-10 mins
Suzamethonium is depolarising NMB
Rocuronium is non depolarising
Suxamethonium metabolised in the plasma
Rocuronium in the liver
38
Pharmacodynamics of ethanol
CNS; sedation, disinhibition, impaired judgement, impaired motor skills, ataxia, slurred speech, coma, respiratory depression
CVS; decreased contractility
Smooth muscle vasodilation = hypothermia
39
Pharmacokinetics of ethanol
Absorption; rapidly absorbed from the GIT (water soluble)
Distribution; Rapid, Vd is total body water
Metabolism; mostly in the liver by alcohol dehydrogenase via zero order kinetics
Excretion; lung and urine
40
What is zero order kinetics
Elimination occurs at a constant rate independent of drug concentration
41
What drugs have zero order kinetics
phenytoin, theophylline, warfarin, salicylate, heparin, ethanol
42
Mechanism of action of benzodiazepines
Binds to components of the GABA-A receptor in neuronal membranes in the CNS
This receptor is a chloride channel
Enhance GABAs effects without directly activating the channel
causes an increased frequency of channel opening
43
Organ effects of Diazepam
Sedation - calming effect, anxiolysis
Hypnosis and anaesthesia at higher doses
anticonvulsant effect
muscle relaxation
respiratory and cardiovascular depression
44
Mechanism of action of carbamazepine
Sodium channel blockers
Binds to those in an inactive state and stabilises them there
Inhibits high frequency repetitive firing neurones
45
Pharmacokinetics of carbamazepine
100% oral bioavailability
Peak level 6-8 hours
70% protein bound
low clearance, 36 hours half life
induces its own metabolism via _450 system effect so dose increase required in the first few weeks of treatment
46
Adverse effects of of carbamazepine?
ataxia
diplopia
sedation
blood dyscrasias - aplastic anaemia, agranulocytosis
skin rash
drug interactions with p450 metabolised drugs
47
Pharmacokinetics of phenytoin
Administration; Oral, IV
high oral bioavailabiliity
Peak serum concentration 3-12 hours
Highly plasma protein bound with moderate volume of distribution
Metabolised in the liver to an inactive metabolites and then renal excretion
Elimination is dose dependent
lower dose is first order kinetics but at higher doses enzymes become saturated and shifts to zero order kinetics
Half life is variable
48
What is the mechanism of action of Phenytoin
Sodium channel blockade
Prolongation of the inactive state of the Na channel
enhances GABA release
Work to inhibit the generation of rapidly repetitive action potentials
49
Why use a loading dose of phenytoin
Need 4 half lives to reach a steady state, so to reach target concentration rapidly
50
Risks of IV phenytoin
Hypotension and bradycardia with rapid infusion
local necrosis if there is extravasation
Purple glove syndrome - black discolouration distal to the IV site
51
Adverse effects of phenytoin
Nystagmus and loss of smooth pursuits is normal with therapeutic levels and not concerning
Anyone with ataxia and diplopia need a decrease in their dose
Ginigival hyperplasia and hirsutism can occue over long term use
Osteolmalacia, abnormal rashes, low vitamin D
Foetal abnormalities
Sedation, coma, cerebellar toxicity
52
Mechanism of action of levetiracetam
Binds the SV2 synaptic vessel protein
Undergoes endocytosis and binds in the vesicle
Prevents release of glutamine during increased frequency activity
53
Pharmacokinetics of levetiracetam
Given orally or IV , rapid oral absorption just over 1 hour
Low protein binding
Half life 6-8 hours so BD dosing
2/3 excreted in urine
1/3 deaminated in the blood
No liver metabolism = mineral interactions compared to other antiepileptics
54
Side effects of levetiracetam
Mild; drowsiness, ataxia, dizziness
severe; behavioural or mood changes - aggression/anxiety
55
What is the dose of levetiracetam in status epilepticus
Paeds 40mg/kg IV/IO up to 3g
Adults 60mg/kg IV/IO up to 4.5g
56
Mechanism of action of sodium valproate
Unknown
57
What are the adverse effects of Sodium Valproate
Mild; nausea, vomiting, abdominal pain
Severe; Cerebral oedema and coma
Hepatic toxicity including acute liver failure
Thrombocytopaenia and bruising from bone marrow depression
Neural tube defects if used in pregnancy
Hyperammonaemia leading to sedation
Inhibits metabolism of p450 enzyme system
Directly displaces phenytoin from plasma proteins
Increases level of carbomazapine
Decreases the clearance of lamotrigine
58
Mechanism by which serotonin syndrome occurs
Excessive stimulation of serotonin receptors in the CNS due to overdose of a single drug or concurrent use of several drugs
Predictable rather than idiosyncratic
59
How do drugs cause excessive stimulation of serotonin receptors
Inhibition of serotonin metabolism - amphetamines
Prevention of serotonin reuptake in nerve terminals - fluoxetine, sertraline, venlafaxine, tramadol, TCAs
serotonin release or increased intake of serotonin precursors - tryrophan, lithium
60
Mechanism of action of tricyclic antidepressants?
Inhibition of serotonin and noradrenaline reuptake
Increases the amount of serotonin and noradrenaline in certain parts of the brain and spinal cord
Also block sodium channels, potassium channels, M1 receptors, Histamine 1 receptors, post synaptic alpha 1 adrenergic receptors
61
Pharmacokinetics of tricyclics antidepressants
Well absorbed orally
Bioavailability 40-50%
long half life
high first pass metabolism
high protein binding
high lipid solubility
large volume distribution
metabolism in the liver with active metabolites
62
Effects of overdose in TCAs
Cardiac; tachycardia, hypotension, prolonged PR, wide QRS, long QT, VT , VF
CNS; Drowsiness, delerium, seziures, coma
Anticholinergic effects; agitation, mydriasis, warm dry flushed skin, urinary retention, ileus
63
Pharmacokinetics of lithium
Administration; orally, rapid and near complete absorption, peak concentration at 1-2 hours but complete 6-8 hours
Volume distribution is in total body water - very slow distribution from extra to intracellular compartments
No protein binding
No metabolism
Excreted unchanged in urine 20% of the creatinine clearance
Plasma half life is 20 hours
64
Some drug interactions with lithium
Thiazide diuretics - cause reduction in lithium clearance
Newer NSAIDS reduce clearance
Osmotic or loop diuretics actually increase clearance
65
Why is levodopa used in combination of carbidopa
Carbidopa is a peripheral dopa carboxylase inhibitor.
It doesn't cross the BBB, reduces the peripheral metabolism of levodopa which leads to increased half life and more dopa being available to enter the CNS to exert its effects
66
What are the adverse effects of levodopa ?
GIT; anorexia, nausea, vomiting is common due to stimulation of emetic centre in the brain
CVS; arrhythmias
Dyskinesis
Behavioural changes
Gout, abnormal LFTs
67
How do sumatriptans work in treatment in migraines?
Triptans are selective agonists for 5HT-1 receptors found on these vessels
Cause vasoconstriction, preventing symptoms
68
Pharmacokinetics of Triptans?
Bioavailability is a low/varied 10-70%
So given subcut or intranasal more often than orally
Half life is 2-3 hours
69
Pros and cons to sumatriptan use?
Pros; only usually mild side effects, tingling weakness
Cons; contraindicated in patients with IHD, expensive
70
Pharmacodynamics of adenosine
Slow conduction through the Av node
Blocks specific adenosine receptors
Mechanism is increased K+ conductance and decreased cAMP induced calcium influx
ECG = increased PR interval
71
Pharmacokinetics of adenosine
Administration: IV with rapid absorption
Distribution to most cells
Metabolism : rapidly degraded by cells, deaminated and phosphorylated
Half life is 10 seconds
72
Indication of Adenosine
SVT
Diagnostic tachyarrhythmias
Adjunct to thallium scanning
73
Pharmacodynamics of adrenaline
Binds to alpha and beta receptors
Act through G proteins
Beta stimulates cAMP
Alpha leads to inhibition cAMP
- relaxes smooth muscle of bronchi
- cardiac stimulation
- skeletal muscular vascular dilation
74
Structure/class amiloride
Potassium sparing diuretic
Not an aldosterone antagonist
75
Pharmacodynamics of amiloride
Reduces Na+ absorption in collecting tubules and ducts and inhibits tubular secretion of K+
76
Pharmacokinetics of amiloride
Administration: orally 5-20mg daily dose
Absorption: excreted unchanged by kidneys
Peak plasma levels in 3-4 hours
Half life 6-9 hours
77
Indication of amiloride
Used to spare potassium when other diuretics are the main agents
Congestive heart failure and HTN
Hepatic cirrhosis with ascites
78
Indication of aminophylline
Bronchospasm
79
Pharmacodynamics of aminophylline
Bronchodilator in reversible airways obstruction
Also causes diuresis, cns and cardiac stimulation and gastric acid secretion by blocking phosphodiesterase.
Increases tissue concentrations of cAMP which promotes catecholamines stimulation of lipolysis, glycogenolysis and gluconeogenesis
Induces release of adrenaline from adrenal medulla
80
Pharmacokinetics of aminophylline
Administration: injection, tablet, suppository
Can be 100% orally absorbed
Loading dose needed
Metabolised in the liver by demethylation and oxidation
Half life variable
10% excreted unchanged in urine
81
Mechanism of action of Promethazine
first generation H1 receptor antagonist
Competitively blocks histamine at the H1 receptor
82
Pharmacokinetics of Promethazine
Absorption; well absorbed orally but has significant first pass effect - bioavailabilty 25%
Distribution; widely distributed throughout the body, enters CNS
Metabolised in the liver, excreted in the urine
83
Organ effects of Promethazine
CNS - sedation, anxiolytic, reduces motion sickness
Respiratory - bronchodilation, reduction in secretions, suppress cough
84
Toxicity of Promethazine
Anticholinergic side effects
Extrapyramidal reactions in high doses
sedation confusion
85
Example of 2nd generation H1 antagonists
Loratadine, cetirizine
86
Mechanism of action of Cimetidine
A second generation H2 receptor antagonist
Competitively inhibits histamine at H2 receptors on parietal cells in the stomach, decrease gastric secretion
87
Pharmacokinetics of Cimetidine
Absorption; Rapid absorption but significant first pass effect, oral bioavailability approximately 50%
Distribution; 20% protein bound
metabolism; liver cytochrome p450
excretion 40-55% unchanged by kidneys
88
Clinical use of Cimetidine
Peptic ulcer disease
GORD
Reflux oesophagitis
Zollinger-Ellison syndrome
Non-ulcer dyspepsia
89
mechanism of action of sumatriptan
selective 5-HT1B and 5-HT1D receptor agonist
Vasoconstriction in cerebral and meningeal vessels
90
Pharmacokinetics of Sumatriptan
Absorption; oral, nasal spray, SC, low oral bioavailability
Distribution; 15-20% protein bound , large volume distribution, crosses BBB
Metabolism; by MAO locally and in the liver
Excretion 60% urine 40% faeces
half life 2 hours
91
Mechanism of action of ondansetron
a 5-HT receptor antagonist
used as an antiemetic
92
Pharmacokinetics of ondansetron
Absorption; rapidly oral absorption, oral bioavailability 60%
Distribution; 76% protein bound
Metabolism; Extensive hepatic metabolism
Excretion; renal and hepatic excretion, serum hlaf life 4-9hours
93
Adverse effect of ondansetron
prolongation of QT interval
94
Mechanism of action of Ergotamine
Agonist, partial agonist and antagonist effects of alpha adrenoreceptors and serotonin (5-HT1A and 5-HT1D) receptors
95
Pharmacokinetics of ergotamine
Absorption; Variable oral dose is about 10 mins larger than IM dose, can be PR, buccal cavity, inhaled
speed of absorption and peak blood levels can be increased by administration with caffeine
Distribution; crosses BBB
extensive metabolism
96
Clinical application of ergotamine
migraine
hyperprolactinaemia
postpartum haemorrhage
97
Toxic effects of Nifedipine
hypotension, tachycardia
peripheral oedema, constipation, flushing, dizziness, nausea, headache
98
mechanism of action of nifedipine
a calcium channel blocker
a dihydropyridine
predominantly vasodilating effects
99
pharmacokinetics of nifedipine
complete oral absorption, bioavailability 50%
highly protein bound
metabolised by the liver
excreted in the urine
100
clinical use of nifedipine
angina
htn
raynauds
coronary artery spasm
preterm labour
101
mechanism of action of captopril
ACEi
binds to ACE with 30000x affinity of ATI preventing formation of ATII
102
pharmacokinetics of captopril
rapid absorption, bioavailability 65%
35% protein bound
renally excreted
103
toxic effects of captopril
hypotension
hyperkalaemia
angioedema
dry cough (bradykinens)
precipitates renal failure
104
what are the 4 classes of antiarrhythmics
Class 1; Sodium channel blockers
Class 2; Sympatholytics, reduce beta adrenergic activity
Class 3; AP duration prolongers, blocking K channels
Class 4; Ca channel blockers
105
What is the mechanism of action of Amiodarone
Class 3 antiarrhythmic
properties of class 1, 2 and 4
Blocks K channels, marked prolongation of AP duration
blockade of inactivated Na channels
weak B blocker
weak ca channel blocker
106
Pharmacokinetics of amiodarone
Administered; orally, IV
98% protein bound, accumulates in many tissues
long half life, large Vd
excreted in bile and faeces
half life has 2 phases, rapid component has half life of 3-10 days, remainder eliminated over weeks.
107
Amiodarone interactions
A substrate for CYP3A4
- conc decreased by inhibitors eg Cimetidine
- conc increased by inducers eg Rifampicin
Inhibits warfarin metabolism
108
examples of Beta blockers with Intrinsic Sympathomimetic activity/partial agonist activity
Cartelol, Acebutolol, Pindolol, Pnebutolol, Labetolol
109
When are Beta Blockers with ISA used?
when non-ISA beta blockers are contraindicated, eg sinus bradycardia, sick sinus syndrome, raynauds , COPD
110
what is the half life of sotolol
12 hours
111
nitroglycerine relieves exertional angina by ?
reduced oxygen consumption
112
is substance P a vasodilator or vasoconstrictor?
potent vasodilator
dependent on NO release
113
what is the elimination half life of sotalol
12 hours
114
Pharmacokinetics of Sotalol
well absorbed orally
bioavailability 100%
not metabolised in the liver
not bound to plasma proteins
excretion via kidneys unchanged
half life 12 hours
115
mechanism of action of labetaolol
mixed alpha/beta adrenergic antagonist
116
mechanism of action of esmolol
selective beta1 antagonist
117
what is streptokinase
non fibrin selective fibrinolytic
118
streptokinase reduces mortality from MI by what %
25%
119
what is Vigabactrins anticonvulsant property due to?
Irreversible inhibition of GABA aminotransferase
120
mechanism of action of propafenone
class 1C antiarrhythmic
weak beta blocking and calcium channel blocking activity
121
mechanism of action labetalol
mixed alpha/beta adrenergic antagonist used to treat high blood pressure
122
Organ effects of GTN;
CVS, Respiratory, GIT, GU, Haematological
Vasodilation (veins first), increase venous capacity, decrease preload, decrease pulmonary pressure, decrease heart size , reflexive tachycardia
widespread smooth muscle relaxation in resp, GI, GU
Decrease Platelet aggregation
123
Mechanism of action of GTN
stimulates NO release, increases cGMP, dephosphorylation of myosin LC and causes smooth muscle relaxation
124
Pharmacokinetics of GTN
sublingual
rapidly absorbed, high first pass metabolism
oral availability <10%
60% protein bound
duration of action 10-20 minutes
metabolised in liver by organic nitrate reductase
excreted renally
125
Name the 2 Calcium channel blockers in the non-dihydropiridine group
Diltiazem
Verapamil
126
Mechanism of action of the non-dihydropyridine calcium channel blockers
L type alpha 1 subunit calcium channel in cardiac and smooth muscle
reduces frequency of calcium channel opening, decreasing calcium channel influx, decrease transmembrane calcium current
127
dihydropyridine calcium channel blocker effects on smooth muscle
relaxation, arterioles > veins
128
non-dihydropyridine calcium channel blocker effects on cardiac muscle
decreases contractility
129
non- dihydropyridine calcium channel blocker effects on SA node
sodium channel blockade, decrease pacemaker potential rate
verapamil has most effect
130
non - dihydropyridine calcium channel blocker effects on AV node
decrease conduction velocity
verapamil has most effect
131
what type of beta blocker is sotalol
beta 1 and beta 2 adrenergic receptor blocker
132
pharmacokinetics of sotalol
well absorbed orally
bioavailability 100%
not metabolised in the liver, not bound to protein
excretion via kidneys unchanged
half life 12 hours
133
what type of antiarrhythmic is sotalol
class II and class III
134
where is noradrenaline released
postganglionic sympathetic fibers
135
how does methyldopa reduce blood pressure
reduces peripheral vascular resistance, central alpha-receptor agonist
centrally acting sympathoplegic agent
an analogue of L-dopa
136
Pharmacokinetics of methyldopa
Absorption; variable absorption of oral dose, extensive first pass effect, bioavailability 25%
Distribution; 50% protein bound
Metabolism; Conjugated to sulphate in intestinal mucosa, metabolised in liver
Excretion 20-40% urine, 2/3 unchanged
half life 2 hours
137
Clinical application of methyldopa
HTN during pregnancy
pre-eclampsia
138
mechanism of action of Clonidine
A centrally acting sympathoplegic agent
Causes direct stimulation of alpha-adrenorecptors both centrally and peripherally
when reaches the medulla decreases SNS and increases PNS
139
Pharmacokinetics of Clonidine
Absorption; rapid oral absorption bioavailability 95%
Lipophilic and readily crosses BBB
65% excreted unchanged in urine, 20% faeces
half life 8-12 hours
140
Clinical applications of Sodium Nitroprusside
Hypertensive emergencies
Severe heart failure
Aortic Dissection
Intraoperative production of hypotension
141
Mechanism of action of Sodium Nitroprusside
a powerful vasodilator
releases NO and increases cGMP
a complexe of iron, cyanide groups and nitroso moiety
142
Pharmacokinetics of sodium nitroprusside
IV administration, onset of action within 1-2 minuts
confined to plasma
Metabolised; uptake into RBCs, excreted renally
143
Organ effects of sodium nitroprusside
CVS; vasodilation of arteries and veins, reflex tachycardia so no change in CO
Respiratory; decrease hypoxic vasoconstriction
CNS; cerebral vasodilation, raised ICP
144
precautions of sodium nitroprusside
Toxicity related to cyanide accumulation
Thiocyanate can accumulate
methaemoglobinaemia
145
Mechanism of action of Hydralazine
Vasodilator that acts on arterioles
A donor of NO that increases cGMP and decreases IP3 which leads to decreased calcium availability
146
Pharmacokinetics of Hydralazine
well absorbed, high first pass extraction, bioavailability 25%
half life 2-4 hours
highly protein bound crosses the placenta
metabolites excreted in urine and faeces
147
Clinical uses of Hydralazine
Chronic moderate to severe HTN
Pre eclampsia
congestive heart failure
148
Clinical use of Minoxidil
HTN
149
Mechanism of action Minoxidil
Orally active vasodilator
Active metabolite opens K+ channels in smooth muscle
150
What does antithrombin III inhibit
factors IIa IXa Xa XIIA
151
What does protein C and S inhibit
Factors Va and VIIA
152
Describe Class 1 antiarrhythmics
Na channel blockers
1A prolong AP duration
1B shorten AP
1C Minimal AP effect, prolongs QRS
153
Examples of 1A anti-arrhythmic
Disopyramide, Quinidine, Procainamide
prolong AP and QRS
## Footnote
"Double quarter pounder'
154
Examples of 1B anti-arrhythmic
Lignocaine, Phenytoin
shortens the refractory period
shorten AP
155
Examples of 1C anti-arrhythmic
Flecainide
increase QRS duration
156
mechanism of action of digoxin
inhibits action of Na/K ATPase
increases intracellular Na
this alters the Na/Ca pump
causes displacement of Ca in SR
overal increases Ca which increases contractility
positive inotrope
increases ventricular excitability, contraction, ejection, cardiac output
157
Pharmacokinetics of Digoxin
administered oral or IV
Loading dose IV
65-80% oral absorption
long half life 36-40 hours
2/3 excreted in kidney
rate is proportional to Cr clearance
158
which drugs reduce digoxin clearance
Verapamil
Amiodarone
Quinidine
159
which drugs potentiate digoxin effect
quinidine
NSAIDs
CCB
Furosemide
160
Mechanism of action of adenosine
acts on a specific adenosine receptor that inhibits adenylyl cyclase and reduces cAMP
Activation of inward rectifier K current, marked hyprpolarisation, calcium channel inhibition and suppress Ca
interrupts re entry pathway of AV node
161
Cardiac effects of adnosine
Inhibits AV node
Increases Av node refractory period
162
What are Class 2 anti arrhythmics
Sympatholytics
reduced beta adrenergic activity
eg B-blockers
163
What are Class 3 antiarrhythmics
AP duration prolongers
block K channels
eg sotolol
164
What are class 4 antiarrhythmics
Ca channel blockers
eg verapamil
165
mechanism of action of verapamil
blocks active and inactive L type Ca channels
prolongs the refractory period
reduces conduction through SA and AV node
increases the refractory period
negative inotropic
166
Calcium channel blockers from quickest to slowest acting
Nifedipine - 5-20 mins
Verapamil - 30 mins
Diltiazem - >30 mins
Felodipine - 2-5 hours
167
mechanism of action of prazosin
competitive piperazinyl quinazoline
management of HTN
highly selective alpa 1 receptor blocker on vascular smooth muscles in arterioles and venules
reduces afterload and preload
168
where do thiazide diuretics work
proximal part of Distal convoluted tubule
169
where does spironolactone work?
DCT and CT
170
where does furosemide work?
Loop of Henle
171
where does acetazolamide work
PCT
172
Mechanism of action of GTN
releases NO
NO activates guanylyl cyclase and increase in cGMP
causes vasodilation
173
what is GTN tolerance to
decrease in sulfhydral groups
174
what type of beta blocker is propanolol
non selective beta blocker
175
what can happen in propanolol overdose
because of its Na channel blocking activity if can cause prolonged QRS and VF arrest
can cause seizures as it crosses the BBB
Treatment is bicarb
176
why does nitroglycerine relieve angina
reduced oxygen consumption
decreased venous return to the heart
176
regarding nitrates what do they do to collateral flow
increase collateral flow even in fixed constriction
177
how do ACEi cause cough
block conversion of ANGI to ANGII
inhibit degradation of bradykinen substance P and enkephalins
inhibiting bradykinin causes cough and angiooedma
178
where does mannitol work in the kidney?
inhibits H2O absroption in proximal tubule, loop of henle, collecting tubule
179
mechanism of action of clonidine
stimulates CENTRAL alpha 2-adrenoceptors which inhibits sympathetic nervous system providing the anti-hypertensive effects.
Initial hypertensive effect is due to direct stimulation of alpha 1-receptors in arterioles following parenteral use
180
mechanism of action of labetalol
competitive selective alpha 1 antagonist and a competitive non selective beta 1 (B1) and 2 (B2) antagonist
181
half life of metoprolol
3-4 hours
182
which antihypertensive can cause necrotizing pancreatitis
thiazides
cause hypercalcaemia and hyperlipidaemia which can predispose to pancreatitis
183
which cardiac drug should not be used with sildenafil
GTN
as both drugs cause vasodilation
184
does sotalol have any anaesthetic action
no
185
what class of antiarrhythmic is sotalol
class II and class III
a non selective Beta 1 and Beta 2 adrenergic blocker
186
side effects of nifedipine
peripheral oedema and constipation
187
administration of nifedipine
usually orally
188
alpha 1 receptors display the following potency series in decreasing potency
Noradrenaline >adrenaline > isoprenaline
189
which calcium channel blocker is predominantly excreted in faeces
nifedipine
190
drug class and indication for Amitriptyline
Tricyclic antidepressant
Depression
Nocturnal enuresis
Chronic pain/migraine/trigeminal neuralgia/phobic anxiety
191
Pharmacodynamics of Amitriptyline
Inhibits;
Sodium-dependent noradrenaline transporter
Sodium-dependent serotonin transporter
Preventing noradrenaline and serotonin reuptake in the pre synaptic terminals
5-HT receptor
has anticholinergic effects
192
Pharmacokinetics of Amitriptyline
Administrated; PO 75mg up to max 300mg
IM/IV 20-30mg
Absorption; orally
half life ~25 hours
95% protein bound
wide volume distribution
metabolised in the liver
excreted in urine 60% and faeces
193
Toxicology of Amitriptyline
>1000mg is toxic
can prolong QRS and ST
agitation, delerium, seizure, coma, arrhythmia, metabolic acidosis, bladder and bowel paralysis
194
Pharmacodynamics of Amoxycillin
Selective inhibitors of bacterial cell wall synthesis
Binds to cell receptors on bacteria, inhibiting transpeptidation and peptidoglycon synthesis is blocked
Bectericidal agents
195
Pharmacokinetics of Amoxicillin
Administration - PO, IV, IM
Absorption - oral bioavailability 93%
best taken one hour before or after food
half life 1-2 hours
86% excreted in the kidneys unchanged
196
Indication and class of drug of Amphetamine
Narcolepsy, Attention deficit, obesity
197
Pharmacodynamics of Amphetamine
Alpha and Beta effects from release of neurotransmitter from synaptic vesicles NOT direct stimulation receptors
198
Pharmacodynamics of Aspirin
COX -1 and COX -2 inhibitor
inhibit platelet aggregation by COX-1 inhibiting thromoxane A2 for about 7-10 days
199
side effects of suxamethonium
tachycardia
muscle fasiculations
excess salivation
200
phase 1 reactions
hydrolysis, oxidation and reduction.
201
Phase 2 reactions
glucuronidation, acetylation, glutathione conjugation, glycine conjugation, sulfate conjugation, methylation, and water conjugation
202
calculation of volume distribution
amount of drug in the body/ concentration of the drug in blood or plasma
203
how to calculate half life
T1/2 = (0.7 x Vd ) / CL
this means Vd is proportional to half life
204
half life of lignocaine
120 minutes
205
what is the bioavailablity of digoxin
70%
206
mechanism of action of naloxone
pure opioid antagonist
has high affinity to mu receptors
207
Define potency
how much of a drug that is required to produce an effect
dose required to bring about 50% of drugs maximal effect
208
Define Affinity
how tight the drug binds to its receptors.
209
Define efficacy
the maximum response produced by a drug regardless of dose
210
Define TD50
the dose required to produce toxic effects in 50% of patients.
211
The Beta 2 sympathomimetic with the longest duration of action is?
A. Terbutaline
B. Salmeterol
C. Isoprotenerol
D. Sotalol
Salmeterol >12 hours
212
How does Cromolyn reduce bronchial reactivity?
Inhibiting mediated mast cell degranulation
213
what does ASPAC stand for
anisoylated plasminogen streptokinase activator complex
214
Half life of warfarin
36hours
215
bioavailability of warfarin
100%
216
217
% of warfarin that is protein bound
99%
218
with regards to clotting what does streptokinase do
forms a complex with endogenous plasminogen;
the plasminogen in this complex undergoes a conformational change that allows it to rapidly convert free plasminogen into plasmin.
219
Heparin induced mild thrombocytopenia is caused by?
antibodies that bind to complexes of platelet factor 4 (PF4) and heparin. This immune reaction leads to a hypercoagulable state that can cause thrombosis
220
LMWH levels are not generally measured except in the setting of
renal insufficiency
obesity
pregnancy
221
what does ticlopidine do
It reduces platelet aggregation by the irreversible inhibition of the ADP-receptor
222
mechanism of action of isoprenalin
pure beta agonist
potent vasodilator
223
side effects and overdose of carbamazepine
diplopia
ataxia
seizure
foetal aplastic anaemia
agranulocytosis
224
mechanism of action of pilocarpine
ciliary muscle contraction
acts on subtype of muscarinic receptor M3 found on the iris sphincter muscle
results in pupil constriction (miosis)
225
mechanism of action of timolol
decreases aqueous secretion
226
mechanism of action Acetazolamide
decreases aqueous secretion due to a lack of HCO3
227
mechanism of action of latanoprost
increased outflow of aqueous
228
how is Vecuronium excreted
by the liver 85%
renal 15%
229
regarding sodium valproate what % is protein bound
90%
229
what is the most common adverse effect of procainamide
Hypotension
230
which muscle relaxant lasts the longest
pancuronium 35-45 mins
231
At low dose, which of the muscle relaxants is most commonly associated with tachycardia?
Gallamine
232
232
mechanism of action of moclobemide
MAO inhibition
Used for depression
233
what class of drug is Imipramine
TCA
234
In a patient with widespread burns who develops shock, what is the underlying mechanism?
Increased vascular permeability
235
Which of the opiates is associated with seizures when given in high dose to patients with renal failure?
pethidine
236
Of the following antipsychotics, which is most likely to cause extrapyramidal side effects?
haloperidol
236
What is the correct order of catecholamine synthesis?
tyrosine
dopa
dopamine
noradrenaline
adrenaline
237
how is atracurium eliminated
hofmann - non renal non liver elimination
238
duration of action of pancuronium and compared vecuronium
>35min
longer then vecuronium
239
what does phenytoin cause in the gums
hyperPLASIA
240
Which local anaesthetic causes methaemoglobinaemia?
prilocaine
241
Which of the cholinoceptor blocking drugs is the least absorbed by the brain?
ipatropium
it is a quarternary amine charged
242
what complication can stemetil cause
It can cause neuroleptic malignant syndrome
243
what is pralidoxime used for
to reactivate acetylcholinesterase inhibited by organophosphates
244
what is diazepam metabolised to
oxazepam
245
Dantrolene is used in malignant hyperthermia. Which statement best describes it's mechanism of action?
It decreases calcium release from sarcoplasmatic reticulum
246
Sulphonamides are a structural analogues of which of the following?
PABA
247
AZT half life
1.1 hours - short
248
A patient with impetigo would be most likely to respond to which drugs?
cephalexin
249
Live attenuated vaccines
Measles, mumps, rubella
Chickenpox
Zoster
Rotavirus
Yellow fever
Oral typhoid
Bacillus Calmette-Guerin
250
2nd generation cephalosporin
cefoxitin
cefaclor
cefotetan, cefuroxime, cefprozil, cefmetazole, loracarbef and cefonicid
251
The cephalosporin with the highest activity against gram positive bacteria is?
Cephalothin
1st generation cephalosporins are very active against gram positive cocci
252
Which class of antibiotics listed below does not possess a beta-lactam ring?
Fluoroquinolones
253
Which of the following antibiotics does not exert its action by inhibiting cell wall synthesis?
erythromycin
it inhibits formation of 50s ribosomal subunit
254
Penicillins reach high concentrations in what organ
tubular fluid in kdineys
255
Acyclovir has therapeutic action against
HSV 1 HSV 2 VZV
256
mechanism of action of cephlasporins
cell wall inhibitor
257
mechanism of action of tetracyclines
inhibit protein synthesis
258
mechanism of action of aminoglycoside (genatmicin)
Inhibit protein synthesis
259
mechanism of action of fluroquinolones (ciprofloxacine)
DNA gyrase inhibition, thereby inhibiting cell division
260
which antibiotics are resistant to staphlococcal beta lactamase?
Isoxazolyl penicillins (eg cloxacillin, oxacillin, dicloxacillin)
nafcillin
methicillin
261
complications of penicillin other than allergy
hypernatraemia - if in high doses with renal or cardiovascular disease
seizure - in patients with renal failure
262
what does amikacin do to bacteria
inhibits 30s ribosome subunit (protein synthesis)
263
what does erythromycin do to bacteria
inhibits protein synthesis
bacteriastatic and at higher concentrations is bactericidal
264
what does vancomycin do to bacteria
inhibits cell wall synthesis
265
what does amphotercin B do to fungus
inhibits cell membrane function
binds to ergosterol and alters the permeability of the cell membrane forming pores
266
what is pentamidine and what is it used for
an antiPROTOZOAL drug
interferes with nuclear metabolism.
used as an agent for prophylaxis against pneumocystosis in immune compromised patients
267
what is a complication of pentamidine
it can cause iatrogenic diabetes
cant be toxic to the beta cells in the pancreas
268
which cephlasporins can cause hypoprothrombinaemia and bleeding disorders?
and how is this preventable?
cephlasporins containing a methylthiotetrazole group
eg Cefotetan , cefamandole, cefmetazole, cefoperzone
administer vitamin K twice weekly
269
antihistamines have signficant effect on what receptors
alpha
serotonin
muscarinic
anaesthetic
270
which is more potent prednisone or hydrocortisone
prednisone is 4 times more potent
271
examples of sulphonylureas
tolbutamide
tolazamide
acetohexamide
chlorpropamide
glyburide
glipizide
glimepiride
272
examples of buguanides
metformin
phenformin
buformin
273
mechanism of action cisapride
5HT4 agonist
used in treatment of GORD and motility disorder
It raises lower oesophageal sphincter pressure
274
what happens to excretion of aspirin if the urine is alkalinised
increase excretion of aspirin
275
What effects do kappa receptors mediate?
slow GI transit
supraspinal analgesia
spinal analgesia
psychotomimetic effect
inhibit ADH release
miosis
sedation
dysphoria
276
what is dextropoxyphene
a centrally acting, synthetic, opioid analgesic
structurally related to methadone
277
naloxone half life
1-2 hours
278
what happens with ethylene glycol toxicity
severe metabolic acidosis
secondary to accumulation of glycolic acid and lactate
calcium oxalate crystals form in the tissues
causes hypocalcaemia, acute renal failure
279
treatment of ethylene glycol toxicity
haemodialysis is definitive
temporising antidote is ethanol or fomepizole
280
mechanism of action of alendronic acid (fosamax)
suppresses the activity of osteoclasts
281
what receptor does morphine affect
Mu receptor for analgesic effects
also is an agonist to kappa and delta
282
Inhibitors of CYP450 enzymes
DRSICCKFACES.COM + Grapefruit
diltiazem,
ritonavir, Sodium valproate; Isoniazid (noting current text states inducer); Clarithromycin, Cimetidine; Ketoconazole; Fluconazole; Alcohol (binge); Chloramphenicol; Erythromycin; Sulphonamides; Ciproflox; Omeprazole; Metronidazole.
283
Inducer of the CYP450 enzyme
CRAP GP'S
Carbamazepine
Rifampicin
Alcohol (chronic)
Phenytoin
Griseofulvin
Phenytoin
Sulphonylureas, St Johns wort
+
Barbiturates,
glucocorticoiDs,
charcoal broiled foods,
284
A patient taking isoniazid for the a TB infection can become susceptible to the following vitamin deficiency
B6
285
A patient requires ongoing muscle relaxation during a lengthy operation. His past medical includes renal and liver impairment form alcohol. Which of the non depolarising blocking drugs can be used?
Atarcurium
- it is cleared from circulation via Hofmann elimination
286
Thiopentone is a “short-lasting” barbiturate because?
It is rapidly distributed throughout the body
287
Mnemonic for resuscitation drugs that may be given down the ET tube is NAVEL
Naloxone
Atropine
Vasopressin
Epinephrine
Lignocaine
288
Which receptor action is required for an antiemetic to be effective?
Dopamine receptor antagonism
289
The anti-hypertensive effects of clonidine occur due to
alpha 2 receptor activation
290
Labetalol has the following pharmacodynamic effect
alpha 1 + B1 +B2 antagonism
291
How many mmols of Sodium does a litre of normal saline contain?
154
292
does atropine cross the bloodbrain barrier
yes - it is a tertiary compound
293
with atropine how long are the mydriatic effects on the iris
>72hrs
294
stool softeners
docusate
glycerin suppository
mineral oil
295
laxative stimulants
senna
aloe, cascara, biscodyl
296
what is ergotamine and when is it used
ergotamine is used solely for the third stage of labour- for the control of late uterine bleeding and must never be used before delivery.
297
The order of blockade by local anaesthetics is?
Sympathetic
pain
temperature
touch
propioception
298
Which receptors do the tricyclic antidepressants NOT block?
dopamine
299
After treatment for hyperthyroidism a patient has fever and neutropenia, which is the likely drug?
propylthiouracil
300
Which drug causes severe hypotension in patient with dehydration?
ACE i
301
with use of magnnesium in preeclampsia what is a sign of toxicity
decreased tendon reflexes
302
use and mechanism of action of moxonidine
centrally acting antihypertensive drug
alpha 2 selective recpetor agonist
303
Which of the following best describes the mechanism of action of ciprofloxacin?
DNA gyrase inhibitor
303
toxicity of theophylline
seizures and arrhythmias
304
Antipsychotics exert their function by antagonising which receptor?
D2 - dopamine
305
Which dopaminergic systems are important for the understanding of schizophrenia
mesolimbic - mesocortical pathway
306
Which NSAID is best AVOIDED in patients with a history of gastro-oesophageal reflux disease?
Indomethacin
has higher selectivity of Cox-1
307
Administration of tetanus toxoid provides what type of immunity?
Artificial active
308
A patient who is now day 4 stay in ICU with airway burns, requires intubation. Which of the following muscle relaxant drugs is CONTRAINDICATED?
SUccinylcholine
due to risk of hyperkalaemia
309
Which of the drug classes interact dangerously with Monoamine Oxidase Inhibitors (MAOI)
SSRIs
life threatening serotonin syndrome can develop
310
Which of the following induction anaesthetics are contraindicated in a patient allergic to eggs?
propofol
contains egg yolk
311
What is the treatment of choice for Trichomoniasis
metronidazole
312
Hypoprothrombinaemia and bleeding disorders can be caused by cephalosporins that contain a methylthiotetrazole group. These include:
cefamandole,
cefmetazole,
cefotetan
cefoperazone.
313
what factor does rivaroxaban bind to
Xa
314
what factor does Argatroban and Digabatron bind to
IIa (thrombin)
315
The risk of transient neurological symptoms is most likely to occur with which local anaesthetic?
lignocaine
TNS is a syndrome of transient pain and or dysaesthesia.
316
Which of the following local anaesthetics is recommended for procedures during labour?
bupivocaine
regarded as a very safe spinal anaesthetic agent
317
Which pharmacological agent is best prescribed for motion sickness
anti-muscarinic agents
318
Which of the following analgesic medications is relatively contraindicated in patients who have a history of seizure activity?
tramadol
central acting analgesia
MoA serotonin reuptake
toxicity associated with seizures
318
A patient presents with cardiac sounding chest pain, tachycardia and hypertension- 220/130. Which drug is the safest and most efficacious to this in this situation?
Nitroglycerin
319
Which of the following metabolites of benzodiazepines are INACTIVE?
lorazepam
has inactive metabolites
320
This short acting muscle relaxant is eliminated by hydrolysing cholinesterases
succinylcholine
321
75 year old man presents to the ED with central chest pain which radiates to the back and has a tearing like quality. Diagnosis of aortic dissection is made. The patient is hypertensive, heart rate 100/min. Your choice of drug for the management of hypertension is?
metoprolol
322
90yr old female undergoes a laparotomy for peritonitis. She is slow to regain muscle strength post-operative. Which drug is responsible?
Gentamicin
Gentamicin increases the effect of the neuromuscular blocking agents (including suxamethonium)
323
A patient with Parkinson’s disease presents to the ED with profuse vomiting. Which is the anti-emetic of choice?
domperidone
well tolerated
does not cross BBB
323
An elderly patient with chronic renal impairment develops a lower respiratory tract infection. Which antibiotic as a single agent is best suited for her?
moxifloxacin - fleuroquinolone
it is non renally cleared
324
Which of the following stages of a drug trial examines the effects and side effects of a drug in a population with the disease?
phase 2
325
On which organ does progesterone have a stimulatory effect?
lungs
325
A patient with renal failure presents in severe pain. Which opioid is recommended?
fentnayl
Hepatic oxidative metabolism is the primary route of degradation of the phenylpiperidine opioids (fentanyl)
no active metabolites
326
Which of the following eye drops are useful to dilate the eye in the emergency department?
Tropicamide
326
What medication is used to decontaminate the body following a toxic iron ingestion?
desferioxamine
327
What is the effect of intravenous phenylephrine on heart rate and blood pressure?
Increased blood pressure, decreased heart rate
327
Which NSAID is a COX-2 selective inhibitor?
meloxicam
328
An elderly man is commenced on tamsulosin for symptoms of urinary retention and hesitancy. He experiences begins to experience symptoms consistent with postural hypotension. What is the mechanism behind this?
alpha 1 receptor antagonism
329
Which cephlasporins have Pseudomonas cover?
cefepime (4th generation)
ceftazidime (3rd generation)
cefoperazone (3rd generation)
330
What is the action of benzodiazepines at their receptor site?
allosteric modulators at the GABA A receptor
increase chloride channel opening frequency
331
What is meant by the term therapeutic index?
The ratio of the median toxic dose to the median effective dose
332
A 23-year-old epileptic has drug concentrations measured and is found to be sub-therapeutic. Her dose is minimally increased and two weeks later on re-testing they are supratherapeutic. Which drug is she likely taking?
phenytoin
333
In a patient on an anti-seizure medication, hyponatraemia is most likely a potential side effect with administration of which of the following medications?
carbamazepine
334
What is the mechanism of action of aminophylline in asthma?
inhibition of PDE enzyme, inhibition of adenosine receptors, and enhanced histone deacetylation
335
A 33-year-old man develops an arrhythmia after administration of a medication used to treat asthma. Which of the following is most likely responsible?
aminophylline
336
A 40-year-old man with chronic renal failure is intubated. Which neuromuscular blocking agent is most appropriate to maintain sedation?
Atracurium
undergoes hepatic metabolism and Hoffman elimination
337
Loop diuretics such as Frusemide can cause hypokalemic metabolic alkalosis. What is the mechanism behind this?
Increased Na reabsorption in the collecting duct in exchange for H and K secretion
338
What is the mechanism of action of tetracycline antibiotics?
Reversible binding to the 30S ribosomal subunit inhibiting protein synthesis
339
Buprenorphine is a partial agonist. Which of the following may occur if it is given to a patient on long-term morphine treatment?
It may precipitate a withdrawal syndrome
339
A medication that is an antagonist at the mu receptor, produces little respiratory depression is:
naltrexone
340
What is the principle mechanism of NAC in paracetamol toxicity?
provision of glutathione
Increased glutathione availability (sulfhydryl donor)
Direct binding to NAPQI
Provision of inorganic sulphate
Reduction of NAPQI back to paracetamol.
341
Sodium phosphate is a laxative medication that can cause which of the following electrolyte abnormalities?
hypernatraemia
342
A healthcare worker suffers a needlestick injury from an HIV+ patient and requires prophylaxis.
zidovudine
343
Azithromycin has been reported to cause which of the following cardiac arrhythmias?
VT
macrolides prolong QT
can lead to TdP
344
A 50-year-old man has develops increasing size of his joints, deepening of his voice and a change in shoe size over the past six months. Which medication is most likely to be effective in treating his condition?
Octreotide
a long-acting somatostatin analogue that inhibits endocrine and paracrine factor secretion, including insulin, glucagon, gastrin, GH and TSH.
345
symptoms of neuroleptic malignant syndrome
initial symptom is marked muscle rigidity- a lead pipe rigidity. Muscle type creatine kinase are usually elevated, reflecting muscle damage.
346
Which drug should not be used in conjunction with Sildenafil?
GTN
347
What is the equivalent dose of dexamethasone and prednisolone compared to 200mg hydrocortisone?
8mg 50mg
348
Which drug has both a greater anti-inflammatory and salt-retaining effecting than hydrocortisone?
fludrocortisone
349
Which antidepressant has an active metabolite?
fluoxetine
349
Adrenaline causes skeletal muscle relaxation via which adrenoreceptor?
beta 2
350
Noradrenaline reduces the production of cAMP via which adrenoreceptor?
alpha 2
351
Which anti-thyroid treatment should be used for a pregnant woman in her 1st trimester?
Propylthiouracil
352
A patient with known liver cirrhosis presents with hepatic encephalopathy. He is on acetazolamide, digoxin, ACE-I and frusemide. Which medication is the most likely cause of his encephalopathy?
Azetazolmide
353
An effect of sotalol is to prolong the QT. Which receptor is involved with this effect?
Potassium
354
A patient with ESRF (end stage renal failure) presents with constipation. You are worried about fluid shifts and electrolyte disturbances. Which laxative should not be used?
Sodium phosphate is an osmotic laxative that can cause hyperphosphataemia, hypocalcaemia, hypernatraemia and hypokalaemia
355
Which neuromuscular blocker is primarily metabolised in the plasma
Succinylcholine
356
Sugammadex has NO affinity for which non-depolarising neuromuscular blocker
Atacurium
357
Heparin exerts its anticoagulant effect primarily by
Enhancing the activity of antithrombin III
increasing its ability to inactivate coag factors including thrombin and Xa
358
Heparin's elimination from the body is best described as
Complex, involving a saturable protein-binding phase followed by dose-dependent elimination
359
Which oral anti-diabetic drug can cause B-12 deficiency
Metformin
interferes with the calcium-dependent absorption of vitamin B12-intrinsic factor complex in the terminal ileum, and vitamin B12 deficiency can occur after many years of metformin use
360
Diuretics and site of action
“MALTS”
Mannitol - PCT
Acetazolamide - PCT
Loop diuretics - ascending loop of henle
Thiazide - DCT
Spironalactone - collecting ducts
