drugs Flashcards
1
Q
propanolol
A
- class 2 b-adrenoceptor antagonist
- inhibition of cardiac sympathetic activity
- decreases phase 4 slope resulting in a decrease in automaticity
- prolongs re-polarisation at AV node thus increasing refractory period of AV action potential
- side effects: cardiac effects, B2 adrenoceptor antagonism, and CNS effects
2
Q
amiodarone
A
- class 3 prolong re-polarisation
- main effect is too decrease re-polarising l(k), therefore prolonging re-polarisation and refractory periods
- side effects: corneal micro deposits, skin photosensitivity, pulmonary fibrosis, hepatic toxicity
3
Q
sotalol
A
- class 2 with class 3 properties
- adverse side effect thus restricted use
4
Q
verapamil
A
- class 4 CCB
- blocks the voltage sensitive calcium channels
- main effect on nodal tissue (phase 0 due to Ca influx)
- SE: cardiac depression, hypo-tension, flushing, constipation
5
Q
adenosine
A
- Atypical anti arrhythmias
- (1) activates k(ach) ion channels
- hyper polarisation of Em reducing the slope of phase 4 depolarisation, decrease SA node firing frequency
- (2) inhibition of adenylyl cyclase
- decreases cAMP thus decrease pKa activity, resulting in decreased opening of calcium channels
6
Q
digoxin
A
- increases the parasympathetic outflow to the AV node 2. blocks the cardiac muscle NA/K ATPase
7
Q
flecainide
A
- IC class 1 Na channel blocker
- predominant effect due to block of fast voltage gated sodium ion channels, use dependent as an increase in block comes with increase in frequency of use, slow conduction velocities and a reduction in automaticity
- strong block, slow association and dissociation, only marginal preference for refractory channels therefore does not preferentially block ectopic beats
- SE: negative inotropic effects, cns effects including dizziness, confusion, blurred vision
8
Q
lignocaine
A
- IB class 1 Na channel blocker
- predominant effect due to block of fast voltage gated sodium ion channels, use dependent as an increase in block comes with increase in frequency of use, slow conduction velocities and a reduction in automaticity
- mild block, rapid block of channels in refractory state therefore preferential effect on depolarised tissue, fast dissociation from ion channel therefore does not block normal cardiac rhythm
- SE: cns effects such as dizziness and confusion
9
Q
quinidine, procainamide, disopyramide
A
-IA class 1 Na channel blocker
-predominant effect due to block of fast voltage gated sodium ion channels, use dependent as an increase in block comes with increase in frequency of use
-slow conduction velocities and a reduction in automaticity
moderate block, slow disassociation from ion channel prolonging re-polarisation
-SE: anticholinergic action and diarrhoea
10
Q
clonidine
A
- a2 receptor agonist
- decreases sympathetic outflow from the CNS thus decreasing NA release from nerves
- a decrease in CO and a decrease in TPR leads to decreased arterial blood pressure
- SE: sedation, dry mouth, dizziness, postural hypotension
11
Q
dihydropyradine, phenylalkalamine, benzothiazepines
A
- CCB’s
- all bind to distinct L type calcium channel
- SE: exacerbation of heart failure, peripheral effects such as headache, flushing, dizziness
12
Q
ACE and ARB’S
A
- ACE - inhibition of angiotensin converting enzyme inhibits the conversion of angiotensin 1 to angiotensin 2
- ARB - blockade of angiotensin receptor, angiotensin antagonist
- SE: contraindicated in heart failure, postural hypotension, angio-oedema (swelling of lips, eyes, and tongue)
13
Q
Renin inhibitor’s
A
- Blocks conversion of angiotensinogen to angiotensin 1
- SE: contraindicated in patients with diabetes, renal impairment and hyperkalaemia, increase risk of stroke in diabetes and renal impairment
14
Q
Doxazosin
A
- a2 antagonists
- decrease sympathetic tone causing dilation of venous smooth muscle decreasing CO and thus decreasing BP
- decreases sympathetic tone causing dilation of arterial smooth muscle decreasing TPR and thus decreasing BP
- SE: first dose hypertension, postural hypotension, urinary frequency, palpitations, drowsiness, dizziness
15
Q
atenolol & propanolol
A
- B1 adrenoceptor antagonist (blockers)
- a decrease in heart rate and a decrease in the force of contraction results in a decreased CO and thus a decreased BP.
- blockade of B1 receptors on juxtaglomerular cells on kidney: decrease in renin secretion results in a decrease in angiotensin 2 production thus decreasing plasma volume and TPR, and a reduced plasma volume and TPR results in decreased arterial blood pressure
- SE: broncho-constriction thus contraindicated in asthma (non selective B2 blocker), fatigue, peripheral vasoconstriction, cardiodepression thus contraindicated in heart failure, hypoglycaemia thus contraindicated in diabetes, and sleep disturbance with propanolol
