Drugs

Question 1

Name a ß-1 antagonist and what it is used to treat

Answer 1

atenolol used to treat hypertension

decrease HR & force of contraction

Question 2

name an a1-antagonist and what it is used to treat

Answer 2

doxazosin

treat hypertension through vasodilation (anti-hypertensive drug), inhibits NA on vascular SM

Question 3

name a mixed adrenoceptor antagonist

Answer 3

carvedilo

not used as too much side effects

Question 4

Name a ß1 agonist and when it is used

Answer 4

dobutamine

relax SM, cardiogenic shock (pump failure)

Question 5

Name a ß2-agonist and when it is used

Answer 5

salbutamol
treat asthma (bronchodilation)

Question 6

What is a muscarinic agonist and when is it used?

Answer 6

pilocarpine used to treat glaucoma (cause constriction)

binds to M3 receptor

Question 7

Wha is a muscarinic antagonist and what are the effects?

Answer 7

atropine
M2: increase HR
M3: cause bronchial (dilation) relaxation (normally M3 cause constriction, parasympathetic)
dilate pupils

Question 8

Name an Na+ blocker and when it is used and how it works

Answer 8

Lidocaine
used after MI to prevent V.tachycardia
acts in open / inactivate state, dissociates rapidly for next AP
stops afterdepolarisation (high Ca2+, long QT)

Question 9

Name a ß-adrenoceptor antagonist and what it does

Answer 9

sympathetic increases after an MI which causes ventricular arrhythmia (tachycardia)
so ß-blocker reduces O2 demand and less Ca2+ (decrease HR & contractility)
slows AVN conduction - prevent supraventricular tachycardia & ventricular rate
slows down funny current (HCN), increasing PR interval from 3-5ss
less cAMP produced, less PKA phosphorylates L-type VOCC, less bind to RyR (decrease force & rate)

Question 10

what is the function of K+ channel blockers and when are they used?

Answer 10

lengthens ARP (phase 3), not used as pro-arrhythmic except amiodarone in W-P-W (re-entry loops, multiple foci, affects QRS)
treat tachycardia 
prolongs QT

Question 11

Function of Ca2+ blockers and when they are used?

Answer 11

blocks L-type Ca2+ channels (upstroke of SAN - depolarisation)
decrease Ca2+ decreasing force of contraction & HR (SAN), doesn’t affect ventricles as Ca2+ in ventricles only affect plateau
slows AVN as SAN i slowed - lengths PR (P also widens)
cause peripheral & coronary vasodilation
if used with ß-blocker cause HF

Question 12

What is adenosine used? what does it act on?

Answer 12

can be produced endogenously
acts on A1 receptors on AV node
phosphorylates K+ channels - hyperpolarise cells of conduction tissues
stops heart arrhythmia: low dose of high conc K+ stops heart suddenly to start again - restore sinus rhythm quickly - like ‘defib’

Question 13

Name an example of a cardiac glycoside and how it functions

Answer 13

digoxin
blocks Na+/K+/ATPase, increases intracellular Na+, so NCX reverses to pump 3Na+ out and 1Ca2+ in, increasing force of contraction and CO
increases vagal nerve (parasympathetic) - slows down HR

Question 14

How do organic nitrates work?

Answer 14

released from endothelial cells, reacts with thiol (-SH) of SM, produces NO2- reduced to NO
causes venodilation (decrease pre-load
dilate collateral arteries
all reduce workload of the heart

Question 15

Which drugs do you give to reduce work load of the heart?

Answer 15

ACE-inhibitors (decrease angiotensin II, less Na+, less water retention, less blood volume)
diuretics
ß-blockers (decrease AC, decrease cAMP, decrease Ca2+ for force of contraction)

Question 16

When are antithrombotic drugs used?

Answer 16

acute fibrillation (HF)
acute MI
mechanical prosthetic heart valves

Question 17

how do ACE-inhibitors work?

Answer 17

decrease pre-load (blood volume decrease)
decrease afterload (vasodilate, decrease vasomotor tone, decrease peripheral vessels resistance)
chronic heart failure