Heart failure drugs Flashcards
What is the mechanism of action of digitoxin
Na/K+ pump inhibitor
What are the consequential actions of Digitoxin
Increased force of contraction
Increased excitability
Increased A-V conduction
Decreased heart rate
What is the effective range (dose) of Digitoxin
1.0-2.5ng/ml
What is the toxic dose of Digitoxin
> 1.5ng/ml
What are the side effects of Digitoxin
GI: -anorexia -abdominal pain -vominting and diarrhoea Arrythmias: -Premature ventricular contractions -Atrial tachycardias -Atrioventircualr dissociation
Where is Digitoxin extracted from
foxglove plant (Digitalis)
What is the use of Digitalis (Digitoxin)
Clearly indicated in failure when atrial flutter/ fibrillation is present
Describe the half life and administration of Digitoxin
The long half life means that careful titration of patient dose is needed
Give examples of receptor sympathomimetics used to treat heart failure
Dobutamine
Dopamine
what is the mechanism of action of Dobutamine and Dopamine
stimulate beta-1 receptors
Give an example of a nitrate used to treat angina
GTN (glycerol trinitrate)
what is the mechanism of action of GTN (glycerol trinitrate)
Increase the amount of NO
Mo causes relaxation of vascular smooth muscle in arteries and veins
This decreases preload and afterload
What are the side effects of GTN (glycerol trinitrate)
heachache
dizziness
Give an example of a loop agent diuretic used to treat heart failure
Furosemide
What is the mechanism of action of furosemide
inhibits reabsorption of 30% of the filtered Na+ in the kidney
What is furosemide used for
Pulmonary and refractory oedema
Kidney failure
What are the side effecs of furosemide
Ototoxicity
Hypovolemia
Hypokalemia
Hypomagnesia
Give an example of a thiazide diuretic
Hydrochlorothiazide
What is the mechanism of action of Hydrochlorothiazide
Mild diuretic effect
Inhibits reabsorption of <10% of filtered Na+
It mainly acts on the distal convoluted tubule
Direct vasodilator action on smooth muscle
When is Hydrochlorothiazide used clinically
Hypertensives
What are the side effects of Hydrochlorothiazide
Potassium loss
Hypotension
Give an example of a K+ sparing diuretic
Amiloride
Spirononlactone
What is the mechanism of action of Amiloride and
Spirononlactone
Weak diuretic effect
inhibits reabsorption of <5% of filtered Na+
What are Amiloride and Spirononlactone useful for
controlling K+ loss
What are the side effects of Amiloride and
Spirononlactone
Hyperkalemia
Spirononlactone has oestrogen like effects
Give examples of ACE inhibitors used to treat heart failure
Captopril
Analpril
What is the mechanism of action of the ACE inhibitors
Inhibit production of angiotensin II and thus:
- inhibit aldosterone production
- Cause vasodilation as inhibit bradykinin breakdown
What are ACE inhibitors useful for
controlling K+ loss
Hypertension
What are the side effects of ACE inhibitors
Cough
Hypotension
Hyperkalemia
Give an example of an angiotensin II receptor blocker used to treat heart failure
Losartan
What is the mechanism of action of losartan
angiotensin II receptor blocker
it reduces BP
Does not effect bradykinin so no cough
What are the side effects of losartan
Less vasodilation than ACE inhibitors
Birth defects
