28. ACE inhibitors, angiotensin II receptor antagonists, vasoactive agents Flashcards
(17 cards)
What are ACE inhibitors?
Angiotensin-converting enzyme (ACE) inhibitors are widely administered to treat chronic congestive heart failure (CHF) in dogs and cats.
ACE inhibitors have also been shown to improve both clinical and echocardiographic parameters in horses with mitral or aortic regurgitation
ACE inhibitors, active substances
- Enalapril
- Benazepril
- Ramipril
ACE inhibitors, mehanism of action
ACE inhibitors block the angiotensin-converting enzyme (ACE), which is responsible for converting angiotensin I to angiotensin II.
Angiotensin II is a potent vasoconstrictor that also stimulates the release of aldosterone.
By inhibiting ACE, these drugs decrease the production of angiotensin II, leading to vasodilation and reduced aldosterone levels.
Lower aldosterone levels result in decreased sodium reabsorption in the kidneys, leading to increased sodium and water excretion and a subsequent decrease in blood pressure.
In short: ACE inhibitors decrease the production of angiotensin II, leading to vasodilation and reduced aldosterone levels
ACE inhibitors, pharmacological effect
- Arterial vasodilation
- Venodilation
- Water excretion
- Decrease blood pressure
ACE inhibitors, indications
- Heart failure
- Hypertension
- Proteinuria
ACE inhibitors, pharmacokinetics
1. Absorption
Per os ⭢ good
Onset of action = approx. 4-6 hours
Duration of action = 12-14 hours (ramipril), 12-25 hours (Benazepril)
2. Excretion
Kidney
ACE inhibitors, side effects
- Hypotension
- GI-disturbances
- Dry cough in horses
- Azotaemia
Angiotensin II receptor antagonists, what are they?
They are administered primarily to treat hypertension and proteinuria in cats and dogs
Angiotensin II receptor antagonists, active substances
- Losartan
- Valsartan
- Telemisartan
Angiotensin II receptor antagonists, mechanism of action
Angiotensin II receptor antagonists block the binding of angiotensin II to its receptors found in various tissues, including blood vessels.
By blocking these receptors, angiotensin II is prevented from exerting its vasoconstricting effects and from stimulating aldosterone release.
This results in vasodilation, reduced sodium reabsorption, and decreased blood volume.
Angiotensin II receptor antagonists, indications
- Congestive heart failure
- Proteinuria
Angiotensin II receptor antagonists, side effects
- Lethargy
- Hypotension
- Azotaemia
Vasoactive agents, what are they?
They are administered in treatment of systemic hypertension in dogs and cats and as adjunctive treatment for congestive heart failure (CHF) in dogs, particularly when CHF is secondary to degenerative mitral valve disease
Vasoactive agents, Active substances
- Amlodipine
- Diltiazem ⭢ Antiarrhythmic drug
Vasoactive agents, mechanism of action
Amlodipine is a dihydropyridine calcium channel blocker, and it works by blocking the calcium channels in the smooth muscles of blood vessels. This blockage prevents calcium from entering the cells, which is necessary for muscle contraction.
By inhibiting the calcium channels, the smooth muscles relax, leading to vasodilation and reduced peripheral resistance and lower blood pressure without directly affecting the heart muscle contraction
Vasoactive agents, Amlodipine
A drug used to treat hypertension in cats.
It works by causing arterial vasodilation, which means it widens the arteries, including the coronary arteries.
The drug is administered orally.
Vasoactive agents, Diltiazem
A drug with a lower vessel and heart selectivity, meaning it affects both to a similar extent. It is classified as an arrhythmic drug, which indicates its use in treating irregular heartbeats = arrhythmias.