Antihypertensives 2 Flashcards
- What is Aliskiren?
Aliskiren is an renin inhibitor used to treat HTN. It inhibits the renin enzyme preventing the conversion of angiotensinogen to angiotensin I. The end result is a decreased in aldosterone production therefore decreased absorption of sodium and water.
- What are the adverse side effects of Aliskiren?
- Hyperkalemia
- Hypotension
- Angioedema (low risk)
- Acute renal failure – pts with bilateral renal artery stenosis
- Rash, fever, altered taste
- What are the different Ca2+ channel blocker drugs?
- Verapamil [non-dihydropyrdine]
- Diltiazem [non-dihydropyrdine]
- Nifedipine [dihydropyrdine]
- Amlodipine [dihydropyrdine]
- What is Verapamil?
Verapamil is one of the least selective calcium channel blockers thereby affecting both the heart and vascular SM. It is used to treat angina, supraventricular tachycardia, HTN, migraine and cerebral vasospasm.
- What is Diltiazem?
Diltiazem is a calcium channel blocker that affects both the heart and vascular SM. It is said to have a good side-effect profile and is used to treat angina, supraventricular tachycardia, HTN, and cerebral vasospasm.
- What are the the dihydropyrdine calcium channel blockers?
Nifedipine (1st generation) and Amlodipine (2nd generation) – these drugs have greater affinity for vascular calcium channels versus cardiac calcium channels therefore are more specific. They reduce the calcium entry into SM to cause coronary and peripheral vasodilation which will lower BP. These drugs are primarily used to treat HTN, but can also help with angina. They are not good with treating cardiac arrhythmias.
- What is the general mechanism of action for calcium blockers?
Calcium blockers block the voltage-sensitive calcium channel (L-type) preventing the entrance of calcium therefore causing myofibril/vascular relaxation.
- What are the clinical uses of calcium channel blockers?
- HTN – esp in black or elderly pts
- Useful in pts with asthma, diabetes, peripheral vascular disease
- Has intrinsic natriuretic effect therefore there is no need for diuretics
- What is a specific side effect to high-doses of short acting dihydropyridine calcium channel blockers?
These calcium channel blockers increase the risk of MI by causing excessive vasodilation that leads to reflex cardiac stimulation. Sustained release preparations are preferred.
- What are the adverse side effects of Verapamil?
Constipation, negative inotropic effects
- What are the adverse side effects of dihydropyridines?
- Hypotension
- Peripheral edema (esp in feet and ankles)
- Dizziness
- Headache
- Fatigue
- Gingival hyperplasia
- Flushing
- Reflex tachycardia
- What are the contraindications of calcium channel blockers?
Non-dihydropyridine (verapamil and diltiazem) should not be given to pts taking B blockers or who have 2nd or 3rd degree AV block, or severe LV systolic dysfunction. This is because there could be an exaggerated negative inotropic effect.
- What B blockers can be used to treat HTN and what receptors do each bind?
- Propranolol → non-selective B1 and B2 receptor antagonist
- Metoprolol and Atenolol [most common] → selective B1 receptor antagonists
- Pindolol → non-selective B1 and B2 partial agonist with intrinsic sympathomimetic activity [preferred B-blocker in pregnancy]
- What is the mechanism of action of B-blockers?
B-blockers inhibit the release of NE and renin (B1) decreasing angiotensin II and aldosterone secretion. The decrease in renin indirectly acts on the heart by decreasing CO. B-blockers can also act directly on the heart where they reduce CO , contractility and HR. There can be a blunt sympathetic reflex with exercise.
- What are the adverse effects of B-blockers?
- bradycardia
- CNS effects – fatigue, lethargy, insomnia, hallucinations
- Hypotension
- Decreased libido and impotence
- Disturbed lipid metabolism → increased TAGs and decreased HDL
- Hypoglycemia (B2 blockers)
- Drug withdrawal → therefore there is a need to taper off dose in pts
- Propranolol is contraindicated in asthmatics and COPD pts