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20 Cards in this Set
- Front
- Back
Beta-Blockers (e.g. propranolol)
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hemodynamic effects:
• Effects that decrease myocardial oxygen demand: ↓ HR, ↓ contractility, ↓ BP • Effects tending to increase oxygen demand: ↑ LV EDV (↑ radius) • Effects on oxygen delivery: o ↓ HR → ↑ diastolic perfusion time → ↑ coronary perfusion o main benefit is on effort angina (brought about by ↓ oxygen demand) • Effective in prevention of attacks in patients with effort angina. o β-blockers may slow HR → ↑ filling → ↑ radius (this would ↑ O2 demand), but net effect is to ↓ oxygen demand o In atherosclerotic CAD may ↑ perfusion during. • By ↓ HR → ↑ time in diastole → ↑ perfusion |
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β-Blocker Adverse Effects:
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• Sudden discontinuation → adverse effects
o Exacerbation of angina o MI o Gradual tapering of dose recommended • Upregulation of β-blockers over time |
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Diltiazem (dil tye’ a zem)
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• Non- dihydropyridine calcium channel blockers
• Lower vascular selectivity – so targets heart more → o ↓ HR o Decrease AV conduction o Decrease contractility |
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Nifedipine (nye fed’ i peen)
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• Dihydropyridine calcium channel blockers
• Higher vascular selectivity → vasodilation → ↑ HR o Little change in HR or may go up a bit o Little effect on AV conduction o Not much change in cardiac contractility • May produce reflexive ↑ in HR |
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Verapamil (ver ap’ a mil)
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• Non- dihydropyridine calcium channel blockers
• Lower vascular selectivity – so targets heart more → o ↓ HR o Decrease AV conduction o Decrease contractility |
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Isosorbide dinitrate (eye soe sor’ bide)
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• Organic Nitrate
• Significant first pass metabolism • Mechanism: Nitrates produce NO → activte guanylylcyclase → ↑ cGMP → smooth muscle relaxation • Dilate veins and arteries o Dilate veins more than arteries at low concentrations o Relaxation of vascular smooth muscle • Relaxation of other smooth muscle • Antiplatelet effect (minor effect) |
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Isosorbide-5-mononitrate
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• Organic Nitrate
• bioavailability = 100% (no significant 1st pass effect) • Mechanism: Nitrates produce NO → activte guanylylcyclase → ↑ cGMP → smooth muscle relaxation • Dilate veins and arteries o Dilate veins more than arteries at low concentrations o Relaxation of vascular smooth muscle • Relaxation of other smooth muscle • Antiplatelet effect (minor effect) |
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Nitroglycerin
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• Organic Nitrate
• Significant first pass metabolism • Mechanism: Nitrates produce NO → activte guanylylcyclase → ↑ cGMP → smooth muscle relaxation • Dilate veins and arteries o Dilate veins more than arteries at low concentrations o Relaxation of vascular smooth muscle • Relaxation of other smooth muscle • Antiplatelet effect (minor effect) |
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Ranolazine (ra noe’ la zeen)
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• Mechanism unknown
• Little effect on HR or BP • Administration: Oral • Metabolism: Extensive metabolism, p-glycoprotein (drug interactions) • Adverse Effects: o Dizziness o Headache o Constipation o Nausea o ↑ QT interval (risk of arrhythmia) – risk of arrhythmia |
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Adverse effects of organic nitrates:
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• Headache
• Tolerance • Orthostatic hypotension • Sildenafil (Viagra) increases hypotensive effect (phosphodiesterase-5-inhibitor) |
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Calcium Channel Blocker Uses:
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Hypertension
Angina Arrhythmias |
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Calcium Channel Blocker Mechanism:
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Vasodilation (mainly arterial), reflexive ↑ HR
o All lower BP (↓ PVR and BP) → ↓ O2 demand o ↓ contractility → ↓ O2 demand o HR – depends on class of CCB • Nifedipine & other dihydropyridines (higher vascular selectivity) o Prominent vasodilation → ↑ HR o Little if any effect AV node conduction o Minor ↓ in cardiac contractility (direct effect) • Verapamil, Diltiazem (lower vascular selectivity), major effects on heart o Direct action on heart → ↓ HR o ↓ AV conduction o ↓ in cardiac contractility |
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Adverse Effects of Calcium Channel Blockers:
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• Excessive vasodilation (dizziness, ↓ BP, headache, flushing)
• Constipation • Peripheral edema • Reported concerns about safety of immediate-release nifedipine • Drug interactions (hepatic metabolism) |
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What are the determinants of myocardial oxygen demand?
Demand: |
a. Wall stress (pressure, radius, thickness)
o ↑ radius → ↑ stress b. Contractility c. Heart Rate |
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List 3 organic nitrates used in the treatment of angina.
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a. Nitroglycerin
b. Isosorbide dinitrate c. Isosorbide-5-mononitrate |
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List 4 routes of administration of organic nitrates.
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a. Sublingual (lingual spray also available) (short-acting)
b. Oral (long-acting) c. Topical (ointment and transdermal patch) (long-acting) d. i.v. (hospital use) |
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Describe the importance of first pass metabolism of orally administered organic nitrates.
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• Oral (NTG & Isosorbide dinitrate) → Significant first pass metabolism
• Isosorbide-5-mononitrate: bioavailability = 100% |
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List the classes of antianginal drugs.
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a. Organic Nitrates
i. Short acting vs. long-acting ii. A given drug can be given by several preparations b. β-Blockers c. Calcium Channel Blockers d. Ranolazine |
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Drugs used in vasospastic angina –
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a. Nitrates
b. Calcium Channel Blockers |
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Uses of β-Blockers
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• Hypertension
• Heart Failure • Arrhythmias • Angina |