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CVS Pharmacology
Cardiovascular system pharmacology- Drugs used in Heart Failure
Question | Answer |
---|---|
Objectives of Long Term Management of Chronic Cardiac Failure: | Improve cardiac performance at rest and during exercise Relieve symptoms Improve myocardial efficiency Improve quality of life (particularly symptom-free and effort tolerance) Improve patient survival |
Problems caused by HF: | Reduced force of contraction Decreased CO Increased total peripheral resistance Inadequate organ perfusion Edema Decreased exercise tolerance IHD Sudden death Ventricular remodeling and decreased function |
What are the non-pharmacologic treatments of Heart Failure? | Salt restriction Treat the cause Moderate exercise Heart Transplantation |
What drug groups are commonly used in HF? | Diuretics Aldosterone receptor antagonists Angiotensin-converting enzyme inhibitors Angiotensin receptor blockers Beta blockers Cardiac glycosides Vasodilators Beta agonists Bipyridines Natriuretic peptide |
What is the purpose of using diuretics in HF? | They mostly treat the congestive symptoms Decrease BP and increase K+ loss Can be used in combination with digitalis |
How are diuretics administered in HF? | IV |
What are the causes of diuretic resistance in HF? | Noncompliance with regimen Excess dietary Na+ intake Decreased renal perfusion and GFR Selective reduction in glomerular perfusion pressure following initiation of ACEI therapy NSAIDs Primary renal pathology Reduced or impaired diuretic absorption |
What are the pharmacological actions of ACEIs? | Reduce A II levels Increase bradykinin Decreased NE release and upregulation of B1 receptors Reduction of afterload and preload Reduce myocyte & fibroblast GFs Decrease aldosterone causing decreased fluid retention, K+ loss, and arrhythmias |
What is the therapeutic value of ACEIs? | DOC in HF No tolerance Retard progression of HF Decrease arrhythmias Only drugs which decrease mortality, but only when the highest tolerated doses are used |
What are the different preparations of ACEIs? | Captopril Enalapril Lisinopril Quinapril Fosinopril All end with the suffix -pril Careless Evidence Leads Questionable Foreigners |
What does toxicity of ACEIs cause? | Hypotension - First dose phenomenon Renal Impairment - Proteinurea K+ retention Cough |
Examples of ARBs: | Losartan Candesartan Valsartan Irbesartan(Approvel) Telmisartan(Micardis) |
When are ARBs used? | When patients can not tolerate ACEIs because of cough |
Effects of Beta Blockers: | Negative inotropic Not useful in refractory HF Slowing of HR, decreased cardiac work and consequently decreased myocardial O2 consumption and enhanced efficiency lessen the frequency of ischemic events and arrhythmias |
How can Beta blockers improve myocardial contractility? | Through resensitization of the down-regulated receptor |
How are Beta blockers administered? | Started with low doses and gradually increased |
Examples of Beta blockers: | Metoprolol Carvedilol Bicindolol Bisiprolol Many Cute Babbling Babies |
When are beta blockers contraindicated? | In severe, refractory, or unstable cases |
How do positive inotropic agents increase force of contraction? | By increasing intracellular cardiac Ca++ concentration |
Examples of Cyclic AMP Independent Agents: | Digitalis Pimobendan |
Examples of Cyclic AMP Dependant Agents: | B-adrenergic Agonists Phosphodiesterase Inhibitors |
General Action of Digitalis: | Inhibits Na/K ATPase |
Action of Pimobendan: | Sensitizes myocytes to Ca++,also inhibits PDE |
Examples of Digitalis glycosides: | Digitalis purpura Digitalis lanata Strophanthus |
Further action of Digitalis glycosides: | Positive Inotropic Effect Vascular Muscle Contraction Vagal Stimulation Effects on Electrical Properties of Cardiac Tissues |
Effects of Digitalis Toxicity: | G.I.T: Anorexia, nausea, cramping, diarrhea Visual: Xanthopsia, color blindness Neurologic: Malaise, confusion, depression, vertigo Cardiac: bradycardia, Palpitations, syncope, arrhythmias, AV node block, VT Interactions |
Pharmacological and toxic effects are greater in | Hypokalemic patients |
Major contributing factor to digoxin toxicity | K+-depleting diuretics |
How is digitalis toxicity treated? | Reduce or stop the drug Cardiac pacemeker for heart block Digitalis antibodies Arrhythmias may be converted to normal sinus rhythm by K+ Antiarrhythmic drugs, such as lidocaine, phenytoin, procainamide, or propranolol, used when K+ conc is high |
Therapeutic benefits of Digitalis glycosides: | Only useful in CCHF with supraventricular arrhythmia Might decrease morbidity |
Examples of B-adrenergic agonists (which are cAMP dependent agents): | NE Ep Dopamine Dobutamine |
Examples of phosphodiesterase inhibitors (which are cAMP dependent agents): | Amrinone Inamrinone Milrinone Vesanirone Sildenafil Adorable Ideas Meet Slimy Verbs |
What is the general function of B-adrenergic agonists? | All increase myocardial oxygen consumption, may be used (IV) for short term or in acute heart failure |
When is NE used? | In cardiogenic shock, but caused severe vasospasm and gangrene |
When is Ep used? | In cardiac arrest, by intracardiac injection |
When is dopamine used? | Widely used in cardiogenic shock |
Low doses of dopamine cause: | Stimulation of DA1 receptors leading to renal vasodilation and improved renal function |
Intermediate doses of dopamine cause: | Positive inotropic actions by working on B1 receptors |
High doses of dopamine cause: | Stimulation of α receptors leading to vasoconstriction and elevation of blood pressure |
Side effects of dopamine: | Arrhythmias Ischemic changes |
What is dobutamine? | Selective β1 agonist |
When is dobutamine used? | Intermittently (IV) in CCHF |
General function of phosphodiesterase inhibitors: | Accumulation of cAMP and cGMP leading to positive inotropic activity and peripheral vasodilation |
Phosphodieserase inhibitors are generally used for: | Parenteral therapy of acute heart failure |
Examples of phosphodiesterase inhibitors: | Inamrinone (PDE-3) Milrinone (PDE-3) Vesanirone (PDE-3) Sildenafil (PDE-5) Individual Men View Stars |
Toxicity, as a result of phosphodiesterase inhibitors leads to: | Arrhythmias Thrombocytopenia |
What is the function of vasodilators? | Affect preload and/or afterload without directly affecting contractility Consequently can decrease myocardial ischemia, enhance coronary blood flow and decrease MVO2 |
When are vasodilators used? | In acute heart failure and for short periods in CCHF |
Action of Hydralazine-Isosorbide dinitrate combination | Decrease mortality Reducing remodeling of the heart |
Vasodilators can be combined with: | ACEI, diuretics and digitalis |
Venous dilators: | Nitroglycerin Isosorbide dinitrate |
Mixed action vasodilators: | Nitroprusside Captopril Enalopril Hydralizine + Nitrate |
Atrial dilators: | Hydralazine Minoxidil |
Examples of organic nitrate vasodilators: | Nitroglycerin Isosorbide dinitrate |
Examples of Nitric oxide donors used for vasodilators | Nitroprusside |
Examples of ACEIs used for vasodilators | Captopril Enalapril Lisinopril |
Examples of ARBs used for vasodilators | Losartan candesartan |
Phosphodiesterase inhibitors used for vasodilators: | Milrinone Inamrinon |
Direct-acting K+ channel agonist used for vasodilators: | Hydralazine Minoxidil |
Adrenergic antagonists used for vasodilators: | Doxazosin Prazosin |
Nonselective a-adrenergic antagonists used for vasodilators: | Phentolamine |
B1-adrenergic antagonists used for vasodilators : | Carvedilol Labetalol |
Ca2+ channel blockers used for vasodilators | Amlodipine Nifedipine Felodipine |
Function of (BNP)-Niseritide: | Binds to receptors in the vasculature, kidney, and other organs, producing potent vasodilation with rapid onset and offset of action by increasing levels of cGMP |
BNP is secreted by: | ventricular myocytes in response to stretch |
Niseritide is used for the treatment of: | Acute decompensated CHF |
Action of niseritide: | Reduces systemic and pulmonary vascular resistances, causing an indirect increase in cardiac output and diuresis |
Why is BNP- Niseritide useful in HF? | Reduction in preload and afterload |
Main side effect in Niseritide? | Hypotension |
Errors in Management of HF | Improper dosage of diuretics Failure to consider long term therapeutic goals Underprescribing ACEIs Use of potentially harmful drugs Failure to use hydralazine-isosorbide combination |