Drugs used for Congestive Heart Failure

Drugs affecting the renin-angiotensin-aldosterone system Drug List Inotropic Drugs Drugs affecting the renin-angiotensin-aldosterone system Diuretics Beta-blockers Vasodilators Digoxin Dobutamine Dopamine Milrinone Captopril Enalaprilat Losartan Spironolactone Furosemide Thiazides Metoprolol Carvedilol Nitrates Hydralazine Nesiritide More drugs have been mentioned in the following slides Nesiritide (Natrecor) is the recombinant form of the 32 amino acid human B-type natriuretic peptide, which is normally produced by the ventricular myocardium. Nesiritide works to facilitate cardiovascular fluid homeostasis through counterregulation of the renin-angiotensin-aldoesterone system, stimulating cyclic guanosine monophosphate, leading to smooth muscle cell relaxation. Neseritide was believed initially to be beneficial for acute decompensated congestive heart failure. It received FDA approval for this purpose in 2001 after initial non-approval. In July 2011 the results of the largest study so far for nesiritide was published in The New England Journal of Medicine (NEJM) showed that nesiritide was not associated with a change in mortality or re-hospitalizations.[1]

Vasodilators: Nitrates that act to directly relax vascular muscle tone and cause decrease in blood pressure with pooling of blood in the veins. The preload and afterload will be decreased ACE inhibitors: are agents that block the conversion of angiotensin 1 to angiotensin 2. These drugs causes vasodilatation and decreased blood volume. The afterload will be decreased. Diuretics: are employed to decrease the blood volume, which decreased the venous return and blood pressure. The results are decreased preload and decreased afterload.

Beta agonists: will stimulate the beta receptors in the heart, increasing the myocardial contraction – called positive inotropic effect Cardio-tonic drugs: These agents effect the intracellular Ca++ levels in the heart muscle cells leading to increased contractility. The result is increased cardiac output, increased renal blood flow, increased perfusion and increased urine formation. Cardiotonic drugs are: Cardiac Glycosides Phosphodiesterase inhibitors

Cardiac glycosides - Digoxin They increase the level of calcium inside the cardiac myocyte by inhibiting the Na+/K+ pump. More Ca++ accumulates in the cytoplasm during depolarization and the myocardium will contract forcefully. This is known as positive inotropic effect Increased cardiac output Increased blood flow to the body organs like the kidney and liver Negative

Effects of Cardiac Glycosides Negative chronotropic effect: The heart rate is slowed due to decreased rate of cellular repolarization Decreased conduction velocity through AV node

Contraindications and Precautions Allergy Ventricular dysrhythmias Heart block Sick sinus syndrome Acute myocardial infarction Aortic stenosis Electrolyte imbalances: Hypokalemia, Hypomagnesemia, hypercalcemia Renal failure may cause accumulation of drug

Adverse effects of digoxin Headache, weakness, seizures and drowsiness Arrhythmias Signs of digitalis toxicity: anorexia, nausea and vomiting, visual changes – yellow halo around objects, palpitations or slow heart rate