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Drugs Affecting the Cardiovascular System. Cardiovascular System. Muscular organ with 4 chambers Pumps 5-6 liters blood/minute. Left Side Oxygenated Pulmonary veins Atrium Mitral valve Ventricle. Right Side Unoxygenated Atrium Tricuspid valve Ventricle Pulmonary arteries.
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Cardiovascular System • Muscular organ with 4 chambers • Pumps 5-6 liters blood/minute
Left Side Oxygenated Pulmonary veins Atrium Mitral valve Ventricle Right Side Unoxygenated Atrium Tricuspid valve Ventricle Pulmonary arteries Chambers of the Heart
Systole and Diastole • Systole: Heart is contracting • Diastole: Heart is relaxed
Renin-Angiotensin-Aldosterone • Renal blood flow decreased • Sympathetic stimulation causes release of renin • Renin + plasma angiotensin forms angiotensin I • Angiotensin I converted in lungs to angiotensin II
Renin-Angiotensin-AldosteroneContinued • Agniotensin II: Produces vasoconstriction Acts directly on kidney to retain sodium & water Stimulates adrenal cortex to secrete aldosterone
Cardiotonic-Inotropic Effects • Increase force of myocardial contraction • Causes improved heart’s pumping ability
Cardiotonic-Inotropic Drugs • Adrenergic • Digitalis glycosides • Amrinone • Milrinone
Inotropic Definition • Force of myocardial contraction • Positive inotropic drug: increases force of contractions • Negative inotropic drug: decreases force of contraction
Digitalis Glycosides • Increase myocardial contractility causing more complete emptying
Digitoxin Absorption: 90-100% Oral Digoxin Absorption: 60-80% Tablet 90-100% Capsule 70-85% Elixir Digitalis Glycosides
Digitoxin Distribution: To most body tissues 90% bound to albumin Digoxin Distribution: Throughout the body Binds to skeletal muscle/20-30% to albumin Digitalis Glycosides Continued
Digitoxin Metabolism: Liver - 8% converted to digoxin Excretion: Kidneys Digoxin Metabolism: Small amount in liver & GI flora Excretion: Unchanged drug from kidneys Digitalis Glycosides Continued
Antianginal Drugs • Organic nitrates: produce vasodilation • Beta-adrenergic blocking drugs: Inhibits sympathetic stimulation • Calcium-channel blockers: Prevents Ca moving into cells
Antihypertensive Drugs • Diuretics • Antiadrenergics • ACE inhibitors • Calcium-channel blockers
Hypotension and Shock • Alpha-adrenergic drugs: increase peripheral vascular resistance • Beta-adrenergic drugs: increase myocardial contractility & heart rate