利尿剂英文.ppt

Classification of Diuretics High efficacy diuretics Moderate efficacy diuretics Low efficacy diuretics * Classification of Diuretics High efficacy diuretics Moderate efficacy diuretics Low efficacy diuretics * High efficacy diuretics Furosemide, bumetanide, ethacrynic acid have their major action on the ascending limb of the loop of Henle —— loop diuretics * Pharmacokinetics absorbed rapidly by oral administration. Bioavailability is 50-70%. If given iv, the effects of furosemide response within 5 mins, duration time 2-3 hrs. 50-60 L of urine excretion within 24 hours after using large doses of furosemide. Protein binding rate is 95%. t1/2 1 hr, which may be prolonged to 10 hr in renal dysfunction. * Mechanism of action inhibit the Na+/K+/2Cl- cotransporter in the thick ascending limb of the loop of Henle reabsorption of Na+, Cl-, Ca2+ and Mg2+ are decreased secretion of K+ is increased the most efficacious of the diuretic drugs the ascending limb accounts for the reabsorption of 25%-30% of filtered NaCl downstream sites are not able to compensate for this increased Na+ load * 1 2 4 5 3 apical membrane Basolateral membrane Na+/K+/2Cl- cotransport system lumen-positive electrical potential H2O diluted Loop diuretics (furosemide) Na+-K+-ATPase interstitial fluid * Pharmacological effects Diuretic activity Diuretic activity is rapid, strong and short Large amounts of Na+, Cl-, K+, Ca2+ and Mg2+ are excreted and Cl- loss is more than Na+ in urine Relative changes in the composition of urine induced by loop diuretics * Pharmacological effects Decrease renal vascular resistance, increase renal blood flow redistribution of blood flow within the renal cortex Increase renin release large volume depletion reflexly activate the sympathetic nervous system and stimulate the intrarenal baroreceptor mechanism induces renal prostaglandins synthesis in the kidney * Pharmacological effects Relieve pulmonary congestion and reduce left ventricular fill