Farmasevtika instituti farmakologiya va klinik farmatsiya kafedrasi

 
Thiazide Diuretics Inhibit Sodium-Chloride Reabsorption in the Early Distal Tubule 
The thiazide derivatives, such as chlorothiazide, act mainly on the early distal tubules to block the 
sodium-chloride co-transporter in the luminal membrane of the tubular cells. Under favorable 
conditions, these agents may cause a maximum of 5 to 10 percent of the glomerular filtrate to pass into 
the urine. This is about the same amount of sodium normally reabsorbed by the distal tubules. 
Sodium Reabsorption from and Potassium Secretion into the Cortical Collecting 
Tubule 
Spironolactone 
and 
eplerenone 
are mineralocorticoidreceptor antagonists that compete with 
aldosterone for receptor binding sites in the cortical collecting tubule epithelialcells and, therefore, can 
decrease the reabsorption of sodium and secretion of potassium in this tubular segment. 
As a consequence, sodium remains in the tubules and acts as an osmotic diuretic, causing 
increased excretionof water, as well as sodium. Because these drugs also block the effect of 
aldosterone to promote potassium secretion in the tubules, they decrease the excretion ofpotassium. 
 
Diuretics That Block Sodium Channels in the Collecting Tubules Decrease Sodium 
Reabsorption 
Amiloride 
and 
triamterene 
also inhibit sodium reabsorption and potassium secretion 
in the collecting tubules, similar to the effects of spironolactone. However, at the cellular level, these 
drugs act directly to block the entry of sodium into the sodium channels of the luminal membraneof 
the collecting tubule epithelial cells.
Acute Renal Failure 
The causes of acute renal failure can be divided into three main 
categories:
1. 
Acute renal failure resulting from decreased bloodsupply to the kidneys; this condition is 
often referred to as 
prerenal acute renal failure 
to reflect the fact that the abnormality occurs as a 
result of an abnormality originating outside the kidneys. For example, prerenal acute renal failure can 
be a consequence of heart failure with reduced cardiac output and low blood pressure or conditions 
associated with diminished blood volume and low blood pressure, such as severe hemorrhage.
2. 
Intrarenal acute renal failure 
resulting from abnormalities within the kidney itself, including those 
that affect the blood vessels, glomeruli, or tubules. 
3. 
Postrenal acute renal failure, 
resulting from 
obstruction of the urinary collecting system anywh re fromthe calyces to the outflow from the bladder.