PHARMACOLOGY OF DRUGS ACTING ON RENAL SYSTEM

BHARAT INSTITUTE OF TECNOLOGY

Mr.B.CHAKRAPANI M.pharm (ph.D)ASSISTANT PROFESSOR

DEPARTMENT OF PHARMACOLOGY

MANGALAPALLY,IBRAHIMPATNAM(M), R.R Dist.

Anatomy of urinary system

Anatomy of urinary system

CortexGlomeruli

MedullaRenal tubules

(with calyces forming the medulary pyramids)

UreterTakes urine to bladder

Blood carried to the kidney by the renal artery and taken away

by the renal vein.

Cortex

Medulla

Renal artery

Renal vein

Renal pelvis

Ureter

Renal hilum

Anatomy of the Kidney

Anatomy of the Urinary System

Kidneys(urine formation)

Lower Urinary TractUreters (2)Bladder (1)Urethra (1)

(urine collection, storage, excretion)

Urinary system organs

Kidney Functions

1. Regulation of water, electrolyte balance, pH

2. Removal of waste from blood and excretion of urine.

3. Secretion of hormones Erythropoietin Renin Vitamin D3

Each KIDNEY consists of 1 million NEPHRONS

Each nephron consists of a:GLOMERULUS (found in cortex)

forms a protein-free filtrate from bloodTUBULE (found in medulla)

processes the filtrate to form urine

Each TUBULE consists of several segments:Proximal tubuleLoop of HenleDistal Tubule

Collecting Ducts.

Pharmacology of drugs acting on Renal System

Diuretics are drugs that increase the excretion of Na+ and water from the body by an action on the kidney.

Their primary effect is to decrease the reabsorption of Na+ and Cl- from the filtrate, increased water loss being secondary to the increased excretion of NaCl.

This can be achieved by: a direct action on the cells of the nephron indirectly modifying the content of the filtrate.

Note that the diuretics which have a direct action on the cells of the nephron (with the exception of spironolactone ) act from within the tubular lumen and reach their sites of action by being secreted into the proximal tubule.

Classification of Diuretic drugs

Carbonic an hydrase inhibitors:AcetazolamideLoopdiuretics:Bumetanide,Ethacrynicacid,Furosem

ide,Torsemide.Thiazidediuretics:Cholorothiazide,Chlorothalidone,

Hydrocholorothiazide,Indapamide,Metolazone. potassium-sparingdiuretics:

Amiloride,Spirnolactone,TriamtereneOsmotic diuretics:Mannitol,urea,

DIURETICS ACTING DIRECTLY ON THE CELLS OF THE NEPHRON

Drugs that cause NaCl loss by an action on cells must obviously affect those parts of the nephron where most of the active and selective solute reabsorption occurs:

the ascending loop of Henle the early distal tubule the collecting tubules and ducts.

Loop diuretics

Loop diuretics are the most powerful of all diuretics, capable of causing 15-25% of the Na+ in the filtrate to be excreted .

They are termed 'high ceiling' diuretics and their action is often described-in a phrase that conjures up a rather uncomfortable picture-as causing 'torrential urine flow'. The main example is furosemide; others are bumetanide, piretanide, torasemide and etacrynic acid.

These drugs act primarily on the thick segment of the ascending loop of Henle, inhibiting the transport of NaCl out of the tubule into the interstitial tissue by inhibiting the Na+/K+/2Cl- carrier in the luminal membrane

DIURETICS ACTING DIRECTLY ON THE CELLS OF THE NEPHRON

Drugs that cause NaCl loss by an action on cells must obviously affect those parts of the nephron where most of the active and selective solute reabsorption occurs: the ascending loop of Henle the early distal tubule the collecting tubules and ducts.

Clinical uses of loop diuretics

Loop diuretics are used in conjunction with dietary salt restriction and often with other classes of diuretic , in the treatment of salt and water over load associated with

Acute pulmonary edemaChronic heart failureCirrhosis of the liver complicated by Ascites.Nephrotic syndromeRenal failureTreatment of hypocalcaemia after replacement of

plasma volume with intra venous NaCl solution.