PHARMACOLOGY – I (PRACTICAL)[PHL 313]

DR. MOHD NAZAM ANSARI

Screening of diuretics Some of pathological conditions associated

with retention of sodium and water in the body e.g. Congestive Heart failure, Pulmonary edema, renal edema and hypertension.

Diuretics are the drugs that causes a net loss of Na+ and water in urine.

The first important site with regard to renal function is the glomerulous itself. Drugs which increase glomerular filteration rate (Xanthines, cardiac glycosides, saline) produces diuresis.

THE FORMATION OF URINE In summary, three processes occurring in

successive portions of the nephron accomplish the function of urine formation: Filtration of water and dissolved substances out of

the blood in the glomeruli and into Bowman's capsule;

Reabsorption of water and dissolved substances out of the kidney tubules back into the blood (note that this process prevents substances needed by the body from being lost in the urine);

Secretion of hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs out of the blood and into the kidney tubules, where they are eventually eliminated in the urine.

Kidney Structures

ClassificationThe different classes and key prototypes of diuretics

include: Osmotic diuretics:

Mannitol Carbonic anhydrase inhibitors:

Acetozolamide Loop diuretics or the high ceiling diuretics:

Furosemide, Torsemide, Bumetanide, Ethacrynic acid

Thiazide and thiazide-like diuretics: Hydrochlorothiazide, Chlorthalidone, chlorothiazide,

Metolazone K+ sparing diuretics:

Na+ channel inhibitors: amiloride, triamterene Aldosterone receptor antagonists: spironolactone,

eplerenone

Nephron: sites of action of diuretics

LAB 9

Lab 8:To study the effects of

diuretics on the production of urine in rats

Requirement: Drugs

Normal saline Urea (900 mg/kg; oral) Frusemide (5 mg/kg; oral)

Instrumentations Metabolic cages Graduated measuring cylinder

Animals Rats

Metabolic cages

Measuring cylinder

Principle: Diuretics are the compound which increase the flow of urine. Normal urine output in rats is very small (1-2 ml/rat/day). Hence, to get the measurable quantity the animals are first hydrated. The urine output is increased after administration of diuretics like urea and furosemide. Increase in volume of urine is measured with the help of measuring cylinder and compared with the normal urine output.

ProcedureAlbino rats of either sex weighing between 150-200 g are fasted

(deprived of food & water) overnight and saline is administered orally.

These rats are divided into three groups as follows:1. Only normal saline

2. Saline + Urea3. Saline + Furosemide

After administration of drugs, rats are placed in the three different metabolic cages.

Urine is collected in measuring cylinder.

Time when the first drop of urine is collected in a cylinder for each group is noted and the volume is recorded at intervals of 15 min for 3-

4 Hours.

The difference in the volume collected at different time interval and total volume can be compared with various diuretics.

Observations are recorded in following table

III II I Groups

After 15 min

Amount of urine

collected (ml)

After 30 min

After 1 Hr

Total volume

Evaluation

Calculate percentage increase in volume of urine taking control value as 100%.

Plot dose response curve taking log doses on X-axis and Percentage response on Y-axis.

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