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من طرف **Shamsology** السبت أغسطس 21, 2010 3:49 am

Diuretics

Classes of diuretics:-

carbonic anhydrase inhibitors

loop diuretics

thiazide diuretics

potassium sparing diuretics

osmotic diuretics

Mechanism of action
- almost all diuretics have to be filtered through glomerulus, to act on the luminal surface of tubule, with exception of spironolactone which works on the other wall of tubule from blood stream
- in severe renal failure, because of impairment blood supply &
therefore glomerular filtration, we cannot used thiazides & other
diuretics; with exception of high ceiling diuretics; becasue they have vasodilation effect; so improve blood flow

Carbonic Anhydrase inhibitors:-
Prototype is acetazolamide
they are weak diuretics; because they act on site that is not
responsible for reabsorption of Na & with continued use its action
disappear; because there will be systemic circulation acidosis &
reduced filtration of bicarbonate
all their function depends on bicarbonate & forming carbonic acid

Clinical uses:

glaucoma

convulsive disorders; in epileptic patient in combination with other drugs

management of high altitude sickness

alkaline urine; patient intoxicated with weak acid drug

side effects:

paresthesias

drowsiness

High ceiling diuretics:
- protoype is Furosemide
- other members: is torsemide, etharcrynic aicd, bimetanide

Mechanism of action:-
very effective because they act on ascending loop of Henle; sites where 20-30% of filtered load of Na takes place

notes:
we use these drugs if there is resistance to thiazides; because of their
dramatic effect, could result in dehydration & alteration in
electrolytes balance

Pharmacokinetics:
- Rapid GI absorption
- given by IM & IV
- short duration of action; so use in acute conditions

Clinical uses:

acute pulmonary edema; because they have diuretic effect on kidney; so decreasing blood volume & vasodilatation effect on pulmonary circulation

other edematous sates; heart faliure & hypertension