Diuretics

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*Acetazolamide*

#Formulations : Tablet, Capsule 

#Brand_Names : Diamox, Synomax, Iopar - SR

#Pharmacological_Action : It is a sulfonamides derivative which noncompetitively but reversibly inhibits carbonic anhydrase in proximal tubular cells resulting in slowing of hydration of CO2. This decreases availability of H+ to exchange with Luminal Na+ through the Na+_ H+ antiporter. Inhibition of brush border carbonic anhydrase retards dehydration of carbonic anhydrase in the tubular fluid so that less carbon dioxide diffuses back into the cells. The net effect is inhibition of Bicarbonate ion reabsorption in proximal tubules. However, the resulting alkaline diuresis is only mild because part of the sodium ion rejected in the proximal tube is reabsorbed at the high capacity TAL segment. 

#Side_Effects : Acidosis, Hypokalaemia, Drowsiness, Paresthesias, Fatigue, abdominal discomfort, Fever, Rashes. 

#Therapeutic_Uses : used as diuretics.

*Frusemide*

#Formulations : Tablet, Injection

#Brand_Names : Lasix, Lasix High Dose, Salinex, Frusenex

#Pharmacological_Action : It directly acts on thick ascending loop of henle therefore called loop diuretics. It inhibits sodium potassium chloride cotransport (site II). A minor component of action on proximal tubules has been demonstrated. It is secreted in proximal tubules by organic anion transport and reaches thick ascending loop of henle where it acts from Luminal side of the membrane. The corticomedullary osmotic gradient is abolished and positive as well as negative free water clearance is blocked. Potassium excretion is increased due to high sodium load reaching distal tubules. It has weak carbonic anhydrase inhibitory action. 

#Dose : 20- 80 mg once daily in the morning. In renal insufficiency upto 200mg 6 hourly has been given by intramuscular or intravenous route. In pulmonary oedema 40-80 mg may be injected intravenous. 

#Therapeutic_Uses : used as diuretics.

*Bumetanide*

#Formulations : Tablet, Injection

#Brand_Names : Bumet

#Pharmacological_Action : It is 40 times more potent than furosemide.  It indices very rapid diuresis and is highly effective in pulmonary edema. The cite of action, ceiling effect, renal haemodynamic changes and duration of action are similar to furosemide. A secondary action in proximal tubules has also been demonstrated. It may act in some cases not responding to furosemide, and may be tolerated by patients allergic to furosemide. Hyperuricaemia, potassium loss, glucose intolerance and ototoxicity are claimed to be less marked, but bumetanide may rarely cause myopathy.

#Dose : 1-5 mg oral OD in the morning, 2-4 mg intramuscular or intravenous route

#Therapeutic_Uses : used as diuretics.

*Methyldopate Hydrochloride*

#Formulations : Tablet

#Pharmacological_Action : This alpha methyl analogue of dopa is converted in the body to alpha methyl noradrenaline which is a selective alpha 2 agonist. In the brain, the alpha methyl noradrenaline generated from methyldopate acts on central alpha 2 receptors to decrease efferent sympathetic activity. However, in contrast to clonidine, methyldopa decreases total physical response more than Heart Rate. It also inhibits the enzyme dopa decarboxylase. It was initially believed that methyldopa acted as Antihypertensive by depressing synthesis of noradrenaline in peripheral sympathetic neurones.


#Side_Effects : Sedation, Lethargy, reduced mental capacity, dryness of mouth, nasal stuffiness, headache, fluid retention, weight gain and impotence.


#Dose : 0.25-0.5g BD - QID oral.


#Therapeutic_Uses : used as Antihypertensive drugs.

*Metolazone*

#Formulations : Tablet, Injection

#Brand_Names : Xaroxolyn, Diurem, Metoral

#Pharmacological_Action : In common with loop diuretics, it is able to evoke a clinically useful response even in severe renal failure (glomerular filtration rate = 15ml/min) , and has marked additive action when combined with furosemide. An additional proximal tubular action has been demonstrated; phosphate reabsorption that occurs in proximal tubules, is inhibited. It is excreted unchanged in urine. 

#Dose : 5-20 mg /day

#Therapeutic_Uses : used as diuretics.

*Spironolactone*

#Formulations : Tablet

#Brand_Names : Aldactone, Aldactide, Lacilactone, Spiromide, Torlactone


#Pharmacological_Action : It is a steroid, chemically related to the mineralocorticoid aldosterone. Aldosterone penetrates the late distal tubules and collecting ductules and acts by combining with an intracellular mineralocorticoid receptors induces the formation of aldosterone induced proteins. It promotes sodium reabsorption by a number of mechanism and potassium secretion. It acts from the interstitial side of the tubular cell, combines with mineralocorticoid receptors and inhibits the formation of AIPs to act as a competitive antagonist.


#Dose : 25-50 mg BD- QID; max 400mg/day


#Therapeutic_Uses : used as diuretics.