Diuretics 2: Loop diuretics

Question 1

Examples of loop diuretics

Answer 1

• Furosemide
• Torsemide
• Ethacrynic acid (non-sulfonamide)

Question 2

Pharmacodynamics of furosemide

Answer 2

High efficacy:
* Powerful, short duration, used for emergencies
* Active excretion in PCT by OASS , therfeore it decreases uri acid excretion, and is inhibited by Probenecid (just like thiazides)
* Acts mainly on the medullary part of thick acending loop of henle –> interfere with countercurrent multiplier system –> excess water excretion
* it decreases positive potential in the lumen –> decreases Ca2+ reabsorption(hypocalcemia)
* Excess Na+ in Late DCT leads to exchange with Mainly K+ and some H+ (hypokalemia)

Question 3

Effect of Loop diuretics on electroytes & Acid base balance

Answer 3

ALL HYPO:
* Hypokalemia
* Hypoclacemia
* Hyponatremia
* Hypovolemia
* hypochloremia
* Hypovloemia

Question 4

Enumerate theraputic uses of loop diuretics

Answer 4

• Edema
• Hypertension
• Acute renal failure
• Hypercalemia

Question 5

Types of edemas treated by Loop diuretics

Answer 5

• Acute pulmonary edema
• Ascites (edema in peritoneum)
• Peripheral edema due to heart failure or renal impaiment

Question 6

Disadvantage of loop diuretics in treatment of hypertension

Answer 6

Short duration

Question 7

state formula given to patient to treat Hypercalcemia with loop diuretics

Answer 7

• Furosemide (loop diuretic)
• elcetrolyte replacement
• IV fluid ( to avoid hemoconcentration)

Question 8

adverse effect of Furosemide

Answer 8

• Hypokalemia
• Hypochloremic alkalosis
• Hypovolemia -> dehydration -> hypotension
• Hyponatermia
• Hypocalcemia
• Hypomagnesemia
• Hyperuricemia
• Hyperglycemia
• Hyperlipidemia
• Hypersensitivity & allergy
• Ototoxicity & deafness (especially if taking Gentamicin)

Question 9

Contraindications of Loop diuretics

Answer 9

(same as Thiazide diuretics but without Kidney disease)

Question 10

Drug interactions of furosemide

Answer 10

• It may displace warfarin
• Decrease renal clearance of Lithium
• if taken with Probenecid, it will reduce its excretion
• NSAIDs block its Antihypertensive effect (by inhibiting prostaglandins)
• Increases digitalis toxicity
• Ototoxicity & Nephrotoxicity when taken with Aminoglycosides (Gentamicin)