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Renal Pharmacology—High-Yield For INI-CET

May 7, 2025

Renal Diuretics

Diuretics: Increase urine volume—measured as urinary flow rate
Increase Na+ excretion in urine: Drugs—Natriuretics
Increased water excretion through urine: Drugs—Aquaretics

Classes of Diuretics

Types	Mechanism	Action
Carbonic anhydrase inhibitors - Acetazolamide	PCT of nephron and inhibit carbonic anhydrase enzyme	Na⁺/HCO₃^- excretion in urine
Osmotic diuretics - Mannitol	Acts on descending limb of Henle/loop of Henle	Inhibit reabsorption of water
Loop diuretics - Furosemide	Na⁺K²⁺Cl^- transporter inhibitors	Acts on the medullary portion of the thick ascending limb
Thiazide diuretics - Chlorothiazide	Inhibition of Na⁺Cl^- symporter	Cortical portion of thick ascending limb + early part of DCT
K⁺ sparing diuretics - Spironolactone	Inhibit the action of aldosterone	Late part of DCT and the cortical portion of the collecting duct

Maximum sodium loss	Loop diuretics > Thiazides > Osmotic diuretics > Carbonic anhydrase inhibitors> K⁺ sparing diuretics
Maximum potassium loss	Carbonic anhydrase inhibitors > Thiazides > Loop diuretics > Osmotic diuretics - Na⁺ absorption is inhibited in the proximal part of the nephron

Also read: Respiratory Drug : INI-CET Quick Revision Guide

Some Other Miscellaneous Diuretics

Theophylline and caffeine:

Drug used in asthma – Theophylline
Drug used in migraine – Caffeine
Causes blockage of adenosine A1 receptor on nephron

Natriuretic peptides:

Includes

Atrial Natriuretic peptides
Brain Natriuretic peptides (Nesiritide – Used in heart failure)
Act on enzyme linked receptors on nephron. Attach to guanylyl cyclase and increase CGMP leading to sodium loss in urine

SGLT-2 Inhibitors

Recommended in diabetes mellitus
Inhibit sodium glucose transporter in nephron
- Na+ loss + Glycosuria
Drugs ends with the word - flozin
- Canagliflozin
- Empagliflozin
- Dapagliflozin

Mechanism of Action

Act on the PCT of nephron
Inhibits carbonic anhydrase enzyme
Na+/HCO3 - excretion in urine

Drugs

Acetazolamide
Methazolamide
Dichlorphenamide
Derivatives of antibiotics—sulfonamide (causes severe allergic reactions)
- Acetazolamide like drugs are contraindicated in sulfa allergy
These drugs are competitive and irreversible inhibitor
Except acetazolamide—a noncompetitive and reversible inhibitor of carbonic anhydrase enzyme
Topical eye drops—recommended in glaucoma
- Brinzolamide
- Dorzolamide

Also read: Microbiology Image Based Questions for NEET PG 2025

Uses of Acetazolamide Like Drugs

Mnemonic GAME Plan

	Action	Uses
G- Glaucoma	Most abundant enzyme- Carbonic anhydrase MOA- Decrease aqueous secretion from ciliary cells	Eye drops of Brinzolamide, Dorzolamide Given in primary open-angle glaucoma IV drugs- Acetazolamide Emergency- Acute congestive glaucoma
A- Alkalinization of urine	Bicarbonate excretion Side effects Increases the risk of alkaline renal stones Increase the risk of calcium phosphate stones Treatment Thiazide diuretics Inhibits calcium excretion	Acidic drug poisoning Acidic stones in the kidney Uric acid stones Cystine stones- Homocystinuria
M- Metabolic acidosis in blood	Increased H+ ions in blood	Acetazolamide- DOC for mountain sickness
E- Epilepsy	Suppresses the activity of neurons	Acetazolamide was earlier used for epilepsy
P- Periodic muscle paralysis	Imbalance of potassium ion in blood Occurs due to Hyperkalemia Hypokalemia	Acetazolamide is used in periodic muscle paralysis

Loop Diuretics

MOA-1

MOA-2

MOA-3

Act on the medullary portion of the thick ascending limb

Na+K2+Cl- transporter inhibitors

Inhibits water reabsorption—reduce medullary hyperosmolarity

Thick ascending limb

↓

Reabsorption of sodium

↓

Increase the osmolarity of medulla

↓

Reabsorption of water into the medulla

Increase the synthesis of prostaglandins in nephron

Prostaglandin

↓

Dilated the blood vessels in

nephrons of kidneys

↓

Increase in blood supply

↓

Increase in GFR

↓

Increased urine production

Drugs Under Loop Diuretics

Mercury Containing → MERSALYL
Phenoxy-acetic Acid → Ethacrynic acid
Sulfa Containing → Furosemide (Frusemide)

Bumetanide: Most potent

Toresamide: longest acting

Also read: Pharmacology Image Based Questions for NEET PG 2025

Adverse Effects of Loop Diuretics

Thiazides

Mechanism of action

Acts on the cortical portion of the thick ascending limb and early part of DCT
Other Name- Distal tubule
Inhibit Na+Cl- symporter

K+ Sparing Diuretics

Mechanism of Action: Inhibits the action of aldosterone at the level of the collecting duct and late part of DCT

Summary Of Diuretics

Diuretics	Blood Na+	K+	H+	Ca+	Mg+	Produce
Carbonic anhydrase inhibitors	↓	↓	↑	↓	↓	Hypokalemic metabolic acidosis
Loop diuretics	↓	↓	↓	↓	↓	Hypokalemic metabolic alkalosis
Thiazides	↓	↓	↓	↑	↓	Hypokalemic metabolic alkalosis
K+ sparing	↓	↑	↑	↑	↑	Hyperkalemic metabolic acidosis
Osmotic	↓	↓	↓	↓	↓	Hypokalemic metabolic alkalosis

Also read: Pathology Image Based Questions for NEET PG 2025

Renal Adh

Vasopressin Agonists

End with the word “PRESSIN”

	Properties	Uses
Terlipressin	V1 agonist Given by Injections only	DOC to control bleeding esophageal varices DOC for hepatorenal syndrome Also given in resistant shock
Felypressin	V1 agonist Given by Injections only	Given as add on to local anesthetic Epinephrine is also used Epinephrine > Felypressin
Desmopressin	Also called DDAVP V2 agonist Only vasopressin is given orally and nasally Longest acting drug Most potent drug- Least dose needed (not easily degraded in the body) Side effect: Dilutional hyponatremia Nausea and vomiting Seizures	Used in the treatment of Hemophilia A (Factor 8 deficiency) DOC for nocturnal enuresis (bed wetting) DOC in neurogenic diabetes insipidus

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