NEET PG Renal Pharmacology Glossary 2026: Diuretics, ACE Inhibitors, ARBs and Calcineurin Inhibitors

You're probably staring at a renal pharmacology question right now, trying to remember whether furosemide causes hypokalemia or hyperkalemia. NEET PG loves testing renal drugs — they show up in 12-15 questions every year across nephrology, medicine, and pharmacology sections. The examiners know these drug mechanisms separate serious candidates from surface-level memorizers.

This glossary covers the 4 highest-yield renal drug classes: diuretics (all 5 types), ACE inhibitors, ARBs, and calcineurin inhibitors. Each entry includes mechanism, key drugs, side effects, contraindications, and battle-tested mnemonics that actually stick under exam pressure.

Skip the textbook chapters. This is your rapid-fire reference for the renal pharmacology that matters in NEET PG 2026.

Diuretics: Complete Drug Class Breakdown

Diuretics are the workhorses of renal pharmacology. NEET PG tests their mechanisms, side effect patterns, and clinical applications relentlessly. Master these 5 categories and you've secured 6-8 questions.

Loop Diuretics (High-Ceiling Diuretics)

Key Drugs: Furosemide, Bumetanide, Torsemide, Ethacrynic acid Mechanism: Block Na-K-2Cl cotransporter (NKCC2) in thick ascending limb of loop of Henle. Prevents 25% of filtered sodium reabsorption — the most potent diuretic effect. Pharmacokinetics:

• Onset: IV (5 mins), PO (30-60 mins)

• Duration: 6-8 hours

• Protein bound (95-99%)

• Renal elimination

Clinical Uses:

• Acute pulmonary edema (first-line)

• Heart failure with fluid overload

• Nephrotic syndrome

• Acute renal failure (non-oliguric)

Side Effects (High-Yield for MCQs):

• Hypokalemia (most tested)

• Hyponatremia, hypomagnesemia

• Hyperuricemia

• Ototoxicity (especially ethacrynic acid)

• Nephrotoxicity

• Glucose intolerance

Mnemonic - Loop Side Effects: "LOOPS KILL"

• Loss of potassium (hypokalemia)

• Ototoxicity

• Oliguria (nephrotoxicity)

• PH imbalance (metabolic alkalosis)

• Sugar high (hyperglycemia)

Kidney stones (hyperuricemia)

• Infection risk

• Loss of hearing

• Loss of sodium/magnesium

When studying loop diuretics on Oncourse's adaptive flashcards, the spaced-repetition system surfaces side-effect cards right before they fade from memory — so you retain "furosemide → hypokalemia" without brute-force cramming.

Thiazide and Thiazide-Like Diuretics

Key Drugs: Hydrochlorothiazide (HCTZ), Chlorthalidone, Indapamide Mechanism: Block Na-Cl cotransporter (NCCT) in distal convoluted tubule. Prevents 10% of filtered sodium reabsorption. Pharmacokinetics:

• Onset: 2-4 hours

• Duration: 12-24 hours (chlorthalidone: 48-72 hours)

• Renal elimination

Clinical Uses:

• Hypertension (first-line)

• Heart failure (mild)

• Nephrogenic diabetes insipidus

• Hypercalciuria/kidney stones

Side Effects:

• Hypokalemia, hyponatremia

• Hypercalcemia (opposite of loops)

• Hyperuricemia

• Glucose intolerance

• Sexual dysfunction (males)

Mnemonic - Thiazide Effects: "THINK GLUCOSE UP"

• Thirty percent glucose rise

• Hypokalemia

• Impotence

• Na loss (hyponatremia)

• Kidney stones prevented (hypercalciuria ↓)

Glucose up

• Lipids up

• Uric acid up

• Calcium up

• Osteoporosis prevented

• Sexual problems

• Ears safe (no ototoxicity)

Urination decreased over time

• Potassium down

Potassium-Sparing Diuretics

#### Aldosterone Receptor Antagonists

Key Drugs: Spironolactone, Eplerenone Mechanism: Block mineralocorticoid receptors in collecting duct. Prevent aldosterone-mediated Na reabsorption and K secretion. Clinical Uses:

• Heart failure (mortality benefit with ACE-I)

• Primary hyperaldosteronism

• Ascites (cirrhosis)

• Hypertension

Side Effects:

• Hyperkalemia (dangerous with ACE-I)

• Gynecomastia (spironolactone only)

• Sexual dysfunction

#### Epithelial Sodium Channel Blockers

Key Drugs: Amiloride, Triamterene Mechanism: Directly block epithelial sodium channels (ENaC) in collecting duct. Clinical Uses:

• Lithium-induced nephrogenic DI

• Combined with thiazides

Side Effects:

• Hyperkalemia

• Metabolic acidosis

Mnemonic - K-Sparing Diuretics: "SPARE THE K"

• Spironolactone (gynecomastia)

• Potassium retention

• Amiloride (direct ENaC block)

• Receptor antagonist (spironolactone)

• Eplerenone (selective)

Triamterene

• Hyperkalemia risk

• ENaC blockade (amiloride/triamterene)

Carbonic Anhydrase Inhibitors

Key Drug: Acetazolamide Mechanism: Inhibits carbonic anhydrase in proximal tubule. Prevents Na-HCO3 reabsorption, causing bicarbonate loss. Clinical Uses:

• Glaucoma (primary indication)

• Altitude sickness

• Epilepsy (adjunct)

• Pseudotumor cerebri

Side Effects:

• Metabolic acidosis (HCO3 loss)

• Hypokalemia

• Kidney stones (calcium phosphate)

• Paresthesias

Practice carbonic anhydrase inhibitor mechanisms with targeted renal pharmacology MCQs — each question comes with detailed AI explanations that map the physiology → drug mechanism → side effect chain.

Osmotic Diuretics

Key Drug: Mannitol Mechanism: Creates osmotic gradient in tubular fluid. Prevents water reabsorption throughout nephron. Clinical Uses:

• Cerebral edema

• Acute glaucoma

• Acute renal failure (prevention)

• Drug overdose (enhance elimination)

Side Effects:

• Volume expansion (initially)

• Pulmonary edema

• Electrolyte imbalance

• Acute renal failure (paradoxically)

Contraindications:

• Anuria

• Severe heart failure

• Pulmonary edema

ACE Inhibitors: Mechanism and Clinical Pearls

Key Drugs: Captopril, Enalapril, Lisinopril, Ramipril, Perindopril Mechanism: Block angiotensin-converting enzyme (ACE). Prevents conversion of angiotensin I to angiotensin II. Also prevents bradykinin degradation.

Pharmacokinetics:

• Captopril: Short-acting (8 hours), needs TID dosing

• Enalapril: Prodrug, needs conversion to enalaprilat

• Lisinopril: Long-acting, no hepatic metabolism

Clinical Uses:

• Hypertension (first-line)

• Heart failure (mortality benefit)

• Post-MI (within 24 hours)

• Diabetic nephropathy

• Proteinuria

Side Effects (NEET PG Favorites):

• Dry cough (10-15% patients, due to bradykinin)

• Hyperkalemia

• Angioedema (rare but dangerous)

• Acute renal failure (bilateral renal artery stenosis)

• First-dose hypotension

Mnemonic - ACE Inhibitor Side Effects: "ACE COUGH"

• Angioedema

• Cough (dry, persistent)

• Elevated potassium

Creatinine rise

• Orthostatic hypotension

• Uremia (in bilateral RAS)

• GFR decrease

• Hypotension (first dose)

Contraindications:

• Bilateral renal artery stenosis

• Pregnancy (teratogenic)

• Hyperkalemia

• Angioedema history

Master ACE inhibitor mechanisms through Oncourse's pharmacology lessons, then reinforce with targeted practice questions that test real NEET PG scenarios.

Angiotensin Receptor Blockers (ARBs): The Cough-Free Alternative

Key Drugs: Losartan, Valsartan, Telmisartan, Candesartan, Olmesartan Mechanism: Block angiotensin II type 1 (AT1) receptors. Prevent angiotensin II effects without affecting bradykinin metabolism. Pharmacokinetics:

• Losartan: Active metabolite (E-3174)

• Telmisartan: Longest half-life (24 hours)

• Most are prodrugs requiring hepatic conversion

Clinical Uses:

• Hypertension (especially with ACE-I intolerance)

• Heart failure (if ACE-I not tolerated)

• Diabetic nephropathy

• Post-MI (alternative to ACE-I)

Side Effects:

• Generally better tolerated than ACE inhibitors

• No cough (doesn't affect bradykinin)

• Hyperkalemia

• Angioedema (rare)

• Hypotension

Mnemonic - ARB vs ACE: "ARBs Are Really Better"

• Angioedema (still possible but rare)

• Renal protection

• Bradykinin unaffected (no cough)

Angiotensin blocked

• RAS inhibition

• Equality in efficacy

Really

• Easy tolerance

• Alternative to ACE

• Lower cough risk

• Long-acting options

• Yields same benefits

Better

• Endured by patients

• Tolerated well

• Teratogenic (still avoid pregnancy)

• Effective in diabetics

• Renoprotective

Students who struggle with RAAS pharmacology can benefit from Oncourse's adaptive targeting — the platform tracks performance by subject tag and serves more ACE inhibitor vs ARB questions until the distinction clicks.

Calcineurin Inhibitors: Immunosuppression with Renal Impact

Key Drugs: Cyclosporine, Tacrolimus (FK506) Mechanism: Inhibit calcineurin phosphatase. Prevent T-cell activation by blocking IL-2 transcription. Also cause renal vasoconstriction. Pharmacokinetics:

• High protein binding

• Extensive hepatic metabolism (CYP3A4)

• Therapeutic drug monitoring required

• Drug interactions common

Clinical Uses:

• Organ transplantation (kidney, liver, heart)

• Severe psoriasis

• Rheumatoid arthritis

• Nephrotic syndrome (minimal change disease)

Side Effects (High-Yield for NEET PG):

• Nephrotoxicity (acute and chronic)

• Hypertension

• Neurotoxicity (tremor, seizures)

• Gum hyperplasia (cyclosporine)

• Hirsutism (cyclosporine)

• Glucose intolerance (tacrolimus > cyclosporine)

Mnemonic - Cyclosporine Side Effects: "CYCLO SPORES"

• Chronic nephrotoxicity

• Yearning for glucose (diabetes)

• Convulsions (neurotoxicity)

• Liver toxicity

• Osteoporosis

Skin changes

• Pressure up (hypertension)

• Oral problems (gum hyperplasia)

• Renal damage

• Excess hair (hirsutism)

• Susceptible to infections

Drug Interactions:

• CYP3A4 inducers (decrease levels): rifampin, phenytoin

• CYP3A4 inhibitors (increase levels): ketoconazole, erythromycin

• Nephrotoxic drugs: aminoglycosides, NSAIDs

High-Yield Drug Comparison Tables

Diuretic Mechanism Summary

ACE Inhibitors vs ARBs: Key Differences

Nephrotoxicity Risk Ranking

Clinical Scenarios: NEET PG Question Patterns

Scenario 1: Heart Failure Management

Question Pattern: "65-year-old with heart failure, already on ACE inhibitor and beta-blocker. Which diuretic provides mortality benefit?" Answer: Spironolactone (aldosterone antagonist) Key: Only K-sparing diuretic with proven mortality benefit in heart failure

Scenario 2: Hypertensive with Cough

Question Pattern: "Patient develops dry cough on enalapril. Best alternative?" Answer: ARB (losartan/valsartan) Key: ARBs dont affect bradykinin, so no cough

Scenario 3: Transplant Patient with Rising Creatinine

Question Pattern: "Kidney transplant patient on tacrolimus, creatinine rising. Most likely cause?" Answer: Calcineurin inhibitor nephrotoxicity Key: Chronic nephrotoxicity is dose-dependent and progressive

Drug Interaction Alert Box

Dangerous Combinations to Remember: 1. ACE-I + K-sparing diuretic = Hyperkalemia risk 2. Loop diuretic + Aminoglycoside = Ototoxicity ↑ 3. Cyclosporine + NSAID = Acute renal failure 4. Thiazide + Lithium = Lithium toxicity 5. ARB + ACE-I = Dual RAAS blockade (hyperkalemia, hypotension)

Check out our cardiovascular pharmacology glossary for more drug interaction patterns, and explore the complete NEET PG pharmacology series covering antimicrobials, CNS drugs, and endocrine agents.

Memory Palace Technique for Renal Drugs

Build a mental hospital ward where each room represents a drug class:

Room 1 (Emergency): Loop diuretics — patients with acute pulmonary edema, loud beeping monitors (ototoxicity), low potassium alarms Room 2 (General Ward): Thiazides — calm hypertensive patients, calcium supplements on bedside tables, glucose meters everywhere Room 3 (ICU): ACE inhibitors — heart failure patients, persistent cough sounds, "No Pregnancy" signs Room 4 (Private Room): ARBs — quiet patients (no cough), same heart benefits, premium pricing Room 5 (Transplant Unit): Calcineurin inhibitors — immunosuppressed patients, kidney function charts, blood level monitoring

Walk through this ward during exam prep, and the spatial memory will trigger drug details automatically.

Common NEET PG Mistakes to Avoid

1. Confusing thiazide calcium effects — Thiazides increase calcium (opposite of loops)
2. Missing ACE-I teratogenicity — Contraindicated in pregnancy (fetal renal dysgenesis)
3. Forgetting aldosterone antagonist mortality benefit — Spironolactone reduces death in heart failure
4. Ignoring drug monitoring — Calcineurin inhibitors need therapeutic levels
5. Mixing up osmotic diuretic indications — Mannitol for cerebral edema, not routine diuresis

Frequently Asked Questions

Which diuretic is safest in pregnancy?

Methyldopa is the first-line antihypertensive in pregnancy. Loop diuretics can be used if essential, but thiazides are avoided due to potential fetal complications. ACE inhibitors and ARBs are absolutely contraindicated.

Can ACE inhibitors and ARBs be used together?

Dual RAAS blockade is generally avoided due to increased risk of hyperkalemia, hypotension, and acute kidney injury. The combination provides no additional cardiovascular benefit over monotherapy.

What's the mechanism behind ACE inhibitor cough?

ACE normally breaks down bradykinin. When ACE is blocked, bradykinin accumulates in lung tissue, causing persistent dry cough in 10-15% of patients. ARBs dont affect bradykinin metabolism.

How do you monitor calcineurin inhibitor therapy?

Regular monitoring includes: serum creatinine, blood pressure, therapeutic drug levels (cyclosporine trough 100-200 ng/mL, tacrolimus trough 5-15 ng/mL), complete blood count, liver function tests, and glucose levels.

Which diuretic combination is most effective for resistant hypertension?

Thiazide + ACE inhibitor + calcium channel blocker is the preferred triple combination. Adding spironolactone as fourth-line agent can help resistant cases, but requires potassium monitoring.

Why do loop diuretics cause ototoxicity?

The inner ear has similar Na-K-2Cl transporters as the thick ascending limb. High-dose loop diuretics (especially ethacrynic acid) can damage these transporters, causing hearing loss or tinnitus.

Master renal pharmacology with the systematic approach this glossary provides, then reinforce your knowledge through spaced repetition on Oncourse's adaptive platform. The combination of high-yield content and intelligent practice transforms memorization into understanding.

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