Pharmacology
MBBS Pharmacology — high-yield long questions and short notes from K.D. Tripathi, covering general pharmacology, autonomic and cardiovascular drugs, CNS, autacoids, chemotherapy, endocrine and more, written to the marks with mechanisms, classification, clinical uses, adverse effects and pearls.
12chapters144questions99High-Yield
Definition
Antihypertensive drugs lower blood pressure by reducing cardiac output, peripheral resistance or blood volume.
Classification
- Diuretics — thiazides (hydrochlorothiazide)
- ACE inhibitors — enalapril; ARBs — losartan
- Calcium-channel blockers — amlodipine
- Beta blockers — atenolol, metoprolol
- α blockers, central agents (methyldopa), vasodilators
Choice of Drug
- Young — ACE inhibitors / β blockers
- Elderly — calcium blockers / diuretics
- Diabetes with proteinuria — ACE inhibitors
- Pregnancy — methyldopa, labetalol, nifedipine
Each drug class lowers BP by targeting output, resistance or volume. Class Example Note ACE inhibitor Enalapril Dry cough CCB Amlodipine Pedal oedema Thiazide HCTZ Hypokalaemia Applied
- ACE inhibitors contraindicated in pregnancy
- Combination therapy for better control
🔑KEY POINTS TO REMEMBER- Classes: diuretics, ACE inhibitors/ARBs, CCBs, β blockers.
- Choice depends on age, diabetes, pregnancy.
- ACE inhibitors contraindicated in pregnancy.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Antianginal drugs relieve angina by improving myocardial oxygen supply or reducing oxygen demand.
Classes
- Nitrates — GTN, isosorbide (venodilation, ↓ preload)
- Beta blockers — ↓ heart rate, ↓ demand
- Calcium-channel blockers — coronary dilation
- Others — ivabradine, trimetazidine, ranolazine
Principle
- ↓ Oxygen demand (↓ HR, ↓ preload, ↓ afterload)
- ↑ Oxygen supply (coronary dilation)
Balance is restored by cutting demand and improving coronary supply. Drug Main action Nitrates ↓ Preload β blockers ↓ HR, demand CCBs Coronary dilation Applied
- Sublingual GTN for acute attack
- β blockers for prophylaxis
🔑KEY POINTS TO REMEMBER- Antianginals ↓ demand or ↑ supply.
- Nitrates (preload), β blockers (HR), CCBs (coronary dilation).
- Sublingual GTN aborts an acute attack.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Drugs for heart failure improve symptoms and survival by reducing preload, afterload and neurohormonal activation.
Drugs Improving Survival
- ACE inhibitors / ARBs
- Beta blockers (carvedilol, metoprolol — start low)
- Aldosterone antagonists (spironolactone)
- SGLT2 inhibitors
Symptomatic Relief
- Diuretics — relieve congestion
- Digoxin — ↑ contractility (positive inotrope)
- Vasodilators
Survival drugs form the base; diuretics and digoxin ease symptoms. Drug Benefit ACE inhibitor Survival β blocker Survival Diuretic Symptoms Applied
- Start β blockers at low dose
- Monitor potassium with spironolactone
🔑KEY POINTS TO REMEMBER- Survival: ACE inhibitors, β blockers, spironolactone.
- Symptoms: diuretics, digoxin.
- β blockers started low and titrated up.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Antiarrhythmic drugs correct abnormal cardiac rhythm by acting on ion channels or receptors, classified by the Vaughan Williams system.
Vaughan Williams Classification
- Class I — sodium-channel blockers (quinidine, lignocaine, flecainide)
- Class II — beta blockers (propranolol)
- Class III — potassium-channel blockers (amiodarone)
- Class IV — calcium-channel blockers (verapamil)
- Others — digoxin, adenosine
Uses
- Atrial fibrillation — β blockers, digoxin, amiodarone
- Ventricular tachycardia — lignocaine, amiodarone
- Supraventricular tachycardia — adenosine, verapamil
Each class targets a different ion channel or receptor to restore rhythm. Class Target Example I Sodium Lignocaine II β receptor Propranolol III Potassium Amiodarone IV Calcium Verapamil Applied
- Amiodarone — thyroid, lung, corneal toxicity
- All antiarrhythmics can be proarrhythmic
🔑KEY POINTS TO REMEMBER- Vaughan Williams: I sodium, II β blocker, III potassium, IV calcium.
- Amiodarone (class III) is broad-spectrum but toxic.
- Adenosine for supraventricular tachycardia.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Diuretics increase urine output by reducing sodium and water reabsorption in the renal tubules.
Classification (by site)
- Loop — furosemide (ascending limb; most powerful)
- Thiazide — hydrochlorothiazide (distal tubule)
- Potassium-sparing — spironolactone, amiloride (collecting duct)
- Carbonic anhydrase inhibitor — acetazolamide
- Osmotic — mannitol
Uses
- Oedema (cardiac, renal, hepatic)
- Hypertension (thiazides)
- Acute pulmonary oedema (furosemide)
- Cerebral oedema, glaucoma (mannitol, acetazolamide)
Blocking sodium reabsorption drags water out, relieving oedema. Diuretic Site Key effect Furosemide Loop Hypokalaemia Thiazide Distal tubule Hypokalaemia Spironolactone Collecting duct Hyperkalaemia Applied
- Monitor electrolytes (potassium)
- Furosemide — ototoxicity in high dose
🔑KEY POINTS TO REMEMBER- Loop (furosemide) most powerful; thiazides for hypertension.
- Potassium-sparing: spironolactone, amiloride.
- Watch potassium: loop/thiazide ↓, spironolactone ↑.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
ACE inhibitors block angiotensin-converting enzyme, reducing angiotensin II formation and thus lowering blood pressure.
Mechanism
- ↓ Angiotensin II → vasodilation
- ↓ Aldosterone → ↓ sodium/water retention
- ↑ Bradykinin (causes cough)
Uses
- Hypertension
- Heart failure (improves survival)
- Diabetic nephropathy (renoprotective)
- Post-myocardial infarction
Blocking angiotensin II production dilates vessels and reduces retention. Feature Detail Example Enalapril, ramipril Adverse Dry cough, hyperkalaemia Contraindicated Pregnancy Applied
- Dry cough → switch to an ARB (losartan)
- Avoid in bilateral renal artery stenosis
🔑KEY POINTS TO REMEMBER- ACE inhibitors ↓ angiotensin II → vasodilation, ↓ aldosterone.
- Uses: hypertension, heart failure, diabetic nephropathy.
- Adverse: dry cough, hyperkalaemia; contraindicated in pregnancy.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Digoxin is a cardiac glycoside that increases myocardial contractility and slows atrioventricular conduction.
Mechanism
- Inhibits Na⁺/K⁺ ATPase pump
- ↑ Intracellular calcium → positive inotropy
- ↑ Vagal tone → negative chronotropy
Uses & Toxicity
- Atrial fibrillation (rate control), heart failure
- Narrow therapeutic index
- Toxicity: nausea, yellow vision, arrhythmias
- Hypokalaemia predisposes to toxicity
Pump inhibition raises calcium, strengthening contraction while slowing rate. Effect Result Inotropy Positive (↑ force) Chronotropy Negative (↓ rate) Applied
- Monitor levels and potassium
- Treat toxicity: stop drug, correct K⁺, digoxin antibody
🔑KEY POINTS TO REMEMBER- Digoxin inhibits Na⁺/K⁺ ATPase → ↑ Ca²⁺ → ↑ contractility.
- ↓ Heart rate (vagal); used in AF and heart failure.
- Narrow TI; hypokalaemia → toxicity (yellow vision, arrhythmia).
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Nitrates such as glyceryl trinitrate (GTN) are vasodilators that relieve angina by releasing nitric oxide.
Mechanism
- Release nitric oxide → ↑ cGMP
- Smooth muscle relaxation
- Mainly venodilation → ↓ preload → ↓ oxygen demand
- Also dilates coronary arteries
Uses & Adverse Effects
- Acute angina (sublingual GTN)
- Prophylaxis (isosorbide mononitrate)
- Acute heart failure / pulmonary oedema
- Adverse: headache, flushing, postural hypotension, tolerance
Nitric oxide relaxes veins, lowering preload and cardiac oxygen demand. Preparation Use Sublingual GTN Acute attack Isosorbide mononitrate Prophylaxis Applied
- Nitrate-free interval prevents tolerance
- Contraindicated with sildenafil (severe hypotension)
🔑KEY POINTS TO REMEMBER- Nitrates release NO → ↑ cGMP → venodilation, ↓ preload.
- Sublingual GTN for acute angina.
- Tolerance prevented by a nitrate-free interval; avoid with sildenafil.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Calcium-channel blockers (CCBs) block L-type calcium channels, causing vasodilation and reduced cardiac work.
Classes
- Dihydropyridines — amlodipine, nifedipine (mainly vascular)
- Non-dihydropyridines — verapamil, diltiazem (cardiac too)
Uses
- Hypertension (amlodipine)
- Angina
- Supraventricular arrhythmias (verapamil, diltiazem)
Less calcium entry means relaxed vessels and a less demanding heart. Class Main site Example Dihydropyridine Vessels Amlodipine Non-dihydropyridine Heart Verapamil Applied
- Adverse: pedal oedema, flushing, constipation (verapamil)
- Avoid verapamil with β blockers (heart block)
🔑KEY POINTS TO REMEMBER- CCBs block L-type calcium channels → vasodilation.
- Dihydropyridines (amlodipine) vascular; verapamil/diltiazem cardiac.
- Adverse: pedal oedema; avoid verapamil + β blocker.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Statins are lipid-lowering drugs that inhibit HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis.
Mechanism
- Inhibit HMG-CoA reductase → ↓ hepatic cholesterol
- ↑ LDL receptors → ↓ plasma LDL
- Modest ↓ triglycerides, ↑ HDL
- Pleiotropic: plaque stabilisation, anti-inflammatory
Uses & Adverse Effects
- Hyperlipidaemia, coronary artery disease
- Primary and secondary prevention
- Adverse: myopathy, rhabdomyolysis, ↑ liver enzymes
Blocking cholesterol synthesis makes the liver pull LDL from the blood. Feature Detail Target HMG-CoA reductase Main effect ↓ LDL Adverse Myopathy Applied
- Given at night (peak synthesis)
- Monitor CPK if muscle pain
🔑KEY POINTS TO REMEMBER- Statins inhibit HMG-CoA reductase → ↓ LDL.
- Used for hyperlipidaemia and cardiovascular prevention.
- Adverse: myopathy, rhabdomyolysis, ↑ liver enzymes.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Loop diuretics such as furosemide are the most powerful diuretics, acting on the thick ascending limb of the loop of Henle.
Mechanism
- Inhibit the Na⁺-K⁺-2Cl⁻ cotransporter
- ↓ Sodium reabsorption → marked diuresis
- Also ↑ calcium and magnesium excretion
Uses & Adverse Effects
- Acute pulmonary oedema (IV, rapid)
- Oedema of cardiac, renal, hepatic origin
- Hypercalcaemia
- Adverse: hypokalaemia, hyponatraemia, ototoxicity, gout
Blocking the loop transporter produces rapid, powerful diuresis. Feature Detail Site Ascending limb Potency Most powerful Adverse Hypokalaemia, ototoxicity Applied
- IV furosemide in acute pulmonary oedema
- Effective even in renal impairment
🔑KEY POINTS TO REMEMBER- Furosemide blocks Na⁺-K⁺-2Cl⁻ in the ascending limb.
- Most powerful diuretic; drug of choice in acute pulmonary oedema.
- Adverse: hypokalaemia, ototoxicity.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.Definition
Spironolactone is a potassium-sparing diuretic that acts as an aldosterone antagonist in the collecting duct.
Mechanism
- Competitively blocks aldosterone receptors
- ↓ Sodium reabsorption, ↓ potassium excretion
- Weak diuretic (potassium-sparing)
Uses & Adverse Effects
- Heart failure (improves survival)
- Hepatic ascites (with cirrhosis)
- Primary hyperaldosteronism (Conn syndrome)
- Adverse: hyperkalaemia, gynaecomastia
Blocking aldosterone loses sodium while sparing potassium. Feature Detail Type Potassium-sparing Adverse Hyperkalaemia, gynaecomastia Applied
- Combined with loop diuretics (offsets potassium loss)
- Monitor potassium, avoid with ACE inhibitors in renal failure
🔑KEY POINTS TO REMEMBER- Spironolactone = aldosterone antagonist (potassium-sparing).
- Used in heart failure, ascites, Conn syndrome.
- Adverse: hyperkalaemia, gynaecomastia.
📚SOURCES: Essentials of Medical Pharmacology (K.D. Tripathi); Goodman & Gilman’s The Pharmacological Basis of Therapeutics; Katzung’s Basic & Clinical Pharmacology.