I now have enough rich material from Lippincott across antiarrhythmics, antianginals, heart failure, and antihypertensives. Let me now compile comprehensive MBBS-level CVS pharmacology notes.Here are your comprehensive CVS Pharmacology notes at MBBS level, sourced from Lippincott Illustrated Reviews: Pharmacology and Katzung's Basic & Clinical Pharmacology.
CVS Pharmacology - MBBS Notes
1. ANTIARRHYTHMIC DRUGS
Background
Arrhythmias arise from:
- Abnormal automaticity - ectopic pacemaker sites fire faster than SA node
- Abnormal conduction - reentry circuits (require unidirectional block + slow conduction)
Key concept - Vaughan-Williams Classification organises drugs by their predominant action on the cardiac action potential.
Proarrhythmic risk: Many antiarrhythmics can CAUSE arrhythmias. K+ channel blockade prolongs QT interval → risk of torsades de pointes (TdP). IV magnesium sulfate is the drug of choice for TdP.
Class I - Sodium Channel Blockers
Block fast Na+ channels → slow Phase 0 depolarization
| Subclass | Mechanism | Drugs | Key Adverse Effects |
|---|
| IA | Slows Phase 0; prolongs repolarization | Quinidine, Procainamide, Disopyramide | QT prolongation, TdP, anticholinergic effects |
| IB | Shortens Phase 3 repolarization | Lidocaine, Mexiletine | CNS toxicity (tremor, seizures), confusion |
| IC | Markedly slows Phase 0; minimal effect on repolarization | Flecainide, Propafenone | Proarrhythmic - AVOID in structural heart disease |
Drug-specific notes:
- Quinidine - Cinchonism (tinnitus, blurred vision, headache, psychosis), hemolytic anemia
- Procainamide - Lupus-like syndrome, hypotension
- Disopyramide - Strong anticholinergic (urinary retention, dry mouth); AVOID in elderly
- Lidocaine - IV only; for ventricular arrhythmias (VT/VF); no effect on atrial tissue
- Mexiletine - Oral lidocaine analogue; nausea/vomiting
- Flecainide - Maintain sinus rhythm in AF/flutter (NO structural heart disease); CYP2D6 metabolised
- Propafenone - Atrial arrhythmias; weak β-blocking effect; AVOID in asthma
Class II - Beta-Blockers
Diminish Phase 4 depolarization → depress automaticity, prolong AV conduction, decrease HR and contractility
Uses: Tachyarrhythmias from sympathetic excess, atrial flutter/fibrillation, AV nodal reentrant tachycardia, post-MI ventricular arrhythmias
| Drug | Selectivity | Notes |
|---|
| Metoprolol | β1-selective | Most widely used cardiac arrhythmia agent; reduced bronchospasm risk |
| Propranolol | Non-selective | Also used in thyrotoxicosis, migraine, essential tremor |
| Esmolol | β1-selective | IV only; ultra-short acting; used in acute settings |
| Atenolol | β1-selective | Oral; renal elimination |
Adverse effects: Bradycardia, fatigue, sleep disturbance, depression, blunted hypoglycemia awareness; bronchospasm in asthmatics (non-selective agents)
Class III - Potassium Channel Blockers
Block K+ channels → prolong repolarization (Phase 3) → prolong QT interval
| Drug | Key Features |
|---|
| Amiodarone | Multiple channel blocker (I, II, III, IV activity); most effective antiarrhythmic; very long half-life (40-55 days) |
| Sotalol | Also has β-blocking activity; requires QT monitoring; can be outpatient-initiated with monitoring |
| Dofetilide | Pure K+ blocker; requires inpatient QT monitoring for initiation |
| Dronedarone | Amiodarone analogue WITHOUT iodine moiety; AVOID in severe/permanent AF with heart failure |
Amiodarone toxicity (PYTILS mnemonic):
- Pulmonary fibrosis (most serious)
- Hypothyroidism or hyperthyroidism (contains iodine)
- Liver toxicity (hepatotoxicity)
- Blue-grey skin discoloration (photosensitivity)
- Corneal microdeposits (usually asymptomatic)
- Peripheral neuropathy
- Teratogen - AVOID in pregnancy
Note: Cinchonism is NOT an amiodarone adverse effect (it belongs to quinidine).
Class IV - Non-Dihydropyridine Calcium Channel Blockers
Block L-type Ca2+ channels in SA/AV node → slow conduction, increase refractoriness
| Drug | Uses |
|---|
| Verapamil | SVT, rate control in AF; AVOID with β-blockers (additive AV block) |
| Diltiazem | SVT, AF rate control |
Contraindicated in accessory pathway tachycardias (e.g., WPW) and in combination with IV β-blockers.
Other Antiarrhythmics
| Drug | Mechanism | Use |
|---|
| Adenosine | Opens K+ channels → hyperpolarizes AV node | Drug of choice for acute SVT; very short half-life (~10 sec) |
| Digoxin | Na+/K+ ATPase inhibitor; vagotonic effect | Rate control in AF; NOT for acute use |
| Magnesium sulfate | Stabilises membranes | Drug of choice for Torsades de Pointes |
| Ranolazine | Late Na+ current inhibitor | Antiarrhythmic + antianginal; prolongs QT |
2. ANTIANGINAL DRUGS
Pathophysiology: Angina = imbalance between myocardial O2 supply and demand.
Goals of therapy: Reduce HR, preload, afterload, or increase coronary blood flow.
A. Nitrates
Mechanism: Metabolised to nitric oxide (NO) → activates guanylyl cyclase → ↑ cGMP → smooth muscle relaxation → venodilation (primarily) + arterial dilation
- Reduces preload (venodilation) and afterload at higher doses
- Net effect: reduces myocardial O2 demand
- Also dilates coronary vessels → useful in vasospastic (Prinzmetal) angina
| Drug | Route | Onset | Duration |
|---|
| Nitroglycerin (GTN) | Sublingual tablet/spray | 1-3 min | 30-60 min |
| Nitroglycerin | IV infusion | Immediate | During infusion |
| Nitroglycerin | Transdermal patch | 30-60 min | 8-12 hr (wear 12h, remove 12h) |
| Isosorbide dinitrate | Oral | 15-30 min | 4-6 hr |
| Isosorbide mononitrate | Oral | ~30 min | 6-8 hr |
Adverse effects:
- Headache (most common)
- Postural hypotension, facial flushing, reflex tachycardia
- Tolerance develops rapidly → provide nitrate-free interval of 10-12 hours (usually overnight; remove patch at night)
- CONTRAINDICATED with PDE5 inhibitors (sildenafil, tadalafil) - dangerous hypotension
- Exception: In variant angina, nitrate-free interval should be in the afternoon (not overnight), as attacks cluster in early morning
B. Beta-Blockers (for Angina)
Mechanism: ↓ HR, ↓ contractility → reduce myocardial O2 demand
- Preferred in stable angina, post-MI
- β1-selective agents preferred: atenolol, metoprolol
- AVOID agents with ISA (e.g., pindolol) in angina
- AVOID in vasospastic (Prinzmetal) angina - can worsen coronary spasm
C. Calcium Channel Blockers (for Angina)
Dihydropyridines (amlodipine, nifedipine, felodipine):
- Primarily vasodilate peripheral arteries → reduce afterload
- Reflex tachycardia with short-acting agents (especially nifedipine)
- Adverse: peripheral oedema, flushing, headache
- Drug of choice for Prinzmetal/vasospastic angina
Non-dihydropyridines (verapamil, diltiazem):
- Reduce HR and contractility + vasodilate
- AVOID combining with β-blockers (additive bradycardia/heart block)
D. Ranolazine
Mechanism: Inhibits late Na+ current (late INa) → reduces intracellular Na+ and Ca2+ overload → improves diastolic function and O2 supply-demand balance
- Used when other antianginals have failed
- Prolongs QT interval - avoid with other QT-prolonging drugs
- Metabolised by CYP3A + CYP2D6; substrate of P-glycoprotein
- Notable: antianginal effect less pronounced in women
3. DRUGS FOR HEART FAILURE
Key Drugs:
| Drug Class | Examples | Mechanism | Role in HF |
|---|
| ACE Inhibitors | Enalapril, Lisinopril, Ramipril | Block ACE → ↓ Angiotensin II → ↓ vasoconstriction, ↓ aldosterone | First-line; reduce mortality; reduce preload + afterload |
| ARBs | Losartan, Valsartan, Candesartan | Block AT1 receptor | Use if ACE-I not tolerated (e.g., cough) |
| Beta-Blockers | Carvedilol, Metoprolol succinate, Bisoprolol | ↓ sympathetic activation | Reduce mortality in HFrEF; START low, go slow |
| Mineralocorticoid Antagonists | Spironolactone, Eplerenone | Block aldosterone receptor → ↓ Na/H2O retention | Reduce mortality; risk of hyperkalemia |
| SGLT2 Inhibitors | Empagliflozin, Dapagliflozin | Glucose/sodium excretion; reduce preload | Reduce HF hospitalisation and mortality |
| ARNI | Sacubitril/Valsartan (Entresto) | Neprilysin inhibitor + ARB → ↑ natriuretic peptides | Superior to ACE-I in HFrEF |
| Diuretics | Furosemide (loop), Thiazides | Reduce fluid overload | Symptom relief (NOT mortality benefit) |
| Digoxin | Digoxin | Na+/K+ ATPase inhibition → ↑ intracellular Ca2+ → positive inotropy + vagotonic → slows AV conduction | Symptomatic benefit in AF + HF; narrow therapeutic index |
| Ivabradine | Ivabradine | If channel blocker → ↓ HR | HFrEF with HR >70 on max beta-blocker |
| Nitrates + Hydralazine | | Vasodilation | For patients intolerant of ACE-I/ARB (especially African-American patients) |
Digoxin toxicity signs:
- Nausea, vomiting, anorexia
- Visual disturbances (yellow-green halos)
- Arrhythmias (bradycardia, heart block, VT)
- Precipitated by: hypokalemia, hypomagnesemia, hypercalcemia, renal impairment, hypothyroidism
- Treatment: Digoxin-specific antibody fragments (Fab); correct electrolytes
4. ANTIHYPERTENSIVE DRUGS
Classification by Mechanism
| Class | Drugs | Key Notes |
|---|
| Thiazide diuretics | Hydrochlorothiazide, Chlorthalidone | First-line in most guidelines; cause hypokalemia, hyperglycemia, hyperuricemia |
| ACE Inhibitors | Lisinopril, Enalapril, Ramipril | First-line; contraindicated in pregnancy; cause dry cough (bradykinin accumulation) |
| ARBs | Losartan, Valsartan, Irbesartan | Better tolerated than ACE-I (no cough); contraindicated in pregnancy |
| Dihydropyridine CCBs | Amlodipine, Nifedipine | Effective + safe in elderly; useful if atherosclerotic angina coexists |
| Non-DHP CCBs | Verapamil, Diltiazem | Also rate-control in AF |
| Beta-Blockers | Metoprolol, Atenolol, Bisoprolol | Less preferred as monotherapy unless heart failure or post-MI |
| Alpha1-blockers | Prazosin, Doxazosin | Used in BPH + hypertension; risk of first-dose hypotension |
| Central alpha2 agonists | Methyldopa, Clonidine | Methyldopa: drug of choice in pregnancy |
| Direct vasodilators | Hydralazine, Minoxidil | Reserved for refractory cases; cause reflex tachycardia |
Special situations:
- Pregnancy: Methyldopa (safest), labetalol, nifedipine; AVOID ACE-I/ARBs (teratogenic)
- Diabetes + HT: ACE-I or ARB (renoprotective)
- HT + HF: ACE-I/ARB + beta-blocker + spironolactone
- HT + asthma: AVOID beta-blockers; prefer CCBs
- Isolated systolic HT in elderly: Thiazides or CCBs; beware of orthostatic hypotension
- HT emergency: IV labetalol, IV nitroprusside, IV hydralazine (in pregnancy)
5. LIPID-LOWERING DRUGS
| Class | Drugs | Mechanism | Primary Effect | Key ADRs |
|---|
| Statins (HMG-CoA reductase inhibitors) | Atorvastatin, Rosuvastatin, Simvastatin | Inhibit rate-limiting step of cholesterol synthesis → ↑ LDL receptors | ↓↓ LDL (primary) | Myopathy/rhabdomyolysis, hepatotoxicity; AVOID in pregnancy |
| Fibrates | Fenofibrate, Gemfibrozil | Activate PPAR-α → ↑ LPL → ↑ TG clearance | ↓↓ TG, ↑ HDL | Myopathy (especially with statins), gallstones |
| Niacin (Nicotinic acid) | Niacin | Inhibits VLDL synthesis in liver; inhibits lipolysis in adipose | ↓ TG, ↓ LDL, ↑↑ HDL | Flushing (↓ with aspirin pretreatment), hyperglycemia, hyperuricemia, hepatotoxicity |
| Bile acid sequestrants | Cholestyramine, Colesevelam | Bind bile acids in gut → ↑ conversion of cholesterol to bile acids | ↓ LDL | Constipation, bloating; impair absorption of fat-soluble vitamins and many drugs |
| Ezetimibe | Ezetimibe | Blocks NPC1L1 transporter → ↓ cholesterol absorption in intestine | ↓ LDL | Generally well tolerated; modest effect alone |
| PCSK9 inhibitors | Alirocumab, Evolocumab | Monoclonal Ab → inhibit PCSK9 → prevent LDL receptor degradation → ↑ LDL uptake | ↓↓↓ LDL | Injection site reactions; expensive |
| Omega-3 fatty acids | Icosapentaenoic acid (EPA) | Reduce hepatic VLDL production | ↓ TG | Fish odour, GI upset |
Statin important notes:
- Most important drug class for cardiovascular risk reduction
- Risk of myopathy increases with: high doses, renal failure, hypothyroidism, CYP3A4 inhibitors (e.g., azole antifungals, macrolides, grapefruit juice)
- Simvastatin + gemfibrozil = high myopathy risk combination
- Monitor: CK (if symptomatic), LFTs (baseline)
6. ANTICOAGULANTS & ANTIPLATELET DRUGS
Antiplatelet Drugs
| Drug | Mechanism | Uses |
|---|
| Aspirin | Irreversibly inhibits COX-1 → ↓ TXA2 → ↓ platelet aggregation | ACS, secondary prevention of MI/stroke |
| Clopidogrel | ADP receptor (P2Y12) blocker (irreversible); prodrug requiring CYP2C19 activation | ACS, post-PCI (with aspirin = DAPT); less effective in poor CYP2C19 metabolisers |
| Ticagrelor | P2Y12 blocker (reversible); NOT a prodrug | ACS; dyspnoea as adverse effect |
| Prasugrel | P2Y12 blocker (irreversible prodrug); more potent than clopidogrel | ACS with PCI; AVOID in history of stroke/TIA or age >75 |
| Abciximab, Tirofiban, Eptifibatide | GP IIb/IIIa receptor antagonists | IV; high-risk PCI |
| Dipyridamole | ↑ cAMP in platelets (PDE inhibitor + adenosine uptake inhibitor) | Secondary stroke prevention (with aspirin) |
Anticoagulants
| Drug | Mechanism | Key Points |
|---|
| Heparin (UFH) | Activates antithrombin III → inactivates thrombin (IIa) + Xa | IV/SC; monitored by aPTT; antidote = protamine sulfate; HIT is a complication |
| LMWH (Enoxaparin, Dalteparin) | Preferentially inhibits Xa | SC; no routine monitoring; safer in pregnancy; antidote = protamine (partial) |
| Fondaparinux | Selective anti-Xa | SC; no HIT risk; antidote = none |
| Warfarin | Inhibits Vitamin K epoxide reductase → ↓ factors II, VII, IX, X (+ protein C, S) | Oral; monitored by INR; antidote = Vitamin K (slow) or FFP (fast); many drug/food interactions |
| Dabigatran | Direct thrombin (IIa) inhibitor | Oral DOAC; antidote = idarucizumab |
| Rivaroxaban, Apixaban, Edoxaban | Direct Factor Xa inhibitors | Oral DOACs; antidote = andexanet alfa |
Heparin-induced thrombocytopenia (HIT):
- Paradoxically causes THROMBOSIS (not just low platelets)
- Stop all heparin immediately → switch to direct thrombin inhibitor (argatroban, bivalirudin)
- Do NOT give warfarin or platelet transfusions initially
Quick Reference - Key Drug Interactions
| Combination | Consequence |
|---|
| Nitrates + PDE5 inhibitors (sildenafil) | Severe hypotension - CONTRAINDICATED |
| Non-DHP CCB + Beta-blocker (IV) | Complete heart block |
| Statin + CYP3A4 inhibitors (azoles, macrolides) | ↑ Myopathy risk |
| Statin + Gemfibrozil | High myopathy/rhabdomyolysis risk |
| ACE-I + ARB + spironolactone (triple) | Severe hyperkalemia |
| Warfarin + NSAIDs | ↑ Bleeding risk |
| Amiodarone + warfarin | ↑ INR; warfarin dose must be reduced |
| Digoxin + hypokalemia | ↑ Digoxin toxicity |
Memory Aids
- Vaughan-Williams Classes: I=Na blocker, II=Beta-blocker, III=K blocker, IV=Ca blocker
- Amiodarone toxicity: Think "THYROID, LIVER, LUNGS, SKIN, EYES, NERVES"
- Nitrate tolerance: "Wear 12, bare 12"
- TdP treatment: "Magnesium is the drug of choice"
- HIT management: "Stop heparin, don't transfuse platelets, start direct thrombin inhibitor"
- Pregnancy hypertension: "Methyl-dopa is safe for MOMS"
- Heart failure quadruple therapy (HFrEF): ACE-I/ARB/ARNI + Beta-blocker + MRA + SGLT2i
Sources: Lippincott Illustrated Reviews: Pharmacology, 7th Ed.; Katzung's Basic and Clinical Pharmacology, 16th Ed.
