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RGUHS MBBS Phase 3 Part 1

Community Medicine - Principles of Epidemiology

Most Repeated Q&A (Based on Park's Textbook & RGUHS Past Papers)

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LONG ESSAY QUESTIONS (10 Marks)

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Q1. Define Epidemiology. Classify epidemiological studies. Explain the merits and demerits of Case Control and Cohort studies. (2+4+6) (Repeated: 2005, 2007, 2009, 2010, 2016, 2017)

Epidemiological Studies
│
├── 1. Observational Studies
│   ├── A. Descriptive Studies
│   │   ├── Case reports / Case series
│   │   ├── Cross-sectional (prevalence) studies
│   │   └── Ecological (correlational) studies
│   └── B. Analytical Studies
│       ├── Case Control Study (Retrospective)
│       └── Cohort Study (Prospective)
│
└── 2. Experimental (Intervention) Studies
    ├── Randomized Controlled Trials (RCTs)
    ├── Field trials
    └── Community trials

1. Relatively quick and inexpensive
2. Suitable for rare diseases and diseases with long latency periods
3. Requires relatively few subjects
4. No risk to subjects; no ethical problems
5. Can study multiple risk factors simultaneously
6. No attrition problem (does not follow up subjects)
7. Useful for generating hypotheses

1. Relies on recall of past exposure - prone to recall bias
2. Validation of information difficult
3. Cannot calculate incidence rates or absolute risk - only Odds Ratio
4. Selection of appropriate control group is difficult
5. Does not allow study of more than one disease at a time
6. Chronological sequence of cause and effect may be uncertain
7. Prone to selection bias and confounding

1. Provides direct incidence rates and Relative Risk (RR)
2. Temporal sequence (cause before effect) is clearly established
3. Can study multiple effects of a single exposure
4. Reduces recall bias (exposure recorded before outcome)
5. Selection bias is minimal
6. Allows study of rare exposures
7. Can examine the natural history of disease

1. Very expensive and time-consuming
2. Large sample size required
3. Attrition (loss to follow-up) is a major problem
4. Not suitable for rare diseases
5. Changes in diagnostic criteria over time may affect results
6. Ethical issues if the exposure is harmful

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Q2. How does Epidemiology differ from Clinical Medicine? Discuss different types of epidemics with examples. (Repeated: 2007, 2012, 2016)

• Exposure is brief and simultaneous
• All cases develop within ONE incubation period
• Epidemic curve: rises and falls rapidly, explosive single peak, no secondary waves
• Example: Food poisoning at a marriage feast (Staphylococcal), Cholera from a contaminated well

• Exposure continues over a prolonged period
• Epidemic curve: sustained plateau, lasts longer
• Example: Typhoid from a continuously contaminated water supply

• Spread from person to person, vector to person, or animal to person
• Epidemic curve: series of progressively increasing peaks, each separated by one incubation period
• Sub-types: (i) Person-to-person: measles, chickenpox (ii) Arthropod vector: malaria, dengue (iii) Animal reservoir: rabies, plague
• Key feature: each case acts as a new source of infection

• Disease increases slowly over decades
• Example: Cancer, cardiovascular disease, obesity epidemic, diabetes
• No classic sharp epidemic curve

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Q3. Define Epidemiology. Enlist types of epidemiological studies. Explain steps of procedure in a descriptive epidemiological study. (2+4+6) (Repeated: 2007)

• When is disease occurring? - Time distribution
• Where is it occurring? - Place distribution
• Who is getting it? - Person distribution

1. Defining the population to be studied
   • Total number, age, sex, occupation, cultural characters
   • Can be whole population or representative sample
2. Defining the disease under study
   • Clear case definition is essential
   • Without clear definitions, interpretation is impossible
3. Describing the disease by Time, Place, Person
   • Time: Secular (long-term) trends, cyclic/periodic trends, seasonal trends, epidemic occurrence
   • Place: International, national, regional, rural-urban differences; spot maps
   • Person: Age, sex, race, occupation, marital status, socioeconomic status, lifestyle
4. Measurement of disease
   • Incidence rate, prevalence rate, mortality rate, morbidity rates
5. Comparing with known indices
   • Compare with baseline or standard population data
6. Formulation of an aetiological hypothesis
   • Based on patterns observed by time, place, person
   • This hypothesis is then tested in analytical studies

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Q4. How will you investigate an epidemic of fever in a block? (Repeated: 2005, 2008, 2010, 2012, S-2014)

• Clinical examination of a sample of cases
• Laboratory investigations (blood culture, serology) to confirm diagnosis
• Do not delay investigation for lab results

• Compare current disease frequency with same period in previous years
• Epidemic = observed frequency exceeds expected frequency
• Threshold: 2 standard errors above endemic level

• Active case finding (house-to-house survey)
• Define cases using a standard case definition
• Collect data on: name, age, sex, address, date of onset, symptoms, possible source

• Time: Draw epidemic curve to determine type (point source vs propagated)
• Place: Spot map to find clustering, identify common source
• Person: Attack rates by age, sex, occupation to identify at-risk groups

• Based on descriptive data, hypothesize: probable source, mode of transmission, causative agent

• Collect specimens (stool, blood, water, food) for laboratory testing
• Conduct case-control study if needed

• Treatment of cases
• Isolation of cases (if indicated)
• Source control: boiling water, closing contaminated food source
• Immunization of contacts
• Vector control if applicable
• Health education

• Document findings, measures taken, recommendations for prevention of recurrence
• Submit to health authorities

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SHORT ESSAY QUESTIONS (5-7 Marks)

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Q5. Describe types of time trends in disease occurrence. (S-2011, 2014, 2017)

• Changes in disease frequency over many years or decades
• Example: Declining TB mortality with BCG vaccination; rising cancer incidence
• Important for evaluating effectiveness of long-term health programs

• Regular recurrence at intervals of several years
• Due to buildup of susceptible population and depletion of immune individuals
• Example: Measles epidemics every 2-3 years; influenza pandemics

• Regular increase in disease at certain times of year
• Due to changes in: agent (survival), host (behaviour), environment (temperature, humidity)
• Example: Malaria peaks in post-monsoon; cholera peaks in summer; respiratory infections in winter

• Sudden increase above the expected (endemic) level
• Usually indicates exposure to a common source or new infectious agent
• Example: A food poisoning outbreak, a measles epidemic

• Changes in diagnostic criteria over time
• Changes in notification/reporting
• Changes in population structure (more elderly = more chronic disease)
• Changes in treatment (affecting survival/case fatality)
• Changes in risk factor prevalence

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Q6. Write a note on Case Control Study - design, uses, and Odds Ratio. (2009, 2010, 2016)

• OR = (a × d) / (b × c)
• OR >1: positive association (exposure increases risk)
• OR = 1: no association
• OR <1: negative association (exposure protective)
• In rare diseases, OR approximates Relative Risk

• Study of rare diseases (cancer, aplastic anaemia)
• Diseases with long latency periods
• Generating and testing hypotheses
• Quick, inexpensive preliminary evidence

1. Recall bias - cases remember exposure better than controls
2. Selection bias - inappropriate selection of controls
3. Confounding - third variable affecting both exposure and disease

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Q7. Write a note on Cohort Study. (2009, 2010, 2016, 2017)

• Good prior evidence of association (from descriptive/case control studies)
• Exposure is rare but disease incidence is high among exposed
• Follow-up is feasible
• Adequate funds available

• RR = Incidence in exposed / Incidence in unexposed
• RR >1: exposure increases risk; RR <1: exposure protective
• Direct calculation of incidence rates possible (unlike case control)

• Establishes temporal sequence (cause before effect)
• Directly measures incidence and RR
• Less prone to recall bias
• Can study multiple effects of one exposure

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Q8. Write a note on Experimental Epidemiology / Randomized Controlled Trials (RCT). (2014, 2016)

1. Animal studies - test vaccines/drugs before human use; have limitations (not all conclusions applicable to humans)
2. Clinical trials (RCTs) - test therapeutic or preventive measures in humans
3. Field trials - conducted in healthy people in the community
4. Community trials - the community is the unit of study

• Phase I: Safety (small group, healthy volunteers)
• Phase II: Efficacy and dosing (small patient group)
• Phase III: Large-scale efficacy and safety (RCT)
• Phase IV: Post-marketing surveillance

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Q9. Write a note on Uses of Epidemiology. (Morris's 7 Uses)

1. Study of historical rise and fall of disease - identify trends, emerging problems, evaluate programs (e.g., smallpox eradication)
2. Community diagnosis - identify and quantify health problems in terms of mortality and morbidity; identify groups at risk; "Epidemiology is the diagnostic tool of community medicine"
3. Planning and evaluation of health services - provides basis for rational allocation of resources; evaluate impact of interventions (e.g., hepatitis vaccine effectiveness)
4. Individual risks and chances - quantify an individual's risk of disease based on their characteristics (e.g., actuary tables, risk factor assessment for CVD)
5. Completing the clinical picture - full spectrum of disease is visible in the community, not just the severe cases seen in hospitals (clinical iceberg)
6. Identification of syndromes - clustering of signs and symptoms in a population helps define new syndromes (e.g., metabolic syndrome, AIDS)
7. Search for causes - identifying risk factors for disease through analytical studies; ultimate and most important use

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SHORT NOTES (3-4 Marks)

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Q10. Epidemic curve - definition and uses

1. Suggests a time relationship with exposure to suspected source
2. Indicates whether epidemic is point source (rapid rise and fall, single peak within one incubation period) or propagated (series of peaks at intervals of one incubation period)
3. Identifies the most likely time of exposure (subtract median incubation period from peak)
4. Predicts end of epidemic

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Q11. Attack Rate

• Expressed as a percentage
• Used during epidemic situations (not long-term)
• Food-specific attack rate: helps identify the vehicle food in food poisoning outbreaks
• Secondary attack rate: measures spread from primary case to contacts; indicates infectivity

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Q12. Relative Risk (RR) vs Odds Ratio (OR)

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Q13. Bias in epidemiological studies

1. Selection bias - error in identifying cases/controls (e.g., Berkson's bias in hospital-based studies)
2. Information/Observation bias - error in collecting data
   • Recall bias: cases recall exposure better than controls
   • Observer bias: interviewer treats cases and controls differently
3. Confounding - a third variable associated with both exposure and outcome distorts the true relationship

• Proper randomization
• Blinding
• Matching cases and controls
• Multivariate analysis

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Q14. Incubation period - epidemiological importance (S-2014)

1. Helps identify the time and source of exposure (subtract IP from onset date)
2. Determines the period of surveillance for contacts
3. Determines the duration of quarantine
4. Identifies the causative agent (each disease has characteristic IP)
5. Helps distinguish type of epidemic (all cases within one IP = point source)
6. Median IP: time for 50% of cases to occur following exposure; used in epidemic curves

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Q15. Quarantine vs Isolation (S-2017)

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REPEATED ONE-LINERS / "JUSTIFY" TYPE (Short Notes, 3 Marks)

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• Screening test: Applied to apparently healthy population to detect pre-symptomatic disease. Requires high sensitivity (detect maximum true cases). Cheap, quick, simple.
• Diagnostic test: Applied to symptomatic patients to confirm disease. Requires high specificity (rule out non-cases). More detailed, may be invasive.
• False positives in screening are followed up by diagnostic tests; false negatives are the main danger.

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• Randomization ensures that each subject has an equal chance of being assigned to experimental or control group
• Eliminates selection bias and confounding
• Ensures comparability of groups for both known and unknown variables
• Allows valid statistical inference; P values and confidence intervals are valid only if randomization is done
• Without randomization, differences in outcome may be due to baseline differences, not the intervention

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• Definition: Study of distribution and determinants of health-related states in specified populations and application to prevention/control (Last)
• Uses: Community diagnosis, planning and evaluation, understanding natural history, identifying risk factors, completing clinical picture, historical study of disease trends

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EXAM STRATEGY TIPS FOR RGUHS

1. Definition and classification of epidemiological studies
2. Case control vs Cohort study (merits/demerits) - appears almost every year
3. Investigation of an epidemic - asked in multiple forms (fever/jaundice/measles/typhoid in hostel/block)
4. Types of epidemics + epidemic curve
5. Descriptive epidemiology - time, place, person
6. Uses of epidemiology (Morris's 7 uses)
7. Experimental epidemiology / RCT
8. Bias, Odds Ratio, Relative Risk

• Long essay (10 marks): Usually one from "define epidemiology + classify + discuss study type" pattern
• Short essay (5-7 marks): Epidemic investigation, types of epidemics, cohort vs case control
• Short notes (3 marks): OR, RR, attack rate, incubation period, quarantine vs isolation, bias, epidemic curve

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RGUHS MBBS Phase 3 Part 1

Pharmacology - Cardiovascular System (CVS)

Most Repeated Q&A (Based on Katzung & RGUHS Past Papers)

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KEY TOPICS IN CVS PHARMACOLOGY (RGUHS)

1. Antihypertensive drugs - classification + mechanism
2. Drugs for Heart Failure - digoxin / ACE inhibitors
3. Antiarrhythmic drugs - Vaughan Williams classification
4. Drugs for Angina - nitrates / beta blockers / CCBs
5. Diuretics in CVS
6. Lipid-lowering drugs (statins)

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LONG ESSAY QUESTIONS (10 Marks)

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Q1. Classify antihypertensive drugs. Describe the mechanism of action, pharmacokinetics, uses and adverse effects of ACE inhibitors. (2+8) (Most repeated topic in RGUHS)

ANTIHYPERTENSIVE DRUGS
│
├── 1. DIURETICS
│   ├── Thiazides - Hydrochlorothiazide, Chlorthalidone
│   ├── Loop diuretics - Furosemide
│   └── Potassium-sparing - Spironolactone, Amiloride
│
├── 2. RENIN-ANGIOTENSIN SYSTEM BLOCKERS
│   ├── ACE Inhibitors - Captopril, Enalapril, Lisinopril, Ramipril
│   ├── Angiotensin Receptor Blockers (ARBs) - Losartan, Valsartan
│   └── Renin Inhibitors - Aliskiren
│
├── 3. CALCIUM CHANNEL BLOCKERS (CCBs)
│   ├── Dihydropyridines - Amlodipine, Nifedipine, Felodipine
│   └── Non-dihydropyridines - Verapamil, Diltiazem
│
├── 4. SYMPATHOPLEGIC AGENTS
│   ├── Central acting - Clonidine, Methyldopa
│   ├── Beta-blockers - Propranolol, Atenolol, Metoprolol
│   ├── Alpha-blockers - Prazosin, Doxazosin
│   └── Alpha+Beta blockers - Labetalol, Carvedilol
│
└── 5. DIRECT VASODILATORS
    ├── Arteriolar - Hydralazine, Minoxidil
    └── Arteriolar + Venodilator - Sodium Nitroprusside

1. Prevents conversion of Angiotensin I → Angiotensin II (a potent vasoconstrictor)
2. Prevents breakdown of bradykinin (a vasodilator that stimulates nitric oxide and prostacyclin release)

• Captopril: Oral bioavailability ~75%, T½ ~2h, duration 6-8h, 2-3 times daily dosing
• Enalapril: A prodrug - hydrolyzed in liver to active enalaprilat; onset slower but duration longer (12-24h), once daily dosing
• Lisinopril: Lysine derivative of enalaprilat; NOT a prodrug; T½ 12h; once daily
• Most ACE inhibitors (except fosinopril, moexipril) are eliminated by the kidneys - reduce dose in renal failure

1. Hypertension (first-line, especially in diabetics and CKD)
2. Heart failure (reduces afterload and preload)
3. Post-myocardial infarction (reduces ventricular remodeling)
4. Diabetic nephropathy (reduces proteinuria, slows progression)
5. Hypertensive emergencies (IV enalaprilat)
6. Secondary prevention in high cardiovascular risk patients

1. Dry cough (most common - due to accumulation of bradykinin) - class effect, use ARB instead
2. Hyperkalemia (due to reduced aldosterone)
3. First-dose hypotension (especially in volume-depleted patients)
4. Angioedema (rare but serious - bradykinin mediated) - contraindication for future use
5. Fetotoxicity - contraindicated in pregnancy (2nd and 3rd trimester - causes renal agenesis, oligohydramnios)
6. Rash, loss of taste (captopril - contains SH group)
7. Acute renal failure in bilateral renal artery stenosis

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Q2. Classify drugs used in heart failure. Describe the pharmacology of cardiac glycosides (Digoxin). (Repeated in RGUHS)

1. Cardiac glycosides - Digoxin
2. Beta-adrenoceptor agonists - Dobutamine, Dopamine
3. Phosphodiesterase inhibitors - Milrinone, Amrinone

1. ACE inhibitors / ARBs - reduce afterload and preload
2. Beta-blockers - Carvedilol, Metoprolol, Bisoprolol (reduce mortality in chronic HF)
3. Diuretics - reduce preload (furosemide, spironolactone)
4. Vasodilators - Nitrates (venodilators), Hydralazine (arteriolar dilator)
5. Aldosterone antagonists - Spironolactone, Eplerenone
6. Neprilysin inhibitors - Sacubitril (combined as Sacubitril/Valsartan - Entresto)

1. Inhibits Na+/K+-ATPase (the sodium pump) in cardiac cell membranes
2. This causes intracellular Na+ to accumulate
3. Increased intracellular Na+ reduces Na+-Ca2+ exchange → intracellular Ca2+ increases
4. Increased intracellular Ca2+ → increased myocardial contractility (positive inotropic effect)

• Enhances vagal (parasympathetic) tone → slows heart rate (negative chronotropic) + slows AV conduction (negative dromotropic)
• Useful in atrial fibrillation - controls ventricular rate

• Oral bioavailability ~75% (tablets); 90-100% (liquid form)
• Half-life: 36-40 hours (long)
• Primarily excreted unchanged by kidneys - reduce dose in renal failure
• Narrow therapeutic index (therapeutic serum level: 0.8-2.0 ng/mL)
• Protein binding: 25%
• Volume of distribution: Large (widely distributed in tissues)

1. Chronic systolic heart failure (reduces symptoms, hospitalization; does NOT reduce mortality)
2. Atrial fibrillation with rapid ventricular rate (controls rate by increasing AV block)
3. Atrial flutter
4. Paroxysmal supraventricular tachycardia (PSVT)

• GI: Nausea, vomiting, diarrhea, anorexia (earliest signs)
• CNS: Headache, fatigue, visual disturbances (yellow-green halos - xanthopsia), confusion

• Any arrhythmia can occur - most characteristic is PVCs (premature ventricular contractions)
• Bigeminy, AV block, ventricular tachycardia, ventricular fibrillation
• Toxicity is worsened by: Hypokalemia (most common precipitant), hypomagnesemia, hypercalcemia, hypothyroidism, renal failure

• Hypokalemia (diuretic use without K+ supplement)
• Amiodarone, Quinidine, Verapamil - increase digoxin levels (reduce dose by 50%)
• Renal failure
• Hypothyroidism
• Old age

1. Stop digoxin
2. Correct hypokalemia (IV KCl)
3. Atropine for bradycardia/AV block
4. Phenytoin or Lidocaine for ventricular arrhythmias
5. Digoxin-specific antibody fragments (Digibind/DigiFab) - for severe toxicity - specific antidote

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SHORT ESSAY QUESTIONS (5-7 Marks)

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Q3. Classify antiarrhythmic drugs (Vaughan Williams classification). Give examples and mechanism of each class. (Repeated)

• Amiodarone has all four classes of action - the most effective antiarrhythmic but with significant toxicity (thyroid, pulmonary, hepatic, corneal microdeposits)
• Adenosine and Magnesium do not fit into the classification - used separately
• Class IC drugs are contraindicated post-MI (CAST trial - increased mortality)
• Esmolol - IV beta-blocker with very short half-life (9 min) - used in acute arrhythmias during surgery

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Q4. Classify drugs used for angina. Describe the mechanism of action and uses of nitrates.

1. Nitrates (organic nitrates) - Nitroglycerin (GTN), Isosorbide dinitrate (ISDN), Isosorbide mononitrate (ISMN)
2. Beta-blockers - Propranolol, Atenolol, Metoprolol
3. Calcium channel blockers - Amlodipine, Diltiazem, Verapamil
4. Newer agents - Ranolazine, Ivabradine, Nicorandil
5. Antiplatelet agents - Aspirin (for acute coronary syndrome)
6. Statins, ACE inhibitors - for secondary prevention

1. Nitrates are biotransformed intracellularly to release Nitric Oxide (NO)
2. NO activates guanylyl cyclase → increases cGMP in vascular smooth muscle
3. cGMP activates protein kinase G → dephosphorylation of myosin light chain → smooth muscle relaxation and vasodilation

• Venodilation (main effect at low doses) → reduces preload → reduces LVEDP and wall tension → reduces O2 demand
• Arteriolar dilation (at higher doses) → reduces afterload
• Coronary vasodilation → relieves coronary spasm (especially in variant/Prinzmetal angina)
• Net: reduces myocardial O2 demand and increases O2 supply

• GTN: Extensive first-pass metabolism → low oral bioavailability (<10-20%)
• Therefore given sublingually (avoids first-pass) → rapid onset (2-5 min), duration 15-30 min
• Isosorbide mononitrate: No first-pass metabolism → good oral bioavailability, given orally

• Sublingual GTN tablet/spray - acute attack of angina (DOC)
• Transdermal GTN patches - prophylaxis
• ISDN oral - prophylaxis
• IV nitroglycerin - unstable angina, acute MI, hypertensive emergencies

1. Acute relief of anginal attack (sublingual GTN - DOC)
2. Prophylaxis of angina (ISDN, ISMN)
3. Acute heart failure / pulmonary edema
4. Hypertensive emergencies (IV nitroprusside)
5. Variant (Prinzmetal) angina

• Continuous exposure causes tolerance (tachyphylaxis)
• Prevention: Nitrate-free interval of 8-12 hours/day (remove patch at night)
• Mechanism: Depletion of SH groups, oxidative stress, neurohormonal activation

1. Headache (most common - due to meningeal vasodilation)
2. Postural hypotension, dizziness, flushing
3. Reflex tachycardia (add beta-blocker to prevent)
4. Methemoglobinemia (with large doses of amyl nitrite/sodium nitrite)
5. Tolerance with chronic use

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Q5. Describe the pharmacology of beta-adrenoceptor blockers in cardiovascular diseases. (Repeated)

• Non-selective (β1+β2): Propranolol, Nadolol, Timolol, Sotalol
• Cardioselective (β1): Atenolol, Metoprolol, Bisoprolol, Acebutolol
• With vasodilatory action: Carvedilol (α1+β), Labetalol (α1+β), Nebivolol (β1 + releases NO)
• With ISA (intrinsic sympathomimetic activity): Pindolol, Acebutolol

1. Block β1 receptors in heart → reduced heart rate (negative chronotropic), reduced contractility (negative inotropic), reduced conduction velocity → reduces cardiac output and BP
2. Block β1 in JGA cells → reduced renin release → reduced Angiotensin II and aldosterone
3. Central effect: reduces sympathetic outflow
4. Beta-2 blockade (non-selective): bronchospasm, peripheral vasoconstriction

1. Hypertension - first-line (especially with tachycardia, IHD, post-MI)
2. Angina pectoris - reduce O2 demand by reducing HR and contractility; especially effort angina
3. Post-myocardial infarction - reduce mortality, prevent sudden death, reduce reinfarction
4. Heart failure - Carvedilol, Metoprolol, Bisoprolol - reduce mortality in stable CHF (start low, go slow)
5. Arrhythmias - SVT, AF rate control, ventricular arrhythmias
6. Hypertrophic cardiomyopathy - reduce outflow obstruction
7. Thyrotoxic crisis, pheochromocytoma (with alpha-blocker first)

1. Bronchoconstriction (avoid in asthma - use cardioselective only if essential)
2. Bradycardia, AV block, worsening of acute HF
3. Cold extremities (peripheral vasoconstriction)
4. Fatigue, depression, sexual dysfunction
5. Masking hypoglycemia in diabetics (avoid non-selective; use cardioselective)
6. Rebound hypertension/angina on abrupt withdrawal - always taper slowly

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Q6. Classify calcium channel blockers. Describe their role in CVS diseases.

• Vascular smooth muscle → vasodilation → reduces peripheral resistance → lowers BP
• Cardiac muscle → negative inotropic effect (especially verapamil)
• SA/AV node → reduces heart rate and conduction (negative chronotropic/dromotropic - mainly verapamil, diltiazem)

• Amlodipine/DHPs: More selective vasodilators, minimal cardiac depression, reflex tachycardia (maintained or increased CO)
• Verapamil: Greatest cardiac depressant effect - reduces HR and CO
• Diltiazem: Intermediate

1. Hypertension - all CCBs; amlodipine preferred (once daily, no reflex tachycardia, good tolerability)
2. Angina pectoris - all three types; especially variant angina (verapamil, diltiazem, amlodipine)
3. Arrhythmias - Verapamil and Diltiazem: SVT (PSVT conversion), AF/flutter rate control
4. Hypertrophic cardiomyopathy - Verapamil
5. Raynaud's phenomenon - Nifedipine
6. Subarachnoid hemorrhage - Nimodipine (prevents vasospasm)

• DHPs: Headache, flushing, peripheral edema (ankle edema - most common), reflex tachycardia (nifedipine)
• Verapamil: Constipation, bradycardia, AV block, worsening HF
• Diltiazem: Bradycardia, AV block (milder than verapamil)
• Short-acting nifedipine not recommended for chronic hypertension (increased MI risk)

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SHORT NOTES (3-4 Marks)

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Q7. Digoxin toxicity - causes, features, treatment

• Hypokalemia (commonest) - diuretic use
• Hypomagnesemia, hypercalcemia
• Renal failure (digoxin accumulates)
• Drug interactions: Amiodarone, Quinidine, Verapamil (all increase digoxin levels - reduce digoxin dose by 50%)
• Hypothyroidism

• GI (earliest): Anorexia, nausea, vomiting, diarrhea
• CNS: Visual disturbances (yellow-green halos/xanthopsia), confusion, fatigue
• Cardiac (most dangerous): PVCs (most common arrhythmia), bigeminy, AV block, VT/VF

1. Stop digoxin
2. Correct hypokalemia (IV KCl if severe)
3. Atropine for bradycardia
4. Lidocaine/Phenytoin for ventricular arrhythmias
5. Digoxin-specific Fab antibody fragments (Digibind) = specific antidote

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Q8. Hydralazine - pharmacology

• Class: Direct arteriolar vasodilator
• Mechanism: Probably increases NO synthesis in vascular endothelium → arteriolar smooth muscle relaxation → reduces afterload
• Reflexes triggered: Compensatory reflex tachycardia and fluid retention (salt and water) - these blunt the antihypertensive effect if used alone
• Therefore always combined with a beta-blocker (blocks tachycardia) + diuretic (prevents fluid retention)

1. Hypertension (especially in combination with beta-blocker + diuretic)
2. Hypertensive emergencies (IV hydralazine)
3. Hypertension in pregnancy (safe; drug of choice with methyldopa and labetalol)
4. Heart failure - combined Hydralazine + Isosorbide dinitrate reduces mortality in African Americans

1. Tachycardia, palpitations
2. Fluid retention
3. Headache, flushing
4. Lupus-like syndrome (drug-induced SLE) - with high doses/long term (slow acetylators more prone)
5. Pyridoxine deficiency (peripheral neuropathy) - rare

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Q9. Sodium Nitroprusside

• Class: Direct arteriolar + venodilator
• Mechanism: Releases NO spontaneously (does not require metabolism) → activates guanylyl cyclase → cGMP → vasodilation
• Route: IV only (cannot be given orally - rapidly metabolized)
• Onset/Duration: Onset <30 sec, duration 1-2 minutes - requires continuous IV infusion with BP monitoring
• Light-sensitive - must be protected from light (wrap bottle in foil)

1. Hypertensive emergencies (malignant hypertension) - drug of choice
2. Acute decompensated heart failure
3. Controlled hypotension during surgery

• Cyanide toxicity (most important) - metabolized to cyanide; risk with high doses/prolonged infusion
• Symptoms: Metabolic acidosis, altered consciousness, convulsions
• Treatment: Sodium thiosulfate (converts cyanide to thiocyanate) + Dicobalt edetate/Hydroxocobalamin
• Thiocyanate toxicity with prolonged use - hypothyroidism, psychosis
• Excessive hypotension

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Q10. Diuretics in hypertension - mechanism and classification

1. Initially: depleting body sodium → reduced plasma volume → reduced cardiac output
2. Long-term: Reduced vascular reactivity (arteriolar tone)

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Q11. Amiodarone - a note

• Class III antiarrhythmic (also has Class I, II, IV actions - multi-class drug)
• Mechanism: Blocks K+ channels (IKr) → prolongs action potential duration and refractory period; also has Na+, Ca2+ channel blocking + sympatholytic properties
• Uses: Almost all arrhythmias (SVT, VT, VF, AF, flutter); drug of choice for VF and pulseless VT in advanced cardiac life support (ACLS)
• Pharmacokinetics: Long half-life (40-55 days), large Vd, poor oral bioavailability (30-65%), no renal excretion
• Adverse effects (multiple organ toxicity - remember with PTLCS):
  • Pulmonary toxicity (pulmonary fibrosis - most serious)
  • Thyroid - hypo or hyperthyroidism (contains iodine - 37% by weight)
  • Liver - hepatotoxicity
  • Corneal microdeposits (asymptomatic, reversible)
  • Skin - photosensitivity, blue-grey skin discoloration
  • Prolongs QT interval - risk of Torsades de Pointes
  • Neurological: Peripheral neuropathy, ataxia
• Interactions: Increases digoxin levels by 50% (reduce digoxin dose)

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Q12. Statins (HMG-CoA Reductase Inhibitors)

• Examples: Lovastatin, Simvastatin, Atorvastatin, Rosuvastatin, Pravastatin
• Mechanism: Competitively inhibit HMG-CoA reductase (rate-limiting enzyme in cholesterol synthesis in liver) → decreased hepatic cholesterol → upregulation of LDL receptors → increased LDL clearance from blood

• LDL cholesterol: ↓↓ (primary effect, 30-60%)
• Triglycerides: ↓ (moderate)
• HDL cholesterol: ↑ (mild)

• Anti-inflammatory
• Plaque stabilization
• Improved endothelial function
• Reduced thrombogenicity

1. Primary and secondary prevention of cardiovascular events (MI, stroke)
2. Hypercholesterolemia, mixed dyslipidemia
3. Acute coronary syndrome (high-dose statin immediately)

1. Myopathy (most important) - myalgia, myositis, rhabdomyolysis (with CK elevation)
   • Risk increased with: CYP3A4 inhibitors (macrolides, azole antifungals, amiodarone), fibrates (especially gemfibrozil), niacin
2. Hepatotoxicity - raised transaminases (check LFTs)
3. New-onset type 2 diabetes (with high-dose statins)
4. Contraindicated in pregnancy

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REPEATED ONE-LINERS / JUSTIFY-TYPE (3 Marks)

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• ACE inhibitors reduce intraglomerular pressure by dilating the efferent arteriole (reduces angiotensin II-mediated efferent constriction)
• Result: Reduced glomerular capillary pressure → reduced proteinuria → slows CKD progression
• Effective even without systemic hypertension
• Recommended in ALL type 1 and type 2 diabetics with microalbuminuria/proteinuria

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• Chronic beta-blocker use causes upregulation (increase in number) of beta-adrenoceptors
• Abrupt withdrawal → these hypersensitized receptors are suddenly exposed to normal catecholamine levels
• Result: Rebound tachycardia, worsening hypertension, precipitating angina or acute MI
• Therefore always taper the dose gradually over 1-2 weeks

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• Tolerance = progressively diminishing response to the same dose after continuous nitrate exposure
• Mechanism: Depletion of thiol (SH) groups needed for NO release; oxidative stress; neurohormonal activation (RAAS)
• Prevention: Eccentric dosing / nitrate-free interval of 8-12 hours daily (remove transdermal patch at night)
• Cross-tolerance exists between all organic nitrates

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• Both cause potassium retention: ACE inhibitors by reducing aldosterone, K+-sparing diuretics by blocking aldosterone action or ENaC
• Combination → severe hyperkalemia → can be fatal (cardiac arrest)
• Exception: Low-dose spironolactone + ACE inhibitor is used in severe heart failure under close monitoring (RALES trial showed mortality benefit)

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• Digoxin enhances vagal (parasympathetic) tone on the SA and AV nodes
• At the AV node: prolonged refractory period, reduced conduction velocity
• Result: Fewer atrial impulses conducted to ventricles → controls ventricular rate in AF
• Note: Digoxin does NOT terminate AF or restore sinus rhythm - it only controls ventricular rate

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EXAM STRATEGY - CVS PHARMACOLOGY (RGUHS)

1. Antihypertensive drug classification + ACE inhibitors in detail - asked almost every year
2. Cardiac glycosides / Digoxin (mechanism, toxicity, treatment) - very frequently asked
3. Drugs for heart failure classification
4. Antiarrhythmic drug classification (Vaughan Williams) - short note common
5. Nitrates for angina
6. Beta-blockers in CVS
7. Calcium channel blockers

• Amiodarone toxicity
• Hydralazine
• Sodium nitroprusside
• Digoxin toxicity treatment
• Diuretics in hypertension