Summary of Answers

Q-1 (Option A) — Bioavailability (2+5+4+4 = 15 marks)

• Definition: Fraction of unchanged drug reaching systemic circulation; IV = 100%; oral < 100% due to incomplete absorption + first-pass metabolism
• 5 Factors: (1) First-pass hepatic metabolism, (2) Physicochemical properties (lipophilicity/hydrophilicity), (3) P-glycoprotein efflux, (4) Drug formulation/dissolution, (5) GI factors (pH, gastric emptying, food)
• IV route = maximum bioavailability (100%) — advantages: immediate onset, precise dosing, bypasses GI | disadvantages: irreversibility, infection risk, needs trained personnel, rapid toxicity possible

Q-1 (Option B) — Anti-Hypertensives + ACE Inhibitors (3+4+4+4 = 15 marks)

• Classification: Diuretics, RAS agents, CCBs, Sympathoplegics, Direct vasodilators
• ACE Inhibitor mechanism: Block Ang I → Ang II conversion + bradykinin accumulation + efferent arteriolar dilation
• Uses: Hypertension, heart failure, post-MI, diabetic nephropathy, CKD
• Adverse effects: Dry cough, hyperkalemia, first-dose hypotension, AKI, angioedema, teratogenicity

Q-2 Short Notes

• Q-2a — Beta-blockers: 3 generations (non-selective, cardioselective, vasodilating); uses in HTN, angina, arrhythmias, heart failure, glaucoma, thyrotoxicosis, migraine
• Q-2b — Gout drugs: Classification; chronic gout: allopurinol (xanthine oxidase inhibitor), febuxostat, probenecid (uricosuric), colchicine (prophylaxis)
• Q-2c — Levodopa/Carbidopa: Mechanism (dopamine precursor crossing BBB); adverse effects (GI, CV, CNS, dyskinesias, on-off); carbidopa rationale (reduces peripheral decarboxylation → 75% dose reduction + fewer peripheral ADRs)
• Q-2d — Iron Deficiency Anemia: Drug classification; management: oral ferrous sulfate, parenteral iron (iron sucrose, ferric carboxymaltose) when oral fails

Q-3 Short Notes

• Q-3a — Asthma drugs: Classification (SABAs, LABAs, theophylline, anticholinergics, ICS, LTRAs, biologics); acute attack management (salbutamol + ipratropium nebulization, IV corticosteroids, O₂, IV aminophylline/magnesium if severe)
• Q-3b — Nitrates: Classification by duration (GTN, ISDN, ISMN); mechanism (NO → cGMP → smooth muscle relaxation); uses (stable angina, Prinzmetal's, unstable angina, acute heart failure); adverse effects (headache, hypotension, tolerance, PDE5 inhibitor contraindication)
• Q-3c — Phenytoin: AED classification; mechanism (Na⁺ channel inactivation → frequency-dependent block); adverse effects (nystagmus → ataxia → confusion; chronic: gingival hyperplasia, hirsutism, megaloblastic anemia, osteomalacia, fetal hydantoin syndrome)