PUD, ANTIEMETICS, CONSTIPATION, DIARRHEA, GIT ANTI-INFECTIVES, IBD/IBS

Question 1

What are the key causes of PUD (peptic ulcer disease)?

Answer 1

H. pylori infection
NSAIDs
Stress ulcers (critically ill)
Zollinger-Ellison Syndrome (gastrinoma)

Question 2

Drug classes used in PUD management?

Answer 2

Antacids
H2 receptor antagonists (H2RAs)
Proton pump inhibitors (PPIs)
Antibiotics for H. pylori
Mucosal protectants (e.g. sucralfate, misoprostol)

Question 3

Proton Pump Inhibitors – names, MOA, and kinetics?

Answer 3

Names: Omeprazole, Esomeprazole, Pantoprazole
MOA: Irreversibly inhibit H⁺/K⁺-ATPase in parietal cells
Prodrugs → activated in acidic environment
Long-lasting (up to 72 hours), CYP metabolism

Question 4

PPI side effects and interactions?

Answer 4

↓ Mg²⁺, B12 absorption
↑ risk of infections (e.g., C. diff, pneumonia)
Interactions: ↓ absorption of drugs needing acid (e.g., ketoconazole), omeprazole inhibits CYP2C19 (→ ↑ clopidogrel)

Question 5

H2 receptor antagonists – examples and MOA?

Answer 5

Names: Ranitidine, Famotidine, Cimetidine
MOA: Competitive inhibition of H2 receptors on parietal cells → ↓ cAMP → ↓ H⁺ secretion
Less potent than PPIs

Question 6

Sucralfate – MOA and cautions?

Answer 6

Forms a protective barrier over ulcers (aluminum complex)
Requires acidic pH to work
Avoid with antacids and PPIs

Question 7

Misoprostol – MOA and contraindication?

Answer 7

PGE1 analog → ↑ mucus and bicarbonate, ↓ acid
Used for NSAID-induced ulcers
Contraindicated in pregnancy (abortifacient)

Question 8

H. pylori triple therapy?

Answer 8

PPI + Amoxicillin + Clarithromycin (PAC) for 14 days
Alternatives: Metronidazole if penicillin allergy

Question 9

Main antiemetic drug classes by receptor target?

Answer 9

H1 antagonists: Promethazine, Diphenhydramine
D2 antagonists: Metoclopramide, Domperidone
5HT3 antagonists: Ondansetron
NK1 antagonists: Aprepitant
Others: Cannabinoids, corticosteroids, anticholinergics

Question 10

Metoclopramide – MOA and safety?

Answer 10

D2 antagonist + prokinetic (↑ ACh in GI tract)
Crosses BBB → extrapyramidal side effects (EPS), sedation
Avoid in Parkinson’s

Question 11

Ondansetron – MOA and use?

Answer 11

5HT3 antagonist in CTZ and GI tract
Used for chemotherapy and post-op nausea
Side effects: QT prolongation, headache, constipation

Question 12

Domperidone vs. Metoclopramide?

Answer 12

Domperidone does not cross BBB → fewer EPS
Better safety in long-term use
Caution: QT prolongation

Question 13

Aprepitant – class, MOA, and use?

Answer 13

NK1 receptor antagonist
Used in combo with dexamethasone + 5HT3 antagonist in chemotherapy nausea

Question 14

Antihistamines and anticholinergics in nausea?

Answer 14

H1: Promethazine (sedating)
M1: Hyoscine (motion sickness)
Side effects: dry mouth, drowsiness, constipation

Question 15

What are the 4 main types of laxatives?

Answer 15

Bulk-forming: Psyllium
Osmotic: Lactulose, PEG
Stimulant: Senna, Bisacodyl
Stool softeners: Docusate sodium

Question 16

How do osmotic laxatives work?

Answer 16

Draw water into colon → soften stool → ↑ peristalsis
Lactulose also ↓ ammonia (used in hepatic encephalopathy)

Question 17

Senna and bisacodyl – class and risk?

Answer 17

Stimulant laxatives
Risk of cramping, dependence if chronic use

Question 18

Lubiprostone and linaclotide – MOA?

Answer 18

Lubiprostone: Cl⁻ channel activator
Linaclotide: GC-C agonist → ↑ cGMP → secretion and motility
Used in IBS-C

Question 19

First-line non-pharm management for diarrhea?

Answer 19

Oral Rehydration Solution (ORS) to correct fluid and electrolyte loss

Question 20

Loperamide – MOA and cautions?

Answer 20

µ-opioid receptor agonist → ↓ GI motility
Does not cross BBB
Contraindicated in bloody/infective diarrhea

Question 21

Adsorbents and anti-secretory agents?

Answer 21

Adsorbents: Kaolin, pectin
Bismuth subsalicylate: mild anti-inflammatory, antimicrobial, anti-secretory

Question 23

What are the key drugs for amoebiasis?

Answer 23

Metronidazole: systemic
Diloxanide furoate: luminal (eradicate cysts)

Question 24

Metronidazole – MOA, cautions, interactions?

Answer 24

DNA strand breakage via nitro radical
Disulfiram-like reaction with alcohol
Metallic taste, neuropathy with long use

Question 25

Drug for giardiasis?

Answer 25

Tinidazole or metronidazole

Question 26

Drug of choice for C. difficile infection (CDI)?

Answer 26

1st episode: Vancomycin PO or Fidaxomicin Metronidazole only if mild and vanco unavailable

Question 27

Difference between IBD and IBS?

Answer 27

IBD: Chronic inflammation (Crohn's or UC), mucosal damage IBS: Functional disorder, no structural abnormalities

Question 28

First-line drug for mild IBD?

Answer 28

5-ASA (Mesalazine, Sulfasalazine) Anti-inflammatory via PPAR-γ agonism ADRs: nephrotoxicity, rash, photosensitivity

Question 29

Corticosteroids in IBD – role and caution?

Answer 29

Prednisone, Budesonide Short-term only (avoid long-term due to systemic effects) Used in flares

Question 30

Immunomodulators used in IBD?

Answer 30

Azathioprine, Methotrexate Slow onset, used for maintenance Monitor LFTs, CBC

Question 31

Biologic agents in IBD?

Answer 31

Anti-TNF: Infliximab, Adalimumab Anti-integrin: Vedolizumab Used in severe or refractory disease

Question 32

IBS treatment by subtype?

Answer 32

IBS-C: Bulk laxatives, lubiprostone, linaclotide IBS-D: Loperamide, rifaximin, eluxadoline Antidepressants (TCAs, SSRIs) for visceral pain