Short Ready-Answer for Problem Based Questions from Pharmacology-III

 

Short Ready-Answer for Problem Based Questions from Pharmacology-III

PBQ–1: Peptic Ulcer with H. pylori Infection

a) H. pylori eradication regimen (4 marks)
Standard Triple Therapy (14 days):

·        Proton Pump Inhibitor: Omeprazole 20 mg twice daily

·        Amoxicillin: 1 g twice daily

·        Clarithromycin: 500 mg twice daily

Alternative (Penicillin allergy):
PPI + Clarithromycin + Metronidazole

b) Mechanism of action of PPIs (2 marks)
PPIs irreversibly inhibit H⁺/K⁺-ATPase (proton pump) in gastric parietal cells, leading to profound and long-lasting suppression of gastric acid secretion.

c) Anti-emetic for nausea (2 marks)
Drug: Metoclopramide

Mechanism:

·        Dopamine (D₂) receptor antagonism in CTZ

·        Enhances gastric emptying (prokinetic action)

d) Drug for constipation with classification (2 marks)
Drug: Lactulose

Class: Osmotic laxative
Mechanism: Draws water into colon → softens stool → increases peristalsis

PBQ–2: Gastro-Esophageal Reflux Disease (GERD)

a) Classification of drugs (3 marks)

·        Proton pump inhibitors: Omeprazole

·        H₂ receptor blockers: Ranitidine

·        Antacids: Aluminium hydroxide

·        Prokinetics: Metoclopramide

 

b) Drug of choice (3 marks)
Omeprazole 20 mg once daily before meals
Highly effective acid suppression and mucosal healing

c) Mechanism of H₂ blockers (2 marks)
Block histamine-mediated stimulation of gastric acid secretion by inhibiting H₂ receptors on parietal cells.

d) Adverse effects of long-term PPI use (2 marks)

·        Vitamin B₁₂ deficiency

·        Increased risk of fractures

PBQ–3: Chronic Constipation

a) Classification of laxatives (4 marks)

·        Bulk forming: Ispaghula

·        Stool softeners: Liquid paraffin

·        Stimulant laxatives: Senna

·        Osmotic laxatives: Lactulose

b) Suitable laxative (2 marks)
Lactulose – Safe in elderly, non-irritant

c) Mechanism of osmotic purgatives (2 marks)
Increase osmotic pressure → retain water → soften stools → stimulate peristalsis

d) Adverse effects of stimulant laxatives (2 marks)

·        Abdominal cramps

·        Electrolyte imbalance

PBQ–4: Acute Diarrhea in Child

a) ORS composition and role (4 marks)
Contains glucose, sodium, potassium, chloride, citrate.
Enhances sodium-glucose co-transport → water absorption → prevents dehydration.

b) Role of zinc (2 marks)

·        Reduces duration and severity of diarrhea

·        Improves intestinal mucosal repair

c) Anti-diarrheal drug (2 marks)
Loperamide – decreases intestinal motility via μ-opioid receptors

d) Contraindicated drugs (2 marks)

·        Diphenoxylate

·        Antibiotics without indication

PBQ–5: Motion Sickness

a) Classification of anti-emetics (4 marks)

·        Anticholinergics: Hyoscine

·        H₁ antihistamines: Promethazine

·        Dopamine antagonists: Metoclopramide

·        5-HT₃ antagonists: Ondansetron

b) Drug of choice (2 marks)
Hyoscine – blocks muscarinic receptors in vestibular system

c) MOA of H₁ blockers (2 marks)
Inhibit histaminergic transmission from vestibular nuclei to vomiting center

d) Adverse effects (2 marks)

·        Dry mouth

·        Blurred vision

PBQ–6: Type 2 Diabetes Mellitus

a) Classification (4 marks)

·        Sulfonylureas

·        Biguanides

·        Thiazolidinediones

·        DPP-4 inhibitors

b) First-line drug (2 marks)
Metformin – improves insulin sensitivity and causes weight loss

c) MOA of metformin (2 marks)
Decreases hepatic gluconeogenesis and increases peripheral glucose uptake

d) Adverse effects of sulfonylureas (2 marks)

·        Hypoglycemia

·        Weight gain

PBQ–7: Diabetes with Renal Impairment

a) Safe drugs (3 marks)

·        Linagliptin

·        Insulin

b) MOA of DPP-4 inhibitors (3 marks)
Increase incretin levels → enhanced insulin secretion → reduced glucagon release

c) Advantages (2 marks)

·        No hypoglycemia

·        Weight neutral

d) Adverse effects (2 marks)

·        Nasopharyngitis

·        Headache

PBQ–8: Hyperthyroidism

a) Classification (4 marks)

·        Thioamides

·        Ionic inhibitors

·        Iodine preparations

·        Radioactive iodine

b) MOA of carbimazole (2 marks)
Inhibits thyroid peroxidase → blocks hormone synthesis

c) Adverse effects (2 marks)

·        Agranulocytosis

·        Hepatotoxicity

d) Use of radioactive iodine (2 marks)
Permanent treatment of hyperthyroidism

PBQ–9: Hypothyroidism

a) Drugs used (2 marks)
Levothyroxine

b) MOA (4 marks)
Replaces deficient thyroid hormone → increases metabolic activity

c) Adverse effects (2 marks)

·        Palpitations

·        Weight loss

d) Drug interactions (2 marks)

·        Iron salts

·        Antacids

PBQ–10: Antibacterial Therapy

a) Principles (4 marks)

·        Identify pathogen

·        Use narrow-spectrum drugs

·        Adequate dose & duration

b) Penicillin classification (3 marks)

·        Natural

·        Semisynthetic

·        Extended spectrum

c) MOA (2 marks)
Inhibit bacterial cell wall synthesis

d) Resistance cause (1 mark)
β-lactamase production

 

PBQ–11: Penicillin Allergy

a) Mechanism of penicillin hypersensitivity (3 marks)
Penicillin acts as a hapten and binds to host proteins, forming antigenic complexes. This triggers IgE-mediated Type I hypersensitivity, leading to urticaria, bronchospasm, or anaphylaxis.

b) Alternative antibiotics (3 marks)

·        Macrolides: Azithromycin, Clarithromycin

·        Tetracyclines: Doxycycline

·        Fluoroquinolones: Ciprofloxacin

c) Mechanism of action of macrolides (2 marks)
Macrolides inhibit protein synthesis by binding to the 50S ribosomal subunit, preventing translocation of peptide chains.

d) Adverse effects of macrolides (2 marks)

·        Gastrointestinal upset

·        QT interval prolongation

 

PBQ–12: Pulmonary Tuberculosis

a) Classification of anti-tubercular drugs (4 marks)

·        Primary drugs: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol

·        Secondary drugs: PAS, Cycloserine, Ethionamide

b) Mechanism of action of isoniazid (2 marks)
Inhibits synthesis of mycolic acid, an essential component of Mycobacterium tuberculosis cell wall.

c) Adverse effects of rifampicin (2 marks)

·        Hepatotoxicity

·        Orange discoloration of body fluids

d) DOTS (2 marks)
Directly Observed Treatment Short-course ensures patient compliance, reduces resistance, and improves cure rate.

 

PBQ–13: Amoebic Dysentery

a) Classification of anti-amoebic drugs (4 marks)

·        Tissue amoebicides: Metronidazole

·        Luminal amoebicides: Diloxanide furoate

·        Mixed amoebicides: Tinidazole

b) Mechanism of action of metronidazole (2 marks)
Generates toxic free radicals that damage DNA of Entamoeba histolytica.

c) Adverse effects of metronidazole (2 marks)

·        Metallic taste

·        Disulfiram-like reaction with alcohol

d) Luminal amoebicide (2 marks)
Diloxanide furoate

 

PBQ–14: Fungal Infection

a) Classification of antifungal drugs (4 marks)

·        Polyenes: Amphotericin-B

·        Azoles: Ketoconazole, Fluconazole

·        Allylamines: Terbinafine

·        Miscellaneous: Griseofulvin

b) Mechanism of action of azoles (2 marks)
Inhibit ergosterol synthesis by blocking fungal cytochrome P450 enzymes.

c) Adverse effects of amphotericin-B (2 marks)

·        Nephrotoxicity

·        Infusion-related fever and chills

d) Topical antifungal (2 marks)
Clotrimazole

 

PBQ–15: HIV Infection

a) Classification of antiretroviral drugs (4 marks)

·        NRTIs: Zidovudine

·        NNRTIs: Nevirapine

·        Protease inhibitors: Indinavir

·        Fusion inhibitors: Enfuvirtide

b) Mechanism of action of zidovudine (2 marks)
Inhibits reverse transcriptase, causing chain termination of viral DNA.

c) HAART (2 marks)
Highly Active Antiretroviral Therapy uses multiple drugs to suppress viral replication and prevent resistance.

d) Adverse effects of ART (2 marks)

·        Bone marrow suppression

·        Hepatotoxicity

 

PBQ–16: Organ Transplantation

a) Classification of immunosuppressants (4 marks)

·        Calcineurin inhibitors: Cyclosporine

·        Antiproliferatives: Azathioprine

·        Glucocorticoids: Prednisolone

·        Antibodies: Muromonab-CD3

b) Mechanism of action of cyclosporine (2 marks)
Inhibits calcineurin, preventing IL-2 production and T-cell activation.

c) Adverse effects of corticosteroids (2 marks)

·        Osteoporosis

·        Hyperglycemia

d) Antibody used in transplantation (2 marks)
Muromonab-CD3

 

PBQ–17: Cancer Chemotherapy

a) Classification of anticancer drugs (4 marks)

·        Alkylating agents

·        Antimetabolites

·        Plant alkaloids

·        Antibiotics

b) Mechanism of action of cyclophosphamide (2 marks)
Alkylates DNA → cross-linking → inhibition of cell division.

c) Adverse effects of doxorubicin (2 marks)

·        Cardiotoxicity

·        Myelosuppression

d) Use of paclitaxel (2 marks)
Treatment of breast and ovarian cancer.

 

PBQ–18: Chemotherapy-Induced Vomiting

a) Classification of anti-emetics (4 marks)

·        5-HT₃ antagonists

·        Dopamine antagonists

·        Corticosteroids

·        Benzodiazepines

b) Mechanism of action of ondansetron (2 marks)
Blocks 5-HT₃ receptors in CTZ and GI tract.

c) Advantages (2 marks)

·        Highly effective

·        Minimal sedation

d) Adverse effects (2 marks)

·        Headache

·        Constipation

PBQ–19: Uterine Atony

a) Classification of uterine stimulants (4 marks)

·        Oxytocin

·        Ergot alkaloids

·        Prostaglandins

b) Mechanism of action of oxytocin (2 marks)
Stimulates uterine smooth muscle contraction via increased intracellular calcium.

c) Adverse effects of ergometrine (2 marks)

·        Hypertension

·        Nausea and vomiting

d) Role of misoprostol (2 marks)
Prevention and treatment of postpartum hemorrhage.

 

PBQ–20: Preterm Labor

a) Classification of uterine relaxants (4 marks)

·        β₂-agonists

·        Calcium channel blockers

·        Magnesium sulfate

·        Progesterone

b) Mechanism of action of nifedipine (2 marks)
Blocks calcium influx → uterine muscle relaxation.

c) Adverse effects of β₂-agonists (2 marks)

·        Tachycardia

·        Tremors

d) Contraindication of tocolytics (2 marks)
Intrauterine infection or fetal distress.

                                                                     END OF THE DOCUMENT

See More: 

1. Twenty-detailed Problem-Based Questions (PBQs) from Pharmacology-III for Practice 

2. Chapters in Pharmacology