Drugs for Gastrointestinal Diseases Practice Questions

Q: Which drug is NOT used in the treatment of H. pylori infection?

Mosapride. **Explanation:** The treatment of *Helicobacter pylori* requires a combination of antibiotics and acid suppressants to eradicate the bacteria and promote ulcer healing [1][2]. **Why Mosapride is the correct answer:** **Mosapride** is a selective **5-HT₄ receptor agonist** used as a **prokinetic agent**. It enhances gastrointestinal motility by facilitating the release of acetylcholine from the enteric nervous system. While it is used for dyspepsia and GERD, it has no antimicrobial activity against *H. pylori* and is not part of any standard eradication regimen (e.g., Triple or Quadruple therapy). **Analysis of incorrect options:** * **Omeprazole (Option B):** A Proton Pump Inhibitor (PPI) that is a mandatory component of all *H. pylori* regimens [3]. It raises gastric pH, which increases the stability and efficacy of antibiotics like Amoxicillin and Clarithromycin. * **Metronidazole (Option A):** A nitroimidazole antibiotic frequently used in "Triple Therapy" (especially in penicillin-allergic patients) or "Quadruple Therapy" to target anaerobic components of the infection [2]. * **Amoxicillin (Option D):** A beta-lactam antibiotic that is a first-line agent in *H. pylori* eradication due to low resistance rates compared to other antibiotics [2]. **Clinical Pearls for NEET-PG:** * **Standard Triple Therapy (7-14 days):** PPI + Amoxicillin + Clarithromycin (Mnemonic: **PAC**) [2]. * **Bismuth Quadruple Therapy:** PPI + Bismuth subsalicylate + Metronidazole + Tetracycline (Used in areas with high Clarithromycin resistance) [2][3]. * **Sequential Therapy:** 5 days of PPI + Amoxicillin, followed by 5 days of PPI + Clarithromycin + Tinidazole. * **Diagnosis:** The **Urea Breath Test** is the non-invasive "Gold Standard" for confirming eradication.

Q: Levosulpiride acts as an antagonist of which central dopamine receptor?

All of the above. ### Explanation **Correct Answer: D. All of the above** **Mechanism of Action:** Levosulpiride is the levo-enantiomer of sulpiride, belonging to the substituted benzamide class. In the context of gastrointestinal pharmacology, it acts as a **selective dopamine (D2, D3, and D4) receptor antagonist**. While its prokinetic effect is primarily mediated by blocking **D2 receptors** at the peripheral level (which prevents dopamine-mediated inhibition of acetylcholine release), it also exerts potent antagonistic effects on central dopamine receptors. Research indicates that Levosulpiride has a high affinity for the **D2 and D3** receptors and also acts on the **D4** subtype. This broad-spectrum antagonism of the D-family receptors is why "All of the above" is the correct choice. **Analysis of Options:** * **A, B, and C:** While Levosulpiride is most famously associated with D2 blockade for its prokinetic and anti-emetic effects, it is not exclusive to D2. It binds to D3 and D4 receptors as well, making these options incomplete on their own. **Clinical Pearls for NEET-PG:** * **Dual Action:** It acts as a prokinetic (peripheral D2 blockade) and an antipsychotic/anti-emetic (central D2/D3/D4 blockade). * **Indications:** Commonly used for functional dyspepsia, diabetic gastroparesis, and GERD. * **Side Effects:** Because it crosses the blood-brain barrier and blocks central D2 receptors, it can cause **extrapyramidal symptoms (EPS)**, parkinsonism, and **hyperprolactinemia** (leading to galactorrhea or gynecomastia). * **Comparison:** Unlike Metoclopramide, Levosulpiride has negligible 5-HT3 antagonism or 5-HT4 agonism at standard doses; its primary prokinetic drive is purely dopaminergic.

Q: Teduglutide is used in small bowel syndrome because its action is similar to which of the following?

Glucagon like peptide 2. **Explanation:** **Teduglutide** is a recombinant analog of human **Glucagon-like Peptide-2 (GLP-2)**. It is specifically indicated for the treatment of **Short Bowel Syndrome (SBS)** in patients who are dependent on parenteral support. 1. **Mechanism of Action (Why C is correct):** GLP-2 is an enterotropic hormone secreted by L-cells of the distal intestine. Teduglutide mimics GLP-2 by binding to receptors on subepithelial myofibroblasts. This triggers the release of growth factors (like IGF-1) that promote **mucosal growth**, increase villus height, and deepen crypts. This expansion of surface area enhances the absorption of fluids and nutrients, reducing the need for intravenous parenteral nutrition. 2. **Why other options are incorrect:** * **A & B (Pancreatic/Biliary Lipase):** These are enzymes involved in the digestion of dietary fats. While fat malabsorption occurs in SBS, Teduglutide does not replace digestive enzymes; it restores the structural integrity of the bowel. * **D (Somatostatin):** Somatostatin (and its analog Octreotide) inhibits gastrointestinal motility and secretions. While sometimes used to reduce diarrhea in SBS, it does not promote intestinal adaptation or mucosal growth; in fact, it can sometimes inhibit the natural adaptive process. **NEET-PG High-Yield Pearls:** * **Half-life:** Teduglutide is modified (substitution of alanine with glycine) to be resistant to degradation by the enzyme **DPP-4**, giving it a significantly longer half-life than native GLP-2. * **Monitoring:** Because it promotes cell growth, patients must be monitored via colonoscopy for **intestinal polyps** or malignancy before and during treatment. * **Other GLP analogs:** Do not confuse GLP-2 (Teduglutide - GI) with **GLP-1** (Exenatide, Liraglutide - Diabetes/Obesity).

Q: Which of the following is a 5-HT3 antagonist?

Ondansetron. **Explanation:** **Correct Answer: B. Ondansetron** Ondansetron is a selective **5-HT3 receptor antagonist**. These receptors are ligand-gated ion channels located peripherally on vagal nerve terminals and centrally in the Chemoreceptor Trigger Zone (CTZ). By blocking these receptors, Ondansetron prevents the initiation of the vomiting reflex. It is the gold standard for managing **Chemotherapy-Induced Nausea and Vomiting (CINV)** and post-operative nausea. **Analysis of Incorrect Options:** * **A. Cisapride:** This is a **5-HT4 agonist** and a prokinetic agent. It was largely withdrawn due to its potential to cause fatal cardiac arrhythmias (Long QT syndrome) by blocking HERG channels. * **C. Clozapine:** An atypical antipsychotic that acts primarily as a **D2 and 5-HT2A antagonist**. While it has affinity for many receptors, it is not classified as a 5-HT3 antagonist. * **D. Buspirone:** An anxiolytic drug that acts as a **selective 5-HT1A partial agonist**. It is used for Generalized Anxiety Disorder (GAD) and lacks sedative or muscle relaxant properties. **High-Yield NEET-PG Pearls:** * **Side Effects of Ondansetron:** Most common are **headache**, constipation, and **QT interval prolongation** (caution in patients with electrolyte imbalances). * **Other -setrons:** Granisetron (more potent), Palonosetron (longest half-life, effective for delayed emesis). * **Drug of Choice:** Ondansetron is the drug of choice for emesis in pregnancy (Hyperemesis Gravidarum) and radiation-induced vomiting, but it is **ineffective** in motion sickness (where H1 or M1 blockers are used).

Q: Which of the following is a prokinetic drug?

Domperidone. **Explanation:** **Domperidone (Option A)** is the correct answer. It is a **prokinetic agent** that acts as a peripheral **D2-receptor antagonist**. By blocking dopamine receptors in the gastrointestinal tract, it removes the inhibitory effect of dopamine on myenteric cholinergic neurons. This leads to increased acetylcholine release, which enhances gastric motility, increases Lower Esophageal Sphincter (LES) tone, and promotes gastric emptying. Unlike Metoclopramide, Domperidone does not cross the blood-brain barrier significantly, resulting in fewer extrapyramidal side effects. **Analysis of Incorrect Options:** * **Cimetidine (Option B):** This is an **H2-receptor antagonist**. It works by inhibiting gastric acid secretion and is used in the treatment of peptic ulcers and GERD, but it has no effect on GI motility. * **Ondansetron (Option C):** This is a **5-HT3 receptor antagonist**. It is a potent antiemetic used primarily to control chemotherapy-induced nausea and vomiting (CINV). It actually tends to cause constipation rather than prokinetic activity. * **Hyoscine (Option D):** Also known as Scopolamine, this is an **anticholinergic (muscarinic antagonist)**. It reduces GI motility and secretions, making it an antispasmodic rather than a prokinetic. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Domperidone is the preferred prokinetic for patients with **Parkinson’s disease** because it does not worsen motor symptoms (due to poor CNS penetration). * **Side Effects:** While it lacks CNS effects, Domperidone can cause **hyperprolactinemia** (galactorrhea, gynecomastia) because the pituitary gland lies outside the blood-brain barrier. * **ECG Warning:** High doses are associated with **QT interval prolongation**, requiring caution in patients with cardiac arrhythmias.

Q: What is the preferred drug for controlling an acute exacerbation of ulcerative colitis?

Prednisolone. **Explanation:** The management of Ulcerative Colitis (UC) is divided into two phases: **Induction of remission** (treating acute exacerbations) and **Maintenance of remission**. **1. Why Prednisolone is Correct:** Corticosteroids like **Prednisolone** (oral) or Hydrocortisone/Methylprednisolone (IV) are the drugs of choice for inducing remission in **acute moderate-to-severe exacerbations**. They act rapidly by inhibiting multiple inflammatory pathways (inhibiting NF-κB, decreasing leukotrienes and prostaglandins). While highly effective for controlling acute flares, they have no role in maintenance therapy due to significant long-term side effects. **2. Why the other options are incorrect:** * **Sulfasalazine & Mesalazine (5-ASA):** These are the first-line agents for **maintaining remission** and treating **mild** active disease. They are not potent enough to control a moderate-to-severe acute exacerbation rapidly. Sulfasalazine also has a higher side-effect profile (due to the sulfapyridine moiety) compared to Mesalazine. * **Vancomycin:** This is an antibiotic used for *Clostridioides difficile* infection. While infections can trigger UC flares, Vancomycin is not a primary treatment for the underlying autoimmune inflammation of UC. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC) for Maintenance of UC:** Mesalazine (5-ASA). * **DOC for Acute Exacerbation (Moderate-Severe):** Corticosteroids. * **Site of Action:** Sulfasalazine is cleaved by bacterial azoreductase in the **colon** to release the active 5-ASA. * **Topical Therapy:** For distal disease (proctitis), topical 5-ASA (suppositories/enemas) is preferred over oral therapy. * **Step-up Therapy:** If steroids fail in acute severe UC, **Infliximab** or **Cyclosporine** are used as "rescue therapy."

Q: The following adverse drug reaction seen in colonoscopy view is due to which of the following agents?

Cascara. ***Cascara*** - **Melanosis coli** (dark brown/black pigmentation of colonic mucosa) is a characteristic adverse effect of chronic **anthraquinone laxative** use, including cascara. - The pigmentation results from **lipofuscin deposits** in macrophages within the lamina propria, visible on colonoscopy as dark discoloration. *Bisacodyl* - This is a **stimulant laxative** that works by increasing intestinal motility but does not cause melanosis coli. - Chronic use may lead to **electrolyte imbalances** and **cathartic colon**, but not the characteristic pigmentation seen in the image. *Castor oil* - Acts as a **ricinoleic acid-based stimulant laxative** that increases intestinal secretions and motility. - Does not contain **anthraquinones** and therefore does not cause the dark pigmentation of melanosis coli. *Loperamide* - This is an **anti-diarrheal agent** that works as an **opioid receptor agonist** to slow intestinal motility. - Would not cause melanosis coli and is therapeutically opposite to laxatives in function.

Question 1

What is the drug of choice for the medical management of bleeding esophageal varices?

Accepted Answer

Octreotide

Answer

Terlipressin

Answer

Propranolol

Answer

Clonidine

Question 2

Which drug is NOT used in the treatment of H. pylori infection?

Accepted Answer

Mosapride

Answer

Metronidazole

Answer

Omeprazole

Answer

Amoxicillin

Question 3

What is true regarding sulfasalazine?

Accepted Answer

Active moiety is 5-aminosalicylic acid in ulcerative colitis.

Answer

Inactive moiety is 5-aminosalicylic acid in ulcerative colitis.

Answer

Inactive moiety in rheumatoid arthritis is sulfapyridine.

Answer

It gets activated in the stomach.

Question 4

What is the drug of choice for antibiotic-associated pseudomembranous colitis?

Accepted Answer

Metronidazole

Answer

Oral vancomycin

Answer

Clindamycin

Answer

Penicillin G

Question 5

Levosulpiride acts as an antagonist of which central dopamine receptor?

Accepted Answer

All of the above

Answer

D2

Answer

D3

Answer

D4

Question 6

Teduglutide is used in small bowel syndrome because its action is similar to which of the following?

Accepted Answer

Glucagon like peptide 2

Answer

Pancreatic lipase

Answer

Biliary lipase

Answer

Somatostatin

Question 7

Which of the following is a 5-HT3 antagonist?

Accepted Answer

Ondansetron

Answer

Cisapride

Answer

Clozapine

Answer

Buspirone

Question 8

Which of the following is a prokinetic drug?

Accepted Answer

Domperidone

Answer

Cimetidine

Answer

Ondansetron

Answer

Hyoscine

Question 9

What is the preferred drug for controlling an acute exacerbation of ulcerative colitis?

Accepted Answer

Prednisolone

Answer

Sulfasalazine

Answer

Mesalazine

Answer

Vancomycin

Question 10

The following adverse drug reaction seen in colonoscopy view is due to which of the following agents?

Accepted Answer

Cascara

Answer

Bisacodyl

Answer

Castor oil

Answer

Loperamide

Drugs for Gastrointestinal Diseases — MCQs

Drugs for Gastrointestinal Diseases — MCQs

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