FMGE 2022 — Pharmacology
3 Previous Year Questions with Answers & Explanations
Which antithyroid drug is safer during the first trimester of pregnancy?
A chronic smoker wants to quit smoking. Which of the following is the MOST appropriate first-line pharmacotherapy for smoking cessation?
A tourist with a travel history to India presents with complaints of abdominal pain and multiple episodes of watery diarrhea. He reports having food at a local restaurant the previous night. Which of the following antidiarrheal agents is used in this condition?
FMGE 2022 - Pharmacology FMGE Practice Questions and MCQs
Question 1: Which antithyroid drug is safer during the first trimester of pregnancy?
- A. Radioactive iodine
- B. Carbimazole
- C. Propylthiouracil (Correct Answer)
- D. Methimazole
- E. Propranolol
Explanation: ***Propylthiouracil*** - **Propylthiouracil (PTU)** is the preferred drug for treating hyperthyroidism in the **first trimester of pregnancy** due to a lower risk of teratogenic effects compared to methimazole or carbimazole. - While PTU carries a risk of hepatic toxicity, it is generally favored during early pregnancy to avoid the established teratogenic risks of other thionamides. *Radioactive iodine* - **Radioactive iodine (RAI)** is absolutely contraindicated in pregnancy as it crosses the placenta and can cause permanent **fetal hypothyroidism** or **agenesis of the fetal thyroid gland**. - Its use can lead to the destruction of the fetal thyroid, which is unacceptable given the availability of safer alternatives. *Carbimazole* - **Carbimazole** is converted to methimazole in the body and is associated with a higher risk of **fetal embryopathy** during the first trimester, including aplasia cutis, choanal atresia, and esophageal atresia. - It should generally be avoided in the first trimester if possible, switching to PTU instead. *Methimazole* - **Methimazole** is structurally similar to carbimazole and also carries a significant risk of **teratogenic effects** such as **aplasia cutis**, omphalocele, and choanal atresia when used in the first trimester. - It is often reserved for the second and third trimesters if a thionamide is required, or for patients who cannot tolerate PTU, but ideally avoided in early pregnancy. *Propranolol* - **Propranolol** is a beta-blocker used for symptomatic management of hyperthyroidism (controlling tachycardia, tremor, anxiety) but is not an antithyroid drug and does not treat the underlying hyperthyroidism. - While generally safe in pregnancy, it only provides adjunctive therapy and cannot replace definitive antithyroid treatment.
Question 2: A chronic smoker wants to quit smoking. Which of the following is the MOST appropriate first-line pharmacotherapy for smoking cessation?
- A. Mirtazapine
- B. Varenicline (Correct Answer)
- C. Bupropion
- D. Nicotine replacement therapy
- E. Clonidine
Explanation: ***Varenicline*** - **Varenicline** is a **partial agonist** at the **α4β2 nicotinic acetylcholine receptor**, the primary receptor involved in nicotine addiction. - It reduces cravings and withdrawal symptoms while blocking the reinforcing effects of nicotine from cigarettes. - Studies show **varenicline has the highest efficacy** among pharmacological agents for smoking cessation, with superior quit rates compared to bupropion and NRT. - **First-line agent** recommended by clinical guidelines for smoking cessation. *Mirtazapine* - Mirtazapine is a **tetracyclic antidepressant** (α2-antagonist, 5-HT2 and 5-HT3 antagonist) used for **major depressive disorder**. - **Not indicated** for smoking cessation and lacks evidence for efficacy in this context. - May cause weight gain and sedation, which are not beneficial for smoking cessation. *Bupropion* - **Bupropion** is an **atypical antidepressant** and **norepinephrine-dopamine reuptake inhibitor (NDRI)** that also antagonizes nicotinic receptors. - Effective **first-line agent** for smoking cessation, reducing cravings and withdrawal symptoms. - However, studies show **lower efficacy compared to varenicline** in head-to-head trials. - Contraindicated in patients with seizure disorders or eating disorders. *Nicotine replacement therapy* - **NRT** (patches, gum, lozenges, inhalers, nasal spray) provides controlled nicotine delivery without harmful tobacco combustion products. - Effective **first-line therapy** that reduces withdrawal symptoms and cravings. - Generally **less effective than varenicline** when used alone, but can be combined with other therapies. - Safest option with minimal contraindications. *Clonidine* - **Clonidine** is a **central α2-agonist** primarily used for hypertension. - Considered a **second-line agent** for smoking cessation, used only when first-line therapies fail or are contraindicated. - Less effective than first-line agents and associated with more adverse effects (sedation, dry mouth, hypotension). - Not routinely recommended for smoking cessation.
Question 3: A tourist with a travel history to India presents with complaints of abdominal pain and multiple episodes of watery diarrhea. He reports having food at a local restaurant the previous night. Which of the following antidiarrheal agents is used in this condition?
- A. Bismuth subsalicylate
- B. Octreotide
- C. Loperamide
- D. Rifaximin (Correct Answer)
- E. Ciprofloxacin
Explanation: ***Rifaximin*** - This patient's symptoms, including **abdominal pain**, **watery diarrhea**, and a recent **travel history to India** coupled with eating at a local restaurant, strongly suggest **traveler's diarrhea**, often caused by bacterial pathogens. - **Rifaximin** is a non-absorbable antibiotic specifically approved for treating non-invasive traveler's diarrhea, as it targets causative bacteria in the gut lumen with minimal systemic absorption. - Rifaximin is preferred due to its **excellent safety profile**, minimal systemic effects, and targeted action against enteric pathogens. *Ciprofloxacin* - **Ciprofloxacin** is a fluoroquinolone antibiotic that can be effective for traveler's diarrhea and has been used historically for this indication. - However, rifaximin is now preferred over ciprofloxacin due to increasing **fluoroquinolone resistance** among enteric pathogens, systemic absorption leading to more side effects, and FDA warnings about serious adverse effects associated with fluoroquinolones. - Ciprofloxacin may be reserved for more severe or invasive diarrhea cases. *Bismuth subsalicylate* - While **bismuth subsalicylate** can be used for symptomatic relief in traveler's diarrhea due to its anti-secretory and anti-inflammatory properties, it is not an antimicrobial agent. - It works by reducing fluid secretion and inflammation but does not directly address the underlying bacterial infection to the same extent as rifaximin. *Octreotide* - **Octreotide** is a somatostatin analog primarily used to treat severe, refractory diarrhea associated with conditions like neuroendocrine tumors or chemotherapy, not typical bacterial traveler's diarrhea. - Its mechanism involves inhibiting gastrointestinal hormone secretion and reducing intestinal motility, which is too potent for this common, self-limiting condition. *Loperamide* - **Loperamide** is an opioid-receptor agonist that acts as an anti-motility agent, reducing the frequency of bowel movements. - It is generally contraindicated as a primary treatment for traveler's diarrhea when an invasive bacterial infection is suspected, as it can prolong the retention of toxins and pathogens in the gut.