Pharmacology
9 questionsWhich of the following drugs is commonly used as a rescue medication for acute asthma attacks?
Maximum effect of bronchodilatation in asthma is caused by -
What is an atypical side effect of montelukast?
Which of the following statements about oral iron preparations is correct?
Which of the following oral antidiabetic drugs is an insulin secretagogue?
Which antithyroid drug is preferred during the first trimester of pregnancy due to relatively lower placental transfer?
What is the mechanism of action of ticagrelor?
Which of the following medications is classified as a stool softener?
What is the drug of choice for drug-induced peptic ulcer?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 511: Which of the following drugs is commonly used as a rescue medication for acute asthma attacks?
- A. Salbutamol (Correct Answer)
- B. Theophylline
- C. Terbutaline
- D. Budesonide
Explanation: ***Salbutamol*** - **Salbutamol** (albuterol) is a **short-acting beta-2 agonist (SABA)** that rapidly relaxes bronchial smooth muscle. - Its quick onset of action makes it ideal for immediate relief of **bronchoconstriction** during an acute asthma attack. - It is the **most commonly used** and **first-line rescue medication** for acute asthma worldwide. *Terbutaline* - **Terbutaline** is also a **short-acting beta-2 agonist (SABA)** similar to salbutamol and can be used as a rescue medication. - While it has comparable bronchodilator effects, **salbutamol is more commonly used** as the preferred rescue inhaler in clinical practice. - Both are SABAs, but salbutamol has become the standard first-choice rescue medication globally. *Theophylline* - **Theophylline** is a **methylxanthine** that acts as a bronchodilator but has a **narrow therapeutic index** and slower onset of action. - It is used as a **maintenance therapy** for chronic asthma and not as a rescue drug for acute exacerbations. *Budesonide* - **Budesonide** is an **inhaled corticosteroid (ICS)** used as a **long-term controller medication** to reduce airway inflammation. - It has a slow onset of action and is *not* effective for immediate relief during an acute asthma attack.
Question 512: Maximum effect of bronchodilatation in asthma is caused by -
- A. Beta 2-Agonist (Correct Answer)
- B. Corticosteroids
- C. Theophylline
- D. Anticholinergic
Explanation: ***Beta 2-Agonist*** - **Beta-2 agonists** directly relax bronchial smooth muscle by stimulating beta-2 adrenergic receptors, leading to significant and rapid bronchodilation. - This direct action on airway muscle relaxation makes them the most potent and fastest-acting bronchodilators for acute asthma symptoms. *Corticosteroids* - **Corticosteroids** reduce airway inflammation and hypersensitivity over time but do not provide immediate or maximal bronchodilation. - Their primary role is in long-term control of asthma, preventing exacerbations rather than acutely reversing bronchospasm. *Theophylline* - **Theophylline** is a methylxanthine that causes modest bronchodilation by inhibiting phosphodiesterase and blocking adenosine receptors. - It has a narrow therapeutic index, numerous side effects, and is less effective than beta-2 agonists for bronchodilation. *Anticholinergic* - **Anticholinergics** (e.g., ipratropium) block muscarinic receptors, preventing acetylcholine-induced bronchoconstriction. - They provide bronchodilation but are generally less potent and have a slower onset of action compared to beta-2 agonists in asthma.
Question 513: What is an atypical side effect of montelukast?
- A. Goodpasture syndrome
- B. Membranous glomerulonephritis
- C. Bronchial asthma
- D. Churg-Strauss syndrome (Correct Answer)
Explanation: ***Churg-Strauss syndrome*** - The apparent development of **Churg-Strauss syndrome** (eosinophilic granulomatosis with polyangiitis) has been reported in patients treated with montelukast, although it is believed to be related more to the unmasking of the disease rather than a direct drug effect. - This typically occurs when **corticosteroids** are tapered or withdrawn as montelukast takes over, revealing the underlying vasculitis. *Goodpasture syndrome* - **Goodpasture syndrome** is an autoimmune disease causing rapidly progressive glomerulonephritis and pulmonary hemorrhage, characterized by anti-glomerular basement membrane (GBM) antibodies. - There is no established association between montelukast use and the development of Goodpasture syndrome. *Membranous glomerulonephritis* - **Membranous glomerulonephritis** is a common cause of nephrotic syndrome, characterized by immune complex deposition on the glomerular basement membrane. - This condition is not typically linked to the use of montelukast. *Bronchial asthma* - **Bronchial asthma** is the condition montelukast is used to treat, acting as a leukotriene receptor antagonist to reduce inflammation and bronchoconstriction. - It is a primary indication for the drug, not a side effect.
Question 514: Which of the following statements about oral iron preparations is correct?
- A. Most commonly used preparation is ferrous gluconate
- B. Ferrous fumarate is most efficient
- C. Ferric preparations are more effective
- D. Different preparations have different bioavailability (Correct Answer)
Explanation: ***Different preparations have different bioavailability*** - The **bioavailability** of oral iron preparations varies depending on the specific salt used, its formulation, and the presence of absorption enhancers or inhibitors. - This difference in absorption impacts the required dose and efficacy in treating **iron deficiency anemia**. *Most commonly used preparation is ferrous gluconate* - **Ferrous sulfate** is the most commonly prescribed and cost-effective oral iron preparation due to its high iron content and good bioavailability. - While ferrous gluconate is used, its iron content is lower than ferrous sulfate, making it less frequently the primary choice. *Ferrous fumarate is most efficient* - While **ferrous fumarate** has a high elemental iron content, its efficiency doesn't necessarily surpass that of ferrous sulfate or other preparations when considering factors like bioavailability and side effect profile. - **Ferrous sulfate** is often considered efficient due to its balance of elemental iron content, bioavailability, and cost-effectiveness. *Ferric preparations are more effective* - **Ferrous (Fe2+)** iron is generally better absorbed than **ferric (Fe3+)** iron, as ferric iron needs to be reduced to its ferrous form before absorption. - Unless specifically formulated for enhanced absorption (e.g., ferric maltol), ferric preparations are typically *less* effective for initial iron repletion.
Question 515: Which of the following oral antidiabetic drugs is an insulin secretagogue?
- A. Metformin
- B. Pioglitazone
- C. Nateglinide (Correct Answer)
- D. Acarbose
Explanation: **Nateglinide** - **Nateglinide** is a **meglitinide**, which is a type of **insulin secretagogue**. - It stimulates **insulin release** from pancreatic beta cells by blocking ATP-sensitive potassium channels. *Metformin* - **Metformin** is a **biguanide** that primarily works by **decreasing hepatic glucose production** and increasing insulin sensitivity in peripheral tissues. - It does not directly stimulate insulin secretion. *Pioglitazone* - **Pioglitazone** is a **thiazolidinedione** (TZD) that improves insulin sensitivity by activating **PPAR-gamma receptors**. - It does not directly affect insulin secretion but rather enhances the body's response to existing insulin. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays the digestion and absorption of carbohydrates in the small intestine. - This reduces postprandial glucose excursions and does not directly stimulate insulin secretion.
Question 516: Which antithyroid drug is preferred during the first trimester of pregnancy due to relatively lower placental transfer?
- A. Carbimazole
- B. Propylthiouracil (Correct Answer)
- C. Both
- D. None of the options
Explanation: ***Propylthiouracil*** - **Propylthiouracil (PTU)** is the preferred antithyroid drug during the **first trimester** of pregnancy because it crosses the placenta less readily than methimazole/carbimazole. - While it still crosses the placenta, its lower placental transfer and association with fewer fetal anomalies in early pregnancy make it a safer initial choice, especially to minimize the risk of **fetal embryopathy** associated with methimazole. *Carbimazole* - **Carbimazole** (which is metabolized to methimazole) can cross the placenta more easily than PTU and has been associated with **fetal anomalies**, particularly in the first trimester. - Its use is generally avoided during the first trimester due to concerns about congenital malformations such as **aplasia cutis** and **esophageal atresia**. *Both* - While both drugs can cross the placenta to some extent, their safety profiles and recommended use during pregnancy differ significantly. - Carbimazole (methimazole) has a higher risk of teratogenicity in the first trimester compared to PTU. *None of the options* - This option is incorrect because propylthiouracil is indeed known to cross the placenta and is commonly used in pregnancy, especially during the first trimester. - The choice of antithyroid drug is a critical consideration in managing hyperthyroidism in pregnancy.
Question 517: What is the mechanism of action of ticagrelor?
- A. Reversible inhibition of ADP action (Correct Answer)
- B. Irreversible inhibition of ADP action
- C. Reversible inhibition of GPIIb/IIIa
- D. Irreversible inhibition of GPIIb/IIIa
Explanation: ***Reversible inhibition of ADP action*** - **Ticagrelor** is a **P2Y12 receptor antagonist** that works by preventing ADP from binding to its receptor on platelets [2]. - This binding is **reversible**, meaning ticagrelor can dissociate from the receptor, allowing for some recovery of platelet function over time [2]. *Irreversible inhibition of ADP action* - **Clopidogrel** and **prasugrel** are examples of **irreversible P2Y12 inhibitors**, forming a permanent bond with the receptor [2]. - Irreversible inhibition leads to a longer duration of platelet inhibition, as new platelets must be generated for function to return [2]. *Reversible inhibition of GPIIb/IIIa* - **GPIIb/IIIa inhibitors** like **eptifibatide** and **tirofiban** block the final common pathway of platelet aggregation by preventing fibrinogen binding [1]. - While their action is reversible, they target a *different* mechanism than ticagrelor. *Irreversible inhibition of GPIIb/IIIa* - **Abciximab** is a GPIIb/IIIa inhibitor that binds **irreversibly** (or with very slow dissociation) to the receptor [1]. - Unlike reversible GPIIb/IIIa inhibitors, abciximab is a monoclonal antibody with a prolonged antiplatelet effect [1]. - This is still an incorrect answer as ticagrelor targets the P2Y12 receptor, not GPIIb/IIIa.
Question 518: Which of the following medications is classified as a stool softener?
- A. Bran
- B. Senna
- C. Phenolphthalein
- D. Docusates (Correct Answer)
Explanation: **Docusates** - **Docusates** (e.g., docusate sodium, docusate calcium) are **stool softeners** that work by reducing the surface tension of stool, allowing water and lipids to penetrate. - This increases the water content in the stool, making it softer and easier to pass, which is particularly useful in preventing straining after surgery or in conditions like hemorrhoids. *Bran* - **Bran** is a **bulk-forming laxative**, a type of dietary fiber that adds mass to the stool. - It absorbs water in the intestines, which increases stool volume and stimulates bowel movements, but it does not directly soften the stool in the same way docusates do. *Senna* - **Senna** is a **stimulant laxative** that works by irritating the bowel wall to promote peristalsis and bowel evacuation. - While it can help move stool, it does not act primarily by softening it, and prolonged use can lead to dependency or electrolyte imbalances. *Phenolphthalein* - **Phenolphthalein** is a **stimulant laxative** that was historically used to promote bowel movements. - It is no longer widely used due to concerns about potential carcinogenicity and other adverse effects, and it does not function as a stool softener.
Question 519: What is the drug of choice for drug-induced peptic ulcer?
- A. Prostaglandin analogues
- B. H2-receptor antagonists
- C. Proton pump inhibitors (Correct Answer)
- D. Antacids
Explanation: ***Proton pump inhibitors*** - **PPIs** are the most effective agents for treating and preventing **NSAID-induced peptic ulcers** by profoundly suppressing gastric acid secretion. - They provide **rapid symptom relief** and promote ulcer healing by creating an environment conducive to mucosal repair. *Prostaglandin analogues* - **Misoprostol**, a prostaglandin E1 analogue, can prevent NSAID-induced ulcers, but its use is limited by **gastrointestinal side effects** such as diarrhea and abdominal cramping. - While they protect the gastric mucosa, their efficacy in healing established ulcers is generally **inferior to PPIs**. *H2-receptor antagonists* - **H2-blockers** are effective in reducing gastric acid, but they are **less potent** than PPIs and typically do not heal **gastric ulcers** as effectively, especially those induced by NSAIDs. - They are more commonly used for preventing **duodenal ulcers** and managing symptoms of GERD. *Antacids* - Antacids provide **immediate, temporary relief** of ulcer symptoms by neutralizing existing stomach acid. - They do not address the underlying pathology or promote **ulcer healing** and are therefore not considered the drug of choice for treatment.
Physiology
1 questionsRebound increase in gastric acid secretion after stopping proton pump inhibitor therapy is due to?
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 511: Rebound increase in gastric acid secretion after stopping proton pump inhibitor therapy is due to?
- A. Parietal cell hyperplasia
- B. Increased histamine release
- C. Hypergastrinemia (Correct Answer)
- D. Hypersensitivity of Ach receptors
Explanation: ***Hypergastrinemia*** - Proton pump inhibitors (PPIs) create a state of **hypochlorhydria** (reduced stomach acid), which in turn stimulates the **G cells** in the stomach to produce more **gastrin**. - This elevated gastrin level leads to a compensatory increase in the number and activity of **parietal cells**, causing a rebound hypersecretion of acid when PPI therapy is discontinued. *Parietal cell hyperplasia* - While parietal cell hyperplasia can occur, it is a consequence of chronic **hypergastrinemia**, not the primary driver of rebound acid secretion. - The direct effect of increased gastrin stimulating existing parietal cells is more immediate and significant for the rebound phenomenon. *Increased histamine release* - Elevated histamine release from **enterochromaffin-like (ECL) cells** is a downstream effect of hypergastrinemia, as gastrin stimulates ECL cells. - While increased histamine contributes to acid secretion, the root cause for its increase in this context is the **hypergastrinemia** induced by PPIs. *Hypersensitivity of Ach receptors* - **Acetylcholine (Ach) receptors** on parietal cells are involved in direct neural stimulation of acid secretion. - There is no evidence that stopping PPIs causes an increased sensitivity of these receptors, or that this is the primary mechanism of rebound acid secretion.