Which of the following is classified as a Type E adverse reaction?
When two different chemicals act on two different receptors and their responses are opposite to each other on the same cell, this phenomenon is called?
Which drug has the highest plasma protein binding?
Which of the following statements about clonidine is incorrect?
Which of the following substances is not classified as a carcinogen for bladder cancer?
Microvesicular fatty liver is caused by ?
Which of the following drugs is used for Smoking Cessation?
Which of the following statements is true regarding omalizumab?
Which route of administration undergoes the maximum first pass metabolism?
Which of the following drugs is known to have low first pass metabolism?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 11: Which of the following is classified as a Type E adverse reaction?
- A. Toxicity
- B. Augmented effect
- C. Teratogenesis
- D. Rebound effect due to drug withdrawal (Correct Answer)
Explanation: ***Rebound effect due to drug withdrawal*** - Type E adverse reactions are related to **end-of-treatment effects**, specifically withdrawal phenomena. - The **rebound effect** after drug cessation, such as worsened angina after stopping beta-blockers, is a classic example of a Type E reaction. *Toxicity* - This is a general term for adverse effects from excessive drug doses and is **not a specific type** in the ABCDEF classification. - Dose-dependent toxic effects typically align with **Type A** (augmented) reactions, which are predictable and related to the drug's pharmacology. *Augmented effect* - An **augmented effect** is classified as a Type A adverse drug reaction, meaning it is **dose-dependent**, predictable from the drug's known pharmacology, and common. - Examples include bleeding with anticoagulants or hypotension with antihypertensives. *Teratogenesis* - **Teratogenesis** refers to drug-induced fetal malformations and is categorized as a **Type D** (delayed) adverse drug reaction. - These effects are often severe, occur after prolonged exposure, and are rare.
Question 12: When two different chemicals act on two different receptors and their responses are opposite to each other on the same cell, this phenomenon is called?
- A. Physiological antagonism (Correct Answer)
- B. Chemical antagonism
- C. Reversible antagonism
- D. Competitive antagonism
Explanation: ***Physiological antagonism*** - This occurs when two drugs act on **different receptors** to produce **opposite physiological effects** within the same system or cell, effectively canceling each other out [1]. - A classic example is the opposing actions of **histamine** (causing bronchoconstriction) and **adrenaline** (causing bronchodilation) on the bronchi [1]. *Chemical antagonism* - This involves a direct **chemical interaction** between two drugs that results in the **inactivation of one or both** of them. - An example is the binding of **chelating agents** to heavy metals, forming an inert complex. *Reversible antagonism* - This describes antagonism where the antagonist binds to the receptor and can be **displaced by a higher concentration of the agonist**. - It does not specifically describe antagonists acting on different receptors or producing opposing physiological effects. *Competitive antagonism* - This occurs when an antagonist directly **competes with an agonist for the same binding site** on a receptor [1]. - The antagonist, while not producing a response itself, prevents the agonist from binding and activating the receptor.
Question 13: Which drug has the highest plasma protein binding?
- A. Warfarin (Correct Answer)
- B. Verapamil
- C. Aspirin
- D. GTN
Explanation: ***Warfarin*** - **Warfarin** exhibits very **high plasma protein binding**, typically greater than 99%, primarily to albumin. - This high binding capacity means that only a small fraction of the drug is free and pharmacologically active. - Due to high protein binding, warfarin is susceptible to drug interactions when displaced from albumin. *Verapamil* - **Verapamil** has a relatively high plasma protein binding, around 90%, but it is not as high as warfarin. - Its binding is predominantly to **albumin** and alpha-1-acid glycoprotein. *Aspirin* - **Aspirin** (acetylsalicylic acid) has moderate plasma protein binding, usually between 50-90%, depending on the dosage. - It binds to **albumin** and can displace other protein-bound drugs. *GTN* - **Glyceryl trinitrate (GTN)** has moderate plasma protein binding, approximately 60%. - Its rapid onset and short duration of action are primarily due to its extensive first-pass metabolism and quick redistribution, rather than protein binding characteristics.
Question 14: Which of the following statements about clonidine is incorrect?
- A. Alpha 2 receptor agonist
- B. Sudden withdrawal causes rebound hypertension
- C. Controls loose motions due to diabetic neuropathy
- D. First line for AMI (Correct Answer)
Explanation: ***First line for AMI*** - Clonidine is **not first-line** for **Acute Myocardial Infarction (AMI)** as it can cause **bradycardia** and **hypotension**, potentially worsening cardiac output. - First-line AMI treatments include **thrombolytics**, **antiplatelet agents** (aspirin), **beta-blockers**, and **ACE inhibitors** for optimal cardiac protection. *Alpha 2 receptor agonist* - Clonidine is indeed an **alpha-2 adrenergic receptor agonist** that acts centrally in the **medulla oblongata**. - It reduces **sympathetic outflow** from the CNS, leading to decreased **heart rate**, **blood pressure**, and **peripheral vascular resistance**. *Sudden withdrawal causes rebound hypertension* - Abrupt clonidine discontinuation causes dangerous **rebound hypertension** due to sudden loss of **sympathetic inhibition**. - **Gradual tapering** over 1-2 weeks is essential to prevent this potentially life-threatening complication. *Controls loose motions due to diabetic neuropathy* - Clonidine effectively treats **diabetic diarrhea** by stimulating **alpha-2 receptors** in the enteric nervous system. - It **slows intestinal transit** and **enhances fluid absorption**, making it useful for **autonomic neuropathy-related** gastrointestinal symptoms.
Question 15: Which of the following substances is not classified as a carcinogen for bladder cancer?
- A. Acrolein
- B. Phenacetin
- C. Benzidine
- D. Isopropyl alcohol (Correct Answer)
Explanation: ***Isopropyl alcohol*** - Research does not link **isopropyl alcohol** to an increased risk of bladder cancer, making it a non-carcinogenic substance in this context. - It is commonly used as a solvent and antiseptic, but has not shown **urogenic carcinogenicity** in studies. *Phenacetin* - **Phenacetin** is an analgesic that has been associated with an increased risk of bladder cancer, particularly due to its metabolite, which can be nephrotoxic. - Its use has significantly declined due to its carcinogenic effects on the urinary system. *Benzidine* - **Benzidine** is a well-known bladder carcinogen, primarily linked to the dye industry, where exposure has led to increased rates of bladder cancer [1]. - This substance has been implicated in **urothelial carcinoma** due to its mutagenic properties. *Acrolein* - **Acrolein** is a toxic compound that can cause bladder irritation and has been studied for its potential carcinogenic effects related to bladder cancer. - It is released during the combustion of materials and is known to contribute to **chemical injury** in the bladder. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 217-218.
Question 16: Microvesicular fatty liver is caused by ?
- A. Valproate (Correct Answer)
- B. Chronic diabetes mellitus (DM)
- C. Prolonged starvation
- D. Chronic inflammatory bowel disease (IBD)
Explanation: ***Valproate*** - **Valproate** is a known cause of **microvesicular steatosis**, particularly in children, due to its interference with mitochondrial fatty acid oxidation. - This can lead to severe liver injury, including **acute liver failure**, as it impairs the liver's ability to metabolize fats. *Chronic diabetes mellitus (DM)* - Chronic DM is commonly associated with **macrovesicular steatosis** (NAFLD), not microvesicular, due to insulin resistance and increased hepatic lipid synthesis. - Unlike microvesicular steatosis, macrovesicular type usually does not immediately impair mitochondrial function. *Prolonged starvation* - Prolonged starvation can lead to **fatty liver**, usually **macrovesicular steatosis**, as the body mobilizes fatty acids from adipose tissue. - While it stresses the liver, it rarely causes the specific **microvesicular** pattern of fat accumulation. *Chronic inflammatory bowel disease (IBD)* - IBD can cause various liver complications, but **microvesicular fatty liver** is not a characteristic feature. - Liver issues in IBD are more often related to **sclerosing cholangitis** or secondary to nutritional deficiencies and medications.
Question 17: Which of the following drugs is used for Smoking Cessation?
- A. Bupropion (Correct Answer)
- B. Methadone
- C. Buprenorphine
- D. Naltrexone
Explanation: ***Bupropion*** - **Bupropion** is an antidepressant that is also approved as a smoking cessation aid. It works by inhibiting the reuptake of **dopamine** and **norepinephrine**, which can help reduce nicotine cravings and withdrawal symptoms. - It is often prescribed as a first-line pharmacotherapy for smoking cessation, with a typical treatment duration of 7-12 weeks. *Buprenorphine* - **Buprenorphine** is a partial opioid agonist primarily used to treat opioid addiction. It is not indicated for smoking cessation. - While it can help manage withdrawal symptoms from opioids, it has no direct mechanism of action that would reduce nicotine dependence or cravings. *Methadone* - **Methadone** is a full opioid agonist primarily used for the treatment of opioid use disorder (OUD) and chronic pain management. It is not used for smoking cessation. - Its mechanism involves binding to opioid receptors to prevent withdrawal symptoms and reduce cravings for other opioids. *Naltrexone* - **Naltrexone** is an opioid antagonist used primarily for the treatment of alcohol dependence and opioid use disorder. It is not indicated for smoking cessation. - It blocks the effects of opioids and reduces alcohol cravings, but does not affect nicotine pathways or dependence.
Question 18: Which of the following statements is true regarding omalizumab?
- A. Anti-IgE
- B. Given subcutaneously
- C. Used as add-on therapy in moderate to severe asthma prophylaxis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** is correct because each statement is true: **Anti-IgE** - Omalizumab is a **humanized monoclonal antibody** that specifically targets and binds to **free IgE** in the circulation - By binding free IgE, it prevents IgE from attaching to **high-affinity receptors** on mast cells and basophils - This reduces the allergic cascade and prevents release of inflammatory mediators **Given subcutaneously** - Omalizumab is administered via **subcutaneous injection** only - Dosing is typically every **2 to 4 weeks** based on patient's body weight and baseline IgE levels - Not available in oral or intravenous formulations for asthma treatment **Used as add-on therapy in moderate to severe asthma prophylaxis** - FDA approved as **add-on maintenance treatment** for patients aged ≥6 years with **moderate to severe persistent allergic asthma** - Indicated when asthma is **inadequately controlled** with inhaled corticosteroids - Reduces frequency of asthma exacerbations and improves asthma control - Also approved for chronic spontaneous urticaria All three statements accurately describe omalizumab's mechanism, administration route, and clinical indication, making **"All of the options"** the correct answer.
Question 19: Which route of administration undergoes the maximum first pass metabolism?
- A. Intra-arterial
- B. Rectal
- C. Oral (Correct Answer)
- D. Intravenous
Explanation: ***Oral*** - Drugs administered orally are absorbed from the **gastrointestinal tract** and transported via the **portal vein** directly to the liver, where they undergo significant **first-pass metabolism** before reaching systemic circulation. - This hepatic metabolism can drastically reduce the **bioavailability** of the drug, requiring higher doses or alternative administration routes. *Intra-arterial* - This route delivers drugs directly into an **artery** supplying a target tissue or organ, largely bypassing systemic circulation and initial hepatic metabolism. - It is used for localized effects, such as **chemotherapy** for specific tumors, minimizing systemic exposure. *Rectal* - While a portion of rectally administered drugs may bypass the portal circulation by entering the **inferior and middle rectal veins**, a significant amount can still be absorbed into the superior rectal vein, which drains into the portal system. - This means rectal administration offers only **partial avoidance** of first-pass metabolism, making it less complete than IV or intra-arterial routes for bypassing the liver altogether. *Intravenous* - Drugs administered intravenously are delivered directly into the **systemic circulation**, completely bypassing the gastrointestinal tract and the liver's first-pass metabolism. - This route ensures **100% bioavailability** and rapid onset of action, as the drug immediately reaches its target.
Question 20: Which of the following drugs is known to have low first pass metabolism?
- A. Lidocaine
- B. Propranolol
- C. Theophylline (Correct Answer)
- D. Morphine
Explanation: ***Theophylline*** - **Theophylline** exhibits **low first-pass metabolism**, meaning a significant portion of the orally administered drug reaches systemic circulation unchanged. - This characteristic contributes to its relatively **high bioavailability** when given orally. *Lidocaine* - **Lidocaine** undergoes extensive **first-pass metabolism** in the liver, leading to very low oral bioavailability. - Due to this, it is typically administered **parenterally** (e.g., intravenously or topically) to achieve therapeutic concentrations. *Propranolol* - **Propranolol** is known for its significant **first-pass metabolism**, which results in a much lower bioavailability after oral administration compared to intravenous. - This extensive metabolism necessitates higher oral doses to achieve the same therapeutic effect as parenteral administration. *Morphine* - **Morphine** also undergoes substantial **first-pass metabolism** in the liver, where it is primarily glucuronidated. - This leads to a lower oral bioavailability compared to other routes of administration and contributes to a higher oral dose requirement.