Pharmacogenomics of Drug Transporters Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Pharmacogenomics of Drug Transporters. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 1: Pharmacodynamics deals with:-
- A. Latency of onset
- B. Mechanism of action of a drug (Correct Answer)
- C. Transport of drug across the biological membranes
- D. Mode of excretion of a drug
Pharmacogenomics of Drug Transporters Explanation: Detailed study of the **Mechanism of action of a drug** [1][2]
- **Pharmacodynamics** describes what the **drug does to the body**, including its **molecular targets** and biochemical effects [3].
- This involves the study of the drug's mechanisms to produce its therapeutic or toxic effects [2].
*Latency of onset*
- **Latency of onset** refers to the time it takes for a drug to start producing its effects, which is a pharmacokinetic rather than a pharmacodynamic parameter.
- It deals with the drug's absorption and distribution rather than its interaction with the body once it reaches its site of action.
*Transport of drug across the biological membranes*
- The **transport of drugs across biological membranes** is a key aspect of **pharmacokinetics**, specifically absorption and distribution [1].
- This process determines how much drug reaches its target site, not how it interacts with the target.
*Mode of excretion of a drug*
- The **mode of excretion** of a drug (e.g., renal, hepatic) falls under **pharmacokinetics**, addressing how the body gets rid of the drug.
- This process influences the drug's duration of action and elimination half-life, not its mechanism of action.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 2: Which among the following is the false statement regarding statins?
- A. These drugs should not be stopped even in severe conditions like injury, surgery etc.
- B. Although HMG-CoA reductase inhibitors substantially reduce the risk of cardiovascular events, there is mild increase in lipoprotein a (Lpa) levels.
- C. With the long term use, there is slight increase in the incidence of type 2 diabetes mellitus.
- D. They can be given with verapamil and other enzyme inhibitors (Correct Answer)
Pharmacogenomics of Drug Transporters Explanation: ***They can be given with verapamil and other enzyme inhibitors***
- This statement is **FALSE** and is the correct answer because **verapamil** (a moderate CYP3A4 inhibitor) and other potent CYP3A4 inhibitors like **clarithromycin** or **azole antifungals** can significantly increase statin concentrations, raising the risk of adverse effects like **myopathy** and **rhabdomyolysis**.
- **Co-administration** of statins with these inhibitors generally requires careful dose adjustments or avoidance, as they increase the systemic exposure to most statins (especially **simvastatin**, **atorvastatin**, and **lovastatin**).
*These drugs should not be stopped even in severe conditions like injury, surgery etc.*
- This statement could be considered false in certain contexts, as statins **can be temporarily held** in acute, severe conditions like sepsis, major trauma, or complex surgery, especially if there's a concern for **acute kidney injury** or **rhabdomyolysis** [1].
- However, in most routine surgical situations, statins are typically continued due to their cardiovascular protective effects.
*Although HMG-CoA reductase inhibitors substantially reduce the risk of cardiovascular events, there is mild increase in lipoprotein a (Lpa) levels.*
- This statement is **TRUE**. Statins are associated with a **modest increase in Lp(a) levels** (approximately 10-20%), which has been consistently demonstrated in clinical studies [2].
- While statins effectively lower **LDL cholesterol**, Lp(a) levels are largely **genetically determined** and may paradoxically increase with statin therapy, though this effect is generally considered clinically insignificant compared to the overall cardiovascular benefits [2].
*With the long term use, there is slight increase in the incidence of type 2 diabetes mellitus.*
- This statement is **TRUE**. Long-term statin use is associated with a **small but statistically significant increase** in the risk of developing **type 2 diabetes mellitus** (approximately 9-12% increased risk), particularly in individuals with pre-existing risk factors like **metabolic syndrome**.
- This risk, however, is generally **outweighed by the cardiovascular benefits** of statin therapy in at-risk patients, making it an acceptable trade-off.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 3: Which drug is metabolized by glutathionation?
- A. Nicotinic acid
- B. Fosfomycin
- C. Benzodiazepines
- D. Dapsone (Correct Answer)
Pharmacogenomics of Drug Transporters Explanation: ***Dapsone***- **Dapsone** undergoes hepatic metabolism via **N-hydroxylation** by CYP450 enzymes (particularly CYP2E1 and CYP3A4), forming reactive **hydroxylamine metabolites**.- These reactive metabolites are toxic and can cause **methemoglobinemia** and **hemolysis**.- **Glutathione conjugation (glutathionation)** serves as an important **detoxification pathway** for these reactive dapsone metabolites [1].- Individuals with **glutathione deficiency** (such as G6PD deficiency) are at increased risk of dapsone-induced hemolytic anemia [2].*Fosfomycin*- **Fosfomycin** is primarily eliminated by the kidneys as an **unchanged drug** (up to 90% excreted unchanged in urine).- It undergoes **minimal hepatic metabolism** and does NOT undergo significant glutathionation.- Its primary route of elimination is **renal excretion** via glomerular filtration.*Benzodiazepines*- **Benzodiazepines** are primarily metabolized in the liver via **CYP450 enzymes** (Phase I oxidation) followed by **glucuronidation** (Phase II conjugation).- They do NOT undergo glutathionation as a significant metabolic pathway.*Nicotinic acid*- **Nicotinic acid** (niacin) undergoes conjugation with **glycine** to form nicotinuric acid and **methylation** to form N-methylnicotinamide.- It does NOT undergo glutathione conjugation.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 4: Which of the following is not considered a pharmacogenetic condition?
- A. Adenosine deaminase deficiency (Correct Answer)
- B. Coumarin insensitivity
- C. G6PD deficiency
- D. Malignant hyperthermia
Pharmacogenomics of Drug Transporters Explanation: ***Adenosine deaminase deficiency***
- **Adenosine deaminase deficiency** (ADA deficiency) is an **autosomal recessive** metabolic disorder causing severe immunodeficiency, primarily affecting gene function rather than drug response.
- While it can be treated with enzyme replacement therapies or gene therapy, it is not primarily characterized by an altered response to standard therapeutic drugs.
*Coumarin insensitivity*
- **Coumarin insensitivity** refers to an individual's reduced response to **warfarin (a coumarin derivative)**, requiring higher doses to achieve effective anticoagulation.
- This is a well-documented **pharmacogenetic condition**, often linked to variations in genes like *CYP2C9* and *VKORC1*.
*G6PD deficiency*
- **Glucose-6-phosphate dehydrogenase (G6PD) deficiency** is an X-linked genetic disorder that can lead to **hemolytic anemia** upon exposure to certain drugs (e.g., antimalarials, sulfonamides, aspirin) and fava beans [1].
- It is a classic example of a **pharmacogenetic condition** where genetic variations dictate drug-induced adverse reactions [1].
*Malignant hyperthermia*
- **Malignant hyperthermia** is a life-threatening, inherited disorder triggered by certain **inhalation anesthetics** (e.g., halothane, isoflurane) and the **depolarizing muscle relaxant succinylcholine**.
- This condition is caused by mutations in genes involved in calcium regulation in muscle cells (e.g., *RYR1*) and is a critical **pharmacogenetic response**.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 5: Which statin is considered most potent based on mg-to-mg LDL reduction capability?
- A. Simvastatin
- B. Pravastatin
- C. Rosuvastatin (Correct Answer)
- D. Atorvastatin
Pharmacogenomics of Drug Transporters Explanation: ***Rosuvastatin***
- **Rosuvastatin** is known for its high potency, achieving significant **LDL-C reduction** at relatively low doses.
- It is often considered the most potent statin on a **milligram-to-milligram basis**.
*Simvastatin*
- **Simvastatin** is a moderate-intensity statin, not as potent as rosuvastatin or atorvastatin in reducing LDL-C.
- While effective, it typically requires higher doses to achieve comparable **LDL-C reductions** seen with high-potency statins.
*Pravastatin*
- **Pravastatin** is a hydrophilic statin, generally considered to be of lower potency compared to other statins like rosuvastatin and atorvastatin.
- It is often used in patients with **hepatic dysfunction** due to its different metabolic profile but offers less aggressive **LDL-C reduction**.
*Atorvastatin*
- **Atorvastatin** is a high-intensity statin, very effective in reducing LDL-C, and often used for aggressive lipid lowering.
- While highly potent, **atorvastatin** is generally considered slightly less potent than **rosuvastatin** on a mg-to-mg basis, though both are used for high-intensity lipid therapy.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 6: Choose the correct options regarding the route of administration and bioavailability.
A- Intravenous =1
B- 0.75< Oral <1
C-0.75 <IM ≤ 1
D- 0.75<SC ≤ 1
IM - Intramuscular
SC- Subcutaneous
- A. A and D
- B. A and C
- C. A, C, D (Correct Answer)
- D. A, B, D
Pharmacogenomics of Drug Transporters Explanation: ***A, C, D***
- Intravenous (IV) administration has **100% bioavailability** because the drug enters the systemic circulation directly, bypassing any absorption barriers.
- Intramuscular (IM) and subcutaneous (SC) routes generally have **high bioavailability**, often between 75% and 100%, as drugs are absorbed directly into the bloodstream without first-pass metabolism.
*A and D*
- While options A and D are correct, this choice is incomplete as option C is also a correct statement regarding bioavailability.
- IM administration typically results in high systemic bioavailability, similar to SC, making its exclusion here incorrect.
*A and C*
- While options A and C are correct, this choice is incomplete as option D is also a correct statement regarding bioavailability.
- Subcutaneous administration also generally results in high bioavailability, as absorption tends to be complete.
*A, B, D*
- While options A and D are correct, option B is typically incorrect for oral bioavailability.
- Oral bioavailability of many drugs is often less than 0.75 (75%) due to factors like **first-pass metabolism** and incomplete absorption in the gastrointestinal tract.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 7: A patient on atorvastatin presents with myalgia; which test is recommended?
- A. Liver function test
- B. Blood urea nitrogen
- C. Serum potassium
- D. Creatine kinase (Correct Answer)
Pharmacogenomics of Drug Transporters Explanation: ***Creatine kinase***
- **Myalgia** in a patient on **atorvastatin** raises concern for **statin-induced myopathy**, which can range from mild muscle aches to severe **rhabdomyolysis** [1].
- **Creatine kinase (CK)** levels are commonly used to assess muscle damage, with significantly elevated levels (e.g., >10 times normal) indicating rhabdomyolysis [1].
*Liver function test*
- While atorvastatin can cause **hepatic dysfunction**, **myalgia** is not a primary symptom of liver injury [1].
- **Liver function tests (LFTs)** would be more relevant if the patient presented with jaundice, dark urine, or other signs of liver damage [1].
*Blood urea nitrogen*
- **Blood urea nitrogen (BUN)** is a marker of **kidney function**, not directly related to muscle pain or statin-induced myopathy.
- While severe **rhabdomyolysis** can lead to **acute kidney injury (AKI)**, BUN would be checked *after* CK levels indicate significant muscle breakdown.
*Serum potassium*
- **Serum potassium** levels are important for **cardiac and muscle function**, but myalgia itself does not directly indicate a potassium imbalance.
- **Hyperkalemia** can occur secondary to severe **rhabdomyolysis** due to the release of intracellular potassium from damaged muscle cells, but CK is the initial diagnostic test for muscle injury.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 8: Major mechanism of transport of drugs across biological membranes is:
- A. Passive diffusion (Correct Answer)
- B. Facilitated diffusion
- C. Active transport
- D. Endocytosis
Pharmacogenomics of Drug Transporters Explanation: ***Passive diffusion***
- This is the **most common mechanism** for drug transport across biological membranes, especially for **lipid-soluble** drugs.
- It occurs down a **concentration gradient** and does not require energy or carrier proteins.
*Facilitated diffusion*
- This process requires **carrier proteins** to move drugs across membranes, but it still occurs down a **concentration gradient** and does not consume energy directly.
- It handles substances that are **too large or too polar** to cross by passive diffusion, but it is not the primary mechanism for most drugs.
*Active transport*
- This mechanism uses **carrier proteins** and **expends energy (ATP)** to move drugs against their **concentration gradient**.
- It is important for the transport of specific drugs, but it is not the predominant mode for the majority of drug molecules.
*Endocytosis*
- This involves the **engulfment of large molecules** or particles by the cell membrane, forming vesicles.
- It is a less common mechanism for drug absorption, primarily used for **very large molecules** like proteins or nanoparticles.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 9: Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?
- A. Cyclophosphamide
- B. Methotrexate
- C. Cisplatin (Correct Answer)
- D. Dacarbazine
Pharmacogenomics of Drug Transporters Explanation: ***Cisplatin***
- **Cisplatin** is a platinum-based chemotherapy drug that forms **DNA cross-links**, inhibiting DNA synthesis and leading to the death of rapidly dividing cells, making it highly effective against **ovarian carcinoma**.
- It is a cornerstone of chemotherapy regimens for ovarian cancer, often used in combination with other agents such as paclitaxel.
*Methotrexate*
- **Methotrexate** is an **antimetabolite** that inhibits dihydrofolate reductase, thereby interfering with DNA synthesis.
- While it is used in various cancers like leukemia, lymphoma, and some solid tumors (e.g., breast cancer, gestational trophoblastic disease), it is **not a primary recommended drug for ovarian carcinoma**.
*Cyclophosphamide*
- **Cyclophosphamide** is an **alkylating agent** that causes DNA damage, leading to cell death.
- It is used in many cancers, including lymphoma, breast cancer, and some leukemias, but it is **not a first-line or primary agent for ovarian carcinoma** in contemporary treatment guidelines.
*Dacarbazine*
- **Dacarbazine** is an **alkylating agent** primarily used in the treatment of **malignant melanoma** and Hodgkin lymphoma.
- It is **not indicated for the treatment of ovarian carcinoma**.
Pharmacogenomics of Drug Transporters Indian Medical PG Question 10: Mechanism of action of allopurinol is
- A. Recombinant uricase
- B. Decrease chemotaxis
- C. Increase uric acid excretion
- D. Xanthine oxidase inhibition (Correct Answer)
Pharmacogenomics of Drug Transporters Explanation: ***Xanthine oxidase inhibition***
- **Allopurinol** acts as a **structural analog of hypoxanthine** and competitively inhibits the enzyme **xanthine oxidase**.
- By inhibiting **xanthine oxidase**, allopurinol prevents the conversion of hypoxanthine to xanthine and then to uric acid, thereby **decreasing uric acid production**.
*Recombinant uricase*
- **Recombinant uricase** (e.g., rasburicase, pegloticase) is an enzyme that catalyzes the breakdown of existing uric acid into allantoin, a more soluble compound.
- This mechanism is distinct from allopurinol, which **prevents uric acid formation**.
*Decrease chemotaxis*
- Medications that **decrease chemotaxis**, such as **colchicine**, work by interfering with the migration of neutrophils to sites of inflammation, which is useful in acute gout flares.
- This is an **anti-inflammatory mechanism**, not related to uric acid synthesis or excretion.
*Increase uric acid excretion*
- Drugs that **increase uric acid excretion** are known as **uricosurics** (e.g., probenecid, lesinurad).
- These agents act on the renal tubules to **inhibit uric acid reabsorption**, thus promoting its elimination from the body.
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