FMGE 2018 — Pharmacology

Q: Exenatide is a new drug used in diabetes mellitus. Mechanism of action of this drug is:-

Release of insulin acting as agonist of GLP-1 receptors. ***Release of insulin acting as agonist of GLP-1 receptors*** - **Exenatide** is a **glucagon-like peptide-1 (GLP-1) receptor agonist**, mimicking the action of endogenous GLP-1. - This leads to glucose-dependent **insulin release**, suppression of **glucagon secretion**, delayed **gastric emptying**, and increased **satiety**, all contributing to improved glycemic control. *Inhibition of DPP-4* - This mechanism describes the action of **DPP-4 inhibitors** (e.g., sitagliptin, saxagliptin), which prevent the breakdown of endogenous GLP-1 and other **incretin hormones**. - While both GLP-1 agonists and DPP-4 inhibitors target the incretin system, exenatide directly acts as an agonist, rather than preventing breakdown. *Inhibiting intestinal absorption of carbohydrates* - This mechanism describes drugs like **alpha-glucosidase inhibitors** (e.g., acarbose, miglitol), which delay carbohydrate absorption from the gut. - Exenatide's primary action is not on carbohydrate absorption but rather on pancreatic hormone secretion and gastric emptying. *Stimulation of PPAR-gamma* - This mechanism describes **thiazolidinediones** (TZDs) like pioglitazone and rosiglitazone, which enhance **insulin sensitivity** by acting on **peroxisome proliferator-activated receptor-gamma (PPAR-gamma)** in adipose tissue. - Exenatide belongs to a different class of antidiabetic drugs with a distinct mechanism of action. [Practice more Pharmacology PYQs on OnCourse]

Q: Shortest-acting muscle relaxant is:

Succinylcholine. ***Correct: Succinylcholine*** - **Succinylcholine** is a depolarizing neuromuscular blocker with a rapid onset and a very short duration of action, typically **5-10 minutes**, due to its rapid hydrolysis by **plasma pseudocholinesterase**. - Its ultrashort action makes it ideal for **rapid sequence intubation** and other procedures requiring brief muscle relaxation. *Incorrect: Atracurium* - **Atracurium** is an intermediate-acting nondepolarizing muscle relaxant with a duration of action of approximately **20-35 minutes**. - Its metabolism occurs via Hoffman elimination and ester hydrolysis, making it suitable for patients with **renal or hepatic dysfunction**. *Incorrect: Tubocurarine* - **Tubocurarine** is a long-acting nondepolarizing muscle relaxant that is now rarely used due to its significant adverse effects, including **histamine release** and ganglion blockade. - Its duration of action can be **60-120 minutes**. *Incorrect: Pancuronium* - **Pancuronium** is a long-acting nondepolarizing muscle relaxant with a duration of action of **60-90 minutes**. - It is eliminated primarily by the **kidneys**, making its duration prolonged in patients with **renal impairment**. [Practice more Pharmacology PYQs on OnCourse]

Q: Pharmacodynamics deals with:-

Mechanism of action of a drug. 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. [Practice more Pharmacology PYQs on OnCourse]

Q: Therapeutic index of a drug is an indicator of:-

Safety. ***Safety*** - The **therapeutic index (TI)** is a ratio comparing the **toxic dose (TD50)** to the **effective dose (ED50)**: TI = TD50/ED50. - It indicates the **margin of safety** of a drug—the wider the margin between therapeutic and toxic doses, the safer the drug. - A **high therapeutic index** means greater safety; a **low therapeutic index** means the drug has a narrow safety margin. *Potency* - **Potency** refers to the amount of drug needed to produce a given effect, represented by the **ED50**. - The therapeutic index is a **ratio**, not a measure of potency alone. - A highly potent drug can still have a narrow therapeutic index if its toxic dose is close to its effective dose. *Efficacy* - **Efficacy** describes the **maximum therapeutic effect** a drug can produce, irrespective of dose. - The therapeutic index does not quantify maximum effect but rather the **safety margin** within which therapeutic effects can be achieved. *All of these* - While potency and efficacy are important drug properties, the therapeutic index **specifically indicates safety**. - TI is not a composite measure of all drug properties—it is exclusively a safety parameter. [Practice more Pharmacology PYQs on OnCourse]

Q: Shortest acting local anaesthetic

Chloroprocaine. ***Chloroprocaine*** - **Chloroprocaine** is known for its rapid onset and very **short duration of action**, typically lasting 30-60 minutes, due to its **rapid hydrolysis** by plasma and liver esterases. - Its quick metabolism makes it suitable for short procedures where a brief blockade is desired, minimizing the risk of systemic toxicity. *Dibucaine* - **Dibucaine** is a local anesthetic with a **long duration of action**, typically 2 to 4 hours, which is much longer than chloroprocaine. - It is used topically and in spinal anesthesia, but its prolonged effect makes it unsuitable as the shortest-acting option. *Procaine* - **Procaine** is an ester-type local anesthetic with a relatively **short duration of action** (approximately 30-60 minutes), but it is generally longer than that of chloroprocaine. - It was one of the first synthetic local anesthetics and is less potent and shorter-acting than many modern agents. *Cocaine* - **Cocaine** has a moderate duration of action as a local anesthetic, typically lasting 60-90 minutes, which is longer than chloroprocaine. - While it is a potent local anesthetic and vasoconstrictor, its high abuse potential and systemic side effects limit its clinical use, mainly to topical application in otolaryngology. [Practice more Pharmacology PYQs on OnCourse]

12 Previous Year Questions with Answers & Explanations

Questions

Exenatide is a new drug used in diabetes mellitus. Mechanism of action of this drug is:-

Shortest-acting muscle relaxant is:

Pharmacodynamics deals with:-

Therapeutic index of a drug is an indicator of:-

Shortest acting local anaesthetic

The drug that causes fall in elderly patients with postural hypotension is:-

For a child 3-5 months of age with H1N1, treatment Oseltamivir dose is

In the management of diabetes mellitus, lactic acidosis is caused by which of the following?

Prophylactic dose of Oseltamivir for infants (3-11 months) is?

Q10

Which of the following drugs is a direct inhibitor of clotting factor Xa?

FMGE 2018 - Pharmacology FMGE Practice Questions and MCQs

Question 1: Exenatide is a new drug used in diabetes mellitus. Mechanism of action of this drug is:-

A. Inhibiting intestinal absorption of carbohydrates
B. Release of insulin acting as agonist of GLP-1 receptors (Correct Answer)
C. Stimulation of PPAR-gamma
D. Inhibition of DPP-4

Explanation: ***Release of insulin acting as agonist of GLP-1 receptors*** - **Exenatide** is a **glucagon-like peptide-1 (GLP-1) receptor agonist**, mimicking the action of endogenous GLP-1. - This leads to glucose-dependent **insulin release**, suppression of **glucagon secretion**, delayed **gastric emptying**, and increased **satiety**, all contributing to improved glycemic control. *Inhibition of DPP-4* - This mechanism describes the action of **DPP-4 inhibitors** (e.g., sitagliptin, saxagliptin), which prevent the breakdown of endogenous GLP-1 and other **incretin hormones**. - While both GLP-1 agonists and DPP-4 inhibitors target the incretin system, exenatide directly acts as an agonist, rather than preventing breakdown. *Inhibiting intestinal absorption of carbohydrates* - This mechanism describes drugs like **alpha-glucosidase inhibitors** (e.g., acarbose, miglitol), which delay carbohydrate absorption from the gut. - Exenatide's primary action is not on carbohydrate absorption but rather on pancreatic hormone secretion and gastric emptying. *Stimulation of PPAR-gamma* - This mechanism describes **thiazolidinediones** (TZDs) like pioglitazone and rosiglitazone, which enhance **insulin sensitivity** by acting on **peroxisome proliferator-activated receptor-gamma (PPAR-gamma)** in adipose tissue. - Exenatide belongs to a different class of antidiabetic drugs with a distinct mechanism of action.

Question 2: Shortest-acting muscle relaxant is:

A. Atracurium
B. Tubocurarine
C. Succinylcholine (Correct Answer)
D. Pancuronium

Explanation: ***Correct: Succinylcholine*** - **Succinylcholine** is a depolarizing neuromuscular blocker with a rapid onset and a very short duration of action, typically **5-10 minutes**, due to its rapid hydrolysis by **plasma pseudocholinesterase**. - Its ultrashort action makes it ideal for **rapid sequence intubation** and other procedures requiring brief muscle relaxation. *Incorrect: Atracurium* - **Atracurium** is an intermediate-acting nondepolarizing muscle relaxant with a duration of action of approximately **20-35 minutes**. - Its metabolism occurs via Hoffman elimination and ester hydrolysis, making it suitable for patients with **renal or hepatic dysfunction**. *Incorrect: Tubocurarine* - **Tubocurarine** is a long-acting nondepolarizing muscle relaxant that is now rarely used due to its significant adverse effects, including **histamine release** and ganglion blockade. - Its duration of action can be **60-120 minutes**. *Incorrect: Pancuronium* - **Pancuronium** is a long-acting nondepolarizing muscle relaxant with a duration of action of **60-90 minutes**. - It is eliminated primarily by the **kidneys**, making its duration prolonged in patients with **renal impairment**.

Question 3: 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

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.

Question 4: Therapeutic index of a drug is an indicator of:-

A. All of these
B. Potency
C. Safety (Correct Answer)
D. Efficacy

Explanation: ***Safety*** - The **therapeutic index (TI)** is a ratio comparing the **toxic dose (TD50)** to the **effective dose (ED50)**: TI = TD50/ED50. - It indicates the **margin of safety** of a drug—the wider the margin between therapeutic and toxic doses, the safer the drug. - A **high therapeutic index** means greater safety; a **low therapeutic index** means the drug has a narrow safety margin. *Potency* - **Potency** refers to the amount of drug needed to produce a given effect, represented by the **ED50**. - The therapeutic index is a **ratio**, not a measure of potency alone. - A highly potent drug can still have a narrow therapeutic index if its toxic dose is close to its effective dose. *Efficacy* - **Efficacy** describes the **maximum therapeutic effect** a drug can produce, irrespective of dose. - The therapeutic index does not quantify maximum effect but rather the **safety margin** within which therapeutic effects can be achieved. *All of these* - While potency and efficacy are important drug properties, the therapeutic index **specifically indicates safety**. - TI is not a composite measure of all drug properties—it is exclusively a safety parameter.

Question 5: Shortest acting local anaesthetic

A. Dibucaine
B. Procaine
C. Chloroprocaine (Correct Answer)
D. Cocaine

Explanation: ***Chloroprocaine*** - **Chloroprocaine** is known for its rapid onset and very **short duration of action**, typically lasting 30-60 minutes, due to its **rapid hydrolysis** by plasma and liver esterases. - Its quick metabolism makes it suitable for short procedures where a brief blockade is desired, minimizing the risk of systemic toxicity. *Dibucaine* - **Dibucaine** is a local anesthetic with a **long duration of action**, typically 2 to 4 hours, which is much longer than chloroprocaine. - It is used topically and in spinal anesthesia, but its prolonged effect makes it unsuitable as the shortest-acting option. *Procaine* - **Procaine** is an ester-type local anesthetic with a relatively **short duration of action** (approximately 30-60 minutes), but it is generally longer than that of chloroprocaine. - It was one of the first synthetic local anesthetics and is less potent and shorter-acting than many modern agents. *Cocaine* - **Cocaine** has a moderate duration of action as a local anesthetic, typically lasting 60-90 minutes, which is longer than chloroprocaine. - While it is a potent local anesthetic and vasoconstrictor, its high abuse potential and systemic side effects limit its clinical use, mainly to topical application in otolaryngology.

Question 6: The drug that causes fall in elderly patients with postural hypotension is:-

A. Acarbose
B. Prazosin (Correct Answer)
C. Nor-adrenaline
D. Metformin

Explanation: ***Prazosin*** - **Alpha-1 adrenergic blocker** used to treat hypertension and benign prostatic hyperplasia (BPH) - Commonly causes **orthostatic hypotension (postural hypotension)** as a side effect by blocking alpha-1 receptors on vascular smooth muscle, preventing compensatory vasoconstriction upon standing - Leads to **dizziness, lightheadedness, and falls**, especially in elderly patients who have reduced baroreceptor sensitivity - **First-dose phenomenon** is particularly notable, with marked hypotension after the initial dose *Acarbose* - Alpha-glucosidase inhibitor used to treat type 2 diabetes by reducing carbohydrate absorption in the intestine - Primary side effects are **gastrointestinal** (flatulence, diarrhea, abdominal discomfort) - Does not affect blood pressure or cause postural hypotension *Nor-adrenaline (Norepinephrine)* - **Vasopressor** and sympathomimetic agent that causes vasoconstriction through alpha-adrenergic receptor stimulation - **Increases blood pressure** and is used to treat severe hypotension in critical care settings - Would not cause falls due to postural hypotension; rather, it counteracts hypotension *Metformin* - **Biguanide** oral hypoglycemic agent for type 2 diabetes that primarily decreases hepatic glucose production and increases insulin sensitivity - Main side effects include gastrointestinal disturbances and rare lactic acidosis - Not associated with postural hypotension or increased risk of falls

Question 7: For a child 3-5 months of age with H1N1, treatment Oseltamivir dose is

A. 12 mg BD X 5 days
B. 25 mg BD X 5 days
C. 20 mg OD X 5 days
D. 20 mg BD X 5 days (Correct Answer)

Explanation: ***20 mg BD X 5 days*** - For infants aged **3-5 months** with H1N1 influenza, the recommended dose of **Oseltamivir** is **20 mg twice daily** (BD) for **5 days**. This dosage is based on weight-based recommendations to ensure appropriate antiviral activity. - This treatment regimen is crucial for reducing the severity and duration of influenza symptoms in this vulnerable age group and should be initiated as early as possible. *12 mg BD X 5 days* - This dosage is typically recommended for younger infants, specifically those aged **less than 1 month up to 2 months** (up to 3 kg body weight). - It is **underdosing** for a child in the 3-5 months age range, which could lead to suboptimal antiviral effect. *25 mg BD X 5 days* - This dosage is generally used for children weighing **between 15 kg and 23 kg**, which is significantly higher than the average weight for an infant aged 3-5 months. - Administering this dose to a 3-5 month old would constitute an **overdose**, potentially leading to increased side effects such as nausea, vomiting, or other adverse reactions. *20 mg OD X 5 days* - While 20 mg is the correct single dose, giving it **once daily (OD)** is incorrect for treating H1N1 influenza in infants. - Oseltamivir requires a **twice-daily (BD)** regimen to maintain therapeutic drug levels and effectively inhibit viral replication over the 24-hour period.

Question 8: In the management of diabetes mellitus, lactic acidosis is caused by which of the following?

A. Pioglitazone
B. Metformin (Correct Answer)
C. Glipizide
D. Tolbutamide

Explanation: ***Metformin*** - Metformin can cause **lactic acidosis**, especially in patients with **renal impairment**, as it inhibits hepatic gluconeogenesis and lactate clearance [1]. - The risk is increased in conditions leading to **tissue hypoperfusion** or **hypoxemia**, where lactate production is elevated. *Pioglitazone* - **Pioglitazone** is a thiazolidinedione that improves insulin sensitivity but is not associated with lactic acidosis [1]. - Its main risks include **fluid retention**, **heart failure**, and increased risk of **bladder cancer**. *Glipizide* - **Glipizide** is a sulfonylurea that stimulates insulin secretion from beta cells but does not cause lactic acidosis [2]. - The primary adverse effect is **hypoglycemia** [2]. *Tolbutamide* - **Tolbutamide** is an older generation sulfonylurea, similar to glipizide, and also acts by stimulating insulin release [2]. - Its main risk is **hypoglycemia**, and it is not associated with lactic acidosis [2].

Question 9: Prophylactic dose of Oseltamivir for infants (3-11 months) is?

A. 3 mg/kg/day (Correct Answer)
B. 5 mg/kg/day
C. 1 mg/kg/day
D. 7 mg/kg/day

Explanation: ***3 mg/kg/day*** - The recommended **prophylactic dose of oseltamivir** for infants aged 3 to 11 months is **3 mg/kg once daily** for 10 days. - This dosage is essential for preventing **influenza** in this vulnerable age group when exposure is known or highly suspected. *5 mg/kg/day* - A dose of **5 mg/kg** is generally used for **treatment** of influenza in infants and children, not for prophylaxis. - This higher dose is administered twice daily for 5 days when a child is already symptomatic. *1 mg/kg/day* - This dosage is **too low** for either prophylactic or treatment use in infants and would likely be ineffective against influenza. - Sub-optimal dosing can lead to **treatment failure** and a higher risk of complications. *7 mg/kg/day* - This dosage is **higher than recommended** for prophylaxis and could potentially lead to increased adverse effects without offering additional benefit. - Higher doses are usually reserved for **severely immunocompromised** patients or specific treatment regimens, not standard prophylaxis.

Question 10: Which of the following drugs is a direct inhibitor of clotting factor Xa?

A. Argatroban
B. Fondaparinux
C. Apixaban (Correct Answer)
D. Aspirin

Explanation: ***Apixaban*** - Apixaban is an **oral direct factor Xa inhibitor**, which means it directly binds to and inactivates factor Xa. - This inhibition prevents the conversion of **prothrombin to thrombin**, thereby disrupting the coagulation cascade. *Argatroban* - Argatroban is a **direct thrombin inhibitor** (DTI), meaning it selectively binds to and inhibits thrombin (factor IIa). - It is often used in cases of **heparin-induced thrombocytopenia (HIT)** due to its non-heparin-based mechanism of action. *Fondaparinux* - Fondaparinux is an **indirect factor Xa inhibitor** that binds to antithrombin, thereby enhancing antithrombin's ability to inactivate factor Xa. - It does not directly bind to factor Xa itself, but rather potentiates the action of a natural anticoagulant. *Aspirin* - Aspirin is an **antiplatelet agent** that inhibits cyclooxygenase (COX-1), thereby reducing the production of thromboxane A2. - This mechanism primarily inhibits **platelet aggregation** and adhesion, rather than directly inhibiting a clotting factor in the coagulation cascade.