NEET-PG 2013 - Pharmacology Practice Questions

Q: Which class of drugs does botulinum toxin mimic in its action?

Anticholinergics. ***Anticholinergics*** - **Botulinum toxin** inhibits the release of **acetylcholine** from **presynaptic nerve terminals** [2] by preventing vesicle fusion, leading to muscle paralysis [1]. - While the **mechanism differs** (botulinum acts presynaptically, anticholinergics act postsynaptically at receptors), the **functional outcome** is similar: reduced cholinergic neurotransmission. - In terms of **clinical effect** at the neuromuscular junction, both reduce acetylcholine's action, making anticholinergics the closest functional parallel among the given options. *Cholinergics* - **Cholinergics** enhance acetylcholine activity, either by increasing its release, mimicking its effects at receptors, or inhibiting its breakdown. - This is the **opposite** of botulinum toxin's action, which reduces acetylcholine's impact. *Adrenergics* - **Adrenergics** stimulate the **sympathetic nervous system** via **adrenergic receptors** (α and β receptors). - They act on **norepinephrine/epinephrine pathways**, not the cholinergic system where botulinum toxin acts. *Antiadrenergic* - **Antiadrenergic drugs** block **adrenergic receptors** or inhibit sympathetic activity. - These are unrelated to botulinum toxin's effect on **cholinergic neuromuscular transmission**.

Q: What is the mechanism of action of Abatacept?

Inhibitor of co-stimulation of T cells. ***Inhibitor of co-stimulation of T cells*** - Abatacept is a **fusion protein** that blocks the **CD28-CD80/86 co-stimulatory pathway**, which is crucial for full T-cell activation. - By binding to **CD80** and **CD86** on antigen-presenting cells, it prevents their interaction with **CD28** on T cells, thus inhibiting T-cell proliferation and cytokine production. *Tumor necrosis factor (TNF) alpha inhibitor* - TNF alpha inhibitors (e.g., **adalimumab**, **infliximab**, **etanercept**) bind to and neutralize **TNF alpha**, a pro-inflammatory cytokine. - While used in similar conditions, their mechanism is distinct from Abatacept's T-cell co-stimulation blockade. *Monoclonal antibody against interleukin-6 (IL-6) receptor* - Drugs like **tocilizumab** target the **IL-6 receptor**, blocking the signaling of **IL-6**, another important inflammatory cytokine. - This mechanism primarily affects cytokine signaling rather than directly inhibiting T-cell activation in the same way as abatacept. *Interleukin-1 (IL-1) receptor antagonist* - **Anakinra** is an example of an **IL-1 receptor antagonist**, which competes with IL-1 for binding to its receptor, thereby blocking its pro-inflammatory effects. - This mechanism focuses on inhibiting the action of IL-1, unlike Abatacept's role in T-cell activation.

Q: Which of the following is the most potent topical corticosteroid?

Clobetasol propionate. ***Clobetasol propionate*** - **Clobetasol propionate** is recognized as one of the most potent **Class I topical corticosteroids**, used for severe inflammatory skin conditions. - Its high potency allows for effective suppression of severe inflammation and pruritus, but also carries a greater risk of **adverse effects** with prolonged use. *Triamcinolone acetonide* - **Triamcinolone acetonide** is a **medium-potency** topical corticosteroid (Class IV-V), less potent than clobetasol propionate. - It is commonly used for moderate inflammatory skin conditions, such as eczema and psoriasis, but not for severe cases requiring maximum potency. *Hydrocortisone acetate* - **Hydrocortisone acetate** is a **low-potency** topical corticosteroid (Class VII), making it the least potent option listed. - It's often used for mild inflammatory conditions, sensitive areas like the face, or for less severe conditions requiring minimal corticosteroid strength. *Betamethasone valerate* - **Betamethasone valerate** is a **medium-to-high potency** topical corticosteroid (Class III-V), placing it among stronger corticosteroids but still less potent than clobetasol propionate. - It is effective for moderate to severe inflammatory skin conditions but does not reach the highest level of potency demonstrated by clobetasol.

Q: Which of the following reduces the efficacy of oral contraceptives?

Griseofulvin. ***Griseofulvin*** - **Griseofulvin** is an antifungal agent known to induce liver enzymes, specifically the **cytochrome P450 system**. - Enzyme induction accelerates the metabolism and clearance of **oral contraceptives**, leading to lower plasma concentrations and reduced efficacy. *Erythromycin* - **Erythromycin** is a macrolide antibiotic that typically inhibits liver enzymes rather than inducing them. - While it can interfere with the metabolism of some drugs, it usually **increases** rather than decreases the plasma levels of co-administered medications, and is not known to reduce oral contraceptive efficacy. *Disulfiram* - **Disulfiram** is used to treat chronic alcoholism and inhibits aldehyde dehydrogenase. - It does not significantly interact with the metabolism of **oral contraceptives** via the cytochrome P450 system or other mechanisms that would reduce their efficacy. *Cimetidine* - **Cimetidine** is an H2 receptor antagonist that is known to inhibit cytochrome P450 enzymes. - This inhibition would likely **increase** the plasma concentration of drugs metabolized by these enzymes, such as oral contraceptives, rather than reducing their efficacy.

Q: Which of the following antidiabetic drugs (other than insulin) is indicated as adjunct therapy for the management of both type I and type II diabetes mellitus?

Pramlintide. Pramlintide - Pramlintide is an amylin analog indicated as an adjunct therapy to insulin for both type 1 and type 2 diabetes, helping to regulate post-prandial glucose. - It slows gastric emptying, suppresses postprandial glucagon secretion, and promotes satiety, leading to reduced insulin requirements and improved glycemic control. Sulphonylureas - Sulphonylureas primarily stimulate insulin secretion from pancreatic beta cells, making them effective only in Type 2 diabetes where some beta-cell function is preserved [2]. - They are not indicated for Type 1 diabetes because these patients have absolute insulin deficiency due to beta cell destruction. Metformin - Metformin is a biguanide that primarily reduces hepatic glucose production and improves insulin sensitivity in peripheral tissues. - It is a first-line treatment for Type 2 diabetes but is generally not used for Type 1 diabetes as it does not address the fundamental lack of insulin. Acarbose - Acarbose is an alpha-glucosidase inhibitor that works by delaying carbohydrate absorption from the gastrointestinal tract, thus reducing postprandial glucose spikes [1]. - While it can be used in Type 2 diabetes to manage postprandial hyperglycemia, it is not typically indicated as an adjunct for Type 1 diabetes alongside insulin [3].

Q: Which of the following statements is FALSE regarding vincristine?

It does not cause alopecia.. ***It does not cause alopecia.*** - This statement is **false** because vincristine, like many chemotherapeutic agents, commonly causes **alopecia** (hair loss) due to its impact on rapidly dividing cells, including hair follicle cells. - While it may be considered less myelosuppressive than some other anticancer drugs, its effect on hair follicles is well-documented. *It is an alkaloid.* - This statement is **true** because vincristine is a **vinca alkaloid**, derived from the Madagascar periwinkle plant (*Catharanthus roseus*). - Vinca alkaloids are a class of antineoplastic agents that target microtubules. *Its use is associated with neurotoxicity.* - This statement is **true** as **neurotoxicity** is a prominent and dose-limiting side effect of vincristine, manifesting as peripheral neuropathy (e.g., paresthesias, foot drop, constipation due to autonomic neuropathy). - This adverse effect arises from its mechanism of action, which involves disrupting microtubules critical for axonal transport. *It is a useful drug for induction of remission in acute lymphoblastic leukemia.* - This statement is **true**; **vincristine** is a cornerstone of combination chemotherapy regimens for **acute lymphoblastic leukemia (ALL)**, particularly during the induction phase. - Its efficacy in ALL is attributed to its ability to arrest cell division in metaphase.

Q: Which of the antithyroid drugs inhibits iodine trapping?

Thiocyanates. ***Thiocyanates*** - **Thiocyanates** are competitive inhibitors of the **sodium-iodide symporter (NIS)**, which is responsible for actively transporting iodide into thyroid follicular cells (iodine trapping) [1]. - By blocking NIS, thiocyanates prevent the thyroid gland from accumulating iodide, thereby inhibiting thyroid hormone synthesis [1]. *Radioactive iodine* - **Radioactive iodine (RAI)** primarily works by being taken up by thyroid cells and emitting **beta particles**, which destroy the thyroid tissue [3]. - It does not inhibit iodine trapping, but rather uses the trapping mechanism to concentrate in the thyroid and exert its destructive effect [3]. *Iodides* - **Iodides** (e.g., Lugol's solution) paradoxically inhibit organification and hormone release from the thyroid gland, an effect known as the **Wolff-Chaikoff effect** [2]. - They also decrease the vascularity and size of the thyroid gland, making them useful in preparing patients for thyroidectomy, but do not directly inhibit iodine trapping [2]. *Methimazole* - **Methimazole** is a **thionamide** drug that primarily inhibits the enzyme **thyroid peroxidase**. - This prevents the **organification of iodide** (incorporation of iodine into tyrosine residues) and the **coupling of iodotyrosines** (forming T3 and T4), not the initial trapping of iodine.

Q: Which of the following is a mineralocorticoid antagonist?

Spironolactone. ***Spironolactone*** - **Spironolactone** is a **potassium-sparing diuretic** that acts as a competitive antagonist of **aldosterone** at the mineralocorticoid receptors in the renal tubules [1], [2]. - Its primary use is in conditions like **heart failure**, **cirrhosis with ascites**, and **primary hyperaldosteronism** (Conn's syndrome) [2]. *Inamrinone* - **Inamrinone** is a **phosphodiesterase-3 inhibitor** (PDE3 inhibitor) and is classified as an **inotropic agent**. - It increases **intracellular cAMP** in cardiac cells, leading to increased **contractility** and **vasodilation**, and is used in severe heart failure. *Nicorandil* - **Nicorandil** is a **potassium channel opener** and a **nitrate-like drug** that causes both venous and arterial vasodilation. - It is primarily used as an **antianginal agent** due to its ability to reduce cardiac workload and improve coronary blood flow. *Ketorolac* - **Ketorolac** is a **nonsteroidal anti-inflammatory drug (NSAID)** that primarily inhibits **cyclooxygenase (COX) enzymes**. - It is used for **short-term management of acute moderate to severe pain** and has no direct activity on mineralocorticoid receptors.

Question 1

Which of the following statements about hypolipidemic drugs is false?

Accepted Answer

Cholesterol reducing drugs are contraindicated in child less than 8 years

Answer

Gemfibrozil causes myopathy

Answer

Gemfibrozil can increase myopathy caused by statins

Answer

Lovastatin can cause hepatic dysfunction

Question 2

Which class of drugs does botulinum toxin mimic in its action?

Accepted Answer

Anticholinergics

Answer

Adrenergics

Answer

Antiadrenergic

Answer

Cholinergics

Question 3

What is the mechanism of action of Abatacept?

Accepted Answer

Inhibitor of co-stimulation of T cells

Answer

Tumor necrosis factor (TNF) alpha inhibitor

Answer

Monoclonal antibody against interleukin-6 (IL-6) receptor

Answer

Interleukin-1 (IL-1) receptor antagonist

Question 4

Which of the following is the most potent topical corticosteroid?

Accepted Answer

Clobetasol propionate

Answer

Triamcinolone acetonide

Answer

Hydrocortisone acetate

Answer

Betamethasone valerate

Question 5

Which of the following reduces the efficacy of oral contraceptives?

Accepted Answer

Griseofulvin

Answer

Disulfiram

Answer

Erythromycin

Answer

Cimetidine

Question 6

What are the primary mechanisms behind cardiac toxicity associated with Tricyclic antidepressants?

Accepted Answer

Both norepinephrine reuptake inhibition and anticholinergic effects on the heart

Answer

Norepinephrine reuptake inhibition only

Answer

Anticholinergic effects on the heart

Answer

Direct membrane stabilizing effects only

Question 7

Which of the following antidiabetic drugs (other than insulin) is indicated as adjunct therapy for the management of both type I and type II diabetes mellitus?

Accepted Answer

Pramlintide

Answer

Sulphonylureas

Answer

Metformin

Answer

Acarbose

Question 8

Which of the following statements is FALSE regarding vincristine?

Accepted Answer

It does not cause alopecia.

Answer

Its use is associated with neurotoxicity.

Answer

It is an alkaloid.

Answer

It is a useful drug for induction of remission in acute lymphoblastic leukemia.

Question 9

Which of the antithyroid drugs inhibits iodine trapping?

Accepted Answer

Thiocyanates

Answer

Radioactive iodine

Answer

Iodides

Answer

Methimazole

Question 10

Which of the following is a mineralocorticoid antagonist?

Accepted Answer

Spironolactone

Answer

Inamrinone

Answer

Nicorandil

Answer

Ketorolac

NEET-PG 2013 — Pharmacology