NEET-PG 2020 - Pharmacology Practice Questions

Q: What electrolyte imbalance is commonly associated with lithium use?

Hypercalcemia. ***Hypercalcemia*** - Long-term lithium therapy can lead to an increased risk of developing **primary hyperparathyroidism** (occurs in approximately 10% of chronic users), which subsequently causes hypercalcemia. - Lithium can affect the **set point of the calcium-sensing receptor** in the parathyroid glands, leading to inappropriate secretion of parathyroid hormone (PTH). - This is a **well-recognized complication** of chronic lithium therapy requiring monitoring of calcium and PTH levels. *Hyponatremia* - **Hyponatremia** is actually a frequently encountered electrolyte disturbance with lithium use, occurring through multiple mechanisms: - Lithium-induced **nephrogenic diabetes insipidus** leading to polyuria, polydipsia, and potential dehydration - Interaction with **thiazide diuretics** (which are sometimes used to treat lithium-induced polyuria, paradoxically) - SIADH-like effects in some patients - However, in the context of this examination question, **hypercalcemia due to hyperparathyroidism** is considered the characteristic chronic complication specifically linked to lithium's unique mechanism of action. *Hyperkalemia* - **Hyperkalemia** is not a commonly reported electrolyte imbalance specifically associated with lithium use. - While lithium can affect renal function and cause **renal tubular dysfunction**, this does not typically manifest as hyperkalemia. *Hypokalemia* - **Hypokalemia** is not typically associated with lithium use. - It is more commonly caused by diuretic use, vomiting, or diarrhea rather than lithium therapy directly.

Q: Which of the following antimicrobials should not be given to a chronic asthmatic patient managed on theophylline therapy?

Erythromycin. ***Erythromycin*** - **Erythromycin**, a macrolide antibiotic, is a potent inhibitor of the **cytochrome P450 (CYP450) enzyme system**, specifically **CYP1A2**, which is the primary enzyme responsible for theophylline metabolism. - Co-administration of erythromycin can significantly **increase theophylline levels**, leading to toxicity such as **nausea, vomiting, seizures, or cardiac arrhythmias.** - This interaction is clinically significant and erythromycin should be avoided in patients on theophylline therapy. *Amoxicillin* - **Amoxicillin** is a penicillin-class antibiotic that has minimal interaction with theophylline metabolism. - It does not significantly inhibit the **CYP1A2 enzyme** and is generally considered safe to use with theophylline. *Cefotaxime* - **Cefotaxime**, a third-generation cephalosporin, does not significantly affect the metabolism of theophylline. - It does not inhibit **CYP1A2 enzymes** and is safe for use in patients on theophylline therapy. *Cotrimoxazole* - **Cotrimoxazole** (trimethoprim/sulfamethoxazole) may slightly increase theophylline levels by inhibiting some CYP450 isoenzymes, but its effect is generally less pronounced than that of erythromycin. - While caution and monitoring are advised, it is not as strongly contraindicated as erythromycin due to a lower risk of significant toxicity in most cases.

Q: All-trans retinoic acid is primarily used in the treatment of which of the following tumors?

PML-RARA. ***PML-RARA*** - **All-trans retinoic acid (ATRA)** is a cornerstone treatment for **acute promyelocytic leukemia (APML)**, which is characterized by the **PML-RARA fusion gene**. - ATRA works by inducing differentiation of leukemic promyelocytes, overcoming the maturation block caused by the **PML-RARA** oncoprotein. *BCR-ABL* - The **BCR-ABL fusion gene** is characteristic of **chronic myeloid leukemia (CML)**, and sometimes in acute lymphoblastic leukemia (ALL). - The primary treatment for **BCR-ABL positive leukemias** involves **tyrosine kinase inhibitors (TKIs)**, such as imatinib, not ATRA. *CMYC* - **CMYC** is an oncogene whose dysregulation is frequently implicated in various cancers, including **Burkitt lymphoma** and some forms of acute myeloid leukemia (AML). - There is no direct therapeutic role for ATRA specifically targeting tumors driven by **CMYC overexpression**. *CEBPA* - **CEBPA** mutations are found in a subset of **acute myeloid leukemia (AML)**, often leading to a favorable prognosis. - While ATRA can be used in some AML subtypes, it is not specifically indicated or primarily effective for AML characterized solely by **CEBPA mutations**; its role is specific to **PML-RARA**.

Q: What is the first-line drug for osteoporosis in postmenopausal women?

Bisphosphonates. ***Bisphosphonates*** - **Bisphosphonates** are the **first-line treatment** for osteoporosis due to their proven efficacy in reducing fracture risk by inhibiting osteoclast activity. - They bind to bone mineral and are internalized by osteoclasts, leading to their **apoptosis** and decreased bone resorption. *OCP* - **Oral contraceptives (OCP)** are not used for treating established osteoporosis; they may have a minor protective effect against bone loss in premenopausal women but are not a primary therapeutic agent postmenopause. - OCPs primarily contain **estrogen and/or progestin** and are used for contraception and managing menstrual irregularities. *Raloxifene* - **Raloxifene** is a **selective estrogen receptor modulator (SERM)** that can be used for osteoporosis prevention and treatment, especially if there's a concern for breast cancer, but it is typically a second-line option. - Although it mimics estrogen's beneficial effects on bone, it does not have the same overall fracture reduction efficacy as bisphosphonates and can increase the risk of **venous thromboembolism**. *Strontium* - **Strontium ranelate** is an anti-osteoporotic agent that both inhibits bone resorption and promotes bone formation. - Its use has been limited due to concerns about serious side effects, including an increased risk of **cardiovascular events** and **venous thromboembolism**, making it a less favored option compared to bisphosphonates.

Q: Which drug can be given as a nail lacquer treatment in onychomycosis?

Ciclopirox olamine (nail lacquer). ***Ciclopirox olamine (nail lacquer)*** - **Ciclopirox olamine** is an antifungal agent formulated as a nail lacquer, specifically designed for topical application in **onychomycosis**. - Its mechanism involves interfering with fungal cellular processes, transported directly to the nail bed where the fungal infection resides. *Terbinafine* - **Terbinafine** is primarily an **oral antifungal** medication or available as a topical cream, but not typically in a nail lacquer formulation for onychomycosis. - While highly effective against dermatophytes causing onychomycosis, its systemic absorption is key to its efficacy when administered orally. *Nystatin* - **Nystatin** is an antifungal agent primarily effective against **Candida** species and is not typically used for dermatophyte-induced onychomycosis, nor is it commonly formulated as a nail lacquer. - Its broad spectrum is limited in this context, as most onychomycosis cases are caused by dermatophytes, which are less susceptible to nystatin. *Itraconazole* - **Itraconazole** is a **systemic antifungal** medication, effective in treating onychomycosis, but it is not available as a nail lacquer. - It works by inhibiting fungal cytochrome P450 enzymes, which are critical for ergosterol synthesis, a component of the fungal cell membrane.

Q: Drug of choice for post menopausal osteoporosis is

Bisphosphonates. ***Bisphosphonates*** - **Bisphosphonates** are considered the **first-line therapy** for established postmenopausal osteoporosis due to their proven efficacy in reducing the risk of vertebral and non-vertebral fractures. - They work by **inhibiting osteoclast activity**, thereby decreasing bone resorption and increasing bone mineral density. *Estrogen* - While **estrogen therapy** can prevent osteoporosis, it is generally not the first-line treatment due to potential risks like increased risk of **breast cancer**, **stroke**, and **venous thromboembolism**. - It is typically reserved for women with severe menopausal symptoms who also require osteoporosis prevention, and often used at the **lowest effective dose for the shortest duration**. *Thyroxine* - **Thyroxine** is a hormone used primarily to treat **hypothyroidism**, a condition where the thyroid gland doesn't produce enough thyroid hormone. - It is **not indicated for the treatment of osteoporosis** and can even worsen bone loss if given in excessive doses, leading to iatrogenic hyperthyroidism. *Teriparatide* - **Teriparatide** is an **anabolic agent** that stimulates new bone formation, making it a powerful option for severe osteoporosis or those who have failed other therapies. - However, it is an injectable medication with a **limited treatment duration** (typically 2 years) and is generally reserved for patients with a **high fracture risk** rather than being the initial drug of choice for all postmenopausal osteoporosis.

Q: A patient of biliary colic presented to hospital. Intern gave an injection and the pain worsened. Which is the most likely injection given?

Morphine. *Morphine*- **Morphine** and other opioids can cause **spasm of the sphincter of Oddi**, leading to increased pressure in the **biliary tree** and worsening of biliary colic.- This effect is mediated through **mu-opioid receptors** on the smooth muscle of the sphincter.*Diclofenac*- **Diclofenac** is a non-steroidal anti-inflammatory drug (NSAID) which is an excellent choice for **biliary colic** because it reduces inflammation and relaxes smooth muscle.- It works by inhibiting **prostaglandin synthesis**, thus reducing pain and spasm of the gallbladder.*Etoricoxib*- **Etoricoxib** is a selective COX-2 inhibitor [1], another type of NSAID, which would typically alleviate pain in biliary colic.- It reduces inflammation and pain [1] without the **sphincter of Oddi spasm** concerns associated with opioids.*Nefopam*- **Nefopam** is a non-opioid analgesic that acts as a centrally acting **serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI)**. It would typically help with pain relief.- It is not known to cause **sphincter of Oddi spasm** and would therefore not usually worsen biliary colic.

Q: Which of the following drugs act by inhibiting DNA replication?

6-Mercaptopurine. ***6-Mercaptopurine*** - This drug is a **purine analog** that acts as an **antimetabolite**, directly interfering with the **synthesis of purine nucleotides** required for DNA replication. - By inhibiting enzymes like **PRPP amidotransferase** and getting incorporated into DNA as a fraudulent nucleotide, it blocks the **de novo synthesis** pathway, preventing normal DNA replication. - This represents **direct inhibition of DNA synthesis** at the nucleotide building block level. *Mitomycin C* - This agent is an **alkylating agent** that **cross-links DNA** strands, causing DNA damage that prevents strand separation. - While it does prevent DNA replication, its mechanism is through **DNA damage and structural disruption** rather than inhibition of the DNA synthesis machinery itself. - It acts by damaging already-formed DNA rather than preventing new DNA synthesis. *Actinomycin D* - Actinomycin D is an **intercalating agent** that inserts itself between DNA base pairs, primarily **inhibiting RNA synthesis** by blocking RNA polymerase movement. - While it binds to DNA, its primary therapeutic action is on **transcription (RNA synthesis)**, not direct inhibition of DNA replication. *Asparaginase* - Asparaginase is an enzyme that **depletes asparagine** from the blood, which is an essential amino acid for certain cancer cells (e.g., leukemic cells). - Its mechanism is to starve cancer cells of asparagine, leading to **inhibition of protein synthesis**, not DNA replication.

Q: Agent that acts through tyrosine kinase receptor is

Insulin. ***Insulin*** - **Insulin** binds to its receptor, which is a **tyrosine kinase receptor**, leading to autophosphorylation and the activation of intracellular signaling pathways. - This activation is crucial for glucose uptake and metabolism by various cells in the body. *MSH* - **Melanocyte-stimulating hormone (MSH)** acts primarily through **G protein-coupled receptors**, specifically melanocortin receptors. - These receptors activate adenylyl cyclase, leading to an increase in intracellular cAMP. *TSH* - **Thyroid-stimulating hormone (TSH)** also acts via a **G protein-coupled receptor** on thyroid follicular cells. - Its binding stimulates adenylyl cyclase, increasing cAMP and thus thyroid hormone synthesis and release. *TRH* - **Thyrotropin-releasing hormone (TRH)** binds to **G protein-coupled receptors** on pituitary thyrotrophs. - This interaction activates the phospholipase C pathway, leading to the release of TSH.

Q: A boy is planning to travel by bus. Which of the following drugs can be used to prevent motion sickness in this person?

Promethazine. **Promethazine** - **Promethazine** is an **H1 antihistamine** with significant **anticholinergic** properties that effectively blocks muscarinic receptors in the **vestibular system**, making it highly effective for preventing motion sickness. - Its **sedating effects** are also beneficial in relieving the discomfort associated with motion sickness. *Fexofenadine* - **Fexofenadine** is a **second-generation H1 antihistamine** that is **non-sedating** and has minimal anticholinergic activity. - While effective for allergies, its lack of central nervous system penetration and anticholinergic action makes it **ineffective for motion sickness**. *Loratadine* - **Loratadine** is another **second-generation H1 antihistamine**, known for being **non-sedating** and having limited entry into the central nervous system. - It does not possess the significant anticholinergic properties necessary to prevent the **vestibular disturbances** that cause motion sickness. *Cetirizine* - **Cetirizine** is a **second-generation H1 antihistamine** that has **moderate sedative effects** (more than other second-generation agents) and some CNS penetration, but lacks the significant **anticholinergic activity** required for motion sickness prevention. - It is primarily used for allergies and is **not recommended** for the prevention or treatment of motion sickness.

Question 1

What electrolyte imbalance is commonly associated with lithium use?

Accepted Answer

Hypercalcemia

Answer

Hyponatremia

Answer

Hyperkalemia

Answer

Hypokalemia

Question 2

Which of the following antimicrobials should not be given to a chronic asthmatic patient managed on theophylline therapy?

Accepted Answer

Erythromycin

Answer

Amoxicillin

Answer

Cefotaxime

Answer

Cotrimoxazole

Question 3

All-trans retinoic acid is primarily used in the treatment of which of the following tumors?

Accepted Answer

PML-RARA

Answer

BCR-ABL

Answer

CMYC

Answer

CEBPA

Question 4

What is the first-line drug for osteoporosis in postmenopausal women?

Accepted Answer

Bisphosphonates

Answer

OCP

Answer

Raloxifene

Answer

Strontium

Question 5

Which drug can be given as a nail lacquer treatment in onychomycosis?

Accepted Answer

Ciclopirox olamine (nail lacquer)

Answer

Terbinafine

Answer

Nystatin

Answer

Itraconazole

Question 6

Drug of choice for post menopausal osteoporosis is

Accepted Answer

Bisphosphonates

Answer

Estrogen

Answer

Thyroxine

Answer

Teriparatide

Question 7

A patient of biliary colic presented to hospital. Intern gave an injection and the pain worsened. Which is the most likely injection given?

Accepted Answer

Morphine

Answer

Diclofenac

Answer

Etoricoxib

Answer

Nefopam

Question 8

Which of the following drugs act by inhibiting DNA replication?

Accepted Answer

6-Mercaptopurine

Answer

Mitomycin C

Answer

Actinomycin D

Answer

Asparaginase

Question 9

Agent that acts through tyrosine kinase receptor is

Accepted Answer

Insulin

Answer

MSH

Answer

TSH

Answer

TRH

Question 10

A boy is planning to travel by bus. Which of the following drugs can be used to prevent motion sickness in this person?

Accepted Answer

Promethazine

Answer

Fexofenadine

Answer

Loratadine

Answer

Cetirizine

NEET-PG 2020 — Pharmacology