Endocrine Pharmacology Practice Questions

Q: Which of the following statements regarding thioamide drugs is correct?

They are safe in children.. Thioamides (Propylthiouracil and Methimazole/Carbimazole) are the mainstay of medical management for hyperthyroidism. **Why Option B is correct:** Thioamides are considered the **first-line treatment for hyperthyroidism in children and adolescents**. Unlike radioactive iodine (RAI), which carries theoretical risks of carcinogenesis or genetic damage in young developing tissues, or surgery, which carries risks of hypoparathyroidism and nerve damage, thioamides are safe for long-term use. Methimazole is generally preferred in children due to the lower risk of severe hepatotoxicity compared to Propylthiouracil (PTU). **Why the other options are incorrect:** * **Option A:** Thioamides do **not** aggravate endocrine exophthalmos. In fact, they are preferred over Radioactive Iodine (RAI) in patients with active Graves' ophthalmopathy, as RAI can acutely worsen eye disease due to the release of thyroid antigens. * **Option C:** Thioamides cause **reversible** inhibition of thyroid hormone synthesis by inhibiting thyroid peroxidase. Once the drug is discontinued, thyroid function typically returns to its baseline state. * **Option D:** Relapse is a significant drawback of thioamide therapy. Even after a full 12–18 month course, the **relapse rate for Graves' disease is approximately 50-60%**. **High-Yield NEET-PG Pearls:** * **Mechanism:** Inhibits Thyroid Peroxidase (TPO) enzyme; PTU also inhibits peripheral conversion of T4 to T3. * **Pregnancy:** PTU is preferred in the **1st trimester** (less teratogenic); Methimazole is preferred in the **2nd and 3rd trimesters** (less hepatotoxic). * **Side Effects:** The most serious side effect is **agranulocytosis** (presents as sore throat/fever); the most common is a maculopapular rash.

Q: Which of the following statements is true?

Cyproterone is a potent antiandrogen.. ### Explanation **Correct Option: D. Cyproterone is a potent antiandrogen.** Cyproterone acetate is a competitive antagonist at the androgen receptor. It also possesses progestational activity, which suppresses LH secretion via negative feedback, further reducing testosterone levels. It is clinically used to treat hirsutism in females, precocious puberty in boys, and as palliative therapy for prostatic carcinoma. **Analysis of Incorrect Options:** * **A. Clomiphene:** While clomiphene acts as an **antiestrogen** in the hypothalamus and pituitary (blocking negative feedback to increase GnRH, FSH, and LH), it acts as a **weak agonist (estrogenic)** in the uterus and vagina. It is classified as a Selective Estrogen Receptor Modulator (SERM). * **B. Danazol:** Danazol is an ethisterone derivative that **decreases** FSH and LH secretion by inhibiting the mid-cycle surge. It creates a "pseudomenopause" state and is used in endometriosis and hereditary angioedema. * **C. Methimazole:** Methimazole (and PTU) inhibits the enzyme **thyroid peroxidase**, thereby blocking the synthesis (organification and coupling) of thyroid hormones. It does **not** inhibit the release of preformed hormones; that is the mechanism of action of **Iodides** (Lugol’s iodine). **High-Yield NEET-PG Pearls:** * **Cyproterone vs. Flutamide:** Flutamide is a pure antiandrogen (no progestational activity) often used in prostatic cancer to prevent the "testosterone flare" caused by GnRH agonists. * **Clomiphene:** The drug of choice for infertility due to anovulation (PCOS). A common side effect is multiple pregnancies. * **Thioamides:** Methimazole is preferred over PTU due to a longer half-life and lower hepatotoxicity, except in the **first trimester of pregnancy** and thyroid storm, where PTU is preferred.

Q: Which of the following statements about biguanides is NOT true?

Renal dysfunction is not a contraindication for their use. **Explanation:** Biguanides, primarily **Metformin**, are the first-line pharmacological agents for Type 2 Diabetes Mellitus. Understanding their safety profile and mechanism is crucial for NEET-PG. **Why Option C is the correct (False) statement:** Metformin is primarily excreted unchanged by the kidneys. In patients with renal impairment, the drug accumulates, significantly increasing the risk of **Lactic Acidosis**—a rare but potentially fatal metabolic complication. Therefore, renal dysfunction is a **strict contraindication**. Current guidelines suggest Metformin should not be initiated if the eGFR is <45 ml/min and must be discontinued if the eGFR falls below 30 ml/min. **Analysis of other options:** * **Option A (True):** Unlike sulfonylureas, biguanides are **euglycemic** agents. They do not stimulate pancreatic beta cells to release insulin; hence, they do not cause hypoglycemia when used as monotherapy. * **Option B (True):** The primary mechanism of Metformin is the activation of **AMP-activated protein kinase (AMPK)**, which leads to decreased hepatic gluconeogenesis (glucose production). * **Option D (True):** Metformin is frequently combined with sulfonylureas (like Glimepiride) to achieve synergistic glycemic control, as they have different mechanisms of action. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mechanism:** Inhibits mitochondrial complex I and activates AMPK. 2. **Weight Neutrality:** Metformin is often associated with modest weight loss, making it ideal for obese diabetics. 3. **Side Effects:** Gastrointestinal upset (most common) and **Vitamin B12 deficiency** (long-term use). 4. **Pleiotropic Benefits:** It improves lipid profiles and is used off-label in Polycystic Ovary Syndrome (PCOS) to improve insulin sensitivity.

Q: All of the following reduce T4 absorption except:

Metformin. **Explanation:** The absorption of **Levothyroxine (T4)** occurs primarily in the duodenum and jejunum and is highly sensitive to the presence of food, gastric pH, and concomitant medications. **Why Metformin is the correct answer:** Metformin does **not** interfere with the gastrointestinal absorption of T4. Instead, Metformin is known for a unique pharmacodynamic effect: it can cause **suppression of TSH levels** in hypothyroid patients without altering free T4 or T3 levels. The mechanism is thought to involve enhanced central dopaminergic tone or direct effects on the thyrotrophs in the pituitary, but it does not reduce the bioavailability of exogenous thyroxine. **Why the other options are incorrect:** * **Iron salts (B):** Ferrous sulfate and other iron supplements form insoluble complexes with thyroxine in the gut, significantly reducing its absorption. * **Raloxifene (C):** This Selective Estrogen Receptor Modulator (SERM) has been shown to malabsorb T4, likely through competitive binding or interference with the intestinal transport mechanism. * **Colesevelam (D):** As a bile acid sequestrant, it binds to thyroxine in the gastrointestinal tract, preventing its absorption. Other resins like Cholestyramine act similarly. **High-Yield Clinical Pearls for NEET-PG:** * **Administration Rule:** T4 should be taken on an **empty stomach** (30–60 minutes before breakfast) to ensure maximum absorption. * **Other drugs reducing T4 absorption:** Calcium carbonate, Proton Pump Inhibitors (PPIs - due to increased gastric pH), Aluminum hydroxide, and Sucralfate. * **Estrogen Effect:** Oral estrogens increase **Thyroxine-Binding Globulin (TBG)**, necessitating an increase in the T4 dose in hypothyroid women starting HRT or OCPs.

Q: Epalrestat is an?

Aldolasereductase inhibitor. **Explanation:** **Epalrestat** is a specific, reversible inhibitor of the enzyme **Aldose Reductase**. **Mechanism of Action:** In states of chronic hyperglycemia (Diabetes Mellitus), the normal glycolytic pathway becomes saturated. Excess glucose is then shunted to the **Polyol Pathway**, where Aldose Reductase converts glucose into **sorbitol**. Sorbitol is polar, does not easily cross cell membranes, and accumulates intracellularly. This leads to osmotic stress, oxidative damage, and decreased nerve conduction velocity. By inhibiting Aldose Reductase, Epalrestat prevents sorbitol accumulation, thereby delaying the progression of **diabetic peripheral neuropathy**. **Analysis of Incorrect Options:** * **Option B (Fructose congener):** Fructose is the end-product of the polyol pathway (sorbitol is converted to fructose by sorbitol dehydrogenase). Epalrestat does not mimic fructose; it prevents its precursor's formation. * **Option C & D (Glucose receptor/reuptake):** Epalrestat does not significantly affect systemic blood glucose levels, insulin receptors, or SGLT transporters. Its action is localized to preventing end-organ damage rather than glycemic control. **Clinical Pearls for NEET-PG:** * **Indication:** Primarily used for the improvement of subjective neuropathy symptoms (numbness, pain) and abnormal vibratory sensation. * **Metabolism:** It is primarily metabolized by the liver; hence, caution is advised in patients with hepatic impairment. * **Side Effects:** Common side effects include elevation of liver enzymes (ALT/AST), nausea, and abdominal pain. * **High-Yield Fact:** While many Aldose Reductase Inhibitors (like Alrestatin or Sorbinil) failed clinical trials due to toxicity, Epalrestat is clinically approved and widely used in countries like India and Japan.

Q: What is the most common side effect of Dapagliflozin?

All of the above. **Explanation:** **Dapagliflozin** is a selective inhibitor of the **Sodium-Glucose Co-transporter 2 (SGLT2)** located in the proximal convoluted tubule of the kidney. By inhibiting this transporter, the drug prevents the reabsorption of filtered glucose, leading to its excretion in the urine. **Why "All of the above" is correct:** The mechanism of action directly leads to the clinical effects listed: 1. **Glycosuria:** This is the primary pharmacodynamic effect. By blocking glucose reabsorption, Dapagliflozin induces significant glucose excretion in the urine. 2. **Weight Loss:** Since glucose is a source of calories (4 kcal/g), the chronic loss of glucose through urine results in a net caloric deficit, leading to modest but consistent weight loss in diabetic patients. 3. **Fatigue:** This can occur as a side effect due to mild volume depletion (osmotic diuresis caused by glycosuria) or as a result of the shift in metabolic substrate utilization. **Clinical Pearls for NEET-PG:** * **Genitourinary Infections:** The most clinically significant side effect to remember is an increased risk of **vulvovaginal candidiasis** and urinary tract infections (UTIs) due to the glucose-rich environment in the urinary tract. * **Euglycemic Ketoacidosis:** A rare but high-yield side effect where patients present with ketoacidosis despite near-normal blood glucose levels. * **Cardiorenal Benefits:** SGLT2 inhibitors are now first-line for patients with Heart Failure (reduced Ejection Fraction) and Chronic Kidney Disease, regardless of diabetic status. * **Contraindication:** They are generally not initiated if the eGFR is <30 mL/min/1.73 m².

Q: Which is the longest-acting insulin?

Degludec. **Explanation:** **Correct Answer: A. Degludec** Insulin Degludec is currently the longest-acting basal insulin analog available. Its prolonged duration of action (over 42 hours) is due to its unique chemical structure: the deletion of threonine at position B30 and the attachment of a 16-carbon fatty acid chain to lysine at B29. Upon subcutaneous injection, it forms **multi-hexamers**, which result in a slow, continuous release into the circulation. This provides a stable, "peakless" profile with significantly less intra-individual variability compared to other insulins. **Incorrect Options:** * **B. Aspart:** This is a **rapid-acting** insulin analog (onset: 10–20 mins; duration: 3–5 hours). It is used for postprandial glucose control. * **C. Regular Insulin:** This is a **short-acting** insulin. It is the only form that can be given intravenously (IV) and is the drug of choice for Diabetic Ketoacidosis (DKA). Its duration is approximately 5–8 hours. * **D. Glargine:** This is a **long-acting** insulin analog. While it was the standard for basal therapy for years, its duration is roughly 24 hours. Degludec has a significantly longer half-life and duration than Glargine U100. **High-Yield Clinical Pearls for NEET-PG:** * **Ultra-long acting:** Degludec (>42h) > Glargine U300 (>36h) > Glargine U100 (24h) > Detemir (~20h). * **Flexibility:** Due to its long half-life, Degludec allows for more flexibility in dosing timing compared to Glargine. * **Safety:** Degludec is associated with a lower risk of **nocturnal hypoglycemia** compared to NPH or Glargine. * **Afrezza:** The only FDA-approved **inhaled** insulin (rapid-acting); contraindicated in smokers and COPD patients.

Q: Metyrapone inhibits which enzyme?

11-beta-hydroxylase. **Explanation:** **Metyrapone** is a selective inhibitor of the enzyme **11-beta-hydroxylase** (CYP11B1) [1]. This enzyme is responsible for the final step of cortisol synthesis in the adrenal cortex, converting 11-deoxycortisol into cortisol [1]. 1. **Why Option A is correct:** By inhibiting 11-beta-hydroxylase, Metyrapone significantly reduces cortisol production. This leads to a compensatory increase in ACTH secretion (due to loss of negative feedback), which in turn causes an accumulation of the precursor **11-deoxycortisol** [1]. This precursor is excreted in the urine as 17-hydroxycorticosteroids, making the "Metyrapone test" a diagnostic tool for assessing pituitary ACTH reserve [1]. 2. **Why Options B and C are incorrect:** Metyrapone does not inhibit **21-beta-hydroxylase**. 21-beta-hydroxylase is an enzyme involved in the earlier steps of both the glucocorticoid and mineralocorticoid pathways (converting progesterone to DOC and 17-OH progesterone to 11-deoxycortisol). Deficiency or inhibition of this enzyme is the most common cause of Congenital Adrenal Hyperplasia (CAH), but it is not the target of Metyrapone. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Use:** Metyrapone is primarily used for the medical management of **Cushing’s Syndrome** (especially in pregnant patients, as it is safer than other options) and for testing the Hypothalamic-Pituitary-Adrenal (HPA) axis [1]. * **Side Effects:** Because it shifts steroid precursors toward the androgen pathway, it can cause **hirsutism** and acne in women. It can also cause hypertension due to the accumulation of 11-deoxycorticosterone (DOC), which has mineralocorticoid activity [1]. * **Comparison:** Unlike Ketoconazole (which inhibits multiple CYP enzymes), Metyrapone is relatively selective for the 11-beta-hydroxylation step [1].

Q: Which of the following antifungal drugs can be used in the treatment of Cushing syndrome?

Ketoconazole. **Explanation:** **Ketoconazole** is the correct answer because of its unique ability to inhibit steroidogenesis. While primarily an antifungal, at high doses, it non-selectively inhibits several cytochrome P450 enzymes, most notably **11β-hydroxylase** and **17α-hydroxylase (CYP17)**. This inhibition blocks the synthesis of cortisol in the adrenal cortex, making it a first-line medical therapy for controlling hypercortisolism in patients with Cushing syndrome (especially those awaiting surgery or with ectopic ACTH production). **Why other options are incorrect:** * **Fluconazole, Itraconazole, and Miconazole:** These are newer-generation azoles designed to be more selective for fungal CYP450 enzymes (lanosterol 14α-demethylase). They lack the potent inhibitory effect on human adrenal steroidogenic enzymes seen with Ketoconazole. Therefore, they do not significantly lower systemic cortisol levels and have no role in treating Cushing syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Ketoconazole inhibits the first step of steroid synthesis (cholesterol side-chain cleavage) and subsequent hydroxylase steps. * **Adverse Effects:** Due to its non-selective nature, it also inhibits testosterone synthesis, leading to **gynecomastia** and decreased libido in males. * **Hepatotoxicity:** It is associated with a risk of severe liver injury; hence, LFTs must be monitored. * **Other Adrenal Inhibitors:** Other drugs used in Cushing include **Metyrapone** (selective 11β-hydroxylase inhibitor), **Mitotane** (adrenolytic), and **Pasireotide** (somatostatin analog).

Q: All of the following are true about GLP-1 analogues EXCEPT?

Exenatide is safe in renal failure. **Explanation:** The correct answer is **B**, as Exenatide is **not** safe in renal failure. **1. Why Option B is the Correct Answer (The False Statement):** Exenatide is primarily eliminated by the kidneys via glomerular filtration. Its clearance is significantly reduced in patients with renal impairment. It is strictly **contraindicated** in patients with severe renal impairment or end-stage renal disease (CrCl <30 mL/min) due to the risk of accumulation and nephrotoxicity. In contrast, Liraglutide is generally considered safer in mild-to-moderate renal impairment as it is not primarily cleared by the kidneys. **2. Analysis of Other Options:** * **Option A (Subcutaneous administration):** Most GLP-1 analogues (Exenatide, Liraglutide, Dulaglutide) are administered subcutaneously. While an oral formulation of Semaglutide exists (Rybelsus), the traditional class characteristic taught for exams is their peptide nature, requiring parenteral delivery to avoid gastric degradation. * **Option C (Acute Pancreatitis):** This is a well-documented, high-yield adverse effect of GLP-1 agonists and DPP-4 inhibitors. Patients presenting with severe abdominal pain radiating to the back should have these drugs discontinued immediately. * **Option D (Retinopathy):** Large clinical trials (like SUSTAIN-6) have shown that rapid improvement in glycemic control with potent GLP-1 agonists like Semaglutide and Liraglutide can lead to a transient worsening of diabetic retinopathy. **Clinical Pearls for NEET-PG:** * **Weight Loss:** GLP-1 analogues are highly effective for weight loss (Liraglutide and Semaglutide are FDA-approved for obesity). * **CV Benefit:** Liraglutide, Dulaglutide, and Semaglutide reduce the risk of Major Adverse Cardiovascular Events (MACE). * **Contraindication:** Avoid in patients with a personal or family history of **Medullary Thyroid Carcinoma (MTC)** or Multiple Endocrine Neoplasia type 2 (MEN 2).

Question 1

Which of the following statements regarding thioamide drugs is correct?

Accepted Answer

They are safe in children.

Answer

They aggregate endocrine exophthalmos.

Answer

They produce irreversible hypothyroidism.

Answer

They do not produce relapse.

Question 2

Which of the following statements is true?

Accepted Answer

Cyproterone is a potent antiandrogen.

Answer

Clomiphene acts as an antiestrogen on both the pituitary and hypothalamus.

Answer

Danazol increases both FSH and LH.

Answer

Methimazole inhibits thyroxine release from the thyroid.

Question 3

Which of the following statements about biguanides is NOT true?

Accepted Answer

Renal dysfunction is not a contraindication for their use

Answer

Do not stimulate insulin release

Answer

Decrease hepatic glucose production

Answer

Can be combined with sulfonylureas

Question 4

All of the following reduce T4 absorption except:

Accepted Answer

Metformin

Answer

Iron salts

Answer

Raloxifene

Answer

Colesevelam

Question 5

Epalrestat is an?

Accepted Answer

Aldolasereductase inhibitor

Answer

Fructose cogener

Answer

Glucose receptor blocker

Answer

Glucose reuptake activator

Question 6

What is the most common side effect of Dapagliflozin?

Accepted Answer

All of the above

Answer

Glycosuria

Answer

Weight loss

Answer

Fatigue

Question 7

Which is the longest-acting insulin?

Accepted Answer

Degludec

Answer

Aspart

Answer

Regular insulin

Answer

Glargine insulin

Question 8

Metyrapone inhibits which enzyme?

Accepted Answer

11-beta-hydroxylase

Answer

21-beta-hydroxylase

Answer

Both enzymes

Answer

Neither enzyme

Question 9

Which of the following antifungal drugs can be used in the treatment of Cushing syndrome?

Accepted Answer

Ketoconazole

Answer

Fluconazole

Answer

Itraconazole

Answer

Miconazole

Question 10

All of the following are true about GLP-1 analogues EXCEPT?

Accepted Answer

Exenatide is safe in renal failure

Answer

All drugs have to be given subcutaneously

Answer

They can lead to acute pancreatitis

Answer

Liraglutide can lead to retinopathy

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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