Endocrine Pharmacology Practice Questions

Q: Which of the following is an anti-progesterone drug?

Mifepristone. **Explanation:** **Mifepristone (RU-486)** is the correct answer because it is a potent **competitive progesterone receptor antagonist**. It binds to progesterone receptors with higher affinity than endogenous progesterone, preventing the hormone from maintaining the decidua. This leads to the detachment of the blastocyst and sensitization of the uterus to prostaglandins. **Analysis of Incorrect Options:** * **Cyproterone:** This is an **anti-androgen** (androgen receptor antagonist) with weak progestational activity. It is used in the management of hirsutism, acne, and precocious puberty. * **Spironolactone:** Primarily a potassium-sparing diuretic, it also acts as an **aldosterone antagonist** and has significant anti-androgenic properties. It is not an anti-progestin. * **Tamoxifen:** This is a **Selective Estrogen Receptor Modulator (SERM)**. It acts as an antagonist in the breast (used in breast cancer) but as an agonist in the bone and endometrium. **High-Yield Clinical Pearls for NEET-PG:** * **Medical Abortion Regimen:** Mifepristone (200 mg orally) is followed 36–48 hours later by **Misoprostol** (400–800 mcg) to induce uterine contractions. This is effective up to 7-9 weeks of gestation. * **Cushing’s Syndrome:** Mifepristone is also FDA-approved for controlling hyperglycemia in patients with endogenous Cushing’s syndrome (due to its **glucocorticoid receptor antagonism** at high doses). * **Emergency Contraception:** Mifepristone can be used as a single dose for emergency contraception (though Levonorgestrel and Ulipristal are more common). * **Ulipristal:** Another important Selective Progesterone Receptor Modulator (SPRM) used for emergency contraception and uterine fibroids.

Q: Which antidiabetic drug acts independently of insulin?

SGLT2 inhibitor. The correct answer is **A. SGLT2 inhibitor** (e.g., Dapagliflozin, Empagliflozin). **Mechanism of Action:** SGLT2 inhibitors act on the proximal convoluted tubule (PCT) of the kidney to inhibit the Sodium-Glucose Co-transporter 2. This prevents the reabsorption of filtered glucose, leading to **glycosuria** (excretion of glucose in the urine). Because this process depends entirely on the renal filtration of glucose and not on pancreatic function or peripheral insulin sensitivity, it is considered **insulin-independent**. This makes them effective even in patients with long-standing Type 2 Diabetes who have significant beta-cell exhaustion. **Why the other options are incorrect:** * **B. DPP4 inhibitors** (e.g., Sitagliptin) and **D. GLP1 agonists** (e.g., Liraglutide) are incretin-based therapies. They work by stimulating the pancreas to release insulin in a glucose-dependent manner [2]. * **C. Meglitinide analogues** (e.g., Repaglinide) are insulin secretagogues [1]. They close ATP-sensitive K+ channels in pancreatic beta cells, directly triggering insulin release [1], [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss & BP:** SGLT2 inhibitors promote weight loss (due to calorie loss via glucose) and lower blood pressure (due to osmotic diuresis). * **Cardio-Renal Protection:** They are the drugs of choice for diabetic patients with **Heart Failure** (reduced HFrEF) and **Chronic Kidney Disease (CKD)**. * **Side Effects:** The most characteristic side effects are **Genital Mycotic Infections** (due to high urinary glucose) and a rare risk of **Euglycemic Ketoacidosis**.

Q: Which of the following agents improves pituitary diabetes insipidus?

Chlorpropamide. **Explanation:** **Pituitary Diabetes Insipidus (Central DI)** is characterized by a deficiency of Antidiuretic Hormone (ADH/Vasopressin). The goal of treatment is to either replace ADH or enhance the body's response to the little ADH remaining [1]. **Why Chlorpropamide is correct:** Chlorpropamide is a first-generation sulfonylurea primarily used for Type 2 Diabetes. However, it has a unique secondary effect: it **potentiates the action of residual ADH** on the renal collecting ducts and may also stimulate the pituitary to release more ADH. It is effective only in partial Central DI where some endogenous ADH production is still present. **Analysis of Incorrect Options:** * **A. Water restriction:** This is the treatment for Primary Polydipsia. In DI, water restriction is dangerous as it leads to severe dehydration and hypernatremia because the kidneys cannot concentrate urine [1]. * **B. Lithium:** Lithium is a well-known cause of **Nephrogenic DI**. It inhibits adenylyl cyclase in the collecting ducts, making them resistant to ADH [2]. * **C. Chlorthiazide:** While Thiazide diuretics are used to treat Nephrogenic DI (by inducing mild hypovolemia and increasing proximal sodium/water reabsorption), they are not the primary choice for Central DI. Chlorpropamide is a more classic "textbook" answer for pharmacological enhancement of ADH in Central DI. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC) for Central DI:** Desmopressin (dDAVP) – a synthetic V2 agonist [1]. * **DOC for Nephrogenic DI:** Thiazide diuretics (e.g., Hydrochlorothiazide) and Amiloride (especially if lithium-induced). * **Other drugs for Central DI:** Carbamazepine and Clofibrate also stimulate ADH release. * **Diagnostic Test:** Water Deprivation Test followed by Desmopressin administration (Central DI shows >50% increase in urine osmolality; Nephrogenic shows little to no change) [1].

Q: Which of the following is a long-acting insulin?

Insulin glargine. ### Explanation Insulin preparations are classified based on their onset and duration of action. Understanding these kinetics is crucial for NEET-PG, as it forms the basis of "Basal-Bolus" therapy. **Correct Answer: A. Insulin glargine** Insulin glargine is a **long-acting (basal) insulin analog**. It is designed with a shifted isoelectric point (by substituting asparagine with glycine and adding two arginines), making it soluble at an acidic pH but poorly soluble at the neutral pH of subcutaneous tissue. Upon injection, it forms micro-precipitates that release insulin slowly over 24 hours. It is often called "peakless" insulin because it provides a steady background level of insulin, mimicking physiological basal secretion. **Incorrect Options:** * **B, C, and D (Lispro, Aspart, Glulisine):** These are **Rapid-acting insulin analogs**. They are designed to dissociate rapidly into monomers after subcutaneous injection, leading to a quick onset (15 mins) and short duration (3–5 hours). They are used as "prandial" or "bolus" insulin to control post-prandial glucose spikes. **High-Yield Clinical Pearls for NEET-PG:** * **Ultra-long acting:** Insulin **Degludec** has the longest half-life (>40 hours) due to the formation of multi-hexamers. * **Intermediate-acting:** **NPH (Isophane)** insulin has a "cloudy" appearance and a duration of 12–18 hours. * **Safety:** Glargine should **not** be mixed in the same syringe with other insulins, as its acidic pH (4.0) can cause the other insulins to precipitate. * **Inhaled Insulin:** Afrezza is a rapid-acting dry powder formulation.

Q: What is the most potent mineralocorticoid?

Aldosterone. **Explanation:** **Aldosterone** is the correct answer because it is the primary and most potent endogenous mineralocorticoid produced by the *zona glomerulosa* of the adrenal cortex. It plays a critical role in electrolyte balance by acting on the distal convoluted tubules and collecting ducts to promote sodium reabsorption and potassium/hydrogen excretion. **Analysis of Options:** * **Aldosterone (A):** It is the physiological gold standard for mineralocorticoid activity. While it has the highest potency, it is not used clinically for replacement therapy because it has poor oral bioavailability and a very short half-life. * **Deoxycorticosterone (DOCA) (B):** This is a precursor to aldosterone. While it possesses significant mineralocorticoid activity, its potency is much lower than that of aldosterone. * **Fludrocortisone (C):** This is a synthetic corticosteroid. While it is the **most potent mineralocorticoid used clinically** (due to its high oral efficacy), its intrinsic mineralocorticoid receptor affinity is still less than that of endogenous aldosterone. * **Triamcinolone (D):** This is a selective intermediate-acting **glucocorticoid**. It is specifically designed to have virtually zero mineralocorticoid activity, making it useful when fluid retention must be avoided. **NEET-PG High-Yield Pearls:** * **Potency Hierarchy:** Aldosterone > Fludrocortisone > DOCA. * **Clinical Use:** Fludrocortisone is the drug of choice for mineralocorticoid replacement in Addison’s disease. * **Spironolactone:** The primary antagonist used to block these potent effects in conditions like Conn’s syndrome (primary hyperaldosteronism). * **Glucocorticoid with least mineralocorticoid activity:** Dexamethasone and Betamethasone (Zero mineralocorticoid effect).

Question 1

Which of the following is an anti-progesterone drug?

Accepted Answer

Mifepristone

Answer

Cyproterone

Answer

Spironolactone

Answer

Tamoxifen

Question 2

Which of the following statements regarding finasteride is FALSE?

Accepted Answer

It blocks the conversion of testosterone to dihydrotestosterone.

Answer

It is used in the treatment of benign prostatic hyperplasia.

Answer

Impotence is well-documented after its use.

Answer

It is a 5-alpha reductase inhibitor.

Question 3

Which antidiabetic drug acts independently of insulin?

Accepted Answer

SGLT2 inhibitor

Answer

DPP4 inhibitor

Answer

Meglitinide analogues

Answer

GLP1 agonist

Question 4

All of the following may be used to treat hypercalcemia, except:

Accepted Answer

Normal saline with forced diuresis with thiazide

Answer

Plicamycin

Answer

Gallium nitrate

Answer

Mitramycin

Question 5

A 21-year-old student is diagnosed with hyperthyroidism and is being counselled on treatment options, including radioactive iodine and antithyroid medications. Carbimazole acts on which part of the thyroid hormone synthesis pathway?

Accepted Answer

Organification of iodide by thyroid peroxidase, incorporating it into tyrosine to form MIT and DIT

Answer

Cleavage of thyroglobulin by proteolysis

Answer

Coupling of monoiodotyrosine (MIT) and diiodotyrosine (DIT) forming triiodothyronine (T3) and thyroxine (T4)

Answer

Dehalogenation of iodinated tyrosine to recycle iodide

Question 6

Conversion of T4 to T3 is inhibited by all except:

Accepted Answer

Methimazole

Answer

Propranolol

Answer

Propylthiouracil

Answer

Amiodarone

Question 7

Which of the following agents improves pituitary diabetes insipidus?

Accepted Answer

Chlorpropamide

Answer

Water restriction

Answer

Lithium

Answer

Chlorthiazide

Question 8

What is the effect of adding progesterone to estrogens?

Accepted Answer

Decrease the occurrence of endometrial cancers

Answer

Decrease the estrogen action on the breast

Answer

Increase the effectiveness of the estrogens

Answer

Inhibit bone resorption

Question 9

Which of the following is a long-acting insulin?

Accepted Answer

Insulin glargine

Answer

Insulin lispro

Answer

Insulin aspart

Answer

Insulin glulisine

Question 10

What is the most potent mineralocorticoid?

Accepted Answer

Aldosterone

Answer

Deoxycorticosterone (DOCA)

Answer

Fludrocortisone

Answer

Triamcinolone

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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