Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 461: What is the standard dosage of Testosterone?

A. 300 mg/week
B. 100 mg/week (Correct Answer)
C. 200 mg/week
D. 150 mg/week

Explanation: **Explanation:** The standard replacement dose for testosterone in male hypogonadism aims to mimic the physiological production of testosterone in a healthy adult male, which is approximately **5–7 mg per day** (roughly 35–50 mg per week). **1. Why 100 mg/week is correct:** When using long-acting esters like **Testosterone Enanthate or Cypionate** (the most common injectable forms), the standard therapeutic dosage is **75–100 mg administered intramuscularly once a week**, or 200 mg every two weeks. This dosage typically maintains serum testosterone levels within the normal physiological range (300–1000 ng/dL) without causing excessive fluctuations or significant erythrocytosis. **2. Analysis of incorrect options:** * **150 mg/week & 200 mg/week:** While these doses are occasionally used in specific clinical scenarios, they often lead to supraphysiological peaks. Chronic administration at these levels increases the risk of side effects like polycythemia, acne, and gynecomastia (due to aromatization to estrogen). * **300 mg/week:** This is considered a **supraphysiological/performance-enhancing dose** rather than a medical replacement dose. It significantly increases the risk of cardiovascular strain and suppression of the HPT (Hypothalamic-Pituitary-Testicular) axis. **Clinical Pearls for NEET-PG:** * **Route of Administration:** Oral testosterone (undecanoate) has high first-pass metabolism; hence, injectable esters or transdermal patches/gels are preferred. * **Monitoring:** Always monitor **Hematocrit** (risk of polycythemia) and **PSA** (Prostate-Specific Antigen) before and during therapy. * **Contraindications:** Carcinoma of the prostate or breast in males is an absolute contraindication. * **Side Effects:** Cholestatic jaundice is specifically associated with **17-alpha-alkylated derivatives** (e.g., Methyltestosterone).

Question 462: Carbimazole causes which of the following congenital anomalies?

A. Aplasia cutis (Correct Answer)
B. Ventricular septal defect
C. Urinary tract anomalies
D. Atrial septal defect

Explanation: **Explanation:** **Carbimazole** (and its active metabolite, Methimazole) is a thionamide used to treat hyperthyroidism. It is considered a **teratogen**, particularly when administered during the first trimester of pregnancy. 1. **Why Aplasia Cutis is correct:** The use of Carbimazole/Methimazole during embryogenesis is specifically associated with **Methimazole Embryopathy**. The hallmark of this condition is **Aplasia Cutis Congenita**, a focal deficiency of all layers of the skin, most commonly presenting as a "punched-out" ulcer or scar on the **scalp**. Other associated features include choanal atresia and esophageal atresia. 2. **Why the other options are incorrect:** * **Ventricular Septal Defect (VSD) & Atrial Septal Defect (ASD):** While some studies suggest a slight increase in various cardiac defects with thionamides, they are not the classic, pathognomonic association for Carbimazole. Lithium, for example, is more specifically linked to Ebstein’s anomaly. * **Urinary tract anomalies:** These are not part of the specific Methimazole Embryopathy syndrome. **Clinical Pearls for NEET-PG:** * **Drug of Choice in Pregnancy:** * **1st Trimester:** **Propylthiouracil (PTU)** is preferred because it is more highly protein-bound, crosses the placenta less readily, and is not associated with aplasia cutis. * **2nd & 3rd Trimester:** Switch to **Methimazole/Carbimazole** to avoid the risk of PTU-induced maternal hepatotoxicity. * **Mechanism:** Carbimazole inhibits the enzyme **thyroid peroxidase**, preventing the iodination of tyrosine residues on thyroglobulin. * **High-Yield Association:** Always link "Scalp defects" or "Choanal atresia" with Methimazole/Carbimazole in fetal pharmacology questions.

Question 463: Which of the following drugs is used in the management of diabetes mellitus?

A. Salmeterol
B. Acetohexamide (Correct Answer)
C. Benserazide
D. Methoxamine

Explanation: Explanation: Correct Answer: B. Acetohexamide Acetohexamide is a first-generation sulfonylurea [2]. The mechanism of action involves binding to the Sulfonylurea Receptor-1 (SUR1) on pancreatic beta cells, which closes ATP-sensitive potassium channels. This leads to cell depolarization, calcium influx, and the subsequent release of stored insulin [1]. While first-generation sulfonylureas are less commonly used today due to the preference for more potent second-generation agents (like Glimepiride) [2], they remain a classic pharmacological category for diabetes management. Analysis of Incorrect Options: A. Salmeterol: A Long-Acting Beta-2 Agonist (LABA) used primarily in the maintenance treatment of asthma and COPD. It has no role in glycemic control. C. Benserazide: A peripheral dopa-decarboxylase inhibitor. It is administered in combination with Levodopa (e.g., Co-beneldopa) to treat Parkinson’s disease by preventing the peripheral conversion of Levodopa to Dopamine. D. Methoxamine: A selective alpha-1 adrenergic agonist. It is used as a vasopressor to treat hypotension, particularly during anesthesia, by inducing systemic vasoconstriction. High-Yield Clinical Pearls for NEET-PG: Sulfonylureas: The most common side effect is hypoglycemia [3]. First-generation agents (Acetohexamide, Chlorpropamide) are more likely to cause a Disulfiram-like reaction with alcohol. Chlorpropamide: Unique among sulfonylureas for causing SIADH (Syndrome of Inappropriate Antidiuretic Hormone). Excretion: Acetohexamide has an active metabolite (hydroxyhexamide) that is renally excreted; thus, it should be avoided in patients with renal impairment.

Question 464: Continuous administration of GnRH -

A. Stimulates the hypothalamic-pituitary axis
B. Suppresses the hypothalamic-pituitary axis (Correct Answer)
C. May suppress or stimulate the hypothalamic-pituitary axis
D. Has no effect on the hypothalamic-pituitary axis

Explanation: **Explanation:** The physiological release of Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus is **pulsatile** (occurring every 90–120 minutes). This pulsatility is essential for stimulating the anterior pituitary to release LH and FSH. **Why Option B is Correct:** When GnRH is administered **continuously** (non-pulsatile), it initially causes a brief "flare" of gonadotropin release. However, this is rapidly followed by the **downregulation and desensitization** of GnRH receptors on the pituitary gonadotropes. This leads to a profound suppression of the hypothalamic-pituitary-gonadal axis, resulting in decreased levels of LH, FSH, and sex steroids (testosterone/estrogen). This pharmacological state is often referred to as "medical castration." **Why Other Options are Incorrect:** * **Option A:** Stimulation only occurs with **pulsatile** administration. Continuous exposure leads to receptor internalization and inhibition. * **Option C:** While there is a transient initial stimulation (flare), the definitive and therapeutic effect of continuous administration is always suppression. * **Option D:** GnRH is a potent regulator of the axis; it never has "no effect." **NEET-PG High-Yield Pearls:** * **GnRH Agonists:** Leuprolide, Goserelin, Nafarelin, Buserelin. * **Clinical Uses of Continuous GnRH:** Prostate cancer, endometriosis, precocious puberty, and uterine fibroids. * **The "Flare" Phenomenon:** In prostate cancer, the initial surge in testosterone can worsen bone pain. This is prevented by co-administering an androgen receptor blocker (e.g., Flutamide) during the first few weeks of therapy. * **GnRH Antagonists:** (e.g., Cetrorelix, Ganirelix) suppress the axis immediately without the initial flare.

Question 465: What is a common side effect of clomiphene citrate?

A. Alopecia
B. Hot flushes
C. Ovarian hyperstimulation syndrome
D. All of the above (Correct Answer)

Explanation: **Explanation:** Clomiphene citrate is a **Selective Estrogen Receptor Modulator (SERM)** and the first-line treatment for ovulatory dysfunction in PCOS. It acts as a competitive antagonist at estrogen receptors in the hypothalamus. By blocking the negative feedback of endogenous estrogen, it leads to an increase in GnRH pulse frequency, subsequently increasing FSH and LH levels to stimulate follicular development. **Why "All of the above" is correct:** * **Hot flushes (Option B):** This is the **most common** side effect (occurring in ~10% of patients). It occurs because clomiphene blocks estrogen receptors in the hypothalamus, mimicking a "hypoestrogenic" state similar to menopause. * **Ovarian Hyperstimulation Syndrome (OHSS) (Option C):** While less common with clomiphene than with gonadotropins, it can still occur due to the stimulation of multiple follicles. It can also lead to **multiple pregnancies** (mostly twins). * **Alopecia (Option A):** Reversible hair thinning is a documented, though less frequent, side effect of clomiphene therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Antagonist at the hypothalamus (blocks negative feedback) but acts as a partial agonist in the ovaries. * **Visual Disturbances:** A high-yield side effect; patients may report blurring or "scintillating scotoma." If these occur, the drug should be discontinued. * **Anti-estrogenic effects:** It can cause thinning of the endometrium and thickening of cervical mucus, which may paradoxically hinder conception despite successful ovulation. * **Risk of Multiple Gestation:** Approximately 5–10% (primarily twins).

Question 466: All of the following drugs cause osteoporosis except?

A. Steroid
B. Alendronate (Correct Answer)
C. Thyroxine
D. Heparin

Explanation: **Explanation:** The correct answer is **Alendronate** because it is a **Bisphosphonate**, which is a drug used to **treat** osteoporosis, not cause it. **1. Why Alendronate is correct:** Alendronate inhibits osteoclast-mediated bone resorption. It binds to hydroxyapatite crystals in the bone and, when taken up by osteoclasts, inhibits the enzyme **farnesyl pyrophosphate synthase**. This leads to osteoclast apoptosis, thereby increasing bone mineral density (BMD) and reducing fracture risk. **2. Why the other options are incorrect:** * **Steroids (Glucocorticoids):** These are the most common cause of drug-induced osteoporosis. They decrease osteoblast activity, increase osteoclast survival, and decrease intestinal calcium absorption. * **Thyroxine:** Excess thyroid hormone (as in hyperthyroidism or over-replacement therapy) increases bone turnover with a net shift toward resorption, leading to secondary osteoporosis. * **Heparin:** Long-term use of unfractionated heparin (UFH) stimulates osteoclasts and inhibits osteoblasts, leading to decreased bone density. (Note: LMWH has a lower risk than UFH). **High-Yield Clinical Pearls for NEET-PG:** * **Other drugs causing osteoporosis:** Phenytoin, Phenobarbital (via Vitamin D metabolism), GnRH agonists, Aromatase inhibitors, and Proton Pump Inhibitors (PPIs). * **Alendronate Administration:** Must be taken on an empty stomach with a full glass of water, and the patient must remain upright for 30 minutes to prevent **erosive esophagitis**. * **Rare side effect of Bisphosphonates:** Osteonecrosis of the Jaw (ONJ) and atypical subtrochanteric fractures.

Question 467: Danazol is used in all of the following conditions except:

A. Fibroadenosis of breast
B. Dysfunctional uterine bleeding
C. Pituitary adenoma (Correct Answer)
D. Endometriosis

Explanation: **Explanation:** **Danazol** is a synthetic ethisterone derivative that acts as a **weak androgen** and a **mixed agonist/antagonist** of steroid receptors. Its primary mechanism involves inhibiting the mid-cycle surge of LH and FSH by suppressing the hypothalamic-pituitary-ovarian axis, leading to a state of "pseudomenopause." **Why Pituitary Adenoma is the Correct Answer:** Danazol is **not** used to treat pituitary adenomas [1]. In fact, because Danazol suppresses the feedback loop, it is contraindicated in patients with undiagnosed abnormal uterine bleeding or significant pituitary dysfunction. Pituitary adenomas (like prolactinomas or GH-secreting tumors) are typically managed with dopamine agonists (Cabergoline), somatostatin analogs (Octreotide), or surgery. **Analysis of Incorrect Options:** * **Endometriosis:** This is the primary clinical indication for Danazol [1]. It causes atrophy of ectopic endometrial tissue by creating a hypoestrogenic, hyperandrogenic environment. * **Fibroadenosis (Fibrocystic Breast Disease):** Danazol reduces breast pain and nodularity by suppressing the hormonal fluctuations that stimulate breast tissue [1]. * **Dysfunctional Uterine Bleeding (DUB):** By inducing endometrial atrophy and inhibiting ovulation, Danazol effectively reduces menstrual blood loss. **High-Yield Clinical Pearls for NEET-PG:** * **Other Indications:** Hereditary Angioedema [1] (increases synthesis of C1 esterase inhibitor) and ITP. * **Side Effects:** Significant androgenic effects (weight gain [1], acne, hirsutism, deepening of voice) and hepatotoxicity [2]. * **Contraindication:** Pregnancy (risk of virilization of female fetus) [2]. * **Mechanism Summary:** "4-I's" — **I**nhibits steroidogenic enzymes, **I**nhibits gonadotropin release, **I**ncreases free testosterone (displaces from SHBG), and **I**nduces endometrial atrophy.

Question 468: An elderly male has benign prostatic hyperplasia. Which of the following medications can be used to suppress prostatic growth?

A. Spironolactone
B. Ketoconazole
C. Finasteride (Correct Answer)
D. Flutamide

Explanation: **Explanation:** **Finasteride** is the correct answer because it is a selective **5-alpha reductase inhibitor**. In the prostate, the enzyme 5-alpha reductase converts testosterone into **Dihydrotestosterone (DHT)**, which is the potent androgen responsible for prostatic cell proliferation. By inhibiting this enzyme, Finasteride reduces intraprostatic DHT levels, leading to a reduction in prostate volume (shrinkage) over 6–12 months. This makes it a disease-modifying drug for Benign Prostatic Hyperplasia (BPH). **Analysis of Incorrect Options:** * **Spironolactone (A):** A potassium-sparing diuretic that also acts as an aldosterone antagonist and weak androgen receptor blocker. While it has anti-androgenic side effects (like gynecomastia), it is not a standard treatment for suppressing prostatic growth in BPH. * **Ketoconazole (B):** An antifungal that inhibits steroid synthesis (including testosterone) at high doses. Due to its significant toxicity (hepatotoxicity and adrenal suppression), it is not used for BPH. * **Flutamide (D):** A pure non-steroidal anti-androgen that blocks androgen receptors. It is primarily used in the management of **Prostate Cancer**, not BPH, due to its side effect profile and the fact that it does not effectively reduce prostate size in non-malignant conditions compared to 5-alpha reductase inhibitors. **NEET-PG High-Yield Pearls:** * **Finasteride vs. Dutasteride:** Finasteride inhibits Type II 5-alpha reductase; Dutasteride inhibits both Type I and Type II. * **Clinical Use:** Finasteride is also used for **Male Pattern Baldness** (Androgenetic Alopecia). * **Dynamic vs. Static:** Alpha-blockers (e.g., Tamsulosin) treat the *dynamic* component (smooth muscle tone), while Finasteride treats the *static* component (size). * **Side Effects:** Decreased libido and erectile dysfunction are common. It also decreases serum PSA levels by approximately 50%.

Question 469: Which of the following is an antiandrogen?

A. Mifepristone
B. Clomiphene citrate
C. Flutamide (Correct Answer)
D. Tamoxifen

Explanation: **Explanation:** The correct answer is **Flutamide**. **1. Why Flutamide is correct:** Flutamide is a potent **non-steroidal competitive antagonist** at the androgen receptor. By blocking the binding of endogenous androgens (testosterone and dihydrotestosterone) to their receptors, it inhibits androgenic effects in target tissues. Clinically, it is primarily used in the management of **prostate carcinoma**, often combined with a GnRH agonist to prevent the "testosterone flare" effect. **2. Why the other options are incorrect:** * **Mifepristone (RU-486):** This is a **progesterone and glucocorticoid receptor antagonist**. It is primarily used for medical termination of pregnancy and in Cushing’s syndrome. * **Clomiphene citrate:** This is a **Selective Estrogen Receptor Modulator (SERM)**. It acts as an antagonist at estrogen receptors in the hypothalamus, interfering with negative feedback and increasing FSH/LH secretion. It is used as an ovulation inducer in infertility. * **Tamoxifen:** Another **SERM** that acts as an estrogen antagonist in breast tissue but as an agonist in the bone and endometrium. It is a mainstay treatment for ER-positive breast cancer. **3. High-Yield Clinical Pearls for NEET-PG:** * **Bicalutamide & Enzalutamide:** Newer antiandrogens preferred over Flutamide due to better side-effect profiles (Flutamide is associated with hepatotoxicity). * **Finasteride/Dutasteride:** These are **5-alpha reductase inhibitors** (prevent conversion of Testosterone to DHT), used for BPH and male pattern baldness; they are *not* receptor antagonists. * **Spironolactone:** A potassium-sparing diuretic that also has significant antiandrogenic activity, often used in treating hirsutism in females. * **Cyproterone acetate:** A steroidal antiandrogen with progestational activity.

Question 470: Which anti-diabetic agents act by increasing insulin sensitivity and are therefore euglycemic?

A. Phenformin
B. Pioglitazone (Correct Answer)
C. Sitagliptin
D. Liraglutide

Explanation: **Explanation:** The correct answer is **Pioglitazone**. **Mechanism of Action:** Pioglitazone belongs to the **Thiazolidinedione (TZD)** class. These drugs are selective ligands for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor gamma). Activation of PPAR-γ regulates the transcription of genes involved in glucose and lipid metabolism. The primary effect is to **increase insulin sensitivity** in peripheral tissues (adipose tissue, skeletal muscle, and liver). Because they do not stimulate direct insulin secretion from the pancreas but rather enhance the action of existing insulin, they are classified as **euglycemics** (they lower elevated blood glucose without causing hypoglycemia). **Analysis of Incorrect Options:** * **Phenformin (A):** While a Biguanide like Metformin, it was withdrawn globally due to a high risk of lactic acidosis. While it improves sensitivity, it is not the primary clinical representative for this mechanism in modern exams. * **Sitagliptin (C):** A **DPP-4 inhibitor** that prevents the breakdown of incretins (GLP-1 and GIP). It acts in a glucose-dependent manner to increase insulin secretion and decrease glucagon. * **Liraglutide (D):** A **GLP-1 receptor agonist**. It mimics incretin hormones to stimulate insulin release and slow gastric emptying. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Action:** TZDs are often called "Glitazones." Their main site of action is **adipose tissue**. * **Side Effects:** Weight gain, **fluid retention/edema** (contraindicated in NYHA Class III/IV Heart Failure), and increased risk of bone fractures. * **Metformin vs. Pioglitazone:** Both are insulin sensitizers, but Metformin primarily acts on the **liver** (inhibiting gluconeogenesis via AMPK activation), while Pioglitazone acts primarily on **peripheral tissues**.

Practice by Chapter

Hypothalamic and Pituitary Hormones

Practice Questions

Thyroid Drugs and Antithyroid Agents

Practice Questions

Insulin and Oral Hypoglycemic Agents

Practice Questions

Adrenocorticosteroids

Practice Questions

Sex Hormones: Estrogens and Progestins

Practice Questions

Androgens and Anabolic Steroids

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Hormonal Contraceptives

Practice Questions

Drugs Affecting Calcium Metabolism

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Drugs for Osteoporosis

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Pharmacological Management of Obesity

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