Endocrine Pharmacology Practice Questions

Q: Which of the following drugs can prevent the peripheral conversion of T4 to T3?

Propylthiouracil. ***Propylthiouracil*** - Propylthiouracil (PTU) is a **thionamide drug** that inhibits thyroid peroxidase, thereby blocking the synthesis of thyroid hormones. - Additionally, PTU specifically inhibits the **5'-deiodinase enzyme**, which is responsible for the peripheral conversion of **thyroxine (T4)** to the more active **triiodothyronine (T3)**. - This is a **unique property** of PTU that distinguishes it from methimazole, making it preferred in thyrotoxic storm. *Propranolol* - Propranolol is a **beta-blocker** primarily used to alleviate the **symptomatic effects** of hyperthyroidism, such as palpitations, tremor, and anxiety. - Although high doses may have a minor effect on T4 to T3 conversion, this is **not clinically significant** and not the reason for its use in thyroid disorders. *Iodides* - High doses of iodides, such as **potassium iodide**, can acutely inhibit thyroid hormone release (the **Wolff-Chaikoff effect**) and decrease thyroid gland vascularity. - Iodides do **not prevent the peripheral conversion of T4 to T3**; their main action is on hormone synthesis and release from the thyroid gland itself. *a and b both* - This option is incorrect because neither propranolol nor iodides have a clinically significant effect on inhibiting peripheral 5'-deiodinase enzyme. - Only **propylthiouracil** has this specific and therapeutically relevant action.

Q: A middle-aged male patient presents with protrusion of the chin, excessive sweating, impaired glucose tolerance, and enlargement of hands and feet. Which of the following is a growth hormone receptor antagonist used to treat this condition?

Pegvisomant. ***Pegvisomant*** - **Pegvisomant** is a **growth hormone receptor antagonist** that binds to growth hormone receptors, preventing endogenous growth hormone from signaling and reducing IGF-1 levels. - It is specifically used in the treatment of **acromegaly**, a condition characterized by excessive growth hormone secretion, which aligns with the patient's symptoms of chin protrusion, excessive sweating, impaired glucose tolerance, and enlarged hands and feet. *Octreotide* - **Octreotide** is a **somatostatin analog** that works by inhibiting growth hormone secretion from the pituitary gland. - While used in acromegaly, it is not a growth hormone receptor antagonist, but rather reduces the production of growth hormone itself. *Cabergoline* - **Cabergoline** is a **dopamine agonist** primarily used to treat hyperprolactinemia by inhibiting prolactin secretion. - It can sometimes be used in acromegaly for patients with co-secretion of prolactin or those who are sensitive to its effects on growth hormone, but it is not a direct growth hormone receptor antagonist. *Olcegepant* - **Olcegepant** is a **calcitonin gene-related peptide (CGRP) receptor antagonist** developed for the treatment of migraine. - It has no known therapeutic role in the management of acromegaly or growth hormone-related disorders.

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

Bisphosphonates. ***Bisphosphonates*** - **Bisphosphonates** are the **first-line treatment** for osteoporosis in postmenopausal women due to their proven efficacy in reducing the risk of fragility fractures. - They work by **inhibiting osteoclast activity**, thereby decreasing bone turnover and increasing bone mineral density. *Oral Contraceptive Pills* - **Oral contraceptive pills** are primarily used for contraception and managing menstrual irregularities; they are **not a treatment for established osteoporosis**. - While estrogen plays a role in bone health, the focus for osteoporosis treatment is on anti-resorptive or anabolic agents. *Strontium* - **Strontium ranelate** has been used in some countries for osteoporosis, but its use is **limited due to concerns about cardiovascular adverse events** and is not typically a first-line drug. - It has a dual mechanism of action, both decreasing bone resorption and increasing bone formation. *Selective Estrogen Receptor Modulator (SERM)* - **SERMs**, such as **raloxifene**, are indicated for the prevention and treatment of osteoporosis, particularly in women with a high risk of **breast cancer**, but they are **not considered first-line** for all postmenopausal women compared to bisphosphonates. - They act as estrogen agonists in bone but are antagonists in breast and uterine tissue.

Q: Misoprostol used in the induction of labour is an analogue of which of the following type of prostaglandin?

PG E1. ***PG E1*** - **Misoprostol** is a synthetic analogue of **prostaglandin E1 (PGE1)**, which is used for cervical ripening and uterine contractions in labor induction. - PGE1 analogues help to soften the cervix, increase its compliance, and stimulate uterine smooth muscle contraction. *PG E2* - **Dinoprostone** is a synthetic analogue of **prostaglandin E2 (PGE2)**, commonly used for cervical ripening and induction of labor. - While PGE2 also induces labor, misoprostol specifically mimics the actions of PGE1. *PG I2* - **Prostacyclin (PGI2)** is primarily known for its role in inhibiting platelet aggregation and causing vasodilation. - It is not routinely used for labor induction due to its primary vascular effects and lack of direct uterine contractile properties at relevant doses. *PG F2alpha* - **Prostaglandin F2-alpha (PGF2α)**, such as **carboprost**, is used for postpartum hemorrhage to cause strong uterine contractions. - While it causes uterine contractions, its primary obstetric use is not for labor induction but rather for stimulating aggressive uterine contraction to stop bleeding.

Q: Niacin therapy is contraindicated in diabetes because it

Increases the blood sugar levels. ***Increases the blood sugar levels*** - **Niacin** can cause an increase in **insulin resistance** and glucose production, leading to elevated **blood sugar levels**. - This effect makes it contraindicated or used with extreme caution in patients with **diabetes mellitus**, as it can exacerbate **hyperglycemia**. *Causes scleroderma* - **Scleroderma** is a **chronic autoimmune** disorder characterized by widespread **fibrosis** and vascular dysfunction; it is not typically caused by niacin. - While niacin can have various side effects, **scleroderma** is not a known adverse reaction of this medication. *Difficult to give injection* - **Niacin** is available in various formulations, including **oral tablets** and **extended-release preparations**, which are easy to administer. - The mode of administration (injectable difficulty) is not a primary reason for its **contraindication in diabetes**. *Increases the metabolism of oral hypoglycemic drugs* - **Niacin** does not typically increase the **metabolism of oral hypoglycemic drugs**; rather, its primary concern in diabetes is its direct impact on **glucose metabolism**. - The interaction of niacin with **antidiabetic medications** is mainly related to its effect on **blood glucose levels**, requiring dose adjustments.

Q: What is the physiological dose of hydrocortisone (mg/m2/day)?

10-12 mg/m²/day. ***10-12 mg/m²/day*** - This range represents the typical **physiological replacement dose** of hydrocortisone, mimicking the body's natural cortisol production. - This dose is used for patients with **adrenal insufficiency** to maintain normal metabolic functions without causing significant side effects. *8-10 mg/m²/day* - This dose is slightly on the lower side of the accepted physiological range and might not be sufficient for complete replacement in all individuals. - While close, it is not the most commonly cited optimal physiological dose for hydrocortisone replacement. *15-18 mg/m²/day* - This dose is typically considered above the physiological replacement level and may begin to cause **mild corticosteroid side effects** with prolonged use. - It might be used for short periods or in specific conditions, but not as a standard physiological replacement. *20-25 mg/m²/day* - This dose is well above the physiological range and would be considered a **pharmacological dose** often used for its anti-inflammatory or immunosuppressive effects. - Prolonged use at this dose would likely lead to significant **corticosteroid side effects** such as Cushingoid features, osteoporosis, and hyperglycemia.

Q: Which of the following drugs is used in SIADH?

Tolvaptan. ***Tolvaptan*** - **Tolvaptan** is a **vasopressin receptor antagonist** that blocks the action of **antidiuretic hormone (ADH)** at the **V2 receptors** in the kidneys [1]. - This action promotes **water excretion (aquaresis)** without significantly affecting electrolyte balance, thereby increasing serum sodium levels in patients with **SIADH** [1]. *Desmopressin* - **Desmopressin** is a synthetic analog of **ADH** that primarily acts on **V2 receptors**, promoting water reabsorption [3], [4]. - It is used in conditions like **diabetes insipidus** [3], [4] or **hemophilia** [2] to increase ADH activity or clotting factors, which is contrary to the goal in SIADH. *Von Willebrand factor* - **Von Willebrand factor** is a **glycoprotein** involved in **hemostasis**, promoting platelet adhesion and carrying **factor VIII**. - It plays no role in the direct management of **SIADH** or fluid balance disorders. *Terlipressin* - **Terlipressin** is an analog of **vasopressin** that primarily acts on **V1 receptors**, causing vasoconstriction [5]. - It is used in conditions like **hepatorenal syndrome** or **esophageal variceal bleeding**, not for treating **SIADH**.

Q: Which of the following is glucocorticoid synthesis inhibitor?

Metyrapone. ***Metyrapone*** - **Metyrapone** inhibits **11-beta-hydroxylase**, an enzyme essential for the final step in cortisol and corticosterone synthesis in the adrenal cortex [2]. - This inhibition leads to a decrease in **cortisol production** and an increase in upstream steroid precursors like 11-deoxycortisol [2]. *Mifepristone* - **Mifepristone** is a **progesterone receptor antagonist** and, at higher doses, a **glucocorticoid receptor antagonist** [1]. - It does not inhibit the synthesis of glucocorticoids but rather blocks their action at the receptor level [1]. *Flutamide* - **Flutamide** is an **androgen receptor antagonist** used primarily in the treatment of prostate cancer. - It works by blocking the binding of androgens to their receptors, thereby inhibiting androgen-mediated effects. *Finasteride* - **Finasteride** is a **5-alpha-reductase inhibitor**, preventing the conversion of testosterone to the more potent dihydrotestosterone (DHT) [3]. - It is used to treat benign prostatic hyperplasia (BPH) and male-pattern baldness, and does not affect glucocorticoid synthesis [3].

Q: Which of the following antidiabetic drugs is a GLP-1 receptor agonist?

Exenatide. ***Exenatide*** - **Exenatide** is a synthetic analog of **glucagon-like peptide-1 (GLP-1)**, acting as a GLP-1 receptor agonist [1]. - It works by stimulating **insulin secretion** in a glucose-dependent manner, suppressing glucagon release, slowing gastric emptying, and promoting satiety [2], [3]. - Other GLP-1 agonists include liraglutide, dulaglutide, and semaglutide [1]. *Pramlintide* - **Pramlintide** is an **amylin analog**, not a GLP-1 receptor agonist. - It is used in both type 1 and type 2 diabetes to slow gastric emptying, suppress glucagon secretion, and promote satiety, but it acts via **amylin receptors**. *Glucomannan* - **Glucomannan** is a **dietary fiber** derived from the konjac plant, used as a food additive and supplement for weight loss and constipation. - It does not directly affect GLP-1 receptors or regulate insulin or glucagon secretion as a pharmacological agent. *Sitagliptin* - **Sitagliptin** is a **DPP-4 inhibitor** (dipeptidyl peptidase-4 inhibitor), not a GLP-1 receptor agonist [2]. - While it enhances endogenous GLP-1 activity by preventing its degradation, it does not directly stimulate GLP-1 receptors like exenatide does [4].

Question 1

Which of the following drugs can prevent the peripheral conversion of T4 to T3?

Accepted Answer

Propylthiouracil

Answer

Propranolol

Answer

Iodides

Answer

a and b both

Question 2

A middle-aged male patient presents with protrusion of the chin, excessive sweating, impaired glucose tolerance, and enlargement of hands and feet. Which of the following is a growth hormone receptor antagonist used to treat this condition?

Accepted Answer

Pegvisomant

Answer

Olcegepant

Answer

Cabergoline

Answer

Octreotide

Question 3

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

Accepted Answer

Bisphosphonates

Answer

Strontium

Answer

Oral Contraceptive Pills

Answer

Selective Estrogen Receptor Modulator (SERM)

Question 4

Misoprostol used in the induction of labour is an analogue of which of the following type of prostaglandin?

Accepted Answer

PG E1

Answer

PG E2

Answer

PG I2

Answer

PG F2alpha

Question 5

Niacin therapy is contraindicated in diabetes because it

Accepted Answer

Increases the blood sugar levels

Answer

Causes scleroderma

Answer

Difficult to give injection

Answer

Increases the metabolism of oral hypoglycemic drugs

Question 6

What is the physiological dose of hydrocortisone (mg/m2/day)?

Accepted Answer

10-12 mg/m²/day

Answer

20-25 mg/m²/day

Answer

15-18 mg/m²/day

Answer

8-10 mg/m²/day

Question 7

Which of the following drugs is used in SIADH?

Accepted Answer

Tolvaptan

Answer

Desmopressin

Answer

Terlipressin

Answer

Von Willebrand factor

Question 8

Which of the following is glucocorticoid synthesis inhibitor?

Accepted Answer

Metyrapone

Answer

Mifepristone

Answer

Flutamide

Answer

Finasteride

Question 9

A 47-year-old woman presents with complaints of nervousness and increased sensitivity to hot weather. She is diagnosed with hyperthyroidism and prescribed propylthiouracil. What is the principal mechanism by which this drug acts?

Accepted Answer

Inhibiting the enzyme thyroid peroxidase, which reduces the synthesis of thyroid hormones.

Answer

Reducing the proteolysis of thyroglobulin.

Answer

Inhibiting the binding of TSH to its receptor.

Answer

Altering the levels of reverse T3 (rT3) in the body.

Question 10

Which of the following antidiabetic drugs is a GLP-1 receptor agonist?

Accepted Answer

Exenatide

Answer

Pramlintide

Answer

Glucomannan

Answer

Sitagliptin

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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