Endocrine Pharmacology Practice Questions

Q: Which of the following medications is not typically used for the treatment of erectile dysfunction?

Beta blockers. ***Beta blockers*** - **Beta blockers** are primarily used to treat conditions like **hypertension** and **heart disease**. - While they can cause ED as a side effect, they are **not used for its treatment**. *Sildenafil* - **Sildenafil** is a **PDE5 inhibitor** that works by increasing **blood flow to the penis**, facilitating an erection. - It is a **first-line oral medication** widely prescribed for erectile dysfunction. *PG-E* - **PG-E** refers to **Prostaglandin E1** (alprostadil), which can be administered via **intracavernosal injection** or **urethral suppository**. - It directly causes **vasodilation** in the penis, leading to an erection, and is used when oral medications are ineffective or contraindicated. *Papaverine* - **Papaverine** is a **non-specific vasodilator** that can be used as an **intracavernosal injection** for ED. - It works by relaxing **smooth muscle** in the penile arteries, increasing blood flow and inducing an erection, often used in combination with phentolamine.

Q: The mechanism by which ergometrine stops postpartum hemorrhage is that it:

Increases tone of uterine muscle. ***Increases tone of uterine muscle*** - **Ergometrine** is an **ergot alkaloid** that directly stimulates **uterine smooth muscle contractions**. - These sustained contractions lead to **compression of blood vessels within the myometrium**, thereby reducing blood flow and controlling **postpartum hemorrhage**. *Causes vasoconstriction of uterine arteries* - While ergometrine does have some generalized **vasoconstrictive effects**, its primary mechanism of action in controlling postpartum hemorrhage is not mainly through direct vasoconstriction of large uterine arteries. - The crucial effect is the **sustained uterine contraction** which mechanically occludes blood vessels, rather than chemical constriction of the vessels themselves. *Induces platelet aggregation* - Ergometrine does not primarily act by inducing **platelet aggregation**; this is a function of specific clotting factors and platelet activators. - Its therapeutic effect against hemorrhage is mediated through its action on **uterine contractility**, not on the cellular components of coagulation. *Promotes coagulation* - Ergometrine does not directly promote the **coagulation cascade** or enhance the formation of fibrin clots. - Its mechanism of action is distinct from agents that affect intrinsic or extrinsic pathways of coagulation.

Q: Which drug is commonly used to treat hyperprolactinemia in women experiencing infertility?

Bromocriptine. ***Bromocriptine*** - **Bromocriptine** is a **dopamine agonist** that directly inhibits **prolactin secretion** from the pituitary gland. - By lowering prolactin levels, it helps restore **ovulatory function** and **fertility** in women with hyperprolactinemia. - It is the **first-line treatment** for hyperprolactinemia-induced infertility. *Gonadotropin-Releasing Hormone (GnRH)* - **GnRH** (or its agonists/antagonists) is primarily used to control **gonadotropin release** for conditions like **endometriosis** or **fibroids**, or in **assisted reproductive technologies**. - It does not directly treat hyperprolactinemia by inhibiting prolactin secretion. *Testosterone (Androgen)* - **Testosterone** is an **androgen** and is generally not used in women for infertility, especially not for hyperprolactinemia. - High testosterone levels in women can cause **hirsutism** and **anovulation**, which would worsen infertility. *Corticosteroids* - **Corticosteroids** are potent **anti-inflammatory** and **immunosuppressive** agents. - They are used to treat various autoimmune conditions or inflammation but have no direct role in treating hyperprolactinemia or female infertility in this context.

Q: A patient has Cushing syndrome due to an adrenal tumor. Which drug should be given?

Ketoconazole. ***Ketoconazole*** - **Ketoconazole** is an antifungal agent that also inhibits several enzymes involved in **steroidogenesis**, including 17α-hydroxylase and 11β-hydroxylase. - This action helps to reduce the overproduction of **cortisol** in Cushing syndrome caused by an adrenal tumor. *Hydrocortisone* - **Hydrocortisone** is a glucocorticoid itself and would exacerbate the symptoms of **Cushing syndrome** by adding to the already elevated cortisol levels. - It is used for **cortisol replacement therapy** in conditions like Addison's disease, where cortisol levels are low. *Dexamethasone* - **Dexamethasone** is a potent synthetic glucocorticoid used to suppress **ACTH production** in cases of ACTH-dependent Cushing's syndrome (e.g., Cushing's disease) or to diagnose Cushing's syndrome. - In an adrenal tumor, which is **ACTH-independent**, dexamethasone would not reduce cortisol production but could instead worsen the hypercortisolism. *Spironolactone* - **Spironolactone** is an **aldosterone antagonist** and a weak antiandrogen, primarily used for conditions like hyperaldosteronism, heart failure, and hirsutism. - It has no direct effect on the overproduction of **cortisol** from an adrenal tumor in Cushing syndrome.

Q: Which of the following drugs can cause thyroid dysfunction?

Amiodarone. ***Amiodarone*** - **Amiodarone** is known to cause both **hypothyroidism** and **hyperthyroidism** due to its high iodine content and direct toxic effects on the thyroid gland. - Its effects can persist for months after discontinuation due to its **long half-life** and accumulation in tissues. *Ampicillin* - **Ampicillin** is an antibiotic that generally does not directly affect thyroid function. - Its primary mechanism of action involves inhibiting **bacterial cell wall synthesis**, with no known significant endocrine side effects. *Ibutilide* - **Ibutilide** is an antiarrhythmic drug used for recent-onset atrial fibrillation or flutter. - It works by blocking potassium channels and has no recognized association with thyroid dysfunction. *Acyclovir* - **Acyclovir** is an antiviral medication used to treat herpes virus infections. - Its mechanism of action involves inhibiting viral DNA replication and it is not known to impact thyroid hormone synthesis or metabolism.

Q: Which of the following is the longest acting glucocorticoid?

Dexamethasone. ***Correct: Dexamethasone*** - **Dexamethasone** is a long-acting glucocorticoid with a **biological half-life of 36–72 hours**, making it the longest acting among the options provided - Its prolonged action is due to its **high affinity for the glucocorticoid receptor** and relatively slow metabolism - Provides sustained anti-inflammatory and immunosuppressive effects *Incorrect: Prednisone* - **Prednisone** is an intermediate-acting glucocorticoid with a biological half-life of 12-36 hours - Requires metabolism in the liver to its active form, prednisolone - Duration of action is significantly shorter than dexamethasone *Incorrect: Prednisolone* - **Prednisolone** is the active form of prednisone, with a similar intermediate duration of action (12-36 hours) - Primarily used when liver conversion of prednisone is impaired - Does not possess the extended duration of action characteristic of dexamethasone *Incorrect: Cortisone* - **Cortisone** is a short-acting glucocorticoid with a biological half-life of 8-12 hours - It is a prodrug that needs to be converted to **hydrocortisone** (cortisol) in the liver to become active - Has the shortest duration among all options

Q: Which of the following statements about sitagliptin is false?

Cannot be used orally. ***Cannot be used orally*** - This statement is **false** because **sitagliptin** is an **oral medication** approved for the treatment of type 2 diabetes mellitus. - As a **DPP-4 inhibitor**, it is designed to be taken by mouth to increase incretin hormone levels. *Used in type II diabetes mellitus* - This statement is **true** as **sitagliptin** is a commonly prescribed **oral antidiabetic drug** for the management of type 2 diabetes. - It works by inhibiting the enzyme **dipeptidyl peptidase-4 (DPP-4)**, which increases levels of **GLP-1** and **GIP** to enhance insulin secretion and reduce glucagon secretion. *Used in combination with other oral hypoglycemic agents* - This statement is **true** as **sitagliptin** is often used as **add-on therapy** with other oral hypoglycemic agents like **metformin** or a **sulfonylurea** when monotherapy is insufficient. - This combination approach helps achieve better glycemic control by targeting different mechanisms of action. *All of the above statements are true* - This statement is **false** because the first statement "Cannot be used orally" is incorrect. - Since sitagliptin is indeed an oral medication, not all the above statements are true, making this option incorrect.

Q: Which of the antithyroid drugs inhibits iodine trapping?

Thiocyanates. ***Thiocyanates*** - **Thiocyanates** are competitive inhibitors of the **sodium-iodide symporter (NIS)**, which is responsible for actively transporting iodide into thyroid follicular cells (iodine trapping) [1]. - By blocking NIS, thiocyanates prevent the thyroid gland from accumulating iodide, thereby inhibiting thyroid hormone synthesis [1]. *Radioactive iodine* - **Radioactive iodine (RAI)** primarily works by being taken up by thyroid cells and emitting **beta particles**, which destroy the thyroid tissue [3]. - It does not inhibit iodine trapping, but rather uses the trapping mechanism to concentrate in the thyroid and exert its destructive effect [3]. *Iodides* - **Iodides** (e.g., Lugol's solution) paradoxically inhibit organification and hormone release from the thyroid gland, an effect known as the **Wolff-Chaikoff effect** [2]. - They also decrease the vascularity and size of the thyroid gland, making them useful in preparing patients for thyroidectomy, but do not directly inhibit iodine trapping [2]. *Methimazole* - **Methimazole** is a **thionamide** drug that primarily inhibits the enzyme **thyroid peroxidase**. - This prevents the **organification of iodide** (incorporation of iodine into tyrosine residues) and the **coupling of iodotyrosines** (forming T3 and T4), not the initial trapping of iodine.

Question 1

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 2

Which of the following medications is not typically used for the treatment of erectile dysfunction?

Accepted Answer

Beta blockers

Answer

Papaverine

Answer

Sildenafil

Answer

PG-E

Question 3

The mechanism by which ergometrine stops postpartum hemorrhage is that it:

Accepted Answer

Increases tone of uterine muscle

Answer

Induces platelet aggregation

Answer

Promotes coagulation

Answer

Causes vasoconstriction of uterine arteries

Question 4

Which of the following statements about Selective Estrogen Receptor Modulators (SERMs) is correct?

Accepted Answer

Some SERMs can act as both agonists and antagonists on estrogen receptors.

Answer

Act as agonists on estrogen receptors.

Answer

Used to reduce the risk of hot flushes and thromboembolism.

Answer

Act as antagonists on estrogen receptors.

Question 5

Which drug is commonly used to treat hyperprolactinemia in women experiencing infertility?

Accepted Answer

Bromocriptine

Answer

Gonadotropin-Releasing Hormone (GnRH)

Answer

Testosterone (Androgen)

Answer

Corticosteroids

Question 6

A patient has Cushing syndrome due to an adrenal tumor. Which drug should be given?

Accepted Answer

Ketoconazole

Answer

Spironolactone

Answer

Hydrocortisone

Answer

Dexamethasone

Question 7

Which of the following drugs can cause thyroid dysfunction?

Accepted Answer

Amiodarone

Answer

Ampicillin

Answer

Ibutilide

Answer

Acyclovir

Question 8

Which of the following is the longest acting glucocorticoid?

Accepted Answer

Dexamethasone

Answer

Prednisone

Answer

Prednisolone

Answer

Cortisone

Question 9

Which of the following statements about sitagliptin is false?

Accepted Answer

Cannot be used orally

Answer

Used in type II diabetes mellitus

Answer

Used in combination with other oral hypoglycemic agents

Answer

All of the above statements are true

Question 10

Which of the antithyroid drugs inhibits iodine trapping?

Accepted Answer

Thiocyanates

Answer

Radioactive iodine

Answer

Iodides

Answer

Methimazole

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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