Endocrine Pharmacology Practice Questions

Q: Precocious puberty is treated by administering

LHRH analogs (e.g., Leuprolide). ***LHRH analogs (e.g., Leuprolide)*** - **LHRH analogs** (GnRH agonists) are the standard treatment for central precocious puberty through continuous, non-pulsatile stimulation of the pituitary. - This leads to **downregulation and desensitization** of GnRH receptors, effectively suppressing gonadotropin (LH and FSH) release. - Suppression halts progression of pubertal development, preventing further development of **secondary sexual characteristics** and preserving final adult height potential. *Oestrogen* - Administering **oestrogen** would worsen precocious puberty by accelerating the development of secondary sexual characteristics and advancing bone age. - Oestrogen is a primary hormone responsible for female pubertal changes, so exogenous administration would **exacerbate** the condition. *Gonadotropin-Releasing Hormone (GnRH)* - Native **GnRH** is not used for treatment because it requires **pulsatile administration** to maintain normal function, which would stimulate (not suppress) gonadotropin release. - Without the continuous receptor exposure that causes downregulation, native GnRH would promote rather than suppress pubertal progression. - Treatment requires **GnRH agonists (LHRH analogs)** that provide sustained receptor stimulation leading to desensitization. *Testosterone* - Administering **testosterone** would accelerate precocious puberty, especially in males, leading to early development of male secondary sexual characteristics. - Testosterone would advance bone age prematurely, potentially compromising the child's **final adult height**.

Q: Which of the following is the drug of choice for the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)?

Demeclocycline. ***Demeclocycline*** - **Demeclocycline** is a **tetracycline antibiotic** that induces **nephrogenic diabetes insipidus**, making the renal tubules less responsive to ADH. - This effect helps in treating SIADH by promoting water excretion and correcting **hyponatremia**. *Vasopressin* - **Vasopressin** (ADH) is the hormone that is excessively secreted in SIADH, leading to water retention. - Administering vasopressin would **aggravate** SIADH symptoms by increasing water reabsorption. *Thiazide diuretic* - **Thiazide diuretics** can worsen hyponatremia in SIADH by causing **sodium loss** and **reducing free water clearance**. - Volume depletion from thiazides can paradoxically enhance ADH activity, making them contraindicated in SIADH. *Chlorpropamide* - **Chlorpropamide** is a **sulfonylurea** that can actually **potentiate ADH action**, thereby worsening SIADH. - It works by increasing the sensitivity of renal tubules to vasopressin, which is counterproductive in SIADH management.

Q: What is the primary condition for which calcitriol is used as a treatment?

Secondary hyperparathyroidism. Secondary hyperparathyroidism - Calcitriol is the active form of vitamin D (1,25-dihydroxyvitamin D₃), and it is crucial for regulating calcium and phosphate levels in the body [1]. - In secondary hyperparathyroidism, often seen in chronic kidney disease (CKD), the kidneys cannot convert vitamin D to its active form, leading to hypocalcemia and increased PTH secretion [1], [2]. - Calcitriol supplementation helps to increase calcium absorption from the gut and suppress the release of parathyroid hormone (PTH), thereby treating the underlying cause of secondary hyperparathyroidism [1], [2]. - This is the primary therapeutic indication for calcitriol in clinical practice. Lichen planus - This is a chronic inflammatory condition affecting the skin, hair, nails, and mucous membranes - Typically treated with corticosteroids or other immunosuppressants - Calcitriol has no primary role in the treatment of lichen planus; its therapeutic applications are predominantly related to calcium and bone metabolism Pemphigus - Pemphigus is a group of rare autoimmune blistering diseases that affect the skin and mucous membranes - Primary treatment involves immunosuppressants like corticosteroids, often in high doses - Calcitriol is not indicated for the treatment of pemphigus, as its mechanism of action is unrelated to the autoimmune processes characteristic of this disease Leprosy - Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae - Treated with multi-drug therapy (MDT), which includes antibiotics like rifampicin, dapsone, and clofazimine - Calcitriol is not an antibiotic and therefore has no role in treating the bacterial infection responsible for leprosy

Q: Which of the following statements is true about atosiban?

is an oxytocin receptor antagonist. ***is an oxytocin receptor antagonist*** - **Atosiban** works by competitively binding to **oxytocin receptors** in the myometrium, thereby preventing oxytocin from stimulating uterine contractions. - This action makes it effective in delaying **preterm labor** by reducing the frequency and intensity of contractions. - Atosiban is classified as a **tocolytic drug** specifically because of its oxytocin receptor antagonism. *is least effective in inhibiting preterm uterine contractions* - **Atosiban** is an **effective tocolytic** used to delay preterm labor, making this statement incorrect. - Studies show it can prolong pregnancy for several days, allowing for the administration of **corticosteroids** for fetal lung maturation. *is a progesterone receptor antagonist* - **Atosiban** specifically targets **oxytocin receptors**, not progesterone receptors. - Progesterone receptor antagonists (e.g., **mifepristone**) would induce labor rather than suppress it. *acts primarily on beta-adrenergic receptors* - **Atosiban** does not act on beta-adrenergic receptors; it is an **oxytocin receptor antagonist**. - Beta-adrenergic agonists like **ritodrine** and **terbutaline** are different tocolytics that work by relaxing uterine smooth muscle through beta-2 receptor stimulation.

Q: Which of the following medications does not cause hirsutism?

Flutamide. ***Flutamide*** - **Flutamide** is an **anti-androgen** that blocks androgen receptors, thereby *reducing* the effects of androgens and preventing hirsutism. - It is used in conditions like prostate cancer to counteract androgenic effects and would not cause increased hair growth. *Norethisterone* - **Norethisterone** is a synthetic progestin that can have **androgenic effects** in some individuals. - These androgenic properties can lead to side effects like **hirsutism**, acne, and oily skin. *Danazol* - **Danazol** is a synthetic androgen that has **pronounced androgenic activity**. - Its androgenic effects are well-known to cause side effects such as **hirsutism**, acne, and deepening of the voice. *Phenytoin* - **Phenytoin** is an anticonvulsant medication that can induce **hirsutism** as a common side effect. - The mechanism is not fully understood but may involve stimulating hair follicle growth.

Q: Which of the following is preferred for infertility treatment of a female with increased prolactin levels?

Cabergoline. ***Cabergoline*** - **Cabergoline** is a **dopamine agonist** that is highly effective in normalizing prolactin levels and restoring fertility in women with hyperprolactinemia. - It has a **longer half-life** and is generally associated with **fewer side effects** compared to other dopamine agonists, allowing for less frequent dosing (once or twice weekly). *Dopamine* - While **dopamine** itself is the natural inhibitor of prolactin secretion, it has a **very short half-life** and cannot be administered orally as a long-term treatment. - It is typically used as an IV pressor agent in critical care and is not suitable for treating chronic hyperprolactinemia. *Carbidopa* - **Carbidopa** is a **decarboxylase inhibitor** used to prevent the peripheral metabolism of levodopa, allowing more levodopa to reach the brain. - It is primarily used in the treatment of **Parkinson's disease** and has no direct role in lowering prolactin levels. *Bromocriptine* - **Bromocriptine** is also a **dopamine agonist** used to treat hyperprolactinemia, but it typically requires **daily dosing** and is associated with a higher incidence of side effects like nausea and dizziness. - While effective, **cabergoline** is generally preferred due to its better tolerability and convenience.

Q: In thyrotoxicosis, which of the following symptoms is least effectively controlled by beta-blockers?

Oxygen consumption. ***Oxygen consumption*** - Beta-blockers primarily address the **adrenergic manifestations** of thyrotoxicosis, but they do not directly inhibit the increased **metabolic rate** or **thyroid hormone production** that drives higher oxygen consumption. - The elevated oxygen consumption in thyrotoxicosis is a direct result of enhanced cellular metabolism due to excess thyroid hormones, which beta-blockers do not counteract. *Tremors* - **Thyrotoxic tremors** are significantly mediated by **beta-adrenergic stimulation**, making them highly responsive to beta-blocker therapy. - Blocking beta-receptors reduces the sympathetic drive that contributes to these fine muscle tremors. *Tachycardia* - **Tachycardia** in thyrotoxicosis is a classic symptom of **increased sympathetic activity**, which beta-blockers effectively block. - Beta-blockers reduce heart rate by inhibiting beta-1 receptors in the myocardium, thereby relieving palpitations and rapid heart rate. *Anxiety* - **Anxiety** is often secondary to the **adrenergic overactivity** and overall heightened metabolic state associated with thyrotoxicosis. - By dampening the sympathetic nervous system, beta-blockers can alleviate anxiety and nervousness.

Q: Among currently prescribed medications for diabetes mellitus, deaths from lactic acidosis are most commonly associated with which one of the following?

Metformin. ***Metformin*** - While generally safe, **lactic acidosis** is a rare but serious complication of metformin, particularly in patients with **renal impairment**, congestive heart failure, or other conditions predisposing to acidosis [1]. - Metformin inhibits **hepatic gluconeogenesis** and increases anaerobic glycolysis, which can lead to lactate accumulation if clearance is compromised [1]. *Tolbutamide* - Tolbutamide is an older **sulfonylurea** medication. - Its primary adverse effect is **hypoglycemia**, not lactic acidosis. *Phenformin* - **Phenformin** is a biguanide like metformin but was withdrawn from most markets due to a significantly higher risk of **lactic acidosis** [2]. - Although it caused frequent deaths from lactic acidosis, it is **no longer a currently prescribed medication** in most countries, making metformin the current agent most commonly associated with this risk. *Glipizide* - Glipizide is a **sulfonylurea** medication. - Its main side effect is **hypoglycemia**, and it does not directly cause lactic acidosis.

Q: Which oral drug is effective for the treatment of acromegaly?

Cabergoline. ***Cabergoline*** - **Cabergoline** is an oral **dopamine agonist** that can effectively suppress growth hormone (GH) secretion in a significant subset of acromegaly patients, particularly those with co-secretion of prolactin [1]. - It works by stimulating **dopamine D2 receptors** on pituitary somatotrophs, leading to a reduction in GH production [1]. *Octreotide* - **Octreotide** is a **somatostatin analog** administered via **injection** (subcutaneously or intramuscularly), not orally [3]. - Although highly effective in treating acromegaly by inhibiting GH release, its parenteral route of administration makes it unsuitable for an oral drug question [3]. *Growth hormone receptor antagonist* - **Growth hormone receptor antagonists** like **pegvisomant** act by blocking the action of GH at its receptor, but they are administered via **subcutaneous injection** [2]. - While effective in normalizing IGF-1 levels, they do not reduce GH secretion and are not available in oral form [2]. *Bromocriptine* - **Bromocriptine** is an older, first-generation **dopamine agonist** that can be taken orally [1]. - While it may lower GH levels in some acromegaly patients, its efficacy is generally **less potent and sustained** compared to cabergoline, making it a less preferred choice for primary treatment [1].

Q: What is the drug of choice for central diabetes insipidus?

Desmopressin. ***Desmopressin*** - **Desmopressin** is a synthetic analog of **vasopressin (ADH)** that selectively acts on V2 receptors in the kidney [1]. - It effectively replaces the deficient ADH in central diabetes insipidus, reducing urine output and increasing urine osmolality [1]. *Leuprolide* - **Leuprolide** is a **GnRH agonist** used to treat conditions like prostate cancer, endometriosis, and precocious puberty. - It has no role in the management of diabetes insipidus as it does not affect ADH production or action. *Thiazide diuretics* - While seemingly counterintuitive, **thiazide diuretics** are sometimes used in **nephrogenic diabetes insipidus** to reduce polyuria. - They are not the drug of choice for central diabetes insipidus because they do not address the primary deficiency of ADH. *Insulin* - **Insulin** is a hormone used to treat **diabetes mellitus**, a condition characterized by high blood glucose levels. - It has no relevance to either central or nephrogenic diabetes insipidus, which are disorders of water balance.

Question 1

Precocious puberty is treated by administering

Accepted Answer

LHRH analogs (e.g., Leuprolide)

Answer

Oestrogen

Answer

Gonadotropin-Releasing Hormone (GnRH)

Answer

Testosterone

Question 2

Which of the following is the drug of choice for the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)?

Accepted Answer

Demeclocycline

Answer

Vasopressin

Answer

Thiazide diuretic

Answer

Chlorpropamide

Question 3

What is the primary condition for which calcitriol is used as a treatment?

Accepted Answer

Secondary hyperparathyroidism

Answer

Pemphigus

Answer

Lichen planus

Answer

Leprosy

Question 4

Which of the following statements is true about atosiban?

Accepted Answer

is an oxytocin receptor antagonist

Answer

is least effective in inhibiting preterm uterine contractions

Answer

is a progesterone receptor antagonist

Answer

acts primarily on beta-adrenergic receptors

Question 5

Which of the following medications does not cause hirsutism?

Accepted Answer

Flutamide

Answer

Danazol

Answer

Phenytoin

Answer

Norethisterone

Question 6

Which of the following is preferred for infertility treatment of a female with increased prolactin levels?

Accepted Answer

Cabergoline

Answer

Dopamine

Answer

Carbidopa

Answer

Bromocriptine

Question 7

In thyrotoxicosis, which of the following symptoms is least effectively controlled by beta-blockers?

Accepted Answer

Oxygen consumption

Answer

Tremors

Answer

Tachycardia

Answer

Anxiety

Question 8

Among currently prescribed medications for diabetes mellitus, deaths from lactic acidosis are most commonly associated with which one of the following?

Accepted Answer

Metformin

Answer

Tolbutamide

Answer

Glipizide

Answer

Phenformin

Question 9

Which oral drug is effective for the treatment of acromegaly?

Accepted Answer

Cabergoline

Answer

Bromocriptine

Answer

Octreotide

Answer

Growth hormone receptor antagonist

Question 10

What is the drug of choice for central diabetes insipidus?

Accepted Answer

Desmopressin

Answer

Leuprolide

Answer

Insulin

Answer

Thiazide diuretics

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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