Endocrine Pharmacology Practice Questions

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: A pregnant female taking carbimazole may have neonates with various congenital anomalies. Which of the following is the MOST characteristic and well-documented anomaly associated with carbimazole exposure?

Scalp defects. ***Scalp defects*** - **Aplasia cutis congenita** (congenital scalp defects) is the most characteristic and well-documented anomaly specifically associated with carbimazole exposure during pregnancy, particularly in the first trimester. - This condition involves areas of absent skin, usually on the scalp, which can range from small lesions to large defects. *Neural tube defects* - While significant congenital anomalies, **neural tube defects** are not specifically or primarily linked to carbimazole exposure. - They are more commonly associated with factors like **folate deficiency** or other teratogens. *Limb reduction defects* - **Limb reduction defects** are severe congenital malformations but are not the characteristic anomaly associated with carbimazole. - These defects are more commonly linked to other teratogens or genetic factors. *Fetal goiter* - **Fetal goiter** can occur with carbimazole use due to its antithyroid effects causing fetal hypothyroidism, but it is not considered the "most characteristic" or defining structural anomaly linked to the drug in the same way scalp defects are. - While it's a known side effect impacting thyroid function and development, it's a functional rather than a typically structural malformation.

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.

Q: Which of the following drugs is contraindicated in patients with diabetes and is used for the treatment of insulinoma?

Diazoxide. ***Diazoxide*** - **Diazoxide** is an **arteriolar vasodilator** that also has a potent **hyperglycemic** effect by **opening K-ATP channels** in pancreatic beta cells, which **inhibits insulin secretion**. - This mechanism makes it the drug of choice for treating **insulinoma** (where excess insulin causes hypoglycemia), but it is **absolutely contraindicated in diabetics** due to its severe hyperglycemic action. - It is the only drug among the options that satisfies both criteria: used for insulinoma AND contraindicated in diabetes. *Nicorandil* - **Nicorandil** is a **potassium channel activator** and nitrate derivative that causes vasodilation, primarily used for **angina pectoris**. - It does not inhibit insulin secretion or cause clinically significant hyperglycemia that would contraindicate its use in diabetes. - Not used for insulinoma treatment. *Minoxidil* - **Minoxidil** is a potent direct **arteriolar vasodilator** primarily used for **severe refractory hypertension** and topically for **alopecia** (hair loss). - While it can occasionally cause minor glucose intolerance, it is not contraindicated in diabetes and has no role in insulinoma treatment. *Hydralazine* - **Hydralazine** is a direct **arteriolar vasodilator** used to treat **hypertension**, particularly in pregnancy (preeclampsia/eclampsia). - It does not have significant effects on glucose metabolism or insulin secretion and is not used for insulinoma treatment.

Q: Which of the following DPP-IV inhibitors is safe for use in chronic kidney disease patients without requiring dose modification?

Linagliptin. ***Linagliptin*** - Unlike other **DPP-IV inhibitors**, **linagliptin** is primarily eliminated via **biliary/fecal excretion** (~85%) rather than renal excretion. - This unique elimination pathway makes it **safe** for use in patients with **chronic kidney disease** at its usual dose, without the need for dose adjustment. - It is the **only DPP-IV inhibitor** that does not require dose modification in CKD. *Sitagliptin* - **Sitagliptin** is primarily eliminated by the **kidneys** (~80% renal excretion), requiring **significant dose adjustments** in patients with **renal impairment**. - Without dose modification, there is an increased risk of **drug accumulation** and adverse effects in CKD patients. *Vildagliptin* - **Vildagliptin** undergoes **hydrolysis** with subsequent **renal excretion** of inactive metabolites, requiring **dose reduction** in patients with moderate to severe **renal impairment**. - Not recommended in severe renal impairment (eGFR <50 mL/min). *Saxagliptin* - **Saxagliptin** is partially eliminated via **renal excretion** and requires **dose reduction** by 50% in patients with moderate to severe **CKD**. - Both parent drug and active metabolite accumulate in renal impairment, necessitating dose adjustment.

Q: All of the following are adverse effects of glucocorticoids except:

Hypoglycemia. ***Hypoglycemia*** - Glucocorticoids are known to **increase blood glucose levels** by promoting gluconeogenesis and glycogenolysis, thus they cause **hyperglycemia**, not hypoglycemia. - They also induce **insulin resistance**, further contributing to elevated blood sugar. *Cataract* - Long-term use of high-dose glucocorticoids can cause **posterior subcapsular cataracts** due to metabolic changes in the lens. - This is a well-recognized ocular side effect of corticosteroids. *Peptic ulcer* - Glucocorticoids can impair the **gastric mucosal barrier**, increase acid secretion, and reduce prostaglandin synthesis, leading to an increased risk of **peptic ulcers**. - This effect is potentiated when used concurrently with NSAIDs. *Infections* - Glucocorticoids are **immunosuppressive**, reducing the body's ability to fight off pathogens. - This increases susceptibility to various infections, including bacterial, viral, fungal, and opportunistic infections.

Q: Which of the following is the synthetic form of Triiodothyronine (T3)?

Liothyronine sodium. ***Liothyronine sodium*** - This is the **synthetic form of Triiodothyronine (T3)**, the more potent and active form of thyroid hormone. - It has a **rapid onset of action** (within a few hours) and shorter half-life compared to T4. - Used in cases where direct T3 replacement is needed, such as in **myxedema coma** or for suppression testing. *Levothyroxine sodium* - This is the synthetic form of **Thyroxine (T4)**, which is then converted to T3 in peripheral tissues. - It is the **most common preparation** for treating hypothyroidism due to its longer half-life (7 days) and stable serum levels. *Liotrix* - Liotrix is a **combination preparation of synthetic T4 and synthetic T3**, typically in a 4:1 ratio. - It aims to mimic the natural physiological ratio; however, its use is **less common** than levothyroxine monotherapy. *Propylthiouracil* - This is an **antithyroid drug** used to treat hyperthyroidism, not a thyroid hormone replacement. - It works by inhibiting thyroid peroxidase and peripheral conversion of T4 to T3.

Q: The drug of choice for hyperthyroidism during the 2nd trimester of pregnancy is:

Carbimazole. ***Carbimazole*** - **Carbimazole** is converted to **methimazole** in the body, which is generally preferred in the second and third trimesters due to a lower risk of serious liver toxicity compared to propylthiouracil. - While propylthiouracil is preferred in the first trimester, **methimazole/carbimazole** is considered safer in later trimesters after the period of major organogenesis. *Propylthiouracil* - **Propylthiouracil (PTU)** is the drug of choice for hyperthyroidism during the **first trimester** of pregnancy because of a lower risk of teratogenicity compared to methimazole/carbimazole. - However, **PTU** carries a risk of **hepatic toxicity** in the mother, making carbimazole/methimazole preferable in the second and third trimesters once the initial teratogenic risk largely passes. *Sodium iodide* - **Sodium iodide** is generally **contraindicated** in pregnancy for routine treatment of hyperthyroidism as it can cross the placenta and potentially cause **fetal goiter** and **hypothyroidism**. - Its use is typically limited to **thyroid storm** or preparation for thyroidectomy when other options are not suitable. *Radioactive iodine* - **Radioactive iodine (I-131)** is **absolutely contraindicated** during any trimester of pregnancy and lactation. - It rapidly crosses the placenta and can **ablate the fetal thyroid gland**, leading to permanent fetal hypothyroidism.

Q: Which of the following drugs does not cause hyperprolactinemia?

Bromocriptine. ***Bromocriptine*** - Bromocriptine is a **dopamine agonist** that directly activates dopamine D2 receptors in the pituitary gland, leading to a **decrease in prolactin secretion** [1], [3]. - It is commonly used in the treatment of **hyperprolactinemia** and prolactinomas, not a cause of it [2]. *Haloperidol* - Haloperidol is a **first-generation antipsychotic** drug that blocks dopamine D2 receptors in the pituitary. - This blockade leads to a **disinhibition of prolactin secretion**, resulting in hyperprolactinemia. *Reserpine* - Reserpine depletes **monoamines**, including dopamine, from presynaptic nerve terminals in the brain. - The resulting **reduction in dopamine availability** at the pituitary level leads to increased prolactin secretion and hyperprolactinemia. *Chlorpromazine* - Chlorpromazine is a **phenothiazine antipsychotic** that significantly blocks dopamine D2 receptors. - This **dopamine antagonism** prevents the tonic inhibition of prolactin release, thereby causing hyperprolactinemia.

Q: Which of the following is a testosterone inhibitor?

Spironolactone. ***Spironolactone*** - Spironolactone is an **androgen receptor antagonist** and also inhibits **testosterone synthesis** by blocking 17α-hydroxylase and 17,20-lyase enzymes. - This dual action reduces the effects and production of testosterone, making it useful in conditions like **hirsutism** and **polycystic ovary syndrome (PCOS)**. *Clomiphene* - Clomiphene is a **selective estrogen receptor modulator (SERM)** that acts as an antagonist in the hypothalamus, thereby increasing the pulsatile release of GnRH. - This leads to increased FSH and LH secretion, stimulating **ovulation in women** and **testosterone production in men**, rather than inhibiting testosterone. *Bremelanotide* - Bremelanotide is a **melanocortin receptor agonist** that acts on the central nervous system to increase sexual desire. - It is used to treat **hypoactive sexual desire disorder (HSDD)** in premenopausal women and has no direct effect on testosterone levels or action. *Sildenafil* - Sildenafil is a **phosphodiesterase-5 (PDE5) inhibitor** that increases blood flow to the penis by enhancing the effects of nitric oxide, leading to an erection. - It is primarily used to treat **erectile dysfunction** and does not directly inhibit testosterone.

Question 1

Which oral drug is effective for the treatment of acromegaly?

Accepted Answer

Cabergoline

Answer

Bromocriptine

Answer

Octreotide

Answer

Growth hormone receptor antagonist

Question 2

A pregnant female taking carbimazole may have neonates with various congenital anomalies. Which of the following is the MOST characteristic and well-documented anomaly associated with carbimazole exposure?

Accepted Answer

Scalp defects

Answer

Limb reduction defects

Answer

Neural tube defects

Answer

Fetal goiter

Question 3

What is the drug of choice for central diabetes insipidus?

Accepted Answer

Desmopressin

Answer

Leuprolide

Answer

Insulin

Answer

Thiazide diuretics

Question 4

Which of the following drugs is contraindicated in patients with diabetes and is used for the treatment of insulinoma?

Accepted Answer

Diazoxide

Answer

Nicorandil

Answer

Minoxidil

Answer

Hydralazine

Question 5

Which of the following DPP-IV inhibitors is safe for use in chronic kidney disease patients without requiring dose modification?

Accepted Answer

Linagliptin

Answer

Sitagliptin

Answer

Vildagliptin

Answer

Saxagliptin

Question 6

All of the following are adverse effects of glucocorticoids except:

Accepted Answer

Hypoglycemia

Answer

Peptic ulcer

Answer

Infections

Answer

Cataract

Question 7

Which of the following is the synthetic form of Triiodothyronine (T3)?

Accepted Answer

Liothyronine sodium

Answer

Levothyroxine sodium

Answer

Liotrix

Answer

Propylthiouracil

Question 8

The drug of choice for hyperthyroidism during the 2nd trimester of pregnancy is:

Accepted Answer

Carbimazole

Answer

Propylthiouracil

Answer

Sodium iodide

Answer

Radioactive iodine

Question 9

Which of the following drugs does not cause hyperprolactinemia?

Accepted Answer

Bromocriptine

Answer

Reserpine

Answer

Chlorpromazine

Answer

Haloperidol

Question 10

Which of the following is a testosterone inhibitor?

Accepted Answer

Spironolactone

Answer

Clomiphene

Answer

Bremelanotide

Answer

Sildenafil

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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