Endocrine Pharmacology Practice Questions

Q: What is the mechanism of action of Pegvisomant?

GH receptor antagonist. ***GH receptor antagonist*** - Pegvisomant is a **growth hormone (GH) receptor antagonist** that binds to GH receptors but does not activate them. - This action blocks the binding of endogenous GH to its receptors, thereby inhibiting the downstream production of **insulin-like growth factor 1 (IGF-1)** and reducing the symptoms of **acromegaly**. *Somatostatin antagonist* - **Somatostatin analogues** (e.g., octreotide, lanreotide) are used to treat acromegaly by inhibiting the release of growth hormone from the pituitary gland. - Pegvisomant does not act on somatostatin receptors; it functions at the level of the **GH receptor**. *Somatotropin antagonist* - **Somatotropin** is another name for **growth hormone (GH)**. - While Pegvisomant opposes the action of somatotropin, its mechanism is specifically at the receptor level, making "GH receptor antagonist" a more precise description. *GH receptor agonist* - A **GH receptor agonist** would stimulate the growth hormone receptor, leading to increased IGF-1 production and exacerbating conditions like acromegaly. - Pegvisomant has the opposite effect, blocking GH action rather than promoting it, making it an **antagonist**.

Q: Which of the following is/are side effect(s) of growth hormone administration?

All of the above. ***All of the above*** - **Growth hormone (GH)** administration can lead to a variety of side effects, including **pain at the injection site**, **glucose intolerance**, and **hypothyroidism**. - These side effects are important considerations when managing patients receiving GH therapy. *Pain at injection site* - This is a common local side effect due to the injection method itself and the substance being administered. - It is typically mild and transient but can affect patient adherence to treatment. *Glucose intolerance* - Growth hormone has **anti-insulin effects**, which can lead to **insulin resistance** and increased blood glucose levels. - This can worsen pre-existing diabetes or induce **glucose intolerance** in susceptible individuals. *Hypothyroidism* - Growth hormone can influence thyroid function, sometimes reducing the conversion of **thyroxine (T4)** to **triiodothyronine (T3)**. - This may lead to **central hypothyroidism** or exacerbate subclinical hypothyroidism, requiring thyroid hormone supplementation.

Q: Which drug is preferred for the treatment of a 21-hydroxylase deficient female fetus to prevent genital virilization?

Maternal dexamethasone. ***Maternal dexamethasone*** - **Dexamethasone** is the preferred corticosteroid because it is not significantly metabolized by the placenta and can effectively reach the fetus to suppress adrenal androgen production. [2] - Its potent **glucocorticoid activity** helps to reduce the overproduction of androgens, preventing the virilization of external genitalia in affected female fetuses. [2] *Maternal cortisol* - **Cortisol** is rapidly metabolized by the placenta via **11β-hydroxysteroid dehydrogenase 2**, making it ineffective in reaching the fetal circulation in sufficient concentrations. - Therefore, it cannot adequately suppress the fetal adrenal gland's androgen production to prevent virilization. *Maternal hydrocortisone* - Similar to cortisol, **hydrocortisone** is also extensively metabolized by the placenta, reducing its bioavailability to the fetus. - It would not achieve the necessary fetal adrenal suppression to prevent **genital virilization**. [1] *Maternal methylprednisolone* - While **methylprednisolone** can cross the placenta, it is less potent than dexamethasone and may not provide sufficient suppression of fetal adrenal androgen synthesis. - **Dexamethasone** is generally considered more effective for this specific indication due to its superior placental transfer and potency.

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

It cannot be used for induction of ovulation.. ***It cannot be used for induction of ovulation.*** - Tamoxifen, as a **selective estrogen receptor modulator (SERM)** with anti-estrogenic effects on the hypothalamus and pituitary, can in fact be used off-label for **ovulation induction** by increasing gonadotropin secretion. - Its anti-estrogenic action at the hypothalamus removes negative feedback, leading to increased **follicle-stimulating hormone (FSH)** release, which stimulates ovarian follicle development. *It increases the risk of venous thromboembolism.* - Tamoxifen exerts **estrogenic effects** on the coagulation system, which can lead to an increased risk of **venous thromboembolism (VTE)**, including deep vein thrombosis and pulmonary embolism. - This side effect is a significant concern, particularly in patients with other risk factors for clotting. *It is a competitive inhibitor of estrogen at receptor site* - Tamoxifen acts as a **selective estrogen receptor modulator (SERM)** by competitively binding to estrogen receptors in target tissues. - This binding prevents **endogenous estrogen** from activating the receptors, thereby exerting its anti-estrogenic effects, particularly in breast tissue. *It is a selective estrogen receptor modulator* - Tamoxifen is indeed classified as a **SERM**, meaning it has both estrogenic and anti-estrogenic effects depending on the target tissue. - It acts as an **estrogen antagonist** in breast tissue, making it effective in treating estrogen receptor-positive breast cancer, and an **estrogen agonist** in other tissues like bone and the endometrium.

Q: Which of the following is not a component of Mala D?

0.15 mg desogestrel. ***0.15 mg desogestrel*** - **Mala D** is a combined oral contraceptive pill that does not contain **desogestrel**. - **Desogestrel** is a progestin primarily found in some *third-generation combined oral contraceptives* or *progestin-only pills*, not Mala D. *0.03 mg Ethinyl estradiol* - **Mala D** contains **0.03 mg of Ethinyl estradiol**, which is the estrogen component of this combined oral contraceptive. - This dosage of estrogen helps to suppress ovulation and stabilize the endometrial lining. *0.15 mg levonorgestrel* - **Mala D** contains **0.15 mg of levonorgestrel**, which is the progestin component of this combined oral contraceptive. - **Levonorgestrel** works by thickening cervical mucus, inhibiting ovulation, and altering the endometrial lining. *Iron tablets* - **Mala D** packs typically include **iron tablets** (usually 75 mg of ferrous fumarate equivalent to 60 mg elemental iron) to be taken during the placebo week. - These iron tablets are included to help prevent or treat **iron-deficiency anemia**, which can occur with menstrual blood loss.

Q: What is the primary reason for hepatic involvement in oral contraceptives?

Estrogen. ***Estrogen*** - **Estrogen** components of oral contraceptives are primarily responsible for potential hepatic side effects, including some cases of **cholestasis** and **hepatocellular adenomas**. - High doses of estrogen can alter **liver enzyme metabolism** and affect bile flow. *Progesterone* - **Progesterone** components alone are generally not associated with significant hepatic dysfunction. - While synthetic progestins are metabolized by the liver, they typically do not induce the same level of hepatic risk as estrogen. *Estrogen + Progesterone* - While both hormones are present in combined oral contraceptives, the **estrogenic component** is the main driver of hepatic involvement. - The liver effects are primarily attributed to estrogen's influence on **hepatic synthesis** and metabolism, with progesterone playing a less direct role in adverse hepatic events. *Mixed trace elements* - **Oral contraceptives** do not contain significant amounts of mixed trace elements that would account for hepatic involvement. - Hepatic issues related to trace elements are usually associated with **toxicity** or deficiency states not relevant to oral contraceptive use.

Q: Which of the following drugs does not cause adrenocortical suppression?

Spironolactone. ***Spironolactone*** - This drug is an **aldosterone antagonist** and a **potassium-sparing diuretic**. While it can interfere with androgen synthesis and bind to androgen and progesterone receptors, it does not directly cause generalized adrenocortical suppression of cortisol or other adrenal hormones. - Its primary actions are on the **renal tubules** to increase sodium and water excretion while retaining potassium. *Prednisone* - Prednisone is a **synthetic glucocorticoid** that, when administered exogenously, suppresses the body's natural production of cortisol by inhibiting the HPA axis (hypothalamic-pituitary-adrenal axis). - Chronic use leads to **adrenal atrophy** and decreased endogenous cortisol secretion, requiring gradual tapering to allow adrenal recovery. *Ketoconazole* - Ketoconazole is an antifungal agent that also inhibits several **cytochrome P450 enzymes** involved in steroid biosynthesis, including 11β-hydroxylase and 17α-hydroxylase. - This inhibition directly reduces the production of **cortisol** and other adrenal steroids, making it useful in conditions like Cushing's syndrome but also causing adrenocortical suppression as a side effect. *Mitotane* - Mitotane is an **adrenolytic agent** specifically used in the treatment of adrenocortical carcinoma. - It causes **selective atrophy and necrosis** of the adrenal cortex, leading to a significant reduction in cortisol and other adrenal steroid production.

Q: Which of the following statements about GnRH agonists is false?

Ganirelix is a GnRH agonist.. ***Ganirelix is a GnRH agonist.*** - **Ganirelix** is a **GnRH antagonist**, meaning it blocks the GnRH receptor and immediately suppresses gonadotropin release. - GnRH agonists initially stimulate the receptor, leading to a surge, before causing downregulation and desensitization. *Used in cases of precocious puberty.* - **GnRH agonists** are indeed used to treat **precocious puberty** by downregulating the GnRH receptors and suppressing endogenous gonadotropin-releasing hormone activity, which halts pubertal progression. - This therapy induces a temporary, reversible **hypogonadotropic hypogonadism**, effectively pausing inappropriate early puberty. *Long acting preparations can be used as nasal spray.* - Some **GnRH agonists**, like **buserelin**, are available as **nasal sprays** for long-term administration. - This route of administration allows for convenience and consistent delivery, particularly in conditions requiring chronic suppression. *They have action similar to gonadotropin releasing hormone.* - **GnRH agonists** are synthetic analogs of natural **gonadotropin-releasing hormone (GnRH)**, sharing a similar molecular structure. - They bind to and stimulate the GnRH receptors in the pituitary, initially causing increased **gonadotropin** release, followed by receptor desensitization and downregulation.

Q: Which of the following medications exhibits an incretin-like function?

Exenatide. ***Exenatide*** - **Exenatide** is a **glucagon-like peptide-1 (GLP-1) receptor agonist**, mimicking the action of naturally occurring incretin hormones. - It helps reduce blood glucose levels by **increasing glucose-dependent insulin secretion**, **reducing glucagon secretion**, and **slowing gastric emptying**. *Miglitol* - **Miglitol** belongs to the class of **alpha-glucosidase inhibitors**. - It works by delaying the digestion and absorption of carbohydrates in the small intestine, thereby reducing postprandial glucose levels. *Pioglitazone* - **Pioglitazone** is a **thiazolidinedione (TZD)** that acts as an agonist for **peroxisome proliferator-activated receptor-gamma (PPAR-γ)**. - It improves insulin sensitivity in peripheral tissues and the liver, leading to increased glucose uptake and utilization. *Repaglinide* - **Repaglinide** is a **meglitinide**, a class of **insulin secretagogues**. - It stimulates insulin release from pancreatic beta cells by binding to and closing ATP-sensitive potassium channels.

Question 1

What is the mechanism of action of Pegvisomant?

Accepted Answer

GH receptor antagonist

Answer

Somatostatin antagonist

Answer

Somatotropin antagonist

Answer

GH receptor agonist

Question 2

Which of the following is/are side effect(s) of growth hormone administration?

Accepted Answer

All of the above

Answer

Hypothyroidism

Answer

Pain at injection site

Answer

Glucose intolerance

Question 3

Which drug is preferred for the treatment of a 21-hydroxylase deficient female fetus to prevent genital virilization?

Accepted Answer

Maternal dexamethasone

Answer

Maternal hydrocortisone

Answer

Maternal methylprednisolone

Answer

Maternal cortisol

Question 4

Which of the following statements about tamoxifen is false?

Accepted Answer

It cannot be used for induction of ovulation.

Answer

It increases the risk of venous thromboembolism.

Answer

It is a competitive inhibitor of estrogen at receptor site

Answer

It is a selective estrogen receptor modulator

Question 5

Which of the following is not a component of Mala D?

Accepted Answer

0.15 mg desogestrel

Answer

0.03 mg Ethinyl estradiol

Answer

0.15 mg levonorgestrel

Answer

Iron tablets

Question 6

What is the primary reason for hepatic involvement in oral contraceptives?

Accepted Answer

Estrogen

Answer

Progesterone

Answer

Mixed trace elements

Answer

Estrogen + Progesterone

Question 7

What is a special feature of glargine insulin?

Accepted Answer

It provides a long duration of action with a smooth, peakless effect.

Answer

It is suitable for once daily administration.

Answer

It is stable at physiological pH.

Answer

It is primarily used for basal insulin control.

Question 8

Which of the following drugs does not cause adrenocortical suppression?

Accepted Answer

Spironolactone

Answer

Prednisone

Answer

Ketoconazole

Answer

Mitotane

Question 9

Which of the following statements about GnRH agonists is false?

Accepted Answer

Ganirelix is a GnRH agonist.

Answer

Long acting preparations can be used as nasal spray.

Answer

Used in cases of precocious puberty.

Answer

They have action similar to gonadotropin releasing hormone.

Question 10

Which of the following medications exhibits an incretin-like function?

Accepted Answer

Exenatide

Answer

Repaglinide

Answer

Pioglitazone

Answer

Miglitol

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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