Endocrine Pharmacology Practice Questions

Q: Prolonged corticosteroid therapy suppresses the hypothalamic-pituitary-adrenal (HPA) axis by primarily inhibiting the secretion of which hormone?

ACTH. ***ACTH*** - **Corticosteroids** act via **negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis**, suppressing the release of **corticotropin-releasing hormone (CRH)** from the hypothalamus and subsequently **ACTH** from the anterior pituitary. - This suppression of **ACTH** leads to **adrenal atrophy** and reduced endogenous **cortisol** production, which is why abrupt withdrawal after prolonged therapy can precipitate **adrenal crisis**. - **HPA axis suppression** is a clinically significant adverse effect requiring **gradual tapering** of corticosteroids and **stress-dose coverage** during illness or surgery. *GH* - **Growth hormone (GH)** is regulated by **GHRH** and **somatostatin**, not the HPA axis. - While chronic corticosteroid use can impair growth in children through multiple mechanisms (including direct effects on bone and cartilage), **GH suppression is not the primary mechanism** of HPA axis inhibition. *FSH* - **Follicle-stimulating hormone (FSH)** is a gonadotropin regulated by **GnRH** from the hypothalamus. - Corticosteroids do not primarily suppress **FSH** as part of their feedback mechanism on the HPA axis. *LH* - **Luteinizing hormone (LH)** is another gonadotropin regulated by the hypothalamic-pituitary-gonadal axis. - **LH suppression** is not part of the primary negative feedback mechanism by which corticosteroids inhibit the HPA axis.

Q: A rapid-acting insulin secretagogue effective in postprandial sugar control is:

Repaglinide. ***Repaglinide*** - **Repaglinide** is a **meglitinide analog** that works by stimulating insulin release from pancreatic beta cells with a **rapid onset** and **short duration of action**. - Its rapid action makes it particularly effective in reducing **postprandial glucose excursions** when taken just before meals. - Provides **flexible dosing** - can be taken with meals and skipped if a meal is skipped. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays carbohydrate digestion and absorption in the small intestine. - While highly effective for postprandial glucose control through a different mechanism (delayed absorption vs. insulin secretion), it is **not an insulin secretagogue**. - Often causes gastrointestinal side effects like flatulence and abdominal discomfort. *Metformin* - **Metformin** is a **biguanide** that primarily reduces **hepatic glucose production** and improves insulin sensitivity. - Its main effect is on fasting glucose rather than specifically targeting rapid postprandial glucose spikes. - **Not an insulin secretagogue**. *Sulfonylurea* - **Sulfonylureas** stimulate insulin secretion but have a **longer duration of action** compared to meglitinides. - More associated with **hypoglycemia risk** if meals are irregular or skipped. - Less suitable for targeted postprandial control due to prolonged action.

Q: Which of the following insulin preparations has the longest duration of action?

Insulin degludec. ***Insulin degludec*** - **Insulin degludec** forms multi-hexamer chains upon subcutaneous injection, leading to a slow and continuous release of monomers and providing the longest duration of action among available insulin preparations, often exceeding **42 hours**. - Its unique mechanism of action allows for once-daily dosing with less variability and a flatter, more stable pharmacokinetic profile compared to other basal insulins. *Insulin glargine* - **Insulin glargine** precipitates in subcutaneous tissue at physiological pH, forming micro-precipitates from which insulin is slowly absorbed, providing a duration of action of approximately **24 hours**. - Although it is a long-acting insulin, its duration is typically less than that of insulin degludec, and it usually requires once-daily administration. *Insulin detemir* - **Insulin detemir** binds reversibly to albumin in the blood, which delays its absorption and degradation, resulting in a duration of action around **12-24 hours**, depending on the dose. - Due to its variable duration, insulin detemir may sometimes require twice-daily dosing in some patients to maintain basal insulin coverage. *Isophane insulin (NPH)* - **Isophane insulin (NPH)** is an intermediate-acting insulin preparation that is formulated with protamine, which delays its absorption, giving it a duration of action of approximately **10-18 hours**. - NPH insulin has a more pronounced peak action compared to newer long-acting analogues, which can lead to a higher risk of nocturnal hypoglycemia.

Q: Which of the following is recombinant parathyroid hormone (rPTH) used in osteoporosis treatment?

Teriparatide. ***Teriparatide*** - **Teriparatide** is a **recombinant human parathyroid hormone (rPTH)**. It is an **anabolic agent** used in osteoporosis treatment. - Unlike antiresorptive agents, teriparatide **stimulates osteoblastic activity** and new bone formation, leading to increased bone mineral density and reduced fracture risk. *Calcipotriol* - **Calcipotriol** is a vitamin D analog primarily used topically for the treatment of **psoriasis**. - It works by regulating cell proliferation and differentiation in the skin, and is **not used for osteoporosis**. *Denosumab* - **Denosumab** is a **monoclonal antibody** that targets RANKL, inhibiting osteoclast formation and function, thus **reducing bone resorption**. - While it is a treatment for osteoporosis, it is an **antiresorptive agent**, not a recombinant parathyroid hormone. *Calcitriol* - **Calcitriol** is the **active form of vitamin D** and is used to treat conditions like hypocalcemia and metabolic bone disease associated with kidney failure. - It primarily helps with **calcium absorption** and bone mineralization, but it is not a recombinant parathyroid hormone and is not a primary anabolic treatment for osteoporosis.

Q: Which of the following is the drug of choice for Addison's disease?

Hydrocortisone. ***Hydrocortisone*** - **Hydrocortisone** is the **glucocorticoid of choice** for Addison's disease because it most closely mimics the body's natural cortisol in terms of **potency and duration of action**. - It is preferred for **physiological replacement therapy** due to its short half-life (8-12 hours), allowing for dosing schedules that mimic the normal circadian rhythm of cortisol secretion. - While hydrocortisone has **some mineralocorticoid activity**, it is usually **combined with fludrocortisone** (a synthetic mineralocorticoid) to provide complete hormone replacement in Addison's disease. - The typical regimen is hydrocortisone **15-25 mg/day in divided doses** plus fludrocortisone **0.05-0.2 mg/day**. *Betamethasone* - **Betamethasone** is a **potent long-acting synthetic glucocorticoid** with **minimal mineralocorticoid activity**. - Its **long duration of action** and high potency make it unsuitable for daily physiological replacement therapy, as it increases the risk of **cushingoid side effects** and cannot mimic normal cortisol circadian rhythm. *Dexamethasone* - **Dexamethasone** is a **very potent long-acting glucocorticoid** with **no mineralocorticoid activity**. - Its **very long half-life (36-72 hours)** makes precise titration for physiological replacement extremely difficult and increases the risk of **overreplacement and cushingoid features**. - It is not suitable for routine replacement therapy in Addison's disease. *Prednisolone* - **Prednisolone** is an intermediate-acting glucocorticoid that can be used as an **alternative to hydrocortisone** for replacement therapy. - However, **hydrocortisone remains preferred** because its pharmacokinetic profile more closely matches physiological cortisol secretion. - Like hydrocortisone, prednisolone also requires **supplementation with fludrocortisone** for complete mineralocorticoid replacement.

Q: Which of the following drugs causes osteoporosis on long-term use?

Prednisolone. ***Prednisolone*** - **Glucocorticoids** like prednisolone inhibit osteoblast function, reduce calcium absorption from the gut, and increase renal calcium excretion, all contributing to **bone loss** and **osteoporosis** with long-term use. - This effect is a significant concern in patients requiring chronic corticosteroid therapy for inflammatory or autoimmune conditions. - **Prednisolone is the most important and well-established cause of drug-induced osteoporosis.** *Etidronate* - **Etidronate** is a **bisphosphonate** drug used to treat and prevent osteoporosis by inhibiting osteoclast activity, thereby reducing bone resorption. - Therefore, it protects against osteoporosis rather than causing it. *Phenytoin* - **Phenytoin** is an antiepileptic drug that can interfere with **vitamin D metabolism** through induction of hepatic enzymes, leading to decreased calcium absorption. - Long-term use can result in **osteomalacia** (defective mineralization) and may also contribute to **osteoporosis** (decreased bone mass). - However, glucocorticoids remain the most clinically significant cause of drug-induced osteoporosis. *Calcitriol* - **Calcitriol** is the active form of **vitamin D** (1,25-dihydroxyvitamin D3), used to increase calcium absorption from the gut and promote bone mineralization. - It is used in the treatment of conditions like hypoparathyroidism, renal osteodystrophy, and osteoporosis to improve bone health and calcium balance.

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

Acarbose. ***Acarbose***- Acarbose is an **alpha-glucosidase inhibitor** that works by delaying carbohydrate digestion and glucose absorption in the gut.- Due to its mechanism of action, which does not stimulate insulin secretion or increase insulin sensitivity directly, it carries a **very low risk of hypoglycemia** when used as monotherapy [1].*Insulin*- **Insulin** is a direct hormone replacement therapy that lowers blood glucose by facilitating glucose uptake into cells.- Administered doses can sometimes exceed the body's needs, leading to **hypoglycemia**, especially with missed meals or increased physical activity [1].*Glimepiride*- Glimepiride is a **sulfonylurea** that stimulates insulin release from pancreatic beta cells, regardless of blood glucose levels.- This persistent stimulation can lead to **hypoglycemia**, which can be severe and prolonged.*Nateglinide*- Nateglinide is a **meglitinide**, a class of drugs that also stimulate insulin secretion from pancreatic beta cells [1, 2].- While its action is more rapid and short-lived compared to sulfonylureas, it still carries a risk of inducing **hypoglycemia**.

Q: Which of the following is a nasally acting GnRH analogue?

Nafarelin. ***Nafarelin (Correct Answer)*** - **Nafarelin** is available as a **nasal spray** (Synarel®), making it a nasally acting GnRH analogue - Administered intranasally for conditions like **endometriosis** and **central precocious puberty** - Its formulation is designed for efficient absorption through the **nasal mucosa** *Goserelin (Incorrect)* - Administered as a **subcutaneous implant** (Zoladex®) for sustained release, not nasally - Used in hormone therapy for **prostate cancer**, **breast cancer**, and **endometriosis** - Not available in nasal formulation *Triptorelin (Incorrect)* - Provided as an **intramuscular or subcutaneous injection** in sustained-release depot formulation - Used for hormone-sensitive cancers and **assisted reproductive technology** - Not formulated for **nasal administration** *Leuprolide (Incorrect)* - Administered via **subcutaneous or intramuscular injection** (Lupron®), including depot formulations - Used for prostate cancer, endometriosis, and uterine fibroids - **Not available in nasal form** for clinical use

Q: Which medication is used for suppression of lactation?

Bromocriptine. ***Bromocriptine*** - **Bromocriptine** is a **dopamine agonist** that suppresses prolactin secretion from the anterior pituitary, thereby inhibiting lactation - Acts by stimulating **D2 dopamine receptors**, which inhibits prolactin release - Historically used for lactation suppression, though its use has declined due to potential cardiovascular side effects (**hypotension**, **stroke**, **myocardial infarction**) - **Cabergoline** (another dopamine agonist) is now preferred when pharmacological suppression is needed due to better tolerability - **Non-pharmacological methods** (breast binding, ice packs, avoiding stimulation) are now first-line recommendations *Pyridoxine* - **Pyridoxine (Vitamin B6)** has been anecdotally mentioned for lactation suppression, but lacks strong scientific evidence - Does not directly affect **prolactin secretion** or milk production mechanisms - Not recommended for this indication *DMPA* - **DMPA (Depot Medroxyprogesterone Acetate)** is a **progestin-only injectable contraceptive** used postpartum - Safe for breastfeeding mothers as its primary function is **contraception**, not lactation suppression - Does not actively suppress established lactation *D-Norgestrel* - **D-Norgestrel** is a **progestin** component found in some oral contraceptive pills - Primary role is **contraception**, not lactation suppression - Progestin-only contraceptives are compatible with breastfeeding

Question 1

Prolonged corticosteroid therapy suppresses the hypothalamic-pituitary-adrenal (HPA) axis by primarily inhibiting the secretion of which hormone?

Accepted Answer

ACTH

Answer

GH

Answer

FSH

Answer

LH

Question 2

A rapid-acting insulin secretagogue effective in postprandial sugar control is:

Accepted Answer

Repaglinide

Answer

Metformin

Answer

Acarbose

Answer

Sulfonylurea

Question 3

Which of the following insulin preparations has the longest duration of action?

Accepted Answer

Insulin degludec

Answer

Insulin glargine

Answer

Isophane insulin (NPH)

Answer

Insulin detemir

Question 4

Which of the following is recombinant parathyroid hormone (rPTH) used in osteoporosis treatment?

Accepted Answer

Teriparatide

Answer

Calcipotriol

Answer

Denosumab

Answer

Calcitriol

Question 5

What are the side effects of diethylstilbestrol when used in a pregnant woman?

Accepted Answer

Infertility and development of vaginal carcinoma in female offspring

Answer

Deep vein thrombosis in pregnant woman

Answer

Feminization of external genitalia of male offspring

Answer

Virilization of the external genitalia of female offspring

Question 6

Which of the following is the drug of choice for Addison's disease?

Accepted Answer

Hydrocortisone

Answer

Betamethasone

Answer

Dexamethasone

Answer

Prednisolone

Question 7

Which of the following drugs causes osteoporosis on long-term use?

Accepted Answer

Prednisolone

Answer

Etidronate

Answer

Calcitriol

Answer

Phenytoin

Question 8

Which of the following drugs does not cause hypoglycemia?

Accepted Answer

Acarbose

Answer

Insulin

Answer

Glimepiride

Answer

Nateglinide

Question 9

Which of the following is a nasally acting GnRH analogue?

Accepted Answer

Nafarelin

Answer

Triptorelin

Answer

Leuprolide

Answer

Goserelin

Question 10

Which medication is used for suppression of lactation?

Accepted Answer

Bromocriptine

Answer

DMPA

Answer

Pyridoxine

Answer

D-Norgestrel

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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