FMGE 2019 - Pharmacology Practice Questions

Q: Mechanism of action of allopurinol is

Xanthine oxidase inhibition. ***Xanthine oxidase inhibition*** - **Allopurinol** acts as a **structural analog of hypoxanthine** and competitively inhibits the enzyme **xanthine oxidase**. - By inhibiting **xanthine oxidase**, allopurinol prevents the conversion of hypoxanthine to xanthine and then to uric acid, thereby **decreasing uric acid production**. *Recombinant uricase* - **Recombinant uricase** (e.g., rasburicase, pegloticase) is an enzyme that catalyzes the breakdown of existing uric acid into allantoin, a more soluble compound. - This mechanism is distinct from allopurinol, which **prevents uric acid formation**. *Decrease chemotaxis* - Medications that **decrease chemotaxis**, such as **colchicine**, work by interfering with the migration of neutrophils to sites of inflammation, which is useful in acute gout flares. - This is an **anti-inflammatory mechanism**, not related to uric acid synthesis or excretion. *Increase uric acid excretion* - Drugs that **increase uric acid excretion** are known as **uricosurics** (e.g., probenecid, lesinurad). - These agents act on the renal tubules to **inhibit uric acid reabsorption**, thus promoting its elimination from the body.

Q: Which of the following drug causes postural hypotension commonly?

Alpha blocker. ***Alpha blocker*** - **Alpha-1 adrenergic blockers** cause common postural hypotension by blocking **alpha-1 receptors** on vascular smooth muscle, leading to vasodilation and reduced peripheral vascular resistance. - This vasodilation, especially in the upright position, can cause blood to pool in the lower extremities, decreasing venous return to the heart and thus lowering blood pressure. *Angiotensin receptor blockers* - These drugs block the effects of **angiotensin II**, leading to vasodilation and decreased aldosterone secretion, typically causing a more gradual and less pronounced drop in blood pressure. - While they can cause hypotension, **postural hypotension** is less common and usually less severe compared to alpha blockers due to their different mechanism of action and less abrupt vasodilation. *Beta blocker* - **Beta-blockers** primarily reduce heart rate and myocardial contractility, thereby decreasing cardiac output, which can contribute to generalized hypotension. - They do not directly cause significant **vasodilation** in the same manner as alpha-blockers, making postural hypotension less common unless there are other contributing factors. *ACE inhibitor* - **ACE inhibitors** prevent the conversion of angiotensin I to **angiotensin II**, leading to vasodilation and reduced aldosterone. - They can cause hypotension, especially with the first dose or in volume-depleted patients, but **postural hypotension** is typically less frequent and severe than with alpha-blockers.

Q: Which of the following is a carbonic anhydrase inhibitor?

Acetazolamide. ***Acetazolamide*** - Acetazolamide is a classic example of a **carbonic anhydrase inhibitor**, primarily used as a diuretic and for managing **glaucoma** and **altitude sickness**. - It works by inhibiting the enzyme **carbonic anhydrase** in the **proximal renal tubule**, reducing bicarbonate reabsorption and thus promoting diuresis. *Hydrochlorothiazide* - Hydrochlorothiazide is a **thiazide diuretic** that acts on the **distal convoluted tubule** to inhibit the reabsorption of sodium and chloride. - It is not a carbonic anhydrase inhibitor. *Mannitol* - Mannitol is an **osmotic diuretic** that works in the **proximal tubule** and **descending limb of Henle's loop** by creating an osmotic gradient. - It is not a carbonic anhydrase inhibitor and functions by drawing water into the renal tubule, leading to increased urine output. *Furosemide* - Furosemide is a **loop diuretic** that acts on the **thick ascending limb of the loop of Henle** by inhibiting the Na+-K+-2Cl- cotransporter. - It is one of the most potent diuretics but does not inhibit carbonic anhydrase.

Q: Which of the following anti-epileptic drugs has the highest teratogenic potential?

Valproate. ***Correct: Valproate*** - **Valproate has the highest teratogenic potential** among all anti-epileptic drugs, with a **10-20% risk of major congenital malformations** - **Neural tube defects** (spina bifida) occur in **1-2% of exposed pregnancies**, which is 10-20 times higher than the general population - Other significant risks include **cardiac malformations, craniofacial abnormalities**, and **neurodevelopmental disorders** (autism spectrum disorder, reduced IQ) - **Fetal valproate syndrome** is a recognized clinical entity - Current guidelines strongly recommend **avoiding valproate in women of childbearing potential** unless no alternatives exist *Incorrect: Carbamazepine* - Has teratogenic risks but significantly **lower than valproate** (2-5% risk of major malformations) - Associated with **neural tube defects** (0.5-1% risk, lower than valproate) - Considered a safer alternative when valproate must be avoided *Incorrect: Phenytoin* - Causes **fetal hydantoin syndrome** with characteristic features: craniofacial anomalies, nail/digital hypoplasia, growth restriction, and developmental delay - Teratogenic risk is **moderate** (approximately 5-10% risk of major malformations) - Risk is significant but **lower than valproate** *Incorrect: Lamotrigine* - Considered **one of the safest anti-epileptic drugs** during pregnancy - Low teratogenic risk with **major malformation rate of 2-3%** (close to baseline population risk) - Slight increased risk of **oral clefts** at higher doses - **Preferred choice** for women of childbearing potential requiring anti-epileptic therapy

Q: Insulin of choice for the treatment of diabetic ketoacidosis is:

Regular Insulin. ***Regular Insulin*** - **Regular insulin** is the insulin of choice for treating **diabetic ketoacidosis (DKA)** because it can be administered intravenously. - Its **short onset of action** and predictable duration allow for rapid and precise titration in a critical care setting. *Insulin lispro* - **Insulin lispro** is a **rapid-acting insulin analog** typically used for mealtime coverage, which has a very quick onset and short duration. - While it acts quickly, its primary use is not for the continuous intravenous infusion required in DKA management. *Insulin glargine* - **Insulin glargine** is a **long-acting insulin analog** designed to provide basal insulin replacement. - It has a prolonged duration of action and a slow, sustained release profile, making it unsuitable for the rapid correction needed in DKA. *NPH insulin* - **NPH insulin** is an **intermediate-acting insulin** that has a delayed onset and peak effect. - Its insoluble nature and variable absorption make it inappropriate for the acute, immediate intravenous insulin therapy required in DKA.

Q: Praziquantel is used for the treatment of

Schistosomiasis. ***Schistosomiasis*** - **Praziquantel** is the primary drug for treating all species of **schistosomiasis**, effectively killing adult worms [1], [2]. - It works by increasing the **calcium permeability** of the worm's cells, leading to muscle contraction and paralysis [2]. *Rhinosporidiosis* - **Rhinosporidiosis** is a fungal infection, and its treatment typically involves **surgical excision** of the lesions. - Antifungal agents like **dapsone** may be used as an adjuvant therapy, but praziquantel is not indicated. *Strongyloidiasis* - **Strongyloidiasis** is caused by the nematode *Strongyloides stercoralis*, and the preferred treatment is **ivermectin** [3]. - **Albendazole** is an alternative treatment option, but praziquantel is ineffective against this parasite [2], [3]. *Trichomoniasis* - **Trichomoniasis** is a sexually transmitted infection caused by the protozoan *Trichomonas vaginalis*. - It is effectively treated with **metronidazole** or **tinidazole**, while praziquantel has no activity against this protozoan.

Q: A lady has taken medication for amoebiasis infection. She drank alcohol on the same day. She has nausea, vomiting, and dizziness. Which anti-amoebic drug could have led to interaction with alcohol to produce these symptoms?

Metronidazole. ***Metronidazole*** - **Metronidazole** is well-known for causing a **disulfiram-like reaction** when consumed with alcohol. - This reaction leads to a rapid accumulation of **acetaldehyde**, manifesting as nausea, vomiting, flushing, headache, and dizziness. *Nitazoxanide* - **Nitazoxanide** is an oral anti-infective agent used for protozoal infections, but it is **not associated with a disulfiram-like reaction** with alcohol. - Its mechanism of action involves interfering with the **pyridoxine ferredoxin oxidoreductase enzyme**, which is distinct from alcohol metabolism. *Paromomycin* - **Paromomycin** is an aminoglycoside antibiotic primarily used for luminal amoebiasis and is **poorly absorbed from the GI tract**. - It does **not typically interact with alcohol** or cause disulfiram-like reactions. *Diloxanide* - **Diloxanide furoate** is a luminal amoebicide primarily used for asymptomatic cyst passers. - It is **not known to cause a disulfiram-like reaction** or significant interactions with alcohol.

Q: Which drug is used as a spermicidal cream in contraceptives?

Nonoxynol-9. **Nonoxynol-9** - **Nonoxynol-9** is a common **spermicide** used in many contraceptive products like creams, foams, and gels. - It works by damaging the **sperm cell membrane**, effectively immobilizing and killing sperm. *Gossypol* - **Gossypol** is a natural compound found in cotton plants that has been studied for its potential as a **male contraceptive**. - It works by inhibiting **spermatogenesis** but has not been approved for widespread use due to toxicity concerns like **hypokalemia**. *Clomiphene* - **Clomiphene** is a **selective estrogen receptor modulator (SERM)** used to induce ovulation in women who are infertile due to anovulation. - It stimulates the release of **gonadotropins** (FSH and LH) from the pituitary gland, leading to follicular development. *Centchroman* - **Centchroman** (also known as Ormeloxifene) is a **non-steroidal oral contraceptive** used in India. - It acts as a **selective estrogen receptor modulator** in the uterus, disrupting the implantation process.

Q: Which is the most cardiotoxic anti-cancer drug among the following?

Anthracyclines. ***Anthracyclines*** - **Anthracyclines** (e.g., doxorubicin, daunorubicin) are notorious for causing **dose-dependent cardiotoxicity**, leading to **irreversible dilated cardiomyopathy** and **heart failure**. - Their cardiotoxic effect is primarily due to the generation of **reactive oxygen species** and interference with cardiac topoisomerase IIβ. *Cyclophosphamide* - Cyclophosphamide can cause cardiotoxicity, particularly at **high doses**, manifesting as **hemorrhagic myocardial necrosis** or **pericarditis**. - However, its cardiotoxicity is generally considered **less frequent and severe** than that of anthracyclines. *Tamoxifen* - Tamoxifen is primarily associated with an **increased risk of thromboembolic events** and **endometrial cancer**. - While some cardiac effects like **QT prolongation** can occur, it is not considered a primary cardiotoxic agent leading to cardiomyopathy. *Imatinib* - Imatinib, a **tyrosine kinase inhibitor**, has been linked to **cardiac dysfunction** including heart failure in some patients. - However, the incidence and severity of cardiotoxicity with imatinib are **lower** compared to anthracyclines, which are broadly cardiotoxic.

Question 1

Mechanism of action of allopurinol is

Accepted Answer

Xanthine oxidase inhibition

Answer

Recombinant uricase

Answer

Decrease chemotaxis

Answer

Increase uric acid excretion

Question 2

Which of the following drug causes postural hypotension commonly?

Accepted Answer

Alpha blocker

Answer

Angiotensin receptor blockers

Answer

Beta blocker

Answer

ACE inhibitor

Question 3

Which of the following is a carbonic anhydrase inhibitor?

Accepted Answer

Acetazolamide

Answer

Hydrochlorothiazide

Answer

Mannitol

Answer

Furosemide

Question 4

Which of the following anti-epileptic drugs has the highest teratogenic potential?

Accepted Answer

Valproate

Answer

Carbamazepine

Answer

Phenytoin

Answer

Lamotrigine

Question 5

Insulin of choice for the treatment of diabetic ketoacidosis is:

Accepted Answer

Regular Insulin

Answer

Insulin lispro

Answer

Insulin glargine

Answer

NPH insulin

Question 6

Praziquantel is used for the treatment of

Accepted Answer

Schistosomiasis

Answer

Rhinosporidiosis

Answer

Strongyloidiasis

Answer

Trichomoniasis

Question 7

A lady has taken medication for amoebiasis infection. She drank alcohol on the same day. She has nausea, vomiting, and dizziness. Which anti-amoebic drug could have led to interaction with alcohol to produce these symptoms?

Accepted Answer

Metronidazole

Answer

Nitazoxanide

Answer

Paromomycin

Answer

Diloxanide

Question 8

Which drug is used as a spermicidal cream in contraceptives?

Accepted Answer

Nonoxynol-9

Answer

Gossypol

Answer

Clomiphene

Answer

Centchroman

Question 9

Which is the most cardiotoxic anti-cancer drug among the following?

Accepted Answer

Anthracyclines

Answer

Cyclophosphamide

Answer

Tamoxifen

Answer

Imatinib

Question 10

Mechanism of action of exenatide in diabetes mellitus is

Accepted Answer

It is analogue of GLP released from gut and increases glucose dependent insulin secretion

Answer

It is DPP-4 inhibitor and results in decreased breakdown of GLP

Answer

It is amylin analogue and decreases glucagon

Answer

It inhibits SGLT-2 and causes glucosuria

FMGE 2019 — Pharmacology