FMGE 2024 - Pharmacology PYQs Practice Questions

Q: What is the mechanism of action of Ethosuximide?

Inhibits calcium channels in thalamic neurons. ***Inhibits calcium channels in thalamic neurons***- Ethosuximide selectively blocks **T-type calcium channels** (**transient type**) primarily found on **thalamic neurons**.- This blockade reduces the **low-threshold burst firing** responsible for the characteristic **3-Hz spike-and-wave discharge** seen in absence seizures.*Enhances GABAergic inhibition*- This mechanism is characteristic of **Benzodiazepines** and **Barbiturates**, which increase the frequency or duration of GABA-A channel opening.- While some broad-spectrum AEDs like **Valproate** also increase GABA levels, this is not the primary mechanism of action for Ethosuximide.*Blocks sodium channels*- Drugs that block neuronal sodium channels, such as **Phenytoin** and **Carbamazepine**, are effective against tonic-clonic and partial seizures.- This mechanism prevents the rapid, sustained firing of action potentials but is largely ineffective against the burst firing characteristic of absence seizures.*Increases serotonin levels*- This is the primary mechanism associated with **Selective Serotonin Reuptake Inhibitors (SSRIs)** and other antidepressants.- It is not relevant to the function of Ethosuximide, which is specific to modulating neuronal excitability through calcium channels. [Practice more Pharmacology PYQs on OnCourse]

Q: A patient having hypertension is on thiazides and is complaining of fatigue and hypokalemia. Which of the following drugs can prevent potassium loss?

Amiloride. ***Amiloride***- Amiloride is a **potassium-sparing diuretic** that acts by blocking the **Epithelial Sodium Channel (ENaC)** in the collecting duct. [5]- By inhibiting Na+ reabsorption here, it decreases the electrical gradient that drives **potassium secretion**, effectively counteracting the hypokalemic effect of thiazides. [2]*Furosemide*- Furosemide is a **loop diuretic** that inhibits the Na-K-2Cl cotransporter in the thick ascending limb.- It is notorious for causing significant urinary **potassium loss** and would worsen the patient's **hypokalemia** and fatigue. [5]*Acetazolamide*- Acetazolamide is a **carbonic anhydrase inhibitor** that increases the delivery of Na+ and bicarbonate (HCO3-) to the collecting duct. [4]- The increased delivery of these ions promotes the secretion and loss of **potassium** in the urine, thus failing to prevent hypokalemia. [4]*Indapamide*- Indapamide is a **thiazide-like diuretic** that, similar to thiazides, inhibits the NaCl cotransporter in the distal convoluted tubule. [1]- Like other thiazides, Indapamide is a **potassium-wasting diuretic** and would exacerbate the existing **hypokalemia**. [3] [Practice more Pharmacology PYQs on OnCourse]

Q: A patient was given an antipsychotic drug, haloperidol, and the patient developed acute dystonia. Which is the next best step?

Give Benztropine. ***Give Benztropine***- **Acute dystonia** is a severe extrapyramidal symptom (EPS) requiring rapid intervention, often treated intramuscularly or intravenously.- **Benztropine** (an anticholinergic agent) is the drug of choice for the immediate management of acute dystonia, working to restore the balance between dopamine and acetylcholine.*Change to clozapine*- While **clozapine** has a significantly lower risk of causing acute dystonia, it is not the initial treatment for an acute episode due to its slow titration requirements and side-effect profile.- Switching to clozapine is a long-term strategy for patients intolerant to other antipsychotics, not an acute rescue medication.*Give Fluphenazine*- **Fluphenazine** is a high-potency first-generation antipsychotic, similar to haloperidol, which also carries a high risk of EPS.- Administering another high-potency antipsychotic would perpetuate the excessive **dopaminergic blockade** responsible for the acute dystonia.*Increase dose of haloperidol*- **Acute dystonia** is a direct dose-related side effect of D2 receptor blockade by haloperidol in the nigrostriatal pathway.- Increasing the dose of **haloperidol** would worsen the underlying neurochemical imbalance, thereby intensifying the dystonic symptoms. [Practice more Pharmacology PYQs on OnCourse]

Q: A group of people are travelling to the mountains, and a girl starts complaining of mountain sickness. What is the drug of choice?

Acetazolamide. ***Acetazolamide*** - This drug is the agent of choice for prophylaxis and treatment of **Acute Mountain Sickness (AMS)** due to its ability to accelerate **acclimatization**. - It functions as a **carbonic anhydrase inhibitor**, inducing a mild metabolic acidosis that stimulates the respiratory center, thereby increasing ventilation and improving blood oxygen saturation. *Promethazine* - This is an **antihistamine** (H1 blocker) often used for its potent **antiemetic** (nausea) and sedative effects. - While it may relieve nausea symptoms associated with AMS, it does not address the underlying physiological disturbances or enhance **acclimatization**. *Dimenhydrinate* - This medication is also an **antihistamine** typically employed to treat and prevent **motion sickness** and vertigo. - It lacks the crucial physiological mechanism (carbonic anhydrase inhibition) required to improve breathing efficiency and accelerate the body's response to **hypoxia**. *Thiazide* - This category of drugs, such as hydrochlorothiazide, are **diuretics** primarily used for hypertension and edema. - They do not possess the necessary respiratory stimulation properties of **Acetazolamide** and are therefore ineffective in treating or preventing mountain sickness. [Practice more Pharmacology PYQs on OnCourse]

Question 1

What is the mechanism of action of Ethosuximide?

Accepted Answer

Inhibits calcium channels in thalamic neurons

Answer

Enhances GABAergic inhibition

Answer

Blocks sodium channels

Answer

Increases serotonin levels

Question 2

What is the primary mechanism of action of methotrexate?

Accepted Answer

Inhibits dihydrofolate reductase, leading to decreased DNA synthesis

Answer

Inhibits RNA synthesis by blocking RNA polymerase

Answer

Interferes with microtubule formation during cell division

Answer

Inhibits DNA synthesis by blocking thymidylate synthase

Question 3

A patient having hypertension is on thiazides and is complaining of fatigue and hypokalemia. Which of the following drugs can prevent potassium loss?

Accepted Answer

Amiloride

Answer

Acetazolamide

Answer

Indapamide

Answer

Furosemide

Question 4

A patient was given an antipsychotic drug, haloperidol, and the patient developed acute dystonia. Which is the next best step?

Accepted Answer

Give Benztropine

Answer

Give Fluphenazine

Answer

Increase dose of haloperidol

Answer

Change to clozapine

Question 5

A group of people are travelling to the mountains, and a girl starts complaining of mountain sickness. What is the drug of choice?

Accepted Answer

Acetazolamide

Answer

Thiazide

Answer

Promethazine

Answer

Dimenhydrinate

Question 6

Which of the following is an atypical antipsychotic with the least metabolic side effects?

Accepted Answer

Ziprasidone

Answer

Risperidone

Answer

Haloperidol

Answer

Quetiapine

FMGE 2024 — Pharmacology