NEET-PG 2013 - Pharmacology Practice Questions

Q: Which of the following is NOT a function of Prostaglandin E1 (PGE1)?

Plays a role in initiating puberty. ***Plays a role in initiating puberty*** - **Prostaglandin E1 (PGE1)** is primarily involved in smooth muscle relaxation, vasodilation, and inflammation, and does not have a direct role in initiating **puberty**. - The initiation of puberty is mainly controlled by the **hypothalamic-pituitary-gonadal (HPG) axis** and surge of **gonadotropin-releasing hormone (GnRH)**. *Used in the management of erectile dysfunction* - **PGE1 formulations** (alprostadil) are used as a topical or intracavernosal injection to treat **erectile dysfunction** by inducing vasodilation in the penis. - Its vasodilatory effects increase blood flow to the corpora cavernosa, leading to **penile erection**. *Modulates inflammatory responses* - **PGE1** is involved in **inflammatory processes**, often exerting both pro- and anti-inflammatory effects depending on the context and specific receptors activated. - It can help to **reduce inflammation** and pain, as well as influencing immune cell function. *Maintains the patency of the ductus arteriosus* - In newborns with **congenital heart defects**, **PGE1** is administered to maintain the **patency of the ductus arteriosus**, allowing for blood flow between the aorta and pulmonary artery. - This is crucial for conditions where pulmonary or systemic blood flow is dependent on a patent ductus, bridging the infant to surgery or other interventions.

Q: Aminophylline inhibits which of the following enzymes?

Phosphodiesterase. ***Phosphodiesterase*** - **Aminophylline** is a methylxanthine derivative that primarily acts as a **phosphodiesterase (PDE) inhibitor** [1], [2]. - By inhibiting PDE, aminophylline increases intracellular levels of **cAMP** and **cGMP**, leading to **bronchodilation** and other effects [2], [3]. *MAO* - **MAO (monoamine oxidase)** inhibitors are antidepressants that prevent the breakdown of neurotransmitters like serotonin, norepinephrine, and dopamine. - Aminophylline does not significantly inhibit MAO. *Alcohol dehydrogenase* - **Alcohol dehydrogenase** is an enzyme responsible for metabolizing alcohol (ethanol) in the liver. - Aminophylline has no direct inhibitory effect on alcohol dehydrogenase. *Cytochrome P450* - **Cytochrome P450 (CYP450)** enzymes are a group of enzymes primarily involved in the metabolism of drugs and other xenobiotics in the liver [4]. - While aminophylline (and its active metabolite theophylline) can be metabolized by and *affect* certain **CYP450** isoenzymes (e.g., CYP1A2), it does not act as a general inhibitor of the entire CYP450 system; its primary therapeutic action is not through CYP450 inhibition.

Q: Which of the following is a mineralocorticoid antagonist?

Spironolactone. ***Spironolactone*** - **Spironolactone** is a **potassium-sparing diuretic** that acts as a competitive antagonist of **aldosterone** at the mineralocorticoid receptors in the renal tubules [1], [2]. - Its primary use is in conditions like **heart failure**, **cirrhosis with ascites**, and **primary hyperaldosteronism** (Conn's syndrome) [2]. *Inamrinone* - **Inamrinone** is a **phosphodiesterase-3 inhibitor** (PDE3 inhibitor) and is classified as an **inotropic agent**. - It increases **intracellular cAMP** in cardiac cells, leading to increased **contractility** and **vasodilation**, and is used in severe heart failure. *Nicorandil* - **Nicorandil** is a **potassium channel opener** and a **nitrate-like drug** that causes both venous and arterial vasodilation. - It is primarily used as an **antianginal agent** due to its ability to reduce cardiac workload and improve coronary blood flow. *Ketorolac* - **Ketorolac** is a **nonsteroidal anti-inflammatory drug (NSAID)** that primarily inhibits **cyclooxygenase (COX) enzymes**. - It is used for **short-term management of acute moderate to severe pain** and has no direct activity on mineralocorticoid receptors.

Q: Which calcium channel blocker has the shortest duration of action?

Nimodipine. ***Nimodipine*** - Nimodipine is a **dihydropyridine calcium channel blocker** specifically formulated for cerebral vasodilation and used in conditions like **subarachnoid hemorrhage**. - It has a relatively **short half-life** and rapid onset, making its duration of action shorter compared to other commonly used calcium channel blockers. *Amlodipine* - Amlodipine is known for its **long duration of action** and once-daily dosing due to its slow absorption and high bioavailability. - Its prolonged action is beneficial for conditions like **hypertension and angina**, where sustained vasodilation is desired. *Diltiazem* - Diltiazem's duration of action is **intermediate** compared to other calcium channel blockers, often requiring BID to TID dosing for immediate-release formulations. - It's a **non-dihydropyridine calcium channel blocker** with effects on both vascular smooth muscle and cardiac conduction. *Verapamil* - Verapamil also has an **intermediate duration of action**, similar to diltiazem, with immediate-release forms requiring multiple daily doses. - As a **non-dihydropyridine calcium channel blocker**, it has significant effects on myocardial contractility and AV nodal conduction.

Q: Which of the following is NOT a side effect of digitalis?

Vasodilatation. **Vasodilatation** - **Digitalis**, primarily digoxin, is known for its **positive inotropic effect**, increasing myocardial contractility, and for its **vasoconstrictive properties** at higher doses due to sympathetic activation and direct smooth muscle effects, not vasodilatation. - While it can indirectly improve cardiac output and thus tissue perfusion, its direct vascular effects do not typically include widespread vasodilatation. *Ventricular tachycardia* - **Digitalis toxicity** can lead to various arrhythmias, including **ventricular tachycardia**, which is a potentially life-threatening side effect. - This occurs due to increased automaticity and delayed afterdepolarizations in ventricular myocytes. *Nausea and vomiting* - **Gastrointestinal symptoms** such as **nausea and vomiting** are common early signs of digitalis toxicity. - These effects are thought to be mediated by the drug's action on the chemoreceptor trigger zone in the brainstem. *Ventricular Bigeminy* - **Ventricular bigeminy**, characterized by alternating normal and premature ventricular beats, is another classic manifestation of **digitalis toxicity**. - This arrhythmia results from enhanced automaticity and altered conduction properties in the ventricles.

Q: Which drug is used for sympathectomy in experimental animals?

Guanethidine. ***Guanethidine*** - **Guanethidine** is a potent **adrenergic neuron blocking drug** that is taken up by noradrenergic neurons and prevents the release of norepinephrine, leading to a chemical sympathectomy. - In experimental animal models, it is used to induce a **pharmacological sympathectomy** to study the effects of sympathetic nervous system blockade on various physiological processes. *Atropine* - **Atropine** is a **muscarinic acetylcholine receptor antagonist** that blocks the effects of acetylcholine at parasympathetic postganglionic terminals. - It is primarily used to block **parasympathetic responses**, not sympathetic ones, and therefore would not induce a sympathectomy. *Diazoxide* - **Diazoxide** is a direct **arteriolar vasodilator** that works by opening potassium channels in vascular smooth muscle. - It is used to quickly reduce blood pressure in **hypertensive emergencies** and for treating hypoglycemia due to insulin oversecretion, and does not cause sympathectomy. *Thebaine* - **Thebaine** is an **opioid alkaloid** found in opium, structurally similar to morphine and codeine, but with primarily stimulatory rather than depressant effects. - It acts as a **convulsant** and is used as a precursor in the synthesis of other opioids, but has no role in causing sympathectomy.

Q: Beta2-agonists cause all except:

Hyperkalemia. ***Hyperkalemia*** - Beta2-agonists actually cause **hypokalemia**, not hyperkalemia, by promoting the intracellular shift of potassium. - This effect is due to the stimulation of the **Na+/K+-ATPase pump** by beta-2 adrenergic receptors. *Hyperglycemia* - Beta2-agonists can lead to **hyperglycemia** by promoting glycogenolysis and gluconeogenesis in the liver. - They also decrease **insulin secretion** and increase insulin resistance. *Tremor* - **Tremor** is a common side effect of beta2-agonists, particularly in the hands, due to direct stimulation of beta2 receptors on skeletal muscle. - This muscle stimulation leads to increased muscle twitching and a fine tremor. *Palpitation* - **Palpitations** can occur due to the systemic absorption of beta2-agonists, leading to activation of beta1 receptors in the heart. - This can cause **tachycardia** and a sensation of a racing heart.

Q: Which of the following medications is most likely to cause reflex tachycardia?

Nifedipine. ***Nifedipine*** - Nifedipine is a **dihydropyridine calcium channel blocker** that causes significant peripheral vasodilation, leading to a rapid drop in blood pressure. - This sudden drop in blood pressure triggers a **baroreflex response**, compensatory increase in heart rate. *Verapamil* - Verapamil is a **non-dihydropyridine calcium channel blocker** that primarily acts on the cardiac pacemaker cells and slows AV nodal conduction. - While it can cause vasodilation, its direct negative chronotropic effect on the heart often **blunts or prevents reflex tachycardia**. *Propranolol* - Propranolol is a **non-selective beta-blocker** that blocks beta-1 and beta-2 adrenergic receptors. - It directly **decreases heart rate and myocardial contractility**, thereby preventing reflex tachycardia. *Amlodipine* - Amlodipine is a **dihydropyridine calcium channel blocker**, similar to nifedipine, but it has a **slower onset of action and a longer half-life**. - Its more gradual onset of vasodilation often results in a significantly **less pronounced or absent reflex tachycardia** compared to nifedipine.

Q: What is a common side effect of salmeterol?

Tremors. ***Tremors*** - **Salmeterol** is a **long-acting beta-2 adrenergic agonist (LABA)** that can stimulate beta-2 receptors in skeletal muscle, leading to **fine muscle tremors**. - This side effect is dose-dependent and more common with higher doses or in patients sensitive to sympathomimetic effects. *Seizures* - **Seizures** are a rare and atypical side effect of **salmeterol** and other beta-2 agonists; they are not considered a common adverse event. - While systemic absorption can occur, the central nervous system effects leading to seizures are not frequently observed. *Hypertension* - While beta-2 agonists can cause a slight increase in **heart rate** due to systemic absorption, **hypertension** is not a common side effect of inhaled salmeterol. - Other cardiovascular effects like palpitations can occur, but significant or sustained hypertension is rare. *Hyperkalemia* - **Hyperkalemia** (elevated potassium) is not a side effect of **salmeterol**; in fact, beta-2 agonists commonly cause the **opposite effect - hypokalemia** (decreased serum potassium). - Beta-2 receptor stimulation activates Na⁺-K⁺-ATPase pumps, driving potassium from serum into cells, causing transient hypokalemia. - This effect is clinically relevant and requires monitoring, especially when combined with other medications that lower potassium.

Q: Which of the following is a renin inhibitor?

Remikiren. **Remikiren** - **Remikiren** is a direct **renin inhibitor** that acts by binding to the active site of renin, preventing its interaction with angiotensinogen. - This inhibition reduces the formation of **angiotensin I** and subsequently **angiotensin II**, leading to decreased blood pressure. *Losartan* - **Losartan** is an **Angiotensin II Receptor Blocker (ARB)**, meaning it blocks AT1 receptors, preventing angiotensin II from binding. - It does not inhibit renin activity directly but rather acts downstream in the **renin-angiotensin-aldosterone system (RAAS)**. *Benazepril* - **Benazepril** is an **Angiotensin-Converting Enzyme (ACE) inhibitor**, which blocks the enzyme responsible for converting **angiotensin I** to **angiotensin II**. - It does not directly inhibit renin production or activity. *Imidapril* - **Imidapril** is also an **Angiotensin-Converting Enzyme (ACE) inhibitor**, similar to benazepril. - Its mechanism of action involves inhibiting ACE, thereby reducing **angiotensin II** levels, rather than directly inhibiting renin.

Question 1

Which of the following is NOT a function of Prostaglandin E1 (PGE1)?

Accepted Answer

Plays a role in initiating puberty

Answer

Modulates inflammatory responses

Answer

Used in the management of erectile dysfunction

Answer

Maintains the patency of the ductus arteriosus

Question 2

Aminophylline inhibits which of the following enzymes?

Accepted Answer

Phosphodiesterase

Answer

MAO

Answer

Alcohol dehydrogenase

Answer

Cytochrome P450

Question 3

Which of the following is a mineralocorticoid antagonist?

Accepted Answer

Spironolactone

Answer

Inamrinone

Answer

Nicorandil

Answer

Ketorolac

Question 4

Which calcium channel blocker has the shortest duration of action?

Accepted Answer

Nimodipine

Answer

Diltiazem

Answer

Amlodipine

Answer

Verapamil

Question 5

Which of the following is NOT a side effect of digitalis?

Accepted Answer

Vasodilatation

Answer

Nausea and vomiting

Answer

Ventricular Bigeminy

Answer

Ventricular tachycardia

Question 6

Which drug is used for sympathectomy in experimental animals?

Accepted Answer

Guanethidine

Answer

Atropine

Answer

Diazoxide

Answer

Thebaine

Question 7

Beta2-agonists cause all except:

Accepted Answer

Hyperkalemia

Answer

Hyperglycemia

Answer

Tremor

Answer

Palpitation

Question 8

Which of the following medications is most likely to cause reflex tachycardia?

Accepted Answer

Nifedipine

Answer

Verapamil

Answer

Propranolol

Answer

Amlodipine

Question 9

What is a common side effect of salmeterol?

Accepted Answer

Tremors

Answer

Seizures

Answer

Hypertension

Answer

Hyperkalemia

Question 10

Which of the following is a renin inhibitor?

Accepted Answer

Remikiren

Answer

Losartan

Answer

Benazepril

Answer

Imidapril

NEET-PG 2013 — Pharmacology