General Pharmacology Practice Questions

Q: For which of the following schedules is a warning written 'To be sold by retail on the prescription of a Registered Medical Practitioner only'?

Schedule H. ### Explanation **Correct Option: A (Schedule H)** Schedule H drugs are defined under the Drugs and Cosmetics Rules, 1945, as "Prescription Drugs." These substances cannot be purchased over the counter (OTC) and must bear the specific mandatory warning: **"To be sold by retail on the prescription of a Registered Medical Practitioner only."** This regulation ensures that potent medications (like most antibiotics, hormones, and antihypertensives) are used only under medical supervision to prevent misuse and drug resistance. **Analysis of Incorrect Options:** * **Schedule X:** These are Narcotic and Psychotropic substances (e.g., Ketamine, Amphetamines). They require a more stringent warning: **"Schedule X drug - Warning: To be sold by retail on the prescription of a Registered Medical Practitioner only."** They also require the pharmacist to maintain a duplicate copy of the prescription for two years. * **Schedule Y:** This schedule details the requirements and guidelines for **Clinical Trials** for the import and manufacture of new drugs. It is not related to retail labeling warnings. * **Schedule J:** This contains a list of diseases and ailments (e.g., AIDS, Blindness, Cancer) which a drug **may not purport to prevent or cure**. It prohibits manufacturers from making false claims regarding these conditions. **High-Yield Clinical Pearls for NEET-PG:** * **Schedule H1:** A sub-category introduced to control the use of 3rd/4th gen antibiotics and anti-TB drugs. It carries a warning in **Red Box** and requires a separate register for sales. * **Schedule G:** Drugs to be taken under **medical supervision** (e.g., Metformin, Antihistamines). Label warning: "Caution: It is dangerous to take this preparation except under medical supervision." * **Schedule K:** Contains a list of drugs **exempted** from certain provisions of manufacture/sale.

Q: Ebstein anomaly is caused by the usage of which drug during pregnancy?

Lithium. **Explanation:** **Lithium (Correct Answer):** Lithium is a mood stabilizer used for Bipolar Disorder. When administered during the first trimester of pregnancy, it acts as a teratogen, specifically affecting cardiac development. It is classically associated with **Ebstein’s Anomaly**, a congenital heart defect characterized by the "atrialization" of the right ventricle due to the downward displacement of the tricuspid valve leaflets. This leads to a small functional right ventricle and severe tricuspid regurgitation. **Analysis of Incorrect Options:** * **Phenytoin:** This anticonvulsant causes **Fetal Hydantoin Syndrome**, characterized by craniofacial dysmorphism (cleft lip/palate), hypoplastic phalanges, and nail hypoplasia. * **Warfarin:** Exposure during the first trimester leads to **Fetal Warfarin Syndrome**, presenting with nasal hypoplasia, depressed nasal bridge, and stippled epiphyses (chondrodysplasia punctata). * **Enalapril (ACE Inhibitor):** These are contraindicated in the 2nd and 3rd trimesters. They cause **fetal renal dysgenesis**, leading to oligohydramnios, which results in pulmonary hypoplasia and skull ossification defects (Potter sequence). **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Risk:** While the *relative risk* of Ebstein anomaly is high with Lithium, the *absolute risk* remains low (approx. 1 in 1,000 to 2,000). * **Management:** If a pregnant woman is stable on Lithium, it is often continued with close fetal echocardiography monitoring, as the risk of bipolar relapse often outweighs the teratogenic risk. * **Other Cardiac Teratogens:** Alcohol (VSD/ASD), Isotretinoin (Transposition of Great Arteries).

Q: Which drug is recommended for chemoprophylaxis one day before induction into high altitude areas?

Acetazolamide. **Explanation:** **Acetazolamide** is the drug of choice for the prevention of **Acute Mountain Sickness (AMS)**. It is a carbonic anhydrase inhibitor that works by inhibiting the enzyme in the proximal convoluted tubule of the kidney. This leads to bicarbonate diuresis, resulting in a mild **metabolic acidosis**. To compensate for this acidosis, the body increases the respiratory rate (hyperventilation), which improves oxygenation and accelerates the natural process of acclimatization. For effective prophylaxis, it is recommended to start the drug 24 hours before ascent. **Analysis of Incorrect Options:** * **Furosemide (Option B):** While it is a potent loop diuretic, it is used in the *treatment* of High-Altitude Pulmonary Edema (HAPE) to reduce fluid in the lungs, but it is not used for routine prophylaxis of AMS. * **Doxycycline (Option C):** This is an antibiotic used for chemoprophylaxis against Malaria or Leptospirosis, having no role in high-altitude illness. * **Paracetamol (Option D):** This is an analgesic used to treat the headache associated with altitude sickness but does not prevent the underlying physiological cause or aid in acclimatization. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Induces metabolic acidosis → stimulates chemoreceptors → increases minute ventilation. * **Side Effects:** Common side effects include **paresthesia** (tingling in fingers/toes) and a **metallic taste** when consuming carbonated beverages. * **Contraindication:** Avoid in patients with a known **Sulfa allergy**. * **Treatment of Choice:** For established HAPE, the drug of choice is **Nifedipine**; for High-Altitude Cerebral Edema (HACE), it is **Dexamethasone**.

Q: Which drug is used for the management of obesity?

Orlistat. **Explanation:** **Correct Option: A. Orlistat** Orlistat is a potent, specific, and long-acting **inhibitor of gastric and pancreatic lipases**. Its mechanism of action involves forming a covalent bond with the active serine site of these enzymes in the lumen of the stomach and small intestine. This prevents the hydrolysis of dietary fat (triglycerides) into absorbable free fatty acids and monoglycerides. Consequently, approximately 30% of dietary fat remains unabsorbed and is excreted in the feces, leading to a caloric deficit and weight loss. **Incorrect Options:** * **B. Rivastigmine:** A pseudo-irreversible acetylcholinesterase inhibitor used primarily in the management of **Alzheimer’s disease** and Parkinson’s dementia. * **C. Nitrous oxide:** An inhalational anesthetic gas (Laughing gas) used for **general anesthesia** and analgesia. * **D. Phenylephrine:** A selective **$\alpha_1$-adrenergic agonist** used as a nasal decongestant and a pressor agent to treat hypotension. **Clinical Pearls for NEET-PG:** * **Side Effects of Orlistat:** Due to fat malabsorption, it commonly causes **steatorrhea** (oily spotting), flatus with discharge, and fecal urgency. It can also interfere with the absorption of **fat-soluble vitamins (A, D, E, K)**; supplementation is often required. * **Other FDA-approved drugs for Obesity:** * **Liraglutide/Semaglutide:** GLP-1 receptor agonists (injectable). * **Phentermine/Topiramate:** Combination therapy (sympathomimetic + antiepileptic). * **Naltrexone/Bupropion:** Combination targeting reward pathways. * **Lorcaserin:** 5-HT$_{2C}$ agonist (withdrawn in many regions due to cancer risk).

Q: Who discovered that nerve terminals release chemicals?

Loewi. **Explanation:** The correct answer is **Otto Loewi (D)**. In 1921, Loewi conducted a landmark experiment using two frog hearts. He stimulated the vagus nerve of the first heart, causing it to slow down, and then transferred the surrounding fluid to a second heart. The second heart slowed down as well, proving that the nerve did not act electrically but released a chemical substance (which he called *Vagusstoff*, later identified as Acetylcholine). This discovery earned him the Nobel Prize and established the concept of **chemical neurotransmission**. **Analysis of Incorrect Options:** * **A. Dale (Sir Henry Dale):** While he worked closely with Loewi and identified Acetylcholine as a neurotransmitter, he is best known for **Dale’s Principle** (the theory that a neuron releases the same neurotransmitter at all its synapses) and for isolating histamine. * **B. Withering (William Withering):** An English physician famous for discovering the clinical use of **Digitalis** (Foxglove) in the treatment of dropsy (heart failure) in 1785. * **C. Domagk (Gerhard Domagk):** A pathologist credited with the discovery of **Prontosil**, the first commercially available sulfonamide (antibacterial), which ushered in the era of modern antibiotics. **High-Yield NEET-PG Pearls:** * **Father of Pharmacology:** Oswald Schmiedeberg. * **Father of Chemotherapy:** Paul Ehrlich (also coined the term "Magic Bullet"). * **Father of Indian Pharmacology:** Ram Nath Chopra. * **Loewi’s Experiment:** Proved chemical transmission; the substance was **Acetylcholine**, the first neurotransmitter to be discovered.

Q: Sildenafil (Viagra) produces its physiological effects by blocking the enzyme that hydrolyzes the second messenger by which nitric oxide produces its physiological effects. What is this second messenger?

Cyclic GMP. **Explanation:** **Mechanism of Action:** Nitric Oxide (NO) is a potent vasodilator released from vascular endothelial cells. It activates the enzyme **Guanylate Cyclase**, which converts GTP into **Cyclic GMP (cGMP)**. cGMP acts as the **second messenger** that triggers protein kinase G, leading to smooth muscle relaxation and increased blood flow (vasodilation). In the corpus cavernosum, this process results in penile erection. Sildenafil is a selective inhibitor of **Phosphodiesterase-5 (PDE-5)**, the enzyme responsible for the hydrolysis (breakdown) of cGMP. By blocking PDE-5, Sildenafil prevents the degradation of cGMP, prolonging its vasodilatory effects. **Analysis of Incorrect Options:** * **A. Bradykinin:** This is a potent vasodilator peptide, not a second messenger. It works by stimulating the release of NO and prostacyclin. * **C. Protein kinase A:** This is the downstream effector for the **cAMP** pathway (e.g., stimulated by Beta-agonists), not the cGMP pathway. * **D. Endothelin:** This is a potent endogenous **vasoconstrictor** peptide, acting in opposition to the effects of Nitric Oxide. **High-Yield NEET-PG Pearls:** * **Drug Interaction:** Sildenafil is strictly contraindicated with **Nitrates** (e.g., Nitroglycerin) because both increase cGMP through different mechanisms, leading to synergistic peripheral vasodilation and life-threatening hypotension. * **Other PDE-5 Inhibitors:** Tadalafil (longer half-life, "the weekend pill") and Vardenafil. * **Other Indications:** PDE-5 inhibitors are also used in the management of **Pulmonary Arterial Hypertension (PAH)**. * **Side Effect:** "Blue vision" (cyanopsia) occurs due to weak inhibition of PDE-6 in the retina.

Q: Which of the following acts as an inverse agonist?

b-carboline. ### Explanation **Concept of Inverse Agonists** An **inverse agonist** is a ligand that binds to the same receptor site as an agonist but produces a pharmacological response **opposite** to that of the agonist. This occurs because inverse agonists reduce the constitutive (basal) activity of receptors that are active even in the absence of a ligand. **Why B-carboline is Correct** The GABA-A receptor is a chloride channel. While GABA (agonist) and Benzodiazepines (facilitatory modulators) increase chloride influx leading to CNS depression/sedation, **$\beta$-carbolines** act as **inverse agonists** at the Benzodiazepine (BZD) site. They decrease chloride conductance, resulting in effects opposite to BZDs—namely **anxiety, restlessness, and convulsions**. **Analysis of Incorrect Options** * **A. Buspirone:** It is a **selective 5-HT1A partial agonist** used as an anxiolytic. It does not act on the GABA-BZD receptor complex. * **C. Flumazenil:** It is a **competitive antagonist** at the BZD receptor. It has no intrinsic activity of its own; it simply blocks the effects of both agonists (BZDs) and inverse agonists ($\beta$-carbolines). * **D. Zolpidem:** It is a **non-benzodiazepine hypnotic** that acts as a **full agonist** at the $\alpha_1$ subunit of the GABA-A receptor. **High-Yield Clinical Pearls for NEET-PG** * **Inverse Agonist Examples:** $\beta$-carboline (GABA-A), Naloxone (at $\mu$ receptors—though traditionally called an antagonist, it shows inverse agonism), and Famotidine (H2 receptors). * **Flumazenil** is the drug of choice for BZD overdose but can precipitate seizures in BZD-dependent patients. * **Constitutive Activity:** The ability of a receptor to show a response without any ligand; inverse agonists are only effective against receptors showing this property.

Question 1

For which of the following schedules is a warning written 'To be sold by retail on the prescription of a Registered Medical Practitioner only'?

Accepted Answer

Schedule H

Answer

Schedule X

Answer

Schedule Y

Answer

Schedule J

Question 2

Ebstein anomaly is caused by the usage of which drug during pregnancy?

Accepted Answer

Lithium

Answer

Phenytoin

Answer

Warfarin

Answer

Enalapril

Question 3

Drug distribution is inversely proportional to which of the following?

Accepted Answer

Plasma protein binding

Answer

Lipid solubility

Answer

Fat layer in the body

Answer

Structure of the drug

Question 4

What are the undesirable but unavoidable pharmacodynamic effects of a drug known as?

Accepted Answer

Side effects

Answer

Toxic effects

Answer

Idiosyncrasy

Answer

Intolerance

Question 5

Which drug is recommended for chemoprophylaxis one day before induction into high altitude areas?

Accepted Answer

Acetazolamide

Answer

Furosemide

Answer

Doxycycline

Answer

Paracetamol

Question 6

Which drug is used for the management of obesity?

Accepted Answer

Orlistat

Answer

Rivastigmine

Answer

Nitrous oxide

Answer

Phenylephrine

Question 7

A bolus of drug K is given intravenously. The drug is noted to follow first-order kinetics. Which of the following describes the elimination of drug K?

Accepted Answer

The rate of elimination of drug K is proportional to its concentration in the patient's plasma.

Answer

The rate of elimination of drug K is dependent on a nonlinear relationship to the plasma protein concentration.

Answer

The rate of elimination of drug K is constant.

Answer

The rate of elimination of drug K is proportional to the patient's renal function.

Question 8

Who discovered that nerve terminals release chemicals?

Accepted Answer

Loewi

Answer

Dale

Answer

Withering

Answer

Domagk

Question 9

Sildenafil (Viagra) produces its physiological effects by blocking the enzyme that hydrolyzes the second messenger by which nitric oxide produces its physiological effects. What is this second messenger?

Accepted Answer

Cyclic GMP

Answer

Bradykinin

Answer

Protein kinase A

Answer

Endothelin

Question 10

Which of the following acts as an inverse agonist?

Accepted Answer

b-carboline

Answer

Buspirone

Answer

Flumazenil

Answer

Zolpidem

General Pharmacology — MCQs

General Pharmacology — MCQs

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