NEET-PG 2015 - Pharmacology Practice Questions

Q: Idoxuridine is used for treatment of?

HSV. ***HSV*** - **Idoxuridine** is a **pyrimidine analog** that inhibits viral DNA synthesis, making it effective against **herpes simplex virus (HSV)** infections, particularly **herpes keratitis** (ophthalmic use). - Its mechanism involves being incorporated into viral DNA, leading to errors in replication and transcription. - It is applied **topically** for ocular HSV infections due to systemic toxicity concerns. *Influenza* - **Idoxuridine** is not active against **influenza viruses**. - **Antiviral drugs** like **oseltamivir** or **zanamivir** are typically used for influenza treatment. *RSV* - **Idoxuridine** is not indicated for the treatment of **respiratory syncytial virus (RSV)**. - **Ribavirin** is the primary antiviral agent used for severe RSV infections, especially in immunocompromised patients. *HIV* - **Idoxuridine** has no significant activity against **human immunodeficiency virus (HIV)**. - **Antiretroviral therapy (ART)**, a combination of drugs targeting various stages of the HIV life cycle, is used for HIV treatment.

Q: Among the following statins, which has the longest half-life?

Rosuvastatin. **Rosuvastatin** - **Rosuvastatin** has the longest half-life among the commonly used statins, approximately **19 hours**, allowing for consistent lipid-lowering effects. - Its prolonged presence in the body contributes to its effectiveness in reducing **LDL-C** at lower doses. *Pravastatin* - **Pravastatin** has a relatively short half-life of about **1.8 hours**, requiring daily dosing to maintain therapeutic concentrations. - Its hydrophilic nature means it is less likely to penetrate non-hepatic tissues, potentially reducing extrahepatic side effects. *Simvastatin* - **Simvastatin** has a short half-life of about **3 hours**, necessitating daily administration. - It is a **prodrug** that requires hepatic activation to its active beta-hydroxy acid form. *Lovastatin* - **Lovastatin** also has a short half-life, around **3 hours**, and is a **prodrug** like simvastatin. - It is often recommended to be taken in the evening due to the diurnal rhythm of cholesterol synthesis.

Q: Which of the following are CYP3A inhibitors?

Both a and c. ***Both a and c (Ritonavir and Verapamil)*** - **Ritonavir** is a **potent CYP3A4 inhibitor**, one of the strongest known, commonly used as a pharmacokinetic booster for other protease inhibitors to increase their bioavailability - **Verapamil** is a **calcium channel blocker** that acts as a **moderate CYP3A4 inhibitor**, leading to clinically significant drug interactions requiring dose adjustments - Both drugs have **clinically relevant and well-established** CYP3A4 inhibitory effects *Ritonavir alone* - While correct that Ritonavir is a potent CYP3A4 inhibitor, this option is incomplete as it excludes Verapamil - Ritonavir's inhibitory effect is so strong that it can increase plasma concentrations of co-administered CYP3A4 substrates by several-fold *Amiodarone* - Amiodarone is primarily a **potent inhibitor of CYP2C9, CYP2D6, and P-glycoprotein** - While it does have **weak to moderate CYP3A4 inhibitory activity**, this effect is **less clinically significant** compared to its effects on other CYP enzymes - In the context of clinically important CYP3A4 inhibitors, Ritonavir and Verapamil are more relevant examples *Verapamil alone* - While correct that Verapamil is a CYP3A4 inhibitor, this option is incomplete as it excludes Ritonavir - Verapamil can increase plasma concentrations of drugs like simvastatin, cyclosporine, and other CYP3A4 substrates

Q: Permission from DCGI [Drug controller general, India] is needed before which phase of drug trial?

Phase 3. ***Phase 3*** - Permission from the **DCGI (Drug Controller General of India)** is mandatory before initiating **Phase 3** clinical trials as per **Schedule Y** of the Drugs and Cosmetics Rules. - Phase 3 trials involve **large-scale studies in Indian patients** to establish efficacy and safety in the target population, requiring explicit regulatory approval. - This is the critical regulatory checkpoint where DCGI evaluates the Phase 1 and 2 data before allowing widespread testing in Indian subjects. *Phase 1* - Phase 1 trials can be conducted after approval from the **Institutional Ethics Committee (IEC)** without requiring prior DCGI permission. - These trials in healthy volunteers focus on safety, pharmacokinetics, and dose-ranging studies. - DCGI is informed but explicit permission is not mandatory at this stage. *Phase 2* - Phase 2 trials also proceed with **IEC approval** and do not require prior DCGI permission. - These trials evaluate therapeutic efficacy and dose determination in a limited number of patients. - Results from Phase 2 are submitted to DCGI when seeking Phase 3 approval. *Phase 4* - Phase 4 trials are **post-marketing surveillance** studies conducted after drug approval. - These are conducted under the Post-Marketing Surveillance (PMS) framework. - While regulatory oversight exists, these are not pre-market trials requiring permission to initiate.

Q: Which of the following medications is classified as a stool softener?

Docusates. **Docusates** - **Docusates** (e.g., docusate sodium, docusate calcium) are **stool softeners** that work by reducing the surface tension of stool, allowing water and lipids to penetrate. - This increases the water content in the stool, making it softer and easier to pass, which is particularly useful in preventing straining after surgery or in conditions like hemorrhoids. *Bran* - **Bran** is a **bulk-forming laxative**, a type of dietary fiber that adds mass to the stool. - It absorbs water in the intestines, which increases stool volume and stimulates bowel movements, but it does not directly soften the stool in the same way docusates do. *Senna* - **Senna** is a **stimulant laxative** that works by irritating the bowel wall to promote peristalsis and bowel evacuation. - While it can help move stool, it does not act primarily by softening it, and prolonged use can lead to dependency or electrolyte imbalances. *Phenolphthalein* - **Phenolphthalein** is a **stimulant laxative** that was historically used to promote bowel movements. - It is no longer widely used due to concerns about potential carcinogenicity and other adverse effects, and it does not function as a stool softener.

Q: Hyoscine is an antagonist at which cholinergic receptor?

Muscarinic. ***Muscarinic*** - **Hyoscine** (scopolamine) is a well-known **antagonist** at **muscarinic cholinergic receptors**. - It blocks the action of **acetylcholine** at these receptors, leading to its anticholinergic effects like treating motion sickness and reducing secretions. *Nicotinic* - **Hyoscine** does not primarily act on **nicotinic cholinergic receptors**. - Drugs acting on nicotinic receptors include **neuromuscular blockers** (e.g., succinylcholine, rocuronium) and **ganglionic blockers**, which have different clinical applications. *Both* - While some drugs may have activity at both receptor types, **hyoscine's primary and clinically significant antagonism is at muscarinic receptors**. - Its therapeutic effects are attributed almost exclusively to its **muscarinic blockade**. *None of the above* - This option is incorrect because **hyoscine is a clear antagonist at muscarinic cholinergic receptors**. - Its widespread use in medicine is based on this specific pharmacological action.

Q: Which of the following is a PGE1 analogue used in medical treatments?

Alprostadil. ***Alprostadil*** - **Alprostadil** is a synthetic **prostaglandin E1 (PGE1)** analogue. - It is used in neonates to maintain the **patency of the patent ductus arteriosus** and in adults for the treatment of **erectile dysfunction**. *Carboprost* - **Carboprost** is a synthetic analogue of **prostaglandin F2 alpha (PGF2α)**. - It is primarily used to manage **postpartum hemorrhage** due to its potent uterotonic effects. *Epoprostenol* - **Epoprostenol** is a synthetic analogue of **prostacyclin (PGI2)**. - It is known for its potent **vasodilatory** and **antiplatelet** properties, making it useful in treating **pulmonary arterial hypertension**. *Dinoprostone* - **Dinoprostone** is a synthetic form of **prostaglandin E2 (PGE2)**. - It is used to **induce labor** or **cervical ripening** due to its role in uterine contractions and cervical dilation.

Q: What is the drug of choice for drug-induced peptic ulcer?

Proton pump inhibitors. ***Proton pump inhibitors*** - **PPIs** are the most effective agents for treating and preventing **NSAID-induced peptic ulcers** by profoundly suppressing gastric acid secretion. - They provide **rapid symptom relief** and promote ulcer healing by creating an environment conducive to mucosal repair. *Prostaglandin analogues* - **Misoprostol**, a prostaglandin E1 analogue, can prevent NSAID-induced ulcers, but its use is limited by **gastrointestinal side effects** such as diarrhea and abdominal cramping. - While they protect the gastric mucosa, their efficacy in healing established ulcers is generally **inferior to PPIs**. *H2-receptor antagonists* - **H2-blockers** are effective in reducing gastric acid, but they are **less potent** than PPIs and typically do not heal **gastric ulcers** as effectively, especially those induced by NSAIDs. - They are more commonly used for preventing **duodenal ulcers** and managing symptoms of GERD. *Antacids* - Antacids provide **immediate, temporary relief** of ulcer symptoms by neutralizing existing stomach acid. - They do not address the underlying pathology or promote **ulcer healing** and are therefore not considered the drug of choice for treatment.

Q: Which of the following is the most characteristic sexual side effect of SSRIs?

Delayed ejaculation. ***Delayed ejaculation*** - **Delayed ejaculation** is a common and characteristic sexual side effect of SSRIs due to their impact on serotonin pathways involved in sexual response. - This effect can lead to significant distress and non-adherence to treatment, and often requires dose adjustment or switching to an alternative antidepressant. *Erectile dysfunction* - While **erectile dysfunction** can occur with SSRIs, it is a less specific and less consistently reported sexual side effect compared to ejaculatory dysfunction. - Many factors, including underlying mood disorder and comorbidities, can contribute to erectile dysfunction, making it less characteristic of SSRI use alone. *Retrograde ejaculation* - **Retrograde ejaculation** is a condition where semen enters the bladder during orgasm, and while it can be a side effect of some medications (e.g., alpha-blockers), it is not a hallmark sexual side effect of SSRIs. - SSRIs primarily affect the process of emission and expulsion, leading more commonly to delayed or absent ejaculation rather than retrograde flow. *Anxiety* - **Anxiety** is generally a *primary symptom* of the conditions SSRIs are prescribed to treat, such as depression or anxiety disorders, not a sexual side effect of the medication itself. - Although SSRIs can initially cause or worsen anxiety in some patients before therapeutic effects are seen, this is a systemic side effect, not a sexual one.

Question 1

Idoxuridine is used for treatment of?

Accepted Answer

HSV

Answer

Influenza

Answer

RSV

Answer

HIV

Question 2

What is the primary mechanism of action of opioids in pain management?

Accepted Answer

Activation of opioid receptors at both spinal and supraspinal levels

Answer

Inhibition of cyclooxygenase (COX) enzymes

Answer

Activation of opioid receptors in the spinal cord only

Answer

Activation of opioid receptors in the brain only

Question 3

Among the following statins, which has the longest half-life?

Accepted Answer

Rosuvastatin

Answer

Pravastatin

Answer

Simvastatin

Answer

Lovastatin

Question 4

Which of the following are CYP3A inhibitors?

Accepted Answer

Both a and c

Answer

Ritonavir

Answer

Amiodarone

Answer

Verapamil

Question 5

Permission from DCGI [Drug controller general, India] is needed before which phase of drug trial?

Accepted Answer

Phase 3

Answer

Phase 1

Answer

Phase 2

Answer

Phase 4

Question 6

Which of the following medications is classified as a stool softener?

Accepted Answer

Docusates

Answer

Bran

Answer

Senna

Answer

Phenolphthalein

Question 7

Hyoscine is an antagonist at which cholinergic receptor?

Accepted Answer

Muscarinic

Answer

Nicotinic

Answer

Both

Answer

None of the above

Question 8

Which of the following is a PGE1 analogue used in medical treatments?

Accepted Answer

Alprostadil

Answer

Carboprost

Answer

Epoprostenol

Answer

Dinoprostone

Question 9

What is the drug of choice for drug-induced peptic ulcer?

Accepted Answer

Proton pump inhibitors

Answer

Prostaglandin analogues

Answer

H2-receptor antagonists

Answer

Antacids

Question 10

Which of the following is the most characteristic sexual side effect of SSRIs?

Accepted Answer

Delayed ejaculation

Answer

Retrograde ejaculation

Answer

Erectile dysfunction

Answer

Anxiety

NEET-PG 2015 — Pharmacology