What is the best skin disinfectant for central line insertion?
Drug of choice for Pneumocystis jirovecii in pregnancy?
Which of the following is the prototypical sympathomimetic agent with both alpha and beta-adrenergic activity?
What is the effect of adding epinephrine to lignocaine (a local anesthetic)?
What is the correct sequence of medication administration for pre-operative prophylaxis in pheochromocytoma?
All of the following are used for treatment of *H. pylori*, except:
Which of the following is not a definite use for Prostaglandin E2 (PGE2)?
All of the following occurs because of prostaglandin use except?
What is the drug of choice for malaria in pregnancy?
What is the maximum cumulative dose of isotretinoin for acne treatment?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 71: What is the best skin disinfectant for central line insertion?
- A. Alcohol
- B. Cetrimide
- C. Chlorhexidine (Correct Answer)
- D. Povidone iodine
Explanation: ***Chlorhexidine*** - **Chlorhexidine (particularly >0.5% chlorhexidine in alcohol-based solution, such as 2% chlorhexidine in 70% isopropyl alcohol)** is the preferred antiseptic for central line insertion per **CDC guidelines**. - It provides **rapid onset of action**, persistent antimicrobial activity (lasting several hours), and broad-spectrum efficacy against gram-positive and gram-negative bacteria, fungi, and some viruses. - Superior to povidone-iodine in reducing catheter-related bloodstream infections (CRBSIs) in multiple studies. - Its mechanism involves disrupting bacterial cell membranes and coagulating intracellular contents, leading to sustained antimicrobial activity on the skin. *Povidone iodine* - **Povidone iodine** has a slower onset of action and is inactivated by organic matter (blood, serum), making it less effective for immediate, sustained disinfection compared to chlorhexidine. - While it has broad-spectrum activity, its residual effect is limited once it dries on the skin. - Studies show higher rates of catheter-related infections compared to chlorhexidine-based antiseptics. *Alcohol* - **Alcohol** (e.g., isopropyl alcohol or ethanol) provides good immediate microbial kill but lacks persistent activity, meaning its effect is short-lived as it evaporates quickly from the skin. - It works by denaturing proteins and dissolving lipids, but its rapid evaporation makes it insufficient as a sole agent for central line insertion. - Often used as a component in combination with chlorhexidine for optimal efficacy. *Cetrimide* - **Cetrimide** is a quaternary ammonium compound with antiseptic properties, but it has a narrower spectrum of activity and is less potent than chlorhexidine for surgical site preparation. - It is often used in combination with other agents or for general skin cleansing rather than for critical procedures like central line insertion. - Not recommended as a primary antiseptic for central venous catheter insertion.
Question 72: Drug of choice for Pneumocystis jirovecii in pregnancy?
- A. Primaquine
- B. Dapsone
- C. Pentamidine
- D. Trimethoprim-sulfamethoxazole (SMZ/TMP) (Correct Answer)
Explanation: ***Trimethoprim-sulfamethoxazole (SMZ/TMP)*** - Despite being a **folate antagonist**, SMZ/TMP is considered safe and the **drug of choice** for treating **Pneumocystis jirovecii pneumonia (PJP)** in pregnant women, particularly as the benefits outweigh the risks. - It is recommended to supplement with **folic acid** during treatment to mitigate potential teratogenic risks, although these risks are generally low. *Primaquine* - **Primaquine** is primarily used for the treatment of **Plasmodium vivax** and **Plasmodium ovale malaria**, specifically targeting hypnozoites in the liver. - It is contraindicated in pregnancy due to the risk of **hemolytic anemia** in the fetus, especially if the fetus has **glucose-6-phosphate dehydrogenase (G6PD) deficiency**. *Dapsone* - **Dapsone** is used in the treatment of **leprosy**, **dermatitis herpetiformis**, and as an alternative for **PJP prophylaxis** in HIV-positive patients. - While it can be used for PJP prophylaxis, its efficacy for **active PJP treatment** is lower than SMZ/TMP, and it carries risks of **hemolytic anemia** and **methemoglobinemia**, particularly in pregnancy. *Pentamidine* - **Pentamidine** is an alternative treatment for **PJP**, especially in patients who cannot tolerate SMZ/TMP. - It is typically reserved for **severe cases** or as a second-line agent due to its potential for **significant toxicity**, including hypotension, nephrotoxicity, and hypoglycemia, which can be particularly concerning in pregnancy.
Question 73: Which of the following is the prototypical sympathomimetic agent with both alpha and beta-adrenergic activity?
- A. Epinephrine (Correct Answer)
- B. Isoproterenol
- C. Norepinephrine
- D. Dopamine
Explanation: ***Epinephrine*** - Epinephrine (adrenaline) is a potent direct-acting **sympathomimetic** that stimulates both **alpha and beta-adrenergic receptors**. - Its diverse effects on the cardiovascular, respiratory, and other systems make it the prototypical agent for demonstrating both receptor activities. *Norepinephrine* - While norepinephrine (noradrenaline) also acts on **alpha and beta-1 receptors**, its affinity for **beta-2 receptors** is significantly lower than epinephrine. - This results in a predominant effect on **vasoconstriction** and cardiac contractility rather than bronchodilation or peripheral vasodilation. *Isoproterenol* - Isoproterenol is a **non-selective beta-adrenergic agonist**, meaning it primarily stimulates **beta-1 and beta-2 receptors**. - It has minimal or no activity at **alpha-adrenergic receptors**, differentiating it from epinephrine's mixed activity. *Dopamine* - Dopamine's effects are **dose-dependent**; at low doses, it primarily stimulates **dopamine receptors** and at moderate doses, it activates **beta-1 receptors**. - At high doses, it can stimulate **alpha-adrenergic receptors**, but its primary and distinguishing characteristic is its agonism at **dopamine receptors**, which epinephrine does not share.
Question 74: What is the effect of adding epinephrine to lignocaine (a local anesthetic)?
- A. Increases distribution of local anesthetic
- B. Decreases absorption of local anesthetic (Correct Answer)
- C. Decreases duration of local anesthetic
- D. Increases metabolism of local anesthetic
Explanation: ***Decreases absorption of local anesthetic*** - Epinephrine causes **vasoconstriction** at the site of injection, which reduces the rate at which the local anesthetic is absorbed into the systemic circulation. - This slower absorption leads to a **higher concentration of the anesthetic** at the nerve fibers, prolonging its effect and reducing systemic toxicity. - This is the primary mechanism by which epinephrine enhances local anesthetic efficacy. *Increases distribution of local anesthetic* - The primary effect of epinephrine is to **localize the anesthetic** by reducing its systemic distribution. - This localization is achieved through **vasoconstriction**, which keeps the drug at the desired site rather than allowing it to distribute widely. *Decreases duration of local anesthetic* - By slowing absorption, epinephrine effectively **increases the duration of action** of the local anesthetic. - The anesthetic remains at the site of action for a longer period, providing **extended pain relief**. *Increases metabolism of local anesthetic* - Epinephrine does not directly affect the **metabolic rate** of local anesthetics. - The primary mechanism of metabolism for amides like lignocaine is in the **liver** by cytochrome P450 enzymes.
Question 75: What is the correct sequence of medication administration for pre-operative prophylaxis in pheochromocytoma?
- A. Beta blockade followed by alpha blockade
- B. Simultaneous alpha and beta blockade
- C. Alpha blockade followed by beta blockade (Correct Answer)
- D. Alpha blockade only
Explanation: ***Alpha blockade followed by beta blockade*** - **Alpha blockade** should always be initiated first to control **hypertension** and prevent a **hypertensive crisis** during surgery. This is critical because pheochromocytoma causes excessive catecholamine release, leading to profound vasoconstriction. - **Beta blockade** is then added only after adequate alpha blockade has been achieved to control **tachycardia** and arrhythmias, preventing **unopposed alpha-adrenergic stimulation** which could paradoxically worsen hypertension. *Simultaneous alpha and beta blockade* - Administering both simultaneously is dangerous because **beta blockade** can mask the effects of inadequate alpha blockade. - This can lead to **unopposed alpha-adrenergic stimulation** after beta blockade, causing severe **vasoconstriction** and hypertensive crisis. *Beta blockade followed by alpha blockade* - Initiating with **beta blockade** without prior **alpha blockade** is absolutely contraindicated in pheochromocytoma. - This can lead to severe and potentially fatal **hypertension** due to **unopposed alpha-adrenergic stimulation** as beta blockade prevents vasodilation. *Alpha blockade only* - While essential for initial management, **alpha blockade alone** might not fully control all symptoms, especially **tachycardia** and **arrhythmias** caused by high circulating catecholamine levels. - Adding a **beta blocker** after achieving adequate alpha blockade helps in controlling these cardiac effects, optimizing patient preparation for surgery.
Question 76: All of the following are used for treatment of *H. pylori*, except:
- A. Metronidazole
- B. Amoxicillin
- C. Clarithromycin
- D. Gentamicin (Correct Answer)
Explanation: ***Gentamicin*** - **Gentamicin** is an **aminoglycoside antibiotic** primarily used for severe Gram-negative bacterial infections and is **not effective** against *H. pylori*. - Its mechanism of action and **toxicity profile** (ototoxicity, nephrotoxicity) make it unsuitable for typical *H. pylori* eradication regimens. *Clarithromycin* - **Clarithromycin** is a **macrolide antibiotic** frequently used in **triple therapy regimens** for *H. pylori* eradication. - It works by **inhibiting bacterial protein synthesis**, significantly contributing to the eradication of the bacteria. *Metronidazole* - **Metronidazole** is an **antibiotic** and **antiprotozoal agent** commonly included in *H. pylori* **quadruple therapy** or when penicillin allergies are present. - It acts by forming **cytotoxic compounds** that disrupt bacterial DNA, making it effective against anaerobic and microaerophilic bacteria like *H. pylori*. *Amoxicillin* - **Amoxicillin** is a **beta-lactam antibiotic** that is a cornerstone of many *H. pylori* **eradication regimens**, particularly in standard triple therapy. - It works by **inhibiting bacterial cell wall synthesis**, leading to bacterial lysis.
Question 77: Which of the following is not a definite use for Prostaglandin E2 (PGE2)?
- A. Induces labour
- B. Keeps patency of PDA (Correct Answer)
- C. Contraception
- D. Therapeutic abortion
Explanation: ***Keeps patency of PDA*** - **Prostaglandin E1 (PGE1)**, not PGE2, is used to maintain the patency of the **ductus arteriosus** in neonates with certain congenital heart defects. - PGE1 causes **vascular smooth muscle relaxation**, preventing closure of the ductus arteriosus. *Contraception* - **PGE2 analogs** are used in various forms of contraception, including emergency contraception and for cervical ripening before elective abortion. - They act by inducing **uterine contractions** and can interfere with implantation or facilitate expulsion of a fertilized egg. *Induces labour* - **PGE2 (dinoprostone)** is commonly used clinically to induce labor by promoting **cervical ripening** and stimulating **uterine contractions**. - It is administered as a vaginal gel or insert to prepare the cervix for delivery. *Therapeutic abortion* - **PGE2 analogs** are used to induce therapeutic abortion, particularly in the second trimester, by causing powerful **uterine contractions** that lead to the expulsion of the fetus. - They are often used in combination with other agents to enhance their efficacy.
Question 78: All of the following occurs because of prostaglandin use except?
- A. Increased motility of bowel
- B. Nausea
- C. Excess water retention (Correct Answer)
- D. Flushes
Explanation: ***Excess water retention*** - **Prostaglandins** generally promote **diuresis** and natriuresis, meaning they help the body excrete water and sodium, rather than retain them [2]. - While some prostaglandins can affect renal blood flow, direct causation of **excess water retention** as a primary side effect is not typical. *Flushes* - **Prostaglandins**, particularly **PGE1** and **PGE2**, are potent **vasodilators** and can cause cutaneous vasodilation, leading to **flushing** and a sensation of warmth [3]. - This effect is often mediated by the relaxation of vascular smooth muscle. *Increased motility of bowel* - Many **prostaglandins**, especially **PGE** and **PGF** series, stimulate **smooth muscle contraction**, including in the gastrointestinal tract [1]. - This increased contraction can lead to **enhanced bowel motility**, sometimes causing diarrhea or abdominal cramping [1]. *Nausea* - **Prostaglandins** can have various systemic effects, and activation of pathways in the central nervous system or direct irritation of the GI tract can lead to symptoms like **nausea** and vomiting [1]. - This is a common side effect, especially with systemic administration.
Question 79: What is the drug of choice for malaria in pregnancy?
- A. Primaquine
- B. Chloroquine (Correct Answer)
- C. Artesunate
- D. Quinine
Explanation: ***Chloroquine*** - **Chloroquine** is the drug of choice for **uncomplicated malaria in pregnancy** caused by **chloroquine-sensitive** strains of *P. vivax*, *P. ovale*, *P. malariae*, and *P. falciparum* [1]. - It has an **established safety profile** in pregnancy across all trimesters and is considered safe by WHO and CDC. - While resistance has emerged in many areas for *P. falciparum*, chloroquine remains effective for *P. vivax* malaria in most regions including India. - For **severe malaria** or **chloroquine-resistant falciparum malaria**, alternative regimens like quinine or artesunate are used [1]. *Quinine* - **Quinine** (usually with clindamycin) is the preferred treatment for **severe malaria** or **chloroquine-resistant *P. falciparum*** malaria in pregnancy, especially in the **first trimester**. - It is safe and effective but can cause side effects like **cinchonism** (tinnitus, headache, nausea) and **hypoglycemia**. - While safe throughout pregnancy, it is not the first-line choice for uncomplicated chloroquine-sensitive malaria. *Primaquine* - **Primaquine** is **contraindicated in pregnancy** because it can cause **hemolytic anemia** in individuals with **G6PD deficiency**, and G6PD status of the fetus cannot be determined [3]. - It is used for **radical cure** of *P. vivax* and *P. ovale* to eliminate liver hypnozoites, but must be deferred until after delivery [3]. *Artesunate* - **Artesunate** and other **artemisinin-based combination therapies (ACTs)** are highly effective antimalarials [2]. - Current WHO guidelines support ACT use in all trimesters for severe malaria when benefits outweigh risks. - For **uncomplicated falciparum malaria**, ACTs are preferred in the **second and third trimesters** in areas with chloroquine resistance [2]. - However, chloroquine remains the classical "drug of choice" for uncomplicated, chloroquine-sensitive malaria in pregnancy [1].
Question 80: What is the maximum cumulative dose of isotretinoin for acne treatment?
- A. 30-60 mg/kg
- B. 60-90 mg/kg
- C. 90-120 mg/kg
- D. 120-150 mg/kg (Correct Answer)
Explanation: ***120-150 mg/kg*** - The goal of **isotretinoin cumulative dosing** is to achieve long-term remission and reduce the risk of relapse. - A cumulative dose in the range of **120-150 mg/kg** has been shown to optimize treatment outcomes for severe or recalcitrant acne. *30-60 mg/kg* - This range is typically considered too low to achieve the optimal **cumulative dose** for sustained remission in severe acne. - Doses within this range might be used in some cases for milder forms of acne or in patients with significant side effects, but not as the standard maximum. *60-90 mg/kg* - While this is closer to an effective cumulative dose, it still often falls short of the recommended range for maximizing the long-term efficacy and reducing relapse rates in patients with severe forms of acne. - Studies suggest that higher cumulative doses correlate with better treatment success and fewer recurrences. *90-120 mg/kg* - This range is often considered a minimal target for a **cumulative dose**, especially at the higher end of the range (120 mg/kg). - While effective for many patients, aiming for the upper end (120-150 mg/kg) often provides a more robust and durable response, particularly in more severe or nodular acne.