UPSC-CMS 2020 — Pharmacology
4 Previous Year Questions with Answers & Explanations
Which one of the following statements regarding Rabies Immunoglobulin is NOT true?
All of the following are true about Bedaquiline (BDQ) EXCEPT:
What is the recommended dose regimen of Vitamin A for the treatment of early stages of Xerophthalmia?
Which one of the following is the antibiotic of choice for the prevention of Rheumatic Heart Disease?
UPSC-CMS 2020 - Pharmacology UPSC-CMS Practice Questions and MCQs
Question 1: Which one of the following statements regarding Rabies Immunoglobulin is NOT true?
- A. It should be administered primarily into or around the wound sites
- B. There is no scientific ground for performing a skin test prior to administering equine immunoglobulin
- C. It can be administered till 15 days after the first dose of anti-rabies vaccine (Correct Answer)
- D. It should be administered only once as soon as possible after the initiation of post exposure prophylaxis
Explanation: ***It can be administered till 15 days after the first dose of anti-rabies vaccine*** - This statement is **incorrect** because Rabies Immunoglobulin (RIG) provides passive immunity and should be given as soon as possible after exposure, ideally within **7 days** of the first vaccine dose. Beyond this period, the vaccine itself is expected to have stimulated active immunity. - Delaying RIG administration significantly reduces its effectiveness, as the goal is to neutralize the virus before the body mounts its own immune response, which typically begins to be robust around day 7-10 after vaccination. *It should be administered primarily into or around the wound sites* - This statement is **true**. The primary goal of RIG is to provide immediate, localized immunity by neutralizing the rabies virus at the site of entry. - Infiltrating as much of the dose as anatomically feasible directly into and around the wound ensures effective local virus neutralization. *There is no scientific ground for performing a skin test prior to administering equine immunoglobulin* - This statement is **true** according to current WHO guidelines. With modern, highly purified RIG products, the risk of severe systemic allergic reactions is low. - Skin testing can be unreliable, lead to unnecessary delays in critical post-exposure prophylaxis, and may not accurately predict a severe allergic reaction. *It should be administered only once as soon as possible after the initiation of post exposure prophylaxis* - This statement is **true**. RIG is a single-dose treatment given at the beginning of post-exposure prophylaxis (PEP) to provide immediate antibodies. - Multiple doses are not recommended as they could interfere with the development of the body's active immune response stimulated by the rabies vaccine.
Question 2: All of the following are true about Bedaquiline (BDQ) EXCEPT:
- A. It has extended half life
- B. It is a bacteriostatic drug (Correct Answer)
- C. It specifically targets mycobacterial ATP synthase
- D. It has high volume of tissue distribution
Explanation: ***It is a bacteriostatic drug*** - **Bedaquiline (BDQ)** is a novel anti-tuberculosis drug that is **bactericidal** against *Mycobacterium tuberculosis*, meaning it kills the bacteria rather than just inhibiting their growth. - Its bactericidal action is crucial for treating multi-drug resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. *It has extended half-life* - **Bedaquiline** has a very **long terminal elimination half-life**, which can extend up to several months. - This extended half-life allows for less frequent dosing schedules (e.g., once daily or thrice weekly after an initial loading phase). *It specifically targets mycobacterial ATP synthase* - **Bedaquiline** specifically inhibits **mycobacterial ATP synthase**, an enzyme essential for energy production in *Mycobacterium tuberculosis* [1]. - This unique mechanism of action contributes to its effectiveness against traditional drug-resistant strains [1]. *It has high volume of tissue distribution* - **Bedaquiline** is highly lipophilic and extensively distributed into tissues, resulting in a **large volume of distribution**. - This extensive tissue distribution contributes to its long half-life and allows it to reach therapeutic concentrations within the infection sites.
Question 3: What is the recommended dose regimen of Vitamin A for the treatment of early stages of Xerophthalmia?
- A. 2 lac IU on two successive days (Correct Answer)
- B. Single massive dose of 2 lac International Units (IU)
- C. 2 doses of 1 lac IU at a gap of one week
- D. 2 doses of 1 lac IU in two successive days
Explanation: ***2 lac IU on two successive days*** - The **WHO-recommended treatment protocol** for xerophthalmia (including early stages) involves a **3-dose regimen**: 200,000 IU immediately, followed by 200,000 IU the next day, and a third dose at least 2 weeks later. - The **first two doses on consecutive days** represent the critical initial treatment phase to rapidly replenish vitamin A stores and prevent progression to sight-threatening corneal damage. - This regimen applies to children **12 months and older and adults**; infants under 12 months receive 100,000 IU doses. *Single massive dose of 2 lac International Units (IU)* - While a high dose is essential, **a single dose alone is insufficient** for treating xerophthalmia according to WHO guidelines. - The second dose on the consecutive day is critical to ensure adequate tissue saturation and prevent progression of corneal lesions. - Single-dose regimens are used for **prophylaxis in high-risk populations**, not for active treatment of xerophthalmia. *2 doses of 1 lac IU at a gap of one week* - **100,000 IU doses** are recommended for **infants under 12 months of age**, not for older children and adults with xerophthalmia. - The one-week interval does not match the WHO protocol, which requires the second dose on the **very next day** to ensure rapid correction. *2 doses of 1 lac IU in two successive days* - This dosing regimen is appropriate for **infants aged 6-12 months** with xerophthalmia, where each dose is 100,000 IU. - For children **12 months and older and adults**, the standard dose is **200,000 IU (2 lac IU)**, making this dosage insufficient for the typical patient population.
Question 4: Which one of the following is the antibiotic of choice for the prevention of Rheumatic Heart Disease?
- A. Benzathine Benzyl Penicillin (Correct Answer)
- B. Doxycycline
- C. Procaine Penicillin
- D. Ciprofloxacin
Explanation: ***Benzathine Benzyl Penicillin*** - It is the antibiotic of choice for the **prevention of Rheumatic Heart Disease (RHD)** due to its **long-acting nature** and effectiveness against **Group A Streptococcus (GAS)**. - A single intramuscular injection provides **sustained therapeutic levels** for several weeks, crucial for preventing recurrent GAS infections that lead to RHD. *Doxycycline* - Not effective for **primary prevention of Rheumatic Fever** or RHD as it is not a first-line agent against **Group A Streptococcus**. - Mainly used for **atypical bacteria** and certain parasitic infections. *Procaine Penicillin* - It has a shorter duration of action compared to **benzathine penicillin**. - Requires more frequent injections, making it less suitable for **long-term prophylaxis** in RHD prevention. *Ciprofloxacin* - This is a **fluoroquinolone antibiotic** and is not the antibiotic of choice for **Group A Streptococcus infections**. - Its use in this context could contribute to **antibiotic resistance** without providing effective prophylaxis for RHD.