General Pharmacology — MCQs

Consider the following statements: 1. The duration of immunity is longer when live vaccine is administered as compared to the administration of killed vaccine. 2. In the case of killed vaccine, single dose is sufficient whereas multiple doses are always required in the case of live vaccines. Which of these statements is/are correct?

Q467

What is the recommended dose regimen of Vitamin A for the treatment of early stages of Xerophthalmia?

Q468

Which of the following is true about clinical therapeutic index?

Q469

Which of the following is false about the selection of essential drugs?

Q470

Hepatitis B subunit vaccine contains which of the following antigens?

General Pharmacology Indian Medical PG Practice Questions and MCQs

Question 461: Which one of the following drugs is a long acting local anaesthetic agent ?

A. Lignocaine
B. Prilocaine
C. Bupivacaine (Correct Answer)
D. Ropivacaine

Explanation: ***Bupivacaine***- **Bupivacaine** is the **classic and most widely recognized long-acting amide local anesthetic** with a duration of action typically ranging from **2 to 8 hours** depending on the concentration and site of administration. [1]- Its prolonged action is due to its high **lipid solubility** and **protein binding** (95%), allowing it to penetrate nerves effectively and stay bound within tissues for extended periods. [1]- It is the **prototypical long-acting local anesthetic** and has been the gold standard for decades in regional anesthesia and pain management. [1]*Lignocaine*- **Lignocaine** (also known as **lidocaine**) is an **intermediate-acting amide local anesthetic**, with a duration of action of **1-2 hours** (much shorter than bupivacaine). [1]- It is frequently used for **infiltration anesthesia**, **nerve blocks**, and **topical anesthesia** but is **not considered long-acting**. *Prilocaine*- **Prilocaine** is an **intermediate-acting amide local anesthetic**, similar to lignocaine, with a duration of action of approximately **1-2 hours**. [1]- A notable side effect of prilocaine, especially at high doses, is the potential for **methemoglobinemia** due to its metabolite o-toluidine. [1]*Ropivacaine*- **Ropivacaine** is a **newer long-acting amide local anesthetic** (duration 2-6 hours) introduced in the 1990s as an alternative to bupivacaine. [1]- While it has a **similar duration of action**, it is distinguished by its **lower cardiotoxicity** and **greater motor-sensory separation** compared to bupivacaine. [1]- However, **bupivacaine remains the classic textbook example** of a long-acting local anesthetic and is the expected answer in most examination contexts. [1]- Ropivacaine is often preferred in obstetric and pediatric anesthesia due to its better safety profile.

Question 462: What is the shelf life of Dukoral (wc-rBS) oral vaccine used for cholera prevention, when stored at a temperature of 2 °C to 8 °C?

A. 2 years (Correct Answer)
B. 3 years
C. 6 months
D. 5 years

Explanation: ***2 years***- Dukoral (wc-rBS) oral vaccine, when stored correctly at **2 °C to 8 °C**, maintains its efficacy and stability for **2 years**. - This is the manufacturer-specified shelf life that ensures the vaccine remains potent and safe for use. - The vaccine contains inactivated whole-cell V. cholerae and recombinant cholera toxin B subunit, with a validated 2-year stability period. *3 years*- A 3-year shelf life is an **overestimation** for Dukoral under standard refrigerated storage conditions. - Beyond the validated 2-year period, the vaccine's potency cannot be guaranteed. - This could lead to administration of potentially ineffective vaccine. *6 months*- A 6-month shelf life is significantly **underestimated** for Dukoral, indicating a lack of understanding of vaccine stability. - Such a short duration would lead to premature discarding of usable vaccine and increased waste. - Most modern refrigerated vaccines have longer shelf lives than this. *5 years*- A 5-year shelf life is a significant **overestimation** for Dukoral (wc-rBS). - This duration exceeds the manufacturer's validated stability data for this oral vaccine. - Using vaccine beyond its validated shelf life poses risks of reduced immunogenicity.

Question 463: Which of the following is a live attenuated vaccine?

A. Salk Vaccine
B. Yellow Fever Vaccine (Correct Answer)
C. Hepatitis B vaccine
D. Rabies Vaccine

Explanation: ***Yellow Fever Vaccine*** - The Yellow Fever vaccine is a **live attenuated vaccine**, meaning it contains a weakened form of the virus that stimulates a strong immune response without causing the disease. - It is highly effective in providing long-lasting immunity against **yellow fever**, a viral hemorrhagic disease transmitted by mosquitoes. *Salk Vaccine* - The Salk vaccine is an **inactivated polio vaccine (IPV)**, meaning it contains killed poliovirus. - It works by stimulating an immune response to the killed virus, but it does not replicate in the host. *Rabies vaccine* - The rabies vaccine is an **inactivated vaccine** prepared from killed rabies virus. - It provides protection by inducing antibodies against the rabies virus glycoprotein. *Hepatitis B vaccine* - The Hepatitis B vaccine is a **recombinant vaccine**, meaning it is produced using genetic engineering techniques to synthesize hepatitis B surface antigen (HBsAg). - It does not contain live or killed virus but rather a purified viral protein to stimulate immunity.

Question 464: Which one of the following vaccines is a killed vaccine?

A. Mumps vaccine
B. Yellow fever vaccine
C. Rubella vaccine
D. Hepatitis B vaccine (Correct Answer)

Explanation: ***Hepatitis B vaccine*** - The Hepatitis B vaccine is a **recombinant subunit vaccine** containing only the **hepatitis B surface antigen (HBsAg)** produced through genetic engineering. - It does **not contain live or killed viral particles**, making it distinct from traditional killed vaccines. - However, it is sometimes **grouped with inactivated vaccines** in broader classifications as it contains no live components and cannot cause infection. - Among the given options, this is the **only non-live vaccine**, making it the **best answer** in this context. *Mumps vaccine* - The mumps vaccine is a **live-attenuated vaccine**, containing a weakened form of the mumps virus. - Live-attenuated vaccines stimulate a strong, long-lasting immune response similar to natural infection. *Yellow fever vaccine* - The yellow fever vaccine is a **live-attenuated vaccine** prepared from the 17D strain of the yellow fever virus. - It induces robust and long-term immunity against yellow fever. *Rubella vaccine* - The rubella vaccine is a **live-attenuated vaccine**, containing a weakened form of the rubella virus. - It is typically administered as part of the **MMR (measles, mumps, rubella)** vaccine.

Question 465: The primary route of administration of measles vaccination is:

A. Subcutaneous (Correct Answer)
B. Intravenous
C. Intranasal
D. Intradermal

Explanation: ***Subcutaneous*** - The **measles, mumps, and rubella (MMR) vaccine** is a live attenuated vaccine typically administered via the **subcutaneous route**. - Subcutaneous injection ensures the vaccine is delivered into the fatty tissue just below the skin, allowing for gradual absorption and an effective immune response. *Intravenous* - **Intravenous administration** delivers substances directly into the bloodstream, which is generally avoided for vaccines due to the risk of systemic reactions and rapid clearance. - This route is typically reserved for emergency medications or those requiring immediate systemic distribution. *Intranasal* - **Intranasal vaccines** are administered through the nasal passages and are designed to stimulate mucosal immunity, particularly against respiratory pathogens. - While some flu vaccines use this route, the standard measles vaccine does not. *Intradermal* - **Intradermal administration** involves injecting into the dermis layer of the skin, often used for sensitivity testing or certain vaccines like BCG. - This route requires a smaller volume and specific technique, which is not the primary method for routine measles vaccination.

Question 466: Consider the following statements: 1. The duration of immunity is longer when live vaccine is administered as compared to the administration of killed vaccine. 2. In the case of killed vaccine, single dose is sufficient whereas multiple doses are always required in the case of live vaccines. Which of these statements is/are correct?

A. 1 only (Correct Answer)
B. 2 only
C. Both 1 and 2
D. Neither 1 nor 2

Explanation: ***1 only*** - **Live attenuated vaccines** stimulate a more robust, long-lasting immune response, often mimicking natural infection, leading to **longer duration of immunity** compared to killed vaccines. - This is because live vaccines can replicate in the host, providing a continuous antigenic stimulus that enhances the breadth and memory of the immune response. *2 only* - This statement is incorrect because **killed vaccines** typically require **multiple doses** (prime and booster shots) to achieve and maintain adequate protective immunity. - In contrast, **live vaccines** often achieve sufficient immunity with a **single dose** due to their ability to replicate and elicit a strong cellular and humoral response. *Both 1 and 2* - This option is incorrect as statement 2 is false. Live vaccines generally provide longer immunity, and killed vaccines usually require multiple doses, while live vaccines often need only one. *Neither 1 nor 2* - This option is incorrect because statement 1 is accurate regarding the longer duration of immunity provided by live vaccines.

Question 467: 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 468: Which of the following is true about clinical therapeutic index?

A. Dose in which efficacy and toxicity can be balanced in an individual (Correct Answer)
B. Therapeutic index is LD50/ED50
C. It is only used for a specific individual
D. It measures therapeutic index in populations rather than individuals

Explanation: ***Dose in which efficacy and toxicity can be balanced in an individual*** - The **clinical therapeutic index** refers to the optimal range of drug dosage that produces the maximum desired therapeutic effect with minimal adverse side effects **in a specific patient**. - It involves a personalized approach to find the **balance between efficacy and toxicity** for individual patient care. *It is only used for specific individual* - While it is applied to specific individuals, the concept of a **clinical therapeutic index** is derived from a broader understanding of drug pharmacokinetics and pharmacodynamics established in clinical trials. - This statement is too restrictive, as population data informs the individual application. *Measures therapeutic index in a population vs individual* - The traditional **therapeutic index (TI)** is typically a population-based measure (LD50/ED50 or TD50/ED50), whereas the **clinical therapeutic index** focuses on the individual patient. - This option incorrectly suggests that the clinical TI measures population rather than focusing on the individual’s treatment optimization. *Therapeutic index is ED50/LD50* - The classic definition of the **therapeutic index (TI)** is **LD50/ED50** (Lethal Dose 50% / Effective Dose 50%), which is a ratio for preclinical animal studies. - For humans, the more relevant measure is the **therapeutic window** or the ratio of **TD50/ED50** (Toxic Dose 50% / Effective Dose 50%), but this is still a population measure, not the clinical therapeutic index for an individual.

Question 469: Which of the following is false about the selection of essential drugs?

A. Cost to benefit has to be considered
B. Fixed drug combination is preferred over single drugs (Correct Answer)
C. An adequate safety profile needs to be established
D. Disease prevalence is considered

Explanation: ***Fixed drug combination is preferred over single drugs*** - The statement that **fixed-drug combinations (FDCs)** are preferred over single drugs for essential drug selection is false. Generally, **single drugs are preferred** to allow for individual dose adjustments and minimize potential adverse effects from unnecessary components. - FDCs are only considered essential when they offer specific advantages, such as **improved adherence** (e.g., in tuberculosis treatment) or a **synergistic effect** not achievable with individual drugs. *Cost to benefit has to be considered* - This statement is true; the **cost-effectiveness** and **cost-benefit ratio** are crucial factors in selecting essential drugs. - Essential drugs aim to provide the most public health benefit at an **affordable cost**, ensuring access for a broad population. *An adequate safety profile needs to be established* - This statement is true; essential drugs must have a **well-established safety profile** with acceptable risks. - The benefits of the drug must significantly outweigh its potential harms, with minimal serious **adverse reactions**. *Disease prevalence is considered* - This statement is true; essential drugs are selected based on their ability to address the **most prevalent diseases** and health needs of a population. - Prioritizing drugs for common conditions ensures that public health resources are effectively allocated to where they are most needed.

Question 470: Hepatitis B subunit vaccine contains which of the following antigens?

A. HbeAg
B. HbsAg (Correct Answer)
C. HbcAg
D. HBV DNA

Explanation: ***HbsAg*** - The Hepatitis B vaccine is a **subunit vaccine** that contains recombinant **hepatitis B surface antigen (HBsAg)**. - This antigen is highly immunogenic and elicits a protective antibody response (anti-HBs) that neutralizes the virus. *HbeAg* - **HBeAg** indicates active viral replication and high infectivity, but it is not the antigen used in the vaccine. - While important for diagnostic purposes, antibodies to HBeAg (anti-HBe) indicate reduced viral replication. *HbcAg* - **HBcAg (hepatitis B core antigen)** is an internal component of the virion and is not found in the subunit vaccine. - Antibodies to HBcAg (anti-HBc) indicate past or current infection but do not confer protective immunity. *HBV DNA* - **HBV DNA** represents the viral genetic material and is a marker of active viral replication and infectivity. - It is not an antigen and therefore not included in a subunit vaccine designed to induce an immune response to viral proteins.

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Pharmacogenetics and Personalized Medicine

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Adverse Drug Reactions and Toxicity

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Drug Interactions

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