General Pharmacology — MCQs

General Pharmacology Indian Medical PG Practice Questions and MCQs

Question 481: Which is the shortest-acting mydriatic?

A. Tropicamide (Correct Answer)
B. Homatropine
C. Atropine
D. Cyclopentolate

Explanation: ***Tropicamide*** - It is an **anticholinergic drug** that produces **mydriasis** (pupil dilation) due to its blocking effect on **muscarinic receptors** in the iris sphincter muscle. - Tropicamide has the **shortest duration of action** among the listed mydriatic agents, typically lasting 4-6 hours. *Homatropine* - Homatropine is an **anticholinergic drug** with a longer duration of action than tropicamide, typically lasting 1-3 days. - It is commonly used for **cycloplegia** and mydriasis in ophthalmology, but not as the shortest-acting agent. *Atropine* - Atropine is a potent **anticholinergic drug** with the **longest duration of action**, causing mydriasis and cycloplegia that can last for 7-14 days. - Due to its prolonged effects, it is less commonly used for routine pupil dilation and more for therapeutic purposes like treating **anterior uveitis**. *Cyclopentolate* - Cyclopentolate is an **anticholinergic agent** that causes mydriasis and cycloplegia with a duration of action of approximately 6-24 hours. - While faster acting than atropine and homatropine, it is still longer-acting than tropicamide.

Question 482: Which of the following is not a side effect of topical beta blockers?

A. Heterochromia iridis (Correct Answer)
B. Asthma
C. Hypoglycemia
D. Bradycardia

Explanation: ***Heterochromia iridis*** - **Heterochromia iridis** (different colored irises) is a well-known side effect of **prostaglandin analogs** (e.g., latanoprost, bimatoprost), not topical beta blockers. - This change in eye color occurs due to increased **melanin production** in melanocytes. *Asthma* - Topical beta blockers can be absorbed systemically and block **beta-2 receptors** in the lungs, leading to **bronchoconstriction** and exacerbating **asthma**. - This side effect is particularly concerning in patients with a history of **reactive airway disease**. *Hypoglycemia* - Topical beta blockers are listed as a concern for **hypoglycemia risk** because they **mask the adrenergic symptoms of hypoglycemia** (tremor, palpitations, tachycardia). - While they don't directly cause hypoglycemia, masking these warning symptoms can lead to **delayed recognition and treatment**, particularly dangerous in **diabetic patients on insulin or sulfonylureas**. *Bradycardia* - Systemic absorption of topical beta blockers can lead to a decrease in **heart rate** (bradycardia) by blocking **beta-1 receptors** in the heart. - This effect is a significant concern for patients with pre-existing **cardiac conduction disorders** or those taking other medications that lower heart rate.

Question 483: Capsaicin acts on ______

A. Vanilloid receptor (Correct Answer)
B. Capsaicoid receptor
C. AMPA receptor
D. NMDA receptor

Explanation: ***Vanilloid receptor*** - Capsaicin is the active component of chili peppers and exerts its effects primarily through activation of the **transient receptor potential vanilloid 1 (TRPV1) receptor**, also known as the vanilloid receptor. - Activation of **TRPV1** by capsaicin leads to an influx of **calcium ions**, causing depolarization and firing of nociceptive neurons, which is perceived as burning pain. *Capsaicoid receptor* - This term is **not a recognized scientific receptor name** for capsaicin's primary target. - It might be a colloquial or misnomer derived from the mechanism of action of capsaicin. *AMPA receptor* - **AMPA receptors** are **ionotropic glutamate receptors** that mediate fast synaptic transmission in the central nervous system. - They are primarily involved in learning, memory, and synaptic plasticity, not directly activated by capsaicin. *NMDA receptor* - **NMDA receptors** are another type of **ionotropic glutamate receptor** that plays a crucial role in synaptic plasticity and learning. - Although also involved in pain processing, they are distinct from the **TRPV1 receptor** and are not directly activated by capsaicin.

Question 484: What is the name of the mumps vaccine?

A. Edmonston
B. Danish 1331
C. OKA
D. Jeryl Lynn (Correct Answer)

Explanation: **Jeryl Lynn**- The **Jeryl Lynn strain** is a widely used and well-established **live attenuated mumps virus vaccine**.- It forms the basis of many **mumps-containing vaccines**, including the combined **MMR (measles, mumps, rubella) vaccine**.*Edmonston*- The **Edmonston strain** is a well-known **measles vaccine strain**, not a mumps vaccine strain.- It is a **live attenuated measles virus vaccine** commonly included in the MMR vaccine.*Danish 1331*- **Danish 1331** refers to a **live attenuated rubella vaccine strain**, not a mumps vaccine strain.- This strain is part of the **MMR vaccine** and protects against rubella.*OKA*- The **OKA strain** is a prominent **live attenuated varicella-zoster virus (VZV) vaccine strain**, used for the chickenpox vaccine.- It is not associated with the **mumps vaccine**.

Question 485: All the following are conjugate vaccines Except

A. Neisseria meningitidis
B. Haemophilus influenzae type b
C. Hepatitis A (Correct Answer)
D. Pneumococcal

Explanation: ***Hepatitis A (Correct Answer)*** - The **Hepatitis A vaccine** is a **killed viral vaccine** (inactivated vaccine), meaning it contains whole hepatitis A virus particles that have been inactivated so they cannot replicate or cause disease. - It is **NOT a conjugate vaccine** - inactivated vaccines primarily induce a **humoral immune response** without the need for a carrier protein conjugated to a polysaccharide. - This makes Hepatitis A the exception among the options listed. *Neisseria meningitidis (Incorrect)* - The most common vaccines against *Neisseria meningitidis* are **conjugate vaccines**, where the **polysaccharide capsule** is chemically linked to a protein carrier to enhance immunogenicity in infants and young children. - This conjugation allows for T-cell dependent immunity, leading to better memory responses and protection. *Haemophilus influenzae type b (Incorrect)* - The **Haemophilus influenzae type b (Hib) vaccine** is a **conjugate vaccine**, linking the **polysaccharide capsule** of the bacterium to a carrier protein. - This helps induce a robust T-cell dependent immune response, which is crucial for protecting infants and young children against **invasive Hib disease**. *Pneumococcal (Incorrect)* - **Pneumococcal conjugate vaccines** (PCV13, PCV15, PCV20) link the **polysaccharide capsule** to a protein carrier, enhancing immunogenicity and memory, especially in young children. - While polysaccharide vaccines (PPSV23) also exist, the conjugate forms are the primary vaccines used in routine immunization schedules.

Question 486: Acetazolamide is:

A. Competitive and reversible carbonic anhydrase inhibitor (Correct Answer)
B. Non-competitive and irreversible carbonic anhydrase inhibitor
C. Non-competitive and reversible carbonic anhydrase inhibitor
D. Competitive and irreversible carbonic anhydrase inhibitor

Explanation: ***Competitive and reversible carbonic anhydrase inhibitor*** - Acetazolamide is a **competitive inhibitor** that binds directly to the **zinc ion in the active site** of carbonic anhydrase. - It **competes with the natural substrate (CO2/HCO3-)** for binding to the active site, which is the hallmark of competitive inhibition. - It is a **reversible inhibitor**, meaning it eventually dissociates from the enzyme and its effects are not permanent. - As a sulfonamide derivative, it mimics the substrate and blocks the enzyme's catalytic activity temporarily. *Competitive and irreversible carbonic anhydrase inhibitor* - While acetazolamide is indeed a **competitive inhibitor**, it is **not irreversible**. - An irreversible inhibitor forms a **permanent covalent bond** with the enzyme, which acetazolamide does not do. - The drug's effects wear off as it is metabolized and excreted, demonstrating its reversible nature. *Non-competitive and reversible carbonic anhydrase inhibitor* - This option is incorrect because acetazolamide **does not bind to an allosteric site**. - It binds directly to the **active site zinc ion**, making it a competitive inhibitor, not non-competitive. - Non-competitive inhibitors bind to sites other than the active site and cannot be overcome by increasing substrate concentration. *Non-competitive and irreversible carbonic anhydrase inhibitor* - Acetazolamide is neither **non-competitive** nor **irreversible**. - It binds to the **active site** (competitive mechanism) and its binding is **reversible**. - This option combines two incorrect characteristics of the drug's mechanism of action.

Question 487: Which drug is used in treatment of vertigo?

A. Metoclopramide
B. Cisapride
C. Cinnarizine (Correct Answer)
D. None of the options

Explanation: ***Cinnarizine***- **Cinnarizine** is an antihistamine and calcium channel blocker known for its anti-vertigo and anti-emetic properties [2].- It works by suppressing the **vestibular system** and reducing the excitability of sensory hair cells in the inner ear [1].*Metoclopramide*- **Metoclopramide** is a **dopamine receptor antagonist** primarily used as an anti-emetic and for treating gastroparesis.- While it can alleviate nausea and vomiting associated with vertigo, it does not directly treat the underlying sensation of **vertigo** itself by acting on the vestibular system.*Cisapride*- **Cisapride** is a **serotonin 5-HT4 receptor agonist** that acts as a gastroprokinetic agent, enhancing gastrointestinal motility [3].- It is not used for vertigo and has been associated with serious **cardiac arrhythmias**, leading to restricted use in many countries [3].*None of the options*- This option is incorrect because **Cinnarizine** is a well-established medication used in the treatment of vertigo [2].- Other options are not primarily indicated for vertigo treatment.

Question 488: Influenza vaccines are administered via:

A. Intradermal
B. Intrathecal
C. Intramuscularly
D. Intranasal spray (Correct Answer)

Explanation: ***Intranasal spray*** * The **live attenuated influenza vaccine (LAIV)** is administered via **intranasal spray**, making it a needle-free option suitable for healthy individuals aged 2-49 years. * This route allows the vaccine to mimic natural infection in the respiratory tract, potentially inducing both systemic and mucosal immunity. *Intramuscularly* * The **inactivated influenza vaccine (IIV)**, or "flu shot," is the **most commonly used** form and is administered **intramuscularly**. * This involves injecting the vaccine into the deltoid muscle in adults or the anterolateral thigh in infants and young children. * Both intramuscular and intranasal routes are valid for influenza vaccination depending on vaccine type and patient eligibility. *Intradermal* * While **intradermal influenza vaccines** have been developed and approved (e.g., Fluzone Intradermal), they are **less commonly used** than IM vaccines. * This route involves injecting the vaccine into the dermis using a microinjection system. * Not the primary route for standard influenza vaccination programs. *Intrathecal* * **Intrathecal administration** involves injecting medication directly into the **cerebrospinal fluid** surrounding the spinal cord. * This route is used for specific neurological conditions or chemotherapy and is **entirely inappropriate and dangerous** for vaccine delivery.

Question 489: Which of the following vaccines is most sensitive to heat?

A. BCG vaccine
B. DPT vaccine
C. Measles vaccine (Correct Answer)
D. Oral Polio vaccine

Explanation: ***Measles vaccine*** - The **measles vaccine** is a live attenuated vaccine that is the **most heat-sensitive** among commonly used vaccines. - It loses potency **rapidly** at temperatures above 8°C and is particularly vulnerable to both heat and light exposure. - Requires the **strictest cold chain maintenance** and must be protected from light at all times to maintain efficacy. *Oral Polio vaccine* - The **oral polio vaccine (OPV)** is a live attenuated vaccine that is also **heat-sensitive** and requires cold chain maintenance. - While highly heat-sensitive, it is equipped with **Vaccine Vial Monitors (VVM)** to track heat exposure, and is slightly more stable than measles vaccine. - Its efficacy declines with temperature excursions, but not as rapidly as measles vaccine. *BCG vaccine* - The **BCG vaccine**, a live attenuated vaccine against tuberculosis, has **moderate heat stability** compared to measles and OPV. - While it still requires cold chain storage, it is less sensitive to brief temperature excursions than both measles and OPV vaccines. *DPT vaccine* - The **DPT vaccine** (diphtheria, pertussis, tetanus) is an inactivated vaccine, which makes it the **most heat-stable** among these options. - It can tolerate exposure to warmer temperatures for longer periods without significant loss of potency compared to live attenuated vaccines.

Question 490: Bremelanotide is indicated for:

A. LUTS
B. Metastatic RCC
C. Hormone refractory prostate cancer
D. Hypoactive sexual desire disorder (HSDD) in premenopausal women (Correct Answer)

Explanation: ***Hypoactive sexual desire disorder (HSDD) in premenopausal women*** - **Bremelanotide** is a **melanocortin receptor agonist** approved specifically for the treatment of **HSDD** in premenopausal women. - It works by activating central melanocortin receptors, influencing pathways involved in sexual arousal and desire. *LUTS* - **LUTS (Lower Urinary Tract Symptoms)** are typically treated with alpha-adrenergic blockers, 5-alpha-reductase inhibitors, or anticholinergics, not bremelanotide. - Bremelanotide does not have an indicated use for urinary symptoms. *Metastatic RCC* - **Metastatic Renal Cell Carcinoma (RCC)** is treated with targeted therapies such as tyrosine kinase inhibitors, immunotherapy, or IL-2, and is unrelated to bremelanotide. - Bremelanotide's mechanism of action is completely different from that of cancer treatments. *Hormone refractory prostate cancer* - **Hormone refractory prostate cancer** is managed with anti-androgens, chemotherapy, or androgen synthesis inhibitors. - Bremelanotide has no role in the treatment of prostate cancer.

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