General Pharmacology — MCQs

General Pharmacology Indian Medical PG Practice Questions and MCQs

Question 611: Which route is the H1N1 live vaccine administered by?

A. Intramuscular
B. Intranasal (Correct Answer)
C. Oral
D. Subcutaneous

Explanation: ***Intranasal*** - The **live attenuated influenza vaccine (LAIV)**, often referred to as the "nasal spray flu vaccine," is administered intranasally. - This route allows the vaccine to replicate in the **nasal passages**, mimicking natural infection and stimulating a localized immune response. *Intramuscular* - The **inactivated influenza vaccine (IIV)**, or the "flu shot," is administered intramuscularly. - This route delivers the vaccine into the **muscle tissue** to stimulate a systemic immune response without local replication. *Subcutaneous* - Subcutaneous administration is used for some vaccines, but it is **not the standard route** for either live or inactivated influenza vaccines. - This route delivers the vaccine into the **fatty tissue** just under the skin. *Oral* - Oral administration is typically used for live vaccines that need to replicate in the **gastrointestinal tract**, such as the rotavirus vaccine. - It is **not an appropriate route** for influenza vaccines as the virus needs to stimulate respiratory immunity.

Question 612: Beta blockers mask all effects of hypoglycemia except?

A. Sweating (Correct Answer)
B. Palpitations
C. Dizziness
D. Tremors

Explanation: ***Sweating*** - **Sweating** is a **cholinergic symptom** mediated by the sympathetic nervous system acting on **muscarinic receptors** (via acetylcholine), NOT beta-adrenergic receptors. - Beta-blockers act on **adrenergic receptors only** and therefore **do not mask sweating**. - This makes **sweating the most reliable clinical sign** of hypoglycemia in patients on beta-blocker therapy. - Sweating remains the classic teaching point for symptoms that persist despite beta-blockade. *Palpitations* - **Palpitations** are an **adrenergic symptom** resulting from increased heart rate and contractility, mediated by **beta-1 adrenergic receptors**. - Beta-blockers effectively **mask** this symptom by blocking these receptors, preventing the cardiovascular response to hypoglycemia. *Dizziness* - **Dizziness** is a **neuroglycopenic symptom** resulting from insufficient glucose supply to the brain. - While technically not masked by beta-blockers (as it's not mediated by beta receptors), dizziness represents a **late and dangerous sign** of severe hypoglycemia. - Sweating is the more reliable and **earlier warning sign** that remains detectable in beta-blocked patients. *Tremors* - **Tremors** are an **adrenergic symptom** caused by stimulation of **beta-2 adrenergic receptors** in skeletal muscle. - Beta-blockers, especially non-selective ones, effectively **mask this symptom** by blocking these receptors.

Question 613: Which of the following is a metabotropic receptor?

A. GABA-A receptor
B. Beta receptor for norepinephrine (Correct Answer)
C. NMDA receptor
D. Nicotinic acetylcholine receptor

Explanation: ***Beta receptor for norepinephrine*** - **Beta-adrenergic receptors** (like those for norepinephrine) are **G protein-coupled receptors**, which are the hallmark of metabotropic receptors. - Activation of these receptors leads to a cascade of **intracellular signaling events** through second messengers, rather than direct ion channel opening. *GABA-A receptor* - The **GABA-A receptor** is a **ligand-gated ion channel** (ionotropic receptor) that, when activated by GABA, allows chloride ions to flow into the neuron. - This influx of **chloride ions** causes hyperpolarization, leading to an inhibitory effect. *Nicotinic acetylcholine receptor* - The **nicotinic acetylcholine receptor** is a **ligand-gated ion channel** (ionotropic receptor) that, upon binding acetylcholine, directly opens to allow the passage of sodium and potassium ions. - This ion movement causes **depolarization** and excitation of the postsynaptic cell. *NMDA receptor* - The **NMDA receptor** is a type of **glutamate receptor** that functions as a **ligand-gated ion channel** (ionotropic receptor) and is permeable to Na+, K+, and Ca2+. - Its activation requires both **glutamate binding** and depolarization to remove a magnesium block, directly leading to ion flow.

Question 614: All of the following are effects of thiopental, except which of the following?

A. Reduces the cerebral metabolic rate
B. Produces dose dependent decrease in blood pressure
C. Causes decrease in minute ventilation and tidal volume
D. Thiopental is highly lipid soluble, leading to rapid redistribution (Correct Answer)

Explanation: ***Thiopental is highly lipid soluble, leading to rapid redistribution.*** - This statement is a factual characteristic of thiopental's pharmacokinetics, describing why its **onset of action is rapid** and its duration of action is short due to redistribution, rather than a direct physiological *effect* on organ systems. - The question asks for an item that is *not* an effect, and pharmacokinetics (how the body handles the drug) is distinct from pharmacodynamics (the drug's effects on the body). *Reduces the cerebral metabolic rate* - Thiopental is a potent cerebral vasoconstrictor and **decreases cerebral blood flow**, leading to a reduction in the **cerebral metabolic rate of oxygen (CMRO2)**. - This effect is beneficial in neurosurgical procedures as it provides **neuroprotection against ischemia**. *Produces dose dependent decrease in blood pressure* - Thiopental causes **vasodilation** and a **negative inotropic effect** on the heart, leading to a dose-dependent decrease in blood pressure. - This hypotensive effect is more pronounced in patients with **hypovolemia** or compromised cardiac function. *Causes decrease in minute ventilation and tidal volume* - Thiopental is a **respiratory depressant** that directly acts on the respiratory centers in the brainstem. - It leads to a reduction in **respiratory rate** and **tidal volume**, often necessitating ventilatory support, especially with higher doses.

Question 615: Which of the following acts on the trabecular meshwork and increases aqueous outflow?

A. Timolol
B. Pilocarpine (Correct Answer)
C. Brimonidine
D. Brinzolamide

Explanation: ***Pilocarpine*** - As a **muscarinic agonist**, pilocarpine contracts the **ciliary muscle**, which pulls on the scleral spur. - This action widens the spacing within the **trabecular meshwork**, increasing aqueous humor outflow. *Timolol* - Timolol is a **beta-blocker** that reduces the production of aqueous humor by the ciliary body. - It does not directly affect the structure or function of the trabecular meshwork to enhance outflow. *Brimonidine* - Brimonidine is an **alpha-2 adrenergic agonist** that reduces aqueous humor production and increases uveoscleral outflow. - It does not primarily act on the trabecular meshwork to facilitate outflow. *Brinzolamide* - Brinzolamide is a **carbonic anhydrase inhibitor** that decreases aqueous humor production by the ciliary body. - Its mechanism of action does not involve directly affecting the trabecular meshwork's outflow capacity.

Question 616: Which of the following anti-gout drugs acts by inhibiting the enzyme xanthine oxidase?

A. Rasburicase
B. Allopurinol (Correct Answer)
C. Probenecid
D. Sulfinpyrazone

Explanation: ***Allopurinol*** - **Allopurinol** is a purine analog that **inhibits xanthine oxidase**, thereby preventing the conversion of hypoxanthine and xanthine to uric acid. - Allopurinol is metabolized to **oxypurinol (alloxanthine)**, which acts as a **competitive inhibitor** of xanthine oxidase. - This action leads to a reduction in **serum uric acid levels**, which is crucial for preventing and treating gout attacks. *Probenecid* - **Probenecid** is a **uricosuric agent** that acts by inhibiting the reabsorption of uric acid in the renal tubules, leading to increased excretion of uric acid in the urine. - It does not affect the production of uric acid by inhibiting xanthine oxidase. *Rasburicase* - **Rasburicase** is a recombinant **uricase enzyme** that catalyzes the oxidation of uric acid to **allantoin**, a more water-soluble compound that is easily excreted by the kidneys. - It is primarily used for the management of **tumor lysis syndrome** and severe hyperuricemia, not by inhibiting xanthine oxidase. *Sulfinpyrazone* - **Sulfinpyrazone** is another **uricosuric agent** similar to probenecid, working by inhibiting the renal tubular reabsorption of uric acid. - Its mechanism of action is distinct from xanthine oxidase inhibition and focuses on enhancing uric acid excretion rather than reducing its production.

Question 617: All of the following are uses of octreotide except for which of the following?

A. Secretory diarrhea
B. Acromegaly
C. Hepatic encephalopathy (Correct Answer)
D. Bleeding esophageal varices

Explanation: ***Hepatic encephalopathy*** - **Octreotide is not typically used for hepatic encephalopathy**. Treatment focuses on reducing ammonia levels, often with **lactulose** or **rifaximin**. - Its mechanism of action (somatostatin analog) does not directly address the pathophysiology of hepatic encephalopathy. *Secretory diarrhea* - Octreotide is highly effective in treating **secretory diarrhea**, especially in cases related to tumors such as **VIPomas** or **carcinoid syndrome** [1, 2]. - It reduces intestinal fluid and electrolyte secretion by mimicking the action of **somatostatin**. *Acromegaly* - Octreotide is a primary treatment for **acromegaly**, a condition caused by excessive growth hormone production [1, 2]. - It suppresses the secretion of **growth hormone (GH)** and **insulin-like growth factor 1 (IGF-1)** from the pituitary gland [1, 2]. *Bleeding esophageal varices* - Octreotide is used to manage acute bleeding from **esophageal varices** by causing splanchnic vasoconstriction [1, 2]. - This action reduces **portal venous pressure**, thereby decreasing blood flow to the varices and stemming the hemorrhage.

Question 618: Which enzyme is primarily inhibited by the drug prednisolone, leading to its anti-inflammatory effects?

A. Lipoxygenase
B. Phosphodiesterase
C. Phospholipase A2 (Correct Answer)
D. Cyclooxygenase

Explanation: ***Phospholipase A2*** - Prednisolone, a corticosteroid, primarily exerts its anti-inflammatory effects by inhibiting **phospholipase A2**. - Inhibition of **phospholipase A2** prevents the release of **arachidonic acid** from cell membrane phospholipids, thereby blocking the synthesis of all downstream inflammatory mediators. *Cyclo oxygenase* - **Cyclooxygenase (COX)** enzymes are responsible for converting arachidonic acid into **prostaglandins, prostacyclins**, and **thromboxanes**. - While COX is involved in inflammation, it is primarily inhibited by **NSAIDs**, not directly by prednisolone as its initial target. *Lipoxygenase* - **Lipoxygenase (LOX)** enzymes metabolize arachidonic acid into **leukotrienes**, other potent inflammatory mediators. - While leukotrienes contribute to inflammation, prednisolone's primary mechanism of action is upstream of both COX and LOX pathways, rather than direct LOX inhibition. *Phosphodiesterase* - **Phosphodiesterases (PDEs)** are a diverse group of enzymes that break down cyclic nucleotides (cAMP and cGMP). - PDE inhibitors are used for conditions like asthma and erectile dysfunction, and their inhibition is not the primary mechanism of action for the anti-inflammatory effects of prednisolone.

Question 619: Action of dopamine at a dose of 1-2 mcg/kg/min is

A. Causes vasoconstriction
B. Enhances renal blood flow (Correct Answer)
C. Increases myocardial contractility
D. Elevates systemic blood pressure

Explanation: ***Enhances renal blood flow*** - At low doses (1-2 mcg/kg/min), dopamine primarily activates **dopamine D1 receptors** in the renal, mesenteric, and coronary vascular beds. - This activation leads to **vasodilation** in these areas, specifically increasing renal blood flow, glomerular filtration rate, and sodium excretion. *Causes vasoconstriction* - **Vasoconstriction** occurs at higher doses of dopamine (10 mcg/kg/min and above) due to stimulation of **alpha-1 adrenergic receptors**. - This effect is generally undesirable for renal perfusion and can lead to increased systemic vascular resistance. *Increases myocardial contractility* - **Increased myocardial contractility** is observed at moderate doses of dopamine (5-10 mcg/kg/min) due to stimulation of **beta-1 adrenergic receptors** in the heart. - This is a common indication for dopamine in cardiogenic shock but does not occur at the low 1-2 mcg/kg/min dose. *Elevates systemic blood pressure* - A significant **elevation in systemic blood pressure** is primarily seen at higher doses of dopamine (greater than 10 mcg/kg/min) due to the combined effects of **vasoconstriction (alpha-1 stimulation)** and increased cardiac output (beta-1 stimulation). - At 1-2 mcg/kg/min, the vasodilatory effects in some vascular beds might even cause a slight decrease or no significant change in systemic blood pressure unless other factors are at play.

Question 620: Which of the following opioids can be given intranasally?

A. Tramadol
B. Pethidine
C. Buprenorphine
D. Butorphanol (Correct Answer)

Explanation: ***Butorphanol*** - **Butorphanol** is a synthetic opioid agonist-antagonist that is commonly available as an **intranasal spray** (Stadols NS) for the treatment of moderate to severe pain, especially for conditions like **migraines** [2]. - Its **high lipid solubility** and **good absorption across nasal mucosa** make it suitable for this route of administration, providing rapid onset of action. - This is the **most well-established and widely used intranasal opioid formulation** in clinical practice. *Tramadol* - **Tramadol** is an opioid analgesic with a primary route of administration that is **oral** or **intravenous**. - It is not typically formulated or administered via the **intranasal route** due to lower bioavailability and potential for local irritation. *Pethidine* - **Pethidine** (meperidine) is an opioid typically given via **intramuscular**, **subcutaneous**, or **intravenous** injection [1]. - It is not formulated for **intranasal use**, and this route would not be an effective or safe delivery method for the drug due to poor absorption and potential for mucosal damage. *Buprenorphine* - **Buprenorphine** is a partial opioid agonist available in various formulations, including **sublingual**, **injectable**, and **transdermal** routes, particularly for opioid dependence treatment and pain management [3]. - While intranasal buprenorphine formulations exist, **sublingual remains the preferred and most commonly used route** in clinical practice due to excellent bioavailability and ease of administration [3]. - **Butorphanol** is the classic intranasal opioid emphasized in medical education.

Practice by Chapter

Pharmacokinetics: Absorption and Distribution

Practice Questions

Pharmacokinetics: Metabolism and Excretion

Practice Questions

Pharmacodynamics and Receptor Theory

Practice Questions

Drug-Receptor Interactions and Dose-Response

Practice Questions

Pharmacogenetics and Personalized Medicine

Practice Questions

Adverse Drug Reactions and Toxicity

Practice Questions

Drug Interactions

Practice Questions

Drug Development and Regulation

Practice Questions

Pediatric and Geriatric Pharmacology

Practice Questions

Placental Transfer and Lactation

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free