General Pharmacology Practice Questions

Q: Pharmacovigilance means:

Monitoring of drug safety. **Explanation:** **Pharmacovigilance (PV)** is defined by the WHO as the science and activities relating to the **detection, assessment, understanding, and prevention of adverse effects** or any other drug-related problems. 1. **Why Option A is Correct:** The primary goal of pharmacovigilance is to ensure **patient safety**. While clinical trials (Phases I-III) provide data on a limited population, rare or long-term adverse drug reactions (ADRs) often emerge only after a drug is marketed to the general public (Phase IV/Post-marketing surveillance). Monitoring drug safety allows for the identification of new safety signals and the implementation of regulatory actions, such as adding "Black Box Warnings" or withdrawing a drug from the market. 2. **Why Other Options are Incorrect:** * **Option B:** Monitoring unethical trade (like smuggling or black marketing) falls under **Drug Regulatory Affairs** and law enforcement (e.g., Narcotics Control Bureau), not pharmacovigilance. * **Option C:** Monitoring students is an academic/administrative function and has no relation to drug safety. * **Option D:** While efficacy is studied in clinical trials, pharmacovigilance specifically focuses on the **risk-benefit ratio**, with a heavy emphasis on the "risk" (safety) aspect. **High-Yield Clinical Pearls for NEET-PG:** * **Phase IV Clinical Trial:** This is the phase most closely associated with pharmacovigilance. * **Pharmacovigilance Programme of India (PvPI):** Launched in 2010; the National Coordinating Centre is the **Indian Pharmacopoeia Commission (IPC)**, Ghaziabad. * **Uppsala Monitoring Centre (UMC):** Located in Sweden, it is the WHO collaborating centre for international drug monitoring. * **Yellow Card Scheme:** A famous spontaneous reporting system for ADRs (originally from the UK).

Q: Which cell membrane receptors activate an ion channel upon binding with agonists?

Nicotinic cholinergic receptors. **Explanation:** The question tests the classification of cell membrane receptors based on their signaling mechanisms. Receptors are broadly divided into four types: Ionotropic, Metabotropic (GPCRs), Enzymatic, and Nuclear receptors. **1. Why Nicotinic Cholinergic Receptors (nAChR) are correct:** Nicotinic receptors are classic examples of **Ionotropic receptors** (Ligand-gated ion channels). Upon binding with an agonist (like Acetylcholine), the receptor undergoes a conformational change that directly opens a central pore, allowing the influx of cations ($Na^+$ and $Ca^{2+}$). This results in rapid depolarization. Because the receptor and the channel are part of the same protein complex, the response is instantaneous (milliseconds). **2. Why the other options are incorrect:** * **Muscarinic Cholinergic Receptors:** These are **G-Protein Coupled Receptors (GPCRs)**. They do not have an intrinsic ion channel; instead, they act through second messengers (like $IP_3/DAG$) or by indirectly opening $K^+$ channels via G-proteins. * **Opioid Receptors ($\mu, \delta, \kappa$):** These are also **GPCRs** (specifically $G_i/G_o$ coupled). They inhibit adenylyl cyclase and indirectly influence ion channels (closing $Ca^{2+}$ or opening $K^+$ channels), but they are not ion channels themselves. **High-Yield Clinical Pearls for NEET-PG:** * **Speed of Response:** Ionotropic (msec) > GPCR (seconds) > Enzymatic (minutes/hours) > Nuclear (hours/days). * **Other Ionotropic Receptors:** $GABA_A$ (Chloride channel), Glycine, 5-$HT_3$ (the only ionotropic Serotonin receptor), and NMDA/AMPA Glutamate receptors. * **Location:** Nicotinic receptors are found at the Neuromuscular Junction ($N_m$) and Autonomic Ganglia ($N_n$). * **Key Distinction:** Remember that **Muscarinic = Metabotropic**, while **Nicotinic = Ionotropic**.

Q: Which of the following pairs represent physiological antagonists?

Glucagon and Insulin. **Explanation:** **Physiological antagonism** (also known as functional antagonism) occurs when two drugs act on **different receptors** and through **different mechanisms**, but produce **opposite effects** on the same physiological system [1]. **1. Why Glucagon and Insulin is correct:** Glucagon and Insulin act on distinct receptors (Glucagon receptors vs. Insulin tyrosine kinase receptors). However, they exert opposing effects on blood glucose levels: Insulin causes hypoglycemia, while Glucagon causes hyperglycemia [2]. Because they cancel each other's functional effects via different pathways, they are classic physiological antagonists [1]. **2. Why the other options are incorrect:** * **Adrenaline and Isoprenaline (Option A):** Both are adrenergic agonists. They act on similar receptors ($\beta$-receptors) to produce synergistic (additive) effects, not antagonistic ones. * **Isoprenaline and Propranolol (Option C):** This is an example of **Pharmacological (Receptor) Antagonism**. Propranolol is a $eta$-blocker that competes with Isoprenaline for the same $eta$-receptor site [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Example:** The most frequently asked example of physiological antagonism is **Adrenaline and Histamine** on bronchial smooth muscle (Adrenaline causes bronchodilation via $eta_2$ receptors; Histamine causes bronchoconstriction via $H_1$ receptors). * **Chemical Antagonism:** Occurs when two drugs react chemically to form an inactive product (e.g., Chelating agents like EDTA for lead poisoning, or Protamine sulfate for Heparin overdose). * **Pharmacokinetic Antagonism:** One drug reduces the concentration of another by interfering with its absorption, metabolism (e.g., Enzyme inducers like Rifampicin), or excretion.

Q: All of the following agents act by intracellular receptors EXCEPT:

Insulin. The mechanism of action of a drug depends on its lipid solubility and the location of its target receptor. Receptors are broadly classified into **Cell Surface Receptors** (for water-soluble ligands) and **Intracellular Receptors** (for lipid-soluble ligands) [1]. **Why Insulin is the Correct Answer:** Insulin is a large peptide hormone that is water-soluble and cannot cross the lipid bilayer of the cell membrane. Therefore, it acts via a **Cell Surface Receptor**, specifically a **Receptor Tyrosine Kinase (Enzyme-linked receptor)** [2]. Binding of insulin to the alpha subunit causes autophosphorylation of the beta subunit, triggering a signaling cascade (PI3K/AKT pathway) to regulate glucose uptake [3]. **Why the Other Options are Incorrect:** Options A, B, and D are all **lipid-soluble (lipophilic)** molecules. They easily cross the cell membrane to bind to **Intracellular Receptors**, which act as ligand-activated transcription factors to alter gene expression [1]: * **Steroids (Glucocorticoids, Sex hormones):** Bind to cytoplasmic receptors (Type I), which then translocate to the nucleus [1]. * **Thyroid Hormones (T3, T4):** Bind directly to receptors already located on the chromatin in the nucleus (Type II). * **Vitamin D:** Acts similarly to steroid hormones, binding to nuclear receptors to regulate calcium-binding protein synthesis. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Intracellular Receptors:** **"VETTT"** – **V**itamin A/D, **E**strogen (and other steroids), **T**hyroid hormones, **T**estosterone, **T**retinoin. * **Fastest acting receptors:** Ionotropic (Ligand-gated ion channels, e.g., Nicotinic ACh receptor). * **Slowest acting receptors:** Nuclear/Intracellular receptors (due to the time required for gene transcription and protein synthesis). * **Insulin & Growth Factors:** Always remember they use **Tyrosine Kinase** pathways.

Q: Which of the following drugs is an enzyme inducer?

Rifampicin. **Explanation** The correct answer is **Rifampicin**. **1. Why Rifampicin is correct:** Rifampicin is a potent inducer of the **Cytochrome P450 (CYP450)** enzyme system, specifically the CYP3A4 isoenzyme. [3] Enzyme inducers work by increasing the synthesis of microsomal enzymes in the liver. This leads to an accelerated metabolism of co-administered drugs (e.g., oral contraceptives, warfarin, theophylline), resulting in decreased plasma concentrations and potential therapeutic failure. [1] **2. Why the other options are incorrect:** * **Isoniazid (INH):** Unlike Rifampicin, Isoniazid is a known enzyme **inhibitor**. It inhibits the metabolism of drugs like phenytoin and carbamazepine, leading to their toxicity. * **Ketoconazole:** This is a classic, potent enzyme **inhibitor** (specifically CYP3A4). [1, 2] It is often used in pharmacology questions to demonstrate drug-drug interactions that lead to increased levels of drugs like statins or benzodiazepines. * **Erythromycin:** This macrolide antibiotic is a well-known enzyme **inhibitor**. [2] It can lead to dangerous elevations of drugs like theophylline or cisapride. (Note: Azithromycin is the only macrolide that does not significantly inhibit CYP enzymes). **3. NEET-PG High-Yield Pearls:** To remember these for the exam, use these popular mnemonics: * **Enzyme Inducers (GPRS Cell Phone):** **G**riseofulvin, **P**henytoin, **R**ifampicin, **S**moking, **C**arbamazepine, **P**henobarbitone. * **Enzyme Inhibitors (VITAMIN K):** **V**alproate, **I**soniazid, **T**imetidine (Cimetidine), **A**miodarone, **M**acrolides (except Azithromycin), **I**ndinavir, **N**etwork (Azoles/Ketoconazole), **K**rapefruit juice (Grapefruit). **Clinical Tip:** Rifampicin-induced enzyme induction can lead to **contraceptive failure** in women on OCPs; patients should be advised to use alternative barrier methods.

Q: Epinephrine added to a solution of lignocaine for a peripheral nerve block will:

Increase the duration of action of the local anesthetic. ### Explanation **1. Why Option B is Correct:** Lignocaine is a local anesthetic (LA) that causes vasodilation at the site of injection. When **Epinephrine (Adrenaline)** is added, it acts on **$\alpha_1$-adrenergic receptors** to cause potent **vasoconstriction**. This results in: * **Decreased systemic absorption:** The LA remains at the nerve site for a longer period. * **Increased duration of action:** Since the drug is not washed away by the bloodstream quickly, the block lasts longer. * **Reduced systemic toxicity:** Slower absorption leads to lower peak plasma levels of the LA. * **Decreased bleeding:** Vasoconstriction provides a bloodless field for minor procedures. **2. Why Other Options are Incorrect:** * **Option A:** Epinephrine actually **decreases** the risk of convulsions. Convulsions are a sign of systemic CNS toxicity (due to high plasma levels of LA). By slowing systemic absorption, epinephrine keeps plasma levels low, thereby reducing the risk of CNS and cardiac toxicity. * **Option C:** Incorrect because the risk of convulsions is decreased, not increased. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Standard Concentration:** Epinephrine is typically added to LAs in a concentration of **1:200,000**. * **Contraindications:** Never use LA with Epinephrine for blocks in **"end-artery" areas** (fingers, toes, nose, ear lobules, and penis) as it can cause ischemia and **gangrene**. * **Hypertension/Cardiac Disease:** Use with caution in patients with uncontrolled hypertension or ischemic heart disease due to potential systemic effects of adrenaline. * **Felypressin:** An alternative vasoconstrictor (vasopressin analogue) sometimes used in dental anesthesia when epinephrine is contraindicated.

Question 1

Teratogenicity results when drugs are given during which period of gestation?

Accepted Answer

First trimester

Answer

Second trimester

Answer

Third trimester

Answer

Soon after birth

Question 2

Pharmacovigilance means:

Accepted Answer

Monitoring of drug safety

Answer

Monitoring of unethical trade of drugs

Answer

Monitoring pharmaceutical students

Answer

Monitoring drug efficacy

Question 3

Which cell membrane receptors activate an ion channel upon binding with agonists?

Accepted Answer

Nicotinic cholinergic receptors

Answer

Muscarinic cholinergic receptors

Answer

Opioid receptors

Answer

All of the above

Question 4

Which of the following pairs represent physiological antagonists?

Accepted Answer

Glucagon and Insulin

Answer

Adrenaline and Isoprenaline

Answer

Isoprenaline and Propranolol

Answer

All of the above

Question 5

All of the following agents act by intracellular receptors EXCEPT:

Accepted Answer

Insulin

Answer

Thyroid hormones

Answer

Vitamin D

Answer

Steroids

Question 6

In which quadrant of the buttock are intramuscular injections typically administered?

Accepted Answer

Superolateral

Answer

Inferomedial

Answer

Superomedial

Answer

Superomedial

Question 7

What is true about inverse agonism?

Accepted Answer

It binds to the same receptor binding site as an agonist but exerts the opposite pharmacological effect.

Answer

Its action on the target receptors is similar to that of an agonist.

Answer

It is effective against receptors having intrinsic activity without acting of a ligand upon them.

Answer

None of the above.

Question 8

Which of the following drugs is an enzyme inducer?

Accepted Answer

Rifampicin

Answer

Isoniazid

Answer

Ketoconazole

Answer

Erythromycin

Question 9

A three-year-old child is brought to the emergency department having just ingested a large overdose of an antihistaminic drug. This drug is a weak base capable of entering most tissues, including the brain. On physical examination, the heart rate is 100/minute, blood pressure is 110/60 mm Hg, and the respiratory rate is 20/minute. In this case of poisoning, which of the following is true regarding the management?

Accepted Answer

Urinary excretion would be accelerated by administration of NH4Cl, an acidifying agent.

Answer

Urinary excretion would be accelerated by administration of NaHCO3, an alkalinizing agent.

Answer

More of the drug would be ionized at blood pH than at stomach pH.

Answer

Absorption of the drug would be faster from the stomach than from the small intestine.

Question 10

Epinephrine added to a solution of lignocaine for a peripheral nerve block will:

Accepted Answer

Increase the duration of action of the local anesthetic

Answer

Increase risk of convulsions

Answer

Both increase risk of convulsions and increase the duration of action of the local anesthetic

Answer

None of these

General Pharmacology — MCQs

General Pharmacology — MCQs

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