INI-CET 2022 - Pharmacology Practice Questions

Q: A man was brought to the emergency room after poisoning with an unknown substance. Muscarinic poisoning was suspected and he was treated for the same. What is the possible presenting feature which led to the diagnosis?

Bradycardia. ***Bradycardia*** - Muscarinic poisoning stimulates **parasympathetic nervous system** activity, leading to a decrease in heart rate. - This **bradycardia** is a classic sign of excessive muscarinic receptor activation, as seen with organophosphate or carbamate poisoning [1, 2].*Diuresis* - While muscarinic receptor activation can increase bladder detrusor contraction (leading to urinary urgency and frequency) [1, 2], **diuresis** (increased urine production) is not a primary or direct presenting feature of muscarinic poisoning. - Instead, the focus is on incontinence rather than simply increased urine output.*Mydriasis* - **Mydriasis** (pupil dilation) is associated with **anticholinergic poisoning**, which blocks muscarinic receptors. - Muscarinic poisoning, conversely, causes **miosis** (pupil constriction) due to excessive stimulation of muscarinic receptors in the iris sphincter muscle.*Muscle fasciculations* - **Muscle fasciculations** are a characteristic sign of **nicotinic receptor overstimulation**, not muscarinic [1, 3]. - While both nicotinic and muscarinic receptors are activated in organophosphate poisoning, fasciculations point to the **nicotinic effects** at the neuromuscular junction [1, 3].

Q: Match the following antiarrhythmic drugs with their mechanism of action: | Mechanism of action | Drug | | :-- | :-- | | 1. Na+ channel blocker | A. Quinidine | | 2. K+ channel blocker | B. Digoxin | | 3. Na+K+ ATPase inhibitor | C. Esmolol | | 4. Beta-blocker | D. Ibutilide |

1-A, 2-D, 3-B, 4-C. ***1-A, 2-D, 3-B, 4-C*** - **Quinidine** is a Class IA antiarrhythmic drug that primarily blocks **sodium channels**, prolonging the action potential duration and refractoriness. - **Ibutilide** is a Class III antiarrhythmic drug that blocks **potassium channels**, leading to delayed repolarization and increased effective refractory period. - **Digoxin** inhibits the **Na+/K+ ATPase pump**, increasing intracellular calcium and affecting AV nodal conduction. - **Esmolol** is a **beta-blocker** (Class II antiarrhythmic) that reduces heart rate and contractility by blocking β1-adrenergic receptors. *1-A, 2-C, 3-D, 4-B* - This option incorrectly matches **Esmolol** (a beta-blocker) with **K+ channel blocker** and **Ibutilide** (K+ channel blocker) with **Na+K+ ATPase inhibitor**. - It also incorrectly matches **Digoxin** (Na+K+ ATPase inhibitor) with **beta-blocker**. *1-D, 2-C, 3-A, 4-B* - This option incorrectly matches **Ibutilide** (K+ channel blocker) with **Na+ channel blocker** and incorrectly matches **Quinidine** (Na+ channel blocker) with **Na+K+ ATPase inhibitor**. - It also incorrectly matches **Digoxin** (Na+K+ ATPase inhibitor) with **beta-blocker**. *1-D, 2-B, 3-A, 4-C* - This option incorrectly matches **Ibutilide** (K+ channel blocker) with **Na+ channel blocker** and **Digoxin** (Na+K+ ATPase inhibitor) with **K+ channel blocker**. - It also incorrectly matches **Quinidine** (Na+ channel blocker) with **Na+K+ ATPase inhibitor**.

Q: Treatment of choice for acute arsenic poisoning is:

Dimercaprol. ***Dimercaprol*** - **Dimercaprol** (also known as British Anti-Lewisite, BAL) is a chelating agent used for **acute arsenic poisoning**. [1] - It works by binding to arsenic, forming a stable, non-toxic complex that can be excreted from the body. - Among the given options, **dimercaprol is the correct choice** for treating acute arsenic poisoning. - **Note:** While dimercaprol is effective, newer chelators like **DMSA (succimer)** and **DMPS (unithiol)** are now preferred in modern practice due to better safety profiles and efficacy, though they are not listed in the options. [1] *Ipecac* - **Ipecac syrup** induces vomiting and is generally **contraindicated** in poisonings with corrosives, hydrocarbons, or substances that can cause rapid central nervous system depression. - It is **not effective** for systemic poisonings like arsenic, where absorption has already occurred, and can cause complications like aspiration. - Ipecac is largely obsolete in modern toxicology practice. *Penicillamine* - **Penicillamine** is another chelating agent, primarily used for **copper poisoning** (e.g., Wilson's disease) and sometimes for lead poisoning. - While it has some chelating properties, it is **less effective** than dimercaprol for acute arsenic toxicity and can have more significant side effects. - It is **not the first-line treatment** for arsenic poisoning. *Activated charcoal* - **Activated charcoal** is effective for adsorbing many toxins in the gastrointestinal tract, preventing their absorption. - However, it has **poor affinity for heavy metals** like arsenic and is therefore **not recommended** as the primary treatment for arsenic poisoning. - It may have limited benefit only if given very early after ingestion, but chelation therapy is the definitive treatment.

Q: Which of these is not a cardiac poison?

Atropa belladonna. ***Atropa belladonna*** - This plant primarily contains **atropine** and other **belladonna alkaloids**, which are **anticholinergic** and cause symptoms like dry mouth, dilated pupils, tachycardia, and hallucinations. - While it can cause *tachycardia*, its primary toxic effects are not directly on the cardiac muscle contractility or rhythmicity leading to a **"cardiac poison"** classification (e.g. arrhythmias or heart failure), but rather through autonomic nervous system modulation. *Aconite* - Aconite, derived from the **monkshood plant**, contains **aconitine**, a potent neurotoxin and cardiotoxin. - It causes severe **arrhythmias**, including ventricular fibrillation, which can be rapidly fatal by directly affecting **sodium channels** in myocardial cells. *Cerbera thevetia* - Commonly known as Yellow Oleander, it contains **cardiac glycosides** similar to digoxin. - These glycosides inhibit the **Na+/K+-ATPase pump** in cardiac myocytes, leading to increased intracellular calcium, enhanced contractility, and dose-dependent **arrhythmias** (bradycardia, heart blocks, ventricular arrhythmias). *Nicotiana tabacum* - Tobacco contains **nicotine**, which primarily acts on **nicotinic acetylcholine receptors**. - Acute poisoning can lead to initial stimulation followed by depression of the autonomic ganglia, causing a range of cardiac effects including **tachycardia**, **hypertension**, and **arrhythmias** due to sympathetic nervous system activation.

Q: Match the following drugs with the targets of their actions: Drugs: A. Trastuzumab B. Infliximab C. Sirolimus D. Imatinib Targets: 1. BCR-ABL tyrosine kinase 2. mTOR 3. TNF alpha 4. HER2/neu

A-4, B-3, C-2, D-1. ***Correct Answer: A-4, B-3, C-2, D-1*** - **Trastuzumab** (Herceptin) is a **monoclonal antibody** that targets the **HER2/neu receptor (4)** [1], [2], commonly overexpressed in certain breast cancers and gastric cancers. - **Infliximab** is another **monoclonal antibody** that specifically targets and neutralizes **TNF-alpha (3)**, an inflammatory cytokine, making it useful in treating autoimmune diseases like rheumatoid arthritis and Crohn's disease. - **Sirolimus** is an **immunosuppressant** drug that inhibits the mammalian target of rapamycin (**mTOR (2)**), a protein kinase involved in cell growth and proliferation, used in transplant medicine and as an anticancer agent. - **Imatinib** is a **tyrosine kinase inhibitor** that primarily targets the **BCR-ABL fusion protein (1)** [1], [2], which is characteristic of chronic myeloid leukemia. *Incorrect: A-2, B-3, C-1, D-4* - This option incorrectly matches Trastuzumab with mTOR and Sirolimus with BCR-ABL, which are not their primary targets. - Trastuzumab targets HER2/neu [1], [2], and Sirolimus targets mTOR. *Incorrect: A-3, B-4, C-2, D-1* - This option incorrectly matches Trastuzumab with TNF-alpha and Infliximab with HER2/neu. - Infliximab targets TNF-alpha, and Trastuzumab targets HER2/neu [1], [2]. *Incorrect: A-4, B-3, C-1, D-2* - This option incorrectly matches Sirolimus with BCR-ABL and Imatinib with mTOR. - Sirolimus inhibits mTOR, and Imatinib inhibits BCR-ABL [1], [2].

Question 1

A man was brought to the emergency room after poisoning with an unknown substance.
Muscarinic poisoning was suspected and he was treated for the same. What is the possible presenting feature which led to the diagnosis?

Accepted Answer

Bradycardia

Answer

Diuresis

Answer

Mydriasis

Answer

Muscle fasciculations

Question 2

Which of the following statements is correct regarding the given graph?

Accepted Answer

Drug 1 represents agonist and drug 4 represents inverse agonist

Answer

Drug 1 represents agonist and drug 2 represents inverse agonist

Answer

Drug 3 represents agonist and drug 4 represents inverse agonist

Answer

Drug 2 represents partial agonist and drug 3 represents inverse agonist

Question 3

Match the following antiarrhythmic drugs with their mechanism of action:

Accepted Answer

1-A, 2-D, 3-B, 4-C

Answer

1-D, 2-B, 3-A, 4-C

Answer

1-A, 2-C, 3-D, 4-B

Answer

1-D, 2-C, 3-A, 4-B

Question 4

Treatment of choice for acute arsenic poisoning is:

Accepted Answer

Dimercaprol

Answer

Ipecac

Answer

Penicillamine

Answer

Activated charcoal

Question 5

Which of these is not a cardiac poison?

Accepted Answer

Atropa belladonna

Answer

Aconite

Answer

Cerbera thevetia

Answer

Nicotiana tabacum

Question 6

A child presents with complaints of fever, rash, body ache, and throat ache. He had a history of thorn prick injury a week back. What antibiotics would you give empirically to this child?

Accepted Answer

Amoxicillin+ clavulanate

Answer

Ceftriaxone

Answer

Vancomycin

Answer

Meropenem

Question 7

Match the following drugs with the targets of their actions:

Drugs:
A. Trastuzumab
B. Infliximab  
C. Sirolimus
D. Imatinib

Targets:
1. BCR-ABL tyrosine kinase
2. mTOR
3. TNF alpha
4. HER2/neu

Accepted Answer

A-4, B-3, C-2, D-1

Answer

A-2, B-3, C-1, D-4

Answer

A-3, B-4, C-2, D-1

Answer

A-4, B-3, C-1, D-2

INI-CET 2022 — Pharmacology