Clinical Pharmacology and Drug Toxicity Practice Questions

Q: Permission from DCGI [Drug controller general, India] is needed before which phase of drug trial?

Phase 3. ***Phase 3*** - Permission from the **DCGI (Drug Controller General of India)** is mandatory before initiating **Phase 3** clinical trials as per **Schedule Y** of the Drugs and Cosmetics Rules. - Phase 3 trials involve **large-scale studies in Indian patients** to establish efficacy and safety in the target population, requiring explicit regulatory approval. - This is the critical regulatory checkpoint where DCGI evaluates the Phase 1 and 2 data before allowing widespread testing in Indian subjects. *Phase 1* - Phase 1 trials can be conducted after approval from the **Institutional Ethics Committee (IEC)** without requiring prior DCGI permission. - These trials in healthy volunteers focus on safety, pharmacokinetics, and dose-ranging studies. - DCGI is informed but explicit permission is not mandatory at this stage. *Phase 2* - Phase 2 trials also proceed with **IEC approval** and do not require prior DCGI permission. - These trials evaluate therapeutic efficacy and dose determination in a limited number of patients. - Results from Phase 2 are submitted to DCGI when seeking Phase 3 approval. *Phase 4* - Phase 4 trials are **post-marketing surveillance** studies conducted after drug approval. - These are conducted under the Post-Marketing Surveillance (PMS) framework. - While regulatory oversight exists, these are not pre-market trials requiring permission to initiate.

Q: Interstitial nephritis is associated with all of the following medications except:

INH. ***INH*** - **Isoniazid (INH)** is primarily associated with **hepatotoxicity** (liver damage) and **peripheral neuropathy**, not typically interstitial nephritis. - While many drugs can rarely cause various adverse effects, INH is not a recognized common cause of **drug-induced interstitial nephritis**. *Beta-lactam antibiotics* - **Beta-lactam antibiotics**, including penicillins and cephalosporins, are among the most common causes of **drug-induced acute interstitial nephritis (AIN)**. - AIN is an **allergic hypersensitivity reaction** characterized by inflammation of the kidney's tubules and interstitium. *Diuretics* - Certain **diuretics**, particularly **thiazide diuretics** and **loop diuretics**, have been implicated in causing **acute interstitial nephritis**. - The mechanism is thought to be an **allergic or hypersensitivity reaction** within the renal tubules and interstitium. *Allopurinol* - **Allopurinol**, used to treat gout and hyperuricemia, is a known cause of **drug-induced acute interstitial nephritis**. - Renal involvement with allopurinol can range from mild tubular dysfunction to severe **acute kidney injury** due to AIN.

Q: Which drug is most commonly associated with causing exanthema?

Sulfonamide. ***Sulfonamide*** - **Sulfonamides** are among the **most common causes** of drug-induced exanthema (maculopapular/morbilliform rash). - They account for a significant proportion of cutaneous adverse drug reactions, with exanthema being the most frequent presentation. - The mechanism typically involves a **delayed hypersensitivity reaction** (Type IV) to the drug or its metabolites. - **Classic presentation:** Symmetrical, erythematous, maculopapular rash appearing 7-14 days after drug initiation. *Phenytoin* - **Phenytoin** can cause exanthematous eruptions, but it is more notably associated with **severe cutaneous adverse reactions** such as: - **DRESS syndrome** (Drug Reaction with Eosinophilia and Systemic Symptoms) - **Stevens-Johnson syndrome (SJS)** and **Toxic Epidermal Necrolysis (TEN)** - While exanthema can occur, **sulfonamides** are more frequently implicated in simple morbilliform rashes. *Atropine* - **Atropine** is an anticholinergic agent primarily causing **predictable pharmacological effects**: - Dry mouth, mydriasis, tachycardia, urinary retention - **Allergic skin reactions** with atropine are rare and not a characteristic adverse effect. - Atropine is **not recognized** as a common cause of exanthema. *All of the options* - This is incorrect because **atropine** is not commonly associated with exanthema. - While both sulfonamides and phenytoin can cause exanthema, only **sulfonamides** are considered among the **most common** causes.

Q: Which of the following antiglaucoma medications can cause drowsiness?

Brimonidine. ***Brimonidine*** - **Brimonidine** is an **alpha-2 adrenergic agonist** [1] that can cause central nervous system depression, leading to side effects such as **drowsiness** and fatigue. - This systemic side effect is more common with the topical ophthalmic formulation due to systemic absorption. *Latanoprost* - **Latanoprost** is a **prostaglandin analog** that primarily works by increasing uveoscleral outflow, and its side effects are mainly localized to the eye (e.g., iris color change, eyelash growth). - It does not typically cause systemic side effects like drowsiness because its systemic absorption is minimal. *Dorzolamide* - **Dorzolamide** is a **topical carbonic anhydrase inhibitor** [1] that reduces aqueous humor production, and its most common side effects include local ocular irritation and a bitter taste. - While systemic carbonic anhydrase inhibitors can cause fatigue and drowsiness, the topical formulation has very limited systemic absorption, making drowsiness uncommon. *Timolol* - **Timolol** is a **non-selective beta-blocker** [1] that reduces aqueous humor production and can cause systemic side effects such as bradycardia, bronchospasm, and hypotension. - While some beta-blockers can cause fatigue, **drowsiness** as a prominent side effect is less common compared to alpha-2 agonists.

Q: Which of the following drugs has not been withdrawn from the Indian market for safety reasons?

Cotrimoxazole. ### Cotrimoxazole - Cotrimoxazole, a combination of **trimethoprim and sulfamethoxazole**, remains a widely used and available antibiotic in India [1], [2]. - It treats various bacterial infections, including **urinary tract infections** and respiratory infections, and has not been withdrawn for safety reasons [1]. ### Gatifloxacin - **Gatifloxacin** was withdrawn from the Indian market due to concerns about **severe glycemic disturbances**, including both hypo- and hyperglycemia. - These side effects posed significant risks, especially in patients with diabetes or those predisposed to blood sugar fluctuations. ### Rofecoxib - **Rofecoxib**, an NSAID, was withdrawn globally, including from India, due to an increased risk of **cardiovascular events** such as heart attack and stroke. - Its selective inhibition of COX-2 was found to disturb the balance of prostaglandins, leading to adverse cardiovascular outcomes. ### Phenformin - **Phenformin**, an oral antidiabetic drug, was withdrawn from the Indian market due to its association with a high incidence of **lactic acidosis**, a severe and often fatal metabolic complication. - This serious side effect made its risk-benefit profile unacceptable for continued use.

Q: Which of the following is not commonly recognized as a hepatotoxic drug?

Streptomycin. ***Streptomycin*** - Streptomycin is primarily associated with **ototoxicity** (vestibular and cochlear damage) and **nephrotoxicity** (kidney damage), not significant hepatotoxicity. - While most drugs can theoretically cause liver injury, streptomycin is not frequently cited as a major hepatotoxin in clinical practice. *Chlorpropamide* - This **sulfonylurea oral hypoglycemic agent** can cause a range of liver injuries, from asymptomatic enzyme elevations to severe **cholestatic hepatitis** or hepatocellular damage. - Its hepatotoxic potential is well-documented, leading to its decreased use compared to newer antidiabetic agents. *Allopurinol* - Allopurinol, used to treat **gout** and hyperuricemia, is known to cause a variety of adverse effects, including **hypersensitivity reactions** that can involve the liver. - It can lead to **hepatocellular injury**, cholestasis, or mixed liver damage, sometimes as part of a severe drug reaction with eosinophilia and systemic symptoms (**DRESS syndrome**). *Halothane* - Halothane is a potent **halogenated inhalational anesthetic** historically associated with a rare but severe form of idiosyncratic liver injury known as **halothane hepatitis**. - This condition involves **massive hepatic necrosis** and has a high mortality rate, leading to its eventual replacement by newer anesthetics.

Q: Which one of the following agents has been associated with hemorrhagic stroke?

Phenylpropanolamine. ***Phenylpropanolamine*** - **Phenylpropanolamine (PPA)** is a sympathomimetic agent that was formerly used as a nasal decongestant and anorectic. - Its use has been linked to an increased risk of **hemorrhagic stroke**, particularly in young women, due to its **vasoconstrictive effects** and potential to cause a sudden, severe rise in blood pressure. *Terfenadine* - **Terfenadine** is a second-generation antihistamine that was voluntarily withdrawn from the market due to its association with severe **cardiac arrhythmias (QT prolongation and Torsades de Pointes)**, not hemorrhagic stroke. - It works by blocking H1 histamine receptors but also had effects on cardiac potassium channels. *Quinidine* - **Quinidine** is an antiarrhythmic drug (Class Ia) primarily used to treat supraventricular and ventricular arrhythmias. - Its main side effects include **gastrointestinal disturbances**, **cinchonism**, and the risk of **QT prolongation** leading to Torsades de Pointes; it is not typically associated with hemorrhagic stroke. *Fenfluramine* - **Fenfluramine** was an anorectic drug used in the treatment of obesity, often in combination with phentermine. - It was withdrawn from the market due to its association with **pulmonary hypertension** and **cardiac valvulopathy**, not hemorrhagic stroke.

Q: Which of the following antiretroviral drugs is not associated with peripheral neuropathy?

Indinavir. ***Indinavir*** - **Indinavir** is a **protease inhibitor** that can cause side effects such as **nephrolithiasis** (kidney stones) and **hyperbilirubinemia**, but it is generally *not associated with peripheral neuropathy*. - It works by blocking the viral protease enzyme, preventing the cleavage of viral polyproteins into functional proteins, which disrupts viral replication. *Stavudine* - **Stavudine** is a **nucleoside reverse transcriptase inhibitor (NRTI)** notorious for causing dose-dependent **peripheral neuropathy**. - This toxicity is due to its interference with **mitochondrial DNA synthesis**, leading to nerve damage. *Zalcitabine* - **Zalcitabine** (ddC) is another **NRTI** strongly associated with a high incidence of **peripheral neuropathy**. - Its mechanism of action and side effect profile are similar to those of stavudine in causing **mitochondrial toxicity**. *Didanosine* - **Didanosine** (ddI) is an **NRTI** known to cause several adverse effects, including **peripheral neuropathy**, particularly at higher doses. - Like other dideoxynucleoside analogs, its toxicity is linked to **mitochondrial dysfunction**.

Q: Which drug is recommended for a truck driver suffering from allergic rhinitis?

Cetirizine. The drug recommended for a truck driver is a second-generation antihistamine like Cetirizine. ***Cetirizine*** - This is a **second-generation antihistamine** that is less sedating compared to first-generation options [2]. - Its **lower risk of drowsiness** makes it suitable for individuals who need to remain alert, such as truck drivers [2]. *Promethazine* - This is a **first-generation antihistamine** known for its significant sedative effects due to its ability to cross the blood-brain barrier [1], [2]. - It would be **unsafe for a truck driver** as it impairs alertness and reaction time [2]. *Buclizine* - This is also a **first-generation antihistamine** with notable sedative properties [1]. - Its use would pose a **driving hazard** due to the likelihood of drowsiness [2]. *Hydroxyzine* - A potent **first-generation antihistamine** with strong sedative and anticholinergic effects [1]. - It is **contraindicated for individuals performing tasks requiring mental alertness**, like driving a truck [2].

Question 1

Permission from DCGI [Drug controller general, India] is needed before which phase of drug trial?

Accepted Answer

Phase 3

Answer

Phase 1

Answer

Phase 2

Answer

Phase 4

Question 2

Interstitial nephritis is associated with all of the following medications except:

Accepted Answer

INH

Answer

Diuretics

Answer

Allopurinol

Answer

Beta-lactam antibiotics

Question 3

Which drug is most commonly associated with causing exanthema?

Accepted Answer

Sulfonamide

Answer

Atropine

Answer

Phenytoin

Answer

All of the options

Question 4

Which of the following antiglaucoma medications can cause drowsiness?

Accepted Answer

Brimonidine

Answer

Latanoprost

Answer

Dorzolamide

Answer

Timolol

Question 5

Which of the following drugs has not been withdrawn from the Indian market for safety reasons?

Accepted Answer

Cotrimoxazole

Answer

Gatifloxacin

Answer

Phenformin

Answer

Rofecoxib

Question 6

Which of the following is not commonly recognized as a hepatotoxic drug?

Accepted Answer

Streptomycin

Answer

Chlorpropamide

Answer

Allopurinol

Answer

Halothane

Question 7

What are the primary mechanisms behind cardiac toxicity associated with Tricyclic antidepressants?

Accepted Answer

Both norepinephrine reuptake inhibition and anticholinergic effects on the heart

Answer

Norepinephrine reuptake inhibition only

Answer

Anticholinergic effects on the heart

Answer

Direct membrane stabilizing effects only

Question 8

Which one of the following agents has been associated with hemorrhagic stroke?

Accepted Answer

Phenylpropanolamine

Answer

Terfenadine

Answer

Quinidine

Answer

Fenfluramine

Question 9

Which of the following antiretroviral drugs is not associated with peripheral neuropathy?

Accepted Answer

Indinavir

Answer

Stavudine

Answer

Zalcitabine

Answer

Didanosine

Question 10

Which drug is recommended for a truck driver suffering from allergic rhinitis?

Accepted Answer

Cetirizine

Answer

Promethazine

Answer

Buclizine

Answer

Hydroxyzine

Clinical Pharmacology and Drug Toxicity — MCQs

Clinical Pharmacology and Drug Toxicity — MCQs

On this page

Practice by Chapter

Want unlimited practice?