Clinical Pharmacology and Drug Toxicity — MCQs

Clinical Pharmacology and Drug Toxicity Indian Medical PG Practice Questions and MCQs

Question 711: Pink's disease is due to

A. Toxicity of Mercury (Correct Answer)
B. Toxicity of Tetracycline
C. Toxicity of Lead
D. Toxicity of Silver

Explanation: ***Toxicity of Mercury*** - **Pink's disease**, also known as **acrodynia** or **Sweating Sickness**, is caused by chronic exposure to **mercury toxicity**, often from environmental sources or certain medications in children. - Key symptoms include **pinkish discoloration of the hands and feet**, **profuse sweating**, irritability, photophobia, and hypertension. *Toxicity of Tetracycline* - **Tetracycline toxicity** is primarily associated with issues such as **tooth discoloration** (yellow-brown staining) in developing teeth and photosensitivity. - It does not cause the characteristic rash or autonomic symptoms seen in Pink's disease. *Toxicity of Lead* - **Lead toxicity** (plumbism) manifests with symptoms like **abdominal pain**, anemia, neurological deficits (e.g., foot drop), and developmental delays in children. - While serious, these symptoms are distinct from the acrodynia presentation. *Toxicity of silver* - **Silver toxicity**, particularly from chronic exposure, leads to **argyria**, a condition characterized by **blue-gray discoloration of the skin, eyes, and mucous membranes**. - This is a cosmetic rather than systemic metabolic issue like acrodynia, and its symptoms differ significantly.

Question 712: Which of the following drugs can produce dramatic improvement in patients with type 2 lepra reaction?

A. Steroids
B. Dapsone
C. Clofazimine
D. Thalidomide (Correct Answer)

Explanation: **Thalidomide** - **Thalidomide** is highly effective in managing **type 2 lepra reactions (erythema nodosum leprosum)**, leading to rapid resolution of symptoms. - Its anti-inflammatory and immunomodulatory properties directly address the inflammatory cascade characteristic of this reaction. *Steroids* - While **steroids** are effective in treating **type 1 lepra reactions** and severe type 2 reactions, they do not produce the same dramatic, rapid improvement seen with thalidomide in typical type 2 reactions. - Long-term steroid use carries significant side effects, making them less ideal for primary management of type 2 reactions when thalidomide is available. *Dapsone* - **Dapsone** is a crucial component of **multi-drug therapy (MDT)** for leprosy itself, but it does not treat reactions. - It has no significant anti-inflammatory effect on the acute immune-mediated processes of lepra reactions. *Clofazimine* - **Clofazimine** is an anti-inflammatory drug used in lepromatous leprosy treatment and sometimes as an alternative for steroid-resistant type 2 reactions. - However, its effect is generally slower and less dramatic compared to thalidomide in the acute management of typical type 2 lepra reactions.

Question 713: Nephrotoxic agent is:

A. N2O
B. Halothane
C. Methoxyflurane (Correct Answer)
D. Isoflurane

Explanation: ***Methoxyflurane*** - Methoxyflurane undergoes significant **metabolism** in the liver, releasing **fluoride ions** and dichloroacetic acid. - The fluoride ions can cause **dose-dependent high-output renal failure** by interfering with the kidney's concentrating ability, leading to nephrotoxicity. *N2O (Nitrous Oxide)* - While widely used, N2O is known for its ability to **oxidize vitamin B12**, which can impair methionine synthase activity. - It does not directly cause nephrotoxicity but is associated with **bone marrow suppression** with prolonged or repeated exposure. *Halothane* - Halothane is a potent **hepatotoxin**, primarily linked to **halothane-induced hepatitis**, ranging from mild liver enzyme elevation to fulminant hepatic failure. - It is not primarily associated with nephrotoxicity; its main organ toxicity concern is the **liver**. *Isoflurane* - Isoflurane is largely **excreted unchanged** by the lungs, with minimal metabolism. - Due to its low metabolism and minimal production of inorganic fluoride, it has a **low risk of nephrotoxicity**.

Question 714: All of the following are adverse effects of thalidomide except:

A. Constipation
B. Myocarditis (Correct Answer)
C. Peripheral neuropathy
D. Sedation

Explanation: ***Myocarditis*** - **Myocarditis** is not an established adverse effect of thalidomide in standard pharmacology references. - While thalidomide can cause cardiovascular effects such as **bradycardia** and **thromboembolic events**, direct myocardial inflammation is not a recognized complication. - This is the correct answer as it is NOT an adverse effect of thalidomide. *Constipation* - **Constipation** is a very common gastrointestinal side effect of thalidomide due to its **anticholinergic-like effects**. - Patients often require proactive management with laxatives to mitigate this side effect. *Peripheral neuropathy* - **Peripheral neuropathy** is the most significant and dose-limiting adverse effect of thalidomide, often presenting as **sensory deficits** in a stocking-glove distribution. - It can be **irreversible** and may necessitate discontinuation of the drug. - This is a major concern requiring regular monitoring during treatment. *Sedation* - **Sedation** and **drowsiness** are common adverse effects of thalidomide due to its **central nervous system depressant properties**. - This effect often leads to administration before bedtime to minimize impact on daily activities.

Question 715: Adverse reactions following whole-cell pertussis immunization include:

A. Fever
B. Anaphylaxis
C. Local swelling
D. All of the options (Correct Answer)

Explanation: ***All of the options*** are well-documented adverse reactions following whole-cell pertussis immunization. *Fever* - **Fever** is a common systemic adverse reaction following whole-cell pertussis immunization, occurring in **10-50%** of recipients - It usually presents within the first **24-48 hours** after vaccination due to the immunostimulatory components of the vaccine - Generally mild and self-limiting, resolving within 1-2 days *Anaphylaxis* - **Anaphylaxis** is a rare but severe allergic reaction that can occur after whole-cell pertussis vaccination (approximately **1 in 1,000,000** doses) - It is an **IgE-mediated type I hypersensitivity reaction** requiring immediate medical intervention with intramuscular epinephrine - Usually occurs within **minutes to hours** after vaccination *Local swelling* - **Local swelling** at the injection site is a very common adverse reaction, occurring in **>50%** of recipients - This reaction is typically mild, localized to the injection site, and represents a normal inflammatory response - Usually resolves spontaneously within **2-3 days** without specific treatment

Question 716: The Drug of choice for a pregnant woman in 2nd trimester with pustular psoriasis is:

A. Prednisolone (Correct Answer)
B. Acitretin
C. Methotrexate
D. Dapsone

Explanation: ***Prednisolone*** - **Systemic corticosteroids** such as prednisolone are considered **safe and effective** for treating severe pustular psoriasis during pregnancy and represent the **best option among the choices provided**. - Pustular psoriasis is a severe systemic condition that can be associated with fever, malaise, and potential complications, necessitating **systemic therapy** rather than topical treatment alone. - While **cyclosporine** is often considered the preferred first-line agent for severe pustular psoriasis in pregnancy in current practice, it is not listed among the options here, making prednisolone the most appropriate choice. - Prednisolone **crosses the placenta minimally** (converted to less active prednisolone by placental 11β-HSD2 enzyme) and has a well-established safety profile in pregnancy. *Acitretin* - **Acitretin** is a systemic **retinoid** that is **highly teratogenic** and can cause severe birth defects including craniofacial, cardiac, thymic, and CNS abnormalities. - It is **absolutely contraindicated in pregnancy** (FDA Category X) and must be avoided for at least 2-3 years before conception due to its long half-life and storage in adipose tissue. *Methotrexate* - **Methotrexate** is an **antimetabolite** and **folate antagonist** that is a potent teratogen, particularly during the first trimester. - It can cause **aminopterin syndrome** (neural tube defects, craniofacial abnormalities, limb defects) and is **absolutely contraindicated in pregnancy** (FDA Category X). - Women on methotrexate must use effective contraception and discontinue the drug at least 3 months before attempting conception. *Dapsone* - **Dapsone** has anti-inflammatory properties and is used in some dermatological conditions, but it is **not indicated for pustular psoriasis**. - Risks in pregnancy include **hemolytic anemia** (particularly in G6PD-deficient individuals), methemoglobinemia in the newborn, and potential neonatal hyperbilirubinemia. - It is **not a first-line or appropriate treatment** for pustular psoriasis in pregnancy.

Question 717: Drug Induced Lupus is caused by all except

A. Hydralazine
B. Sulphonamides
C. Isoniazid
D. Procaine (Correct Answer)

Explanation: ***Procaine*** - While **procainamide**, a derivative of procaine, is a known cause of **drug-induced lupus (DIL)**, **procaine** itself is not typically implicated. - Procaine is a **local anesthetic** and its mechanism of action does not commonly lead to the immunological reactions seen in DIL. *Hydralazine* - **Hydralazine** is a well-established cause of **drug-induced lupus (DIL)**, particularly with higher doses and prolonged use. - It frequently results in the development of **anti-histone antibodies**, a hallmark of DIL. *Sulphonamides* - Various **sulphonamide antibiotics** (e.g., sulfasalazine, sulfamethoxazole) are known to induce **lupus-like syndromes**. - These drugs can trigger immune responses leading to symptoms characteristic of **systemic lupus erythematosus (SLE)**. *Isoniazid* - **Isoniazid**, an anti-tuberculosis medication, is a recognized cause of **drug-induced lupus (DIL)**. - It often leads to the formation of **anti-histone antibodies** and clinical manifestations resembling spontaneous lupus.

Question 718: All of the following drugs cause amorphous whorl like corneal deposits except:

A. Chlorpromazine
B. Amiodarone
C. Chloroquine
D. Indomethacin (Correct Answer)

Explanation: ***Indomethacin*** - While indomethacin can cause various ocular side effects, **corneal deposits** are not typically described as the **amorphous whorl-like type** seen with the other listed drugs. - Ocular side effects of indomethacin more commonly include **corneal opacities** and **retinal changes** but not the specific **"cornea verticillata"** pattern. *Chlorpromazine* - **Chlorpromazine** can cause **corneal and lenticular deposits**, but these are typically described as **fine granular or stellate deposits** rather than the classic whorl pattern. - While these deposits can accumulate in the corneal epithelium, they do not characteristically present with the **"cornea verticillata"** (whorl keratopathy) pattern seen with amiodarone and chloroquine. - The deposits are generally benign but can lead to visual disturbances. *Amiodarone* - **Amiodarone** is a classic cause of **cornea verticillata**, or **whorl keratopathy**, with amorphous, whorl-like deposits in the corneal epithelium. - These deposits occur in **>90% of patients** on long-term therapy and are typically benign and rarely affect vision. - The whorl pattern is highly characteristic and reversible upon drug discontinuation. *Chloroquine* - **Chloroquine** (and hydroxychloroquine) commonly causes **corneal deposits** known as **cornea verticillata**, which appear as gray-brown, whorl-like opacities in the corneal epithelium. - While these deposits are usually asymptomatic, high doses or prolonged use can lead to visual blurring or halos. - The whorl pattern is a characteristic finding with this class of drugs.

Question 719: Thalidomide is useful in:

A. Treatment of type II lepra reaction (Correct Answer)
B. Treatment of leprosy
C. Treatment of type I lepra reaction
D. Treatment of neuritic leprosy

Explanation: ***Treatment of type II lepra reaction*** - **Thalidomide** is highly effective in managing the severe inflammatory response seen in **Type II lepra reaction** (erythema nodosum leprosum, ENL). - Its efficacy in ENL is primarily due to its **anti-inflammatory** and **immunomodulatory** properties, inhibiting TNF-α. *Treatment of leprosy* - **Thalidomide** is not a primary antibacterial drug and thus does not directly treat the underlying **Mycobacterium leprae infection**. - Its role is limited to modulating the immune response during a reaction, not eradicating the bacteria. *Treatment of type I lepra reaction* - **Type I lepra reaction** (reversal reaction) is typically managed with **corticosteroids**, not thalidomide. - Type I reactions involve a delayed-type hypersensitivity response, distinct from the immune complex-mediated Type II reaction. *Treatment of neuritic leprosy* - **Neuritic leprosy** refers to nerve damage caused by the infection itself, or during both types of reactions, and its treatment focuses on preventing further damage with **multidrug therapy** and corticosteroids. - While thalidomide can reduce inflammation in Type II reactions that might contribute to nerve damage, it's not a direct treatment for the established nerve damage itself.

Question 720: Not true about thalidomide:

A. Causes phocomelia
B. Still has restricted clinical use
C. Not tested in pregnant animals before introduction
D. Has no antiangiogenesis action against tumour (Correct Answer)

Explanation: ***Has no antiangiogenesis action against tumour*** - Thalidomide is known to possess **anti-angiogenic properties**, meaning it inhibits the formation of new blood vessels, which is crucial for tumour growth. This makes the statement "has no antiangiogenesis action against tumour" incorrect. - Its anti-angiogenic effects are one of the mechanisms proposed for its use in certain cancers, such as **multiple myeloma**. *Causes phocomelia* - **Phocomelia**, a severe birth defect characterized by malformed or absent limbs, is the most infamous **teratogenic effect** of thalidomide. - This adverse effect led to its withdrawal from the market in the early 1960s. *Still has restricted clinical use* - Despite its teratogenic risks, thalidomide has been reintroduced with strict regulations due to its unique immunomodulatory and anti-inflammatory properties. - It is currently used in the treatment of conditions like **multiple myeloma**, **erythema nodosum leprosum**, and certain autoimmune diseases. *Not tested in pregnant animals before introduction* - A significant reason for the thalidomide tragedy was the **lack of robust teratogenicity testing** in pregnant animals before its widespread introduction to the market. - If such testing had been adequately conducted, its severe teratogenic effects might have been identified earlier, preventing widespread harm.

Practice by Chapter

Principles of Clinical Pharmacology

Practice Questions

Therapeutic Drug Monitoring

Practice Questions

Drug Toxicity and Overdose

Practice Questions

Antidotes and Their Applications

Practice Questions

Management of Drug Poisoning

Practice Questions

Drug-Induced Liver Injury

Practice Questions

Drug-Induced Kidney Injury

Practice Questions

Drug-Induced Blood Dyscrasias

Practice Questions

Drug-Induced QT Prolongation

Practice Questions

Pharmacovigilance

Practice Questions

Want unlimited practice?

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

Start For Free