Clinical Pharmacology and Drug Toxicity — MCQs
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Anion-gap metabolic acidosis with decreased vision occurs with the following poisoning.
A patient with cancer received an extreme degree of radiation toxicity. Further history revealed that the dose adjustment of a particular drug was missed during the course of radiotherapy. Which of the following drugs required a dose adjustment in that patient during radiotherapy to prevent radiation toxicity?
Vi polysaccharide vaccine is a parenteral typhoid vaccine consisting of purified Vi polysaccharide from the Salmonella typhi bacterial capsule. Which of the following is a TRUE statement regarding Vi polysaccharide vaccine?
Claviceps purpurea produces which of the following toxins?
Which of the following is not an adverse effect of chronic amiodarone therapy?
Which of the following drugs can cause drug-induced systemic lupus erythematosus?
Pralidoxime is not useful in poisoning with which of the following?
Which of the following drugs is not associated with hepatotoxicity?
Which of the following DPP-IV inhibitors is safe for use in chronic kidney disease patients without requiring dose modification?
What is the role of marijuana in managing AIDS-related cachexia?
Clinical Pharmacology and Drug Toxicity Indian Medical PG Practice Questions and MCQs
Question 1041: Anion-gap metabolic acidosis with decreased vision occurs with the following poisoning.
- A. Cadmium
- B. Mercury
- C. Ethanol
- D. Methanol (Correct Answer)
Explanation: ***Methanol*** - **Methanol poisoning** leads to the formation of **formic acid**, which causes **anion-gap metabolic acidosis** and direct toxicity to the optic nerve, resulting in **decreased vision** and potential **blindness**. - The delayed onset of symptoms (12-24 hours) is due to the time required for methanol to be metabolized into its toxic byproducts. *Cadmium* - **Cadmium poisoning** primarily affects the **kidneys** (proximal tubular dysfunction), **lungs**, and **bones**, leading to conditions like osteomalacia and emphysema. - It does not typically cause **anion-gap metabolic acidosis** or acute visual disturbances. *Mercury* - **Mercury poisoning**, whether elemental, inorganic, or organic, primarily affects the **nervous system** (tremors, ataxia, cognitive impairment) and kidneys. - While it can cause neurological deficits, **decreased vision** and **anion-gap metabolic acidosis** are not characteristic features. *Ethanol* - **Ethanol** (drinking alcohol) poisoning can cause **respiratory depression**, **hypoglycemia**, and **metabolic acidosis** (often ketosis or lactic acidosis at very high levels), but it typically results in a **normal anion gap** unless there are co-ingestions or severe complications. - It does not directly cause **decreased vision** via toxic metabolites like methanol does.
Question 1042: A patient with cancer received an extreme degree of radiation toxicity. Further history revealed that the dose adjustment of a particular drug was missed during the course of radiotherapy. Which of the following drugs required a dose adjustment in that patient during radiotherapy to prevent radiation toxicity?
- A. Dactinomycin (Correct Answer)
- B. Vincristine
- C. Cyclophosphamide
- D. 6-Mercaptopurine
Explanation: ***Dactinomycin*** - **Dactinomycin (Actinomycin D)** is known to potentiate radiation effects, meaning it can significantly increase the tissue damage from radiation. - When given concurrently with radiation or prior to radiation, its dose must be carefully adjusted or avoided to prevent severe radiation toxicity, including **radiation recall** phenomena. *Vincristine* - **Vincristine** is a vinca alkaloid primarily used for its antimitotic activity, interfering with microtubule formation. - While it has its own significant toxicities (e.g., neurotoxicity), it is not typically associated with directly potentiating radiation toxicity to the same extent as dactinomycin, nor does it commonly require dose adjustment due to radiation interaction to prevent severe toxicity of this nature. *Cyclophosphamide* - **Cyclophosphamide** is an alkylating agent often used in chemotherapy and immunosuppression. - Although it has various toxicities (e.g., hemorrhagic cystitis, myelosuppression), it is not specifically known for significantly enhancing radiation toxicity in a manner that necessitates routine dose adjustment during concurrent radiotherapy to prevent extreme local radiation effects. *6-Mercaptopurine* - **6-Mercaptopurine** is an antimetabolite primarily used in acute lymphoblastic leukemia. - It interferes with nucleic acid synthesis but is not typically highlighted as a drug that critically requires dose adjustment during radiotherapy to avoid extreme radiation potentiation or recall reactions.
Question 1043: Vi polysaccharide vaccine is a parenteral typhoid vaccine consisting of purified Vi polysaccharide from the Salmonella typhi bacterial capsule. Which of the following is a TRUE statement regarding Vi polysaccharide vaccine?
- A. Has a high incidence of local reactions
- B. Has significant adverse effects
- C. Can be given along with yellow fever and hepatitis vaccines (Correct Answer)
- D. Contraindicated in hepatitis
Explanation: ***Can be given along with yellow fever and hepatitis vaccines***- The **Vi polysaccharide vaccine** has a good safety profile, allowing co-administration with other vaccines like **yellow fever** and **hepatitis A/B** without compromising efficacy or safety.- This co-administration is often practical for travelers requiring multiple vaccinations, simplifying the immunization schedule.*Has a high incidence of local reactions*- The Vi polysaccharide vaccine generally has a **low incidence of local reactions**, primarily mild pain or redness at the injection site, which are typically transient.- It does not cause severe or frequent local reactions that would be considered "high incidence."*Has significant adverse effects*- This vaccine is known for its **minimal systemic adverse effects**, which are usually mild and self-limiting, such as low-grade fever or headache.- Serious adverse events are extremely rare, making it a safe option for typhoid prevention.*Contraindicated in hepatitis*- There is **no contraindication** for the Vi polysaccharide vaccine in individuals with **hepatitis** (acute or chronic).- Its safety profile allows for administration in patients with liver conditions, as the vaccine itself is not hepatotoxic or known to exacerbate liver disease.
Question 1044: Claviceps purpurea produces which of the following toxins?
- A. Ergot alkaloids (Correct Answer)
- B. Aflatoxins
- C. Sanguinarine alkaloid
- D. Pyrazolidone drug
Explanation: ***Ergot alkaloids*** - **Claviceps purpurea** is a fungus that infects cereals, particularly rye, and produces a group of toxic compounds known as **ergot alkaloids**. - These alkaloids can cause a condition called **ergotism**, which includes symptoms like hallucinations, gangrene, and severe vasoconstriction. *Aflatoxins* - **Aflatoxins** are produced by species of **Aspergillus fungi**, such as *A. flavus* and *A. parasiticus*, not *Claviceps purpurea*. - They are potent **carcinogens** and are commonly found in contaminated crops like peanuts and maize. *Sanguinarine alkaloid* - **Sanguinarine** is an alkaloid derived from plants like **bloodroot (Sanguinaria canadensis)**, not *Claviceps purpurea*. - It has been linked to **glaucoma** and liver toxicity. *Pyrazolidone drug* - **Pyrazolidone** is a classification of synthetic drugs, often used as **non-steroidal anti-inflammatory drugs (NSAIDs)**, such as phenylbutazone. - This is a pharmaceutical compound and not naturally derived from *Claviceps purpurea* or any fungus.
Question 1045: Which of the following is not an adverse effect of chronic amiodarone therapy?
- A. Hypothyroidism
- B. Pulmonary Fibrosis
- C. Systemic lupus erythematosus (Correct Answer)
- D. Hyperthyroidism
Explanation: ***Systemic lupus erythematosus*** - Amiodarone is not typically associated with inducing or exacerbating **systemic lupus erythematosus** (SLE). - SLE is an **autoimmune disease** with a distinct set of symptoms and serological markers, rarely linked to amiodarone. *Pulmonary Fibrosis* - **Pulmonary fibrosis** is a well-known, potentially severe adverse effect of chronic amiodarone therapy, occurring due to drug accumulation in lung tissue. - Patients may present with **dyspnea, cough**, and diffuse interstitial infiltrates on chest imaging. *Hypothyroidism* - Amiodarone contains **iodine**, and its metabolites can inhibit thyroid hormone synthesis and release, leading to **hypothyroidism**. - This is a common endocrine side effect, often requiring **thyroid hormone replacement**. *Hyperthyroidism* - Amiodarone can also cause **hyperthyroidism** through two main mechanisms: an iodine-induced type (Type 1) or a destructive thyroiditis (Type 2). - Both types lead to excessive thyroid hormone levels and distinct clinical presentations.
Question 1046: Which of the following drugs can cause drug-induced systemic lupus erythematosus?
- A. Hydralazine
- B. Procainamide
- C. All of these (Correct Answer)
- D. INH
Explanation: ***All of these*** - **Hydralazine**, **procainamide**, and **isoniazid (INH)** are all well-known medications identified to cause drug-induced systemic lupus erythematosus (DILE). - DILE typically presents with symptoms similar to idiopathic SLE, often including **arthralgia**, **myalgia**, and **serositis**, and usually resolves upon discontinuation of the culprit drug. *Hydralazine* - This **antihypertensive medication** is a common cause of DILE, particularly at higher doses and with prolonged use. - The mechanism is thought to involve its metabolism into reactive intermediates that can modify proteins and induce an **autoimmune response**. *Procainamide* - This **antiarrhythmic drug** is one of the most frequently implicated medications in causing DILE. - It often leads to the development of **anti-histone antibodies**, a hallmark of drug-induced lupus. *INH* - **Isoniazid**, an antibiotic used to treat **tuberculosis**, can also induce DILE. - Similar to other DILE-inducing drugs, INH's metabolic pathways are thought to contribute to the autoimmune process leading to lupus-like symptoms.
Question 1047: Pralidoxime is not useful in poisoning with which of the following?
- A. Parathion
- B. Malathion
- C. Carbamate (Correct Answer)
- D. DFP
Explanation: ***Carbamate*** - Pralidoxime (2-PAM) is an **acetylcholinesterase reactivator** that works by detaching organophosphates from the active site of the enzyme. - Carbamates bind **reversibly** to acetylcholinesterase, and the enzyme-carbamate complex dissociates spontaneously within hours, making pralidoxime **unnecessary**. - Since the enzyme reactivates on its own, pralidoxime offers no therapeutic benefit in carbamate poisoning and is therefore **not indicated**. *Malathion* - Malathion is an **organophosphate insecticide** that inhibits acetylcholinesterase irreversibly. - Pralidoxime is effective in reactivating acetylcholinesterase inhibited by malathion, especially if administered early. *Parathion* - Parathion is an **organophosphate insecticide** that causes irreversible inhibition of acetylcholinesterase. - Pralidoxime is indicated for parathion poisoning to restore enzyme function and reverse cholinergic symptoms. *DFP* - DFP (Diisopropylfluorophosphate) is a potent **organophosphate nerve agent** that irreversibly inhibits acetylcholinesterase. - Pralidoxime is used in the treatment of DFP poisoning to reactivate the enzyme.
Question 1048: Which of the following drugs is not associated with hepatotoxicity?
- A. Allopurinol
- B. Streptomycin (Correct Answer)
- C. Sulfonamide
- D. Isoniazid
Explanation: ***Streptomycin*** - **Streptomycin** is an aminoglycoside antibiotic primarily associated with **ototoxicity** (vestibular and cochlear damage) and **nephrotoxicity**, but not commonly with significant hepatotoxicity [1]. - While all drugs can theoretically cause liver injury in susceptible individuals, streptomycin's established adverse effect profile does not highlight hepatotoxicity as a common or primary concern [1]. *Allopurinol* - **Allopurinol**, used to treat gout, can cause a range of adverse effects, including **hypersensitivity reactions** which may manifest with liver injury, such as **hepatitis** or **cholestasis**. - Severe cases can lead to allopurinol hypersensitivity syndrome, involving **rash**, **eosinophilia**, **fever**, and **hepatotoxicity**. *Sulfonamide* - **Sulfonamides** are a class of antibiotics known for various adverse effects, including **hypersensitivity reactions** that can lead to **drug-induced liver injury**. - They can cause different patterns of hepatotoxicity, including **cholestatic hepatitis**, **granulomatous hepatitis**, and even **fulminant hepatic failure** in rare cases. *Isoniazid* - **Isoniazid** (INH), a first-line anti-tuberculosis drug, is well-known for causing **drug-induced hepatotoxicity**, ranging from asymptomatic elevation of liver enzymes to **acute hepatitis** and **fulminant hepatic failure** [2]. - Risk factors include advanced age, concurrent use of rifampicin, alcohol consumption, and slow acetylator status [2]. - Regular monitoring of liver function tests is recommended during INH therapy [2].
Question 1049: Which of the following DPP-IV inhibitors is safe for use in chronic kidney disease patients without requiring dose modification?
- A. Sitagliptin
- B. Vildagliptin
- C. Linagliptin (Correct Answer)
- D. Saxagliptin
Explanation: ***Linagliptin*** - Unlike other **DPP-IV inhibitors**, **linagliptin** is primarily eliminated via **biliary/fecal excretion** (~85%) rather than renal excretion. - This unique elimination pathway makes it **safe** for use in patients with **chronic kidney disease** at its usual dose, without the need for dose adjustment. - It is the **only DPP-IV inhibitor** that does not require dose modification in CKD. *Sitagliptin* - **Sitagliptin** is primarily eliminated by the **kidneys** (~80% renal excretion), requiring **significant dose adjustments** in patients with **renal impairment**. - Without dose modification, there is an increased risk of **drug accumulation** and adverse effects in CKD patients. *Vildagliptin* - **Vildagliptin** undergoes **hydrolysis** with subsequent **renal excretion** of inactive metabolites, requiring **dose reduction** in patients with moderate to severe **renal impairment**. - Not recommended in severe renal impairment (eGFR <50 mL/min). *Saxagliptin* - **Saxagliptin** is partially eliminated via **renal excretion** and requires **dose reduction** by 50% in patients with moderate to severe **CKD**. - Both parent drug and active metabolite accumulate in renal impairment, necessitating dose adjustment.
Question 1050: What is the role of marijuana in managing AIDS-related cachexia?
- A. Reduces viral load
- B. Enhances CD4 cell count
- C. Stimulates appetite (Correct Answer)
- D. Boosts immune response
Explanation: **_Stimulates appetite_** - **Marijuana** (cannabis) and its derivatives, particularly **delta-9-tetrahydrocannabinol (THC)**, are known for their **appetite-stimulating effects** which can combat **cachexia** (wasting syndrome) in AIDS patients [1], [2]. - By increasing appetite, marijuana helps patients consume more calories, thereby reducing **weight loss** and improving overall nutritional status. *Reduces viral load* - There is **no scientific evidence** to suggest that marijuana directly reduces the **viral load** in HIV-infected individuals. - **Antiretroviral therapy (ART)** is the primary and proven method for reducing viral load in AIDS patients. *Enhances CD4 cell count* - Marijuana does **not directly enhance** the **CD4 cell count**, which is a key indicator of immune function in HIV/AIDS. - **Improved nutrition** due to appetite stimulation might indirectly support immune health, but it does not directly increase CD4 cells. *Boosts immune response* - The effect of marijuana on the **immune system** is complex and not fully understood, but it is generally **not considered an immune booster**. - Some studies suggest that cannabinoids may have **immunosuppressive properties**, which would be counterproductive in AIDS [2].
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