Anti-inflammatory agents – Phenylbutazone MCQs With Answer

Anti-inflammatory agents – Phenylbutazone MCQs With Answer

Anti-inflammatory agents are essential in pharmacology and Phenylbutazone is a classic NSAID often discussed in B. Pharm curricula. This focused set of MCQs covers Phenylbutazone’s chemical class, mechanism of action, metabolism, therapeutic uses, adverse effects, drug interactions, monitoring parameters and regulatory status. Questions emphasize clinical pharmacology, toxicology and formulation considerations relevant to pharmacy students preparing for exams or clinical practice. Each question is designed to deepen understanding of prostaglandin inhibition, bone marrow toxicity, renal and hepatic risks, and pharmacokinetic principles. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which chemical class does phenylbutazone belong to?

• Pyrazolidinedione derivative
• Salicylate derivative
• Propionic acid derivative
• Oxicam derivative

Correct Answer: Pyrazolidinedione derivative

Q2. The primary mechanism of action of phenylbutazone is:

• Selective COX-2 inhibition
• Non-selective inhibition of COX enzymes reducing prostaglandin synthesis
• Inhibition of leukotriene synthesis via 5-LOX blockade
• Activation of glucocorticoid receptors

Correct Answer: Non-selective inhibition of COX enzymes reducing prostaglandin synthesis

Q3. Phenylbutazone is primarily metabolized in the body to which active metabolite?

• Ibuprofen
• Oxyphenbutazone
• Salicylate
• Naproxen

Correct Answer: Oxyphenbutazone

Q4. A major serious hematologic adverse effect associated with phenylbutazone is:

• Hemolytic hyperbilirubinemia
• Aplastic anemia and agranulocytosis
• Thrombocytosis
• Polycythemia vera

Correct Answer: Aplastic anemia and agranulocytosis

Q5. Phenylbutazone’s high plasma protein binding primarily affects which pharmacokinetic property?

• Renal excretion by glomerular filtration only
• Volume of distribution and potential drug displacement interactions
• Intrinsic hepatic clearance independent of binding
• Bioavailability via intestinal transporters

Correct Answer: Volume of distribution and potential drug displacement interactions

Q6. Which clinical indication was historically common for phenylbutazone in humans?

• Type 1 diabetes management
• Gout and inflammatory arthritides
• Antibiotic-resistant infections
• Anticoagulation therapy

Correct Answer: Gout and inflammatory arthritides

Q7. Due to safety concerns, phenylbutazone is now predominantly used in which field?

• Pediatrics
• Veterinary medicine (especially equine)
• Ophthalmology
• Dermatology for topical use

Correct Answer: Veterinary medicine (especially equine)

Q8. Which organ system is especially vulnerable to NSAID-induced damage that phenylbutazone can precipitate?

• Central nervous system (neurotoxicity)
• Renal system (papillary necrosis, interstitial nephritis)
• Endocrine system (thyroid suppression)
• Musculoskeletal system (myopathy)

Correct Answer: Renal system (papillary necrosis, interstitial nephritis)

Q9. A significant drug interaction risk with phenylbutazone arises from its ability to:

• Induce P-glycoprotein efflux in the gut
• Displace other drugs from plasma proteins increasing free drug levels
• Irreversibly inhibit hepatic CYP3A4 only
• Enhance renal elimination of aminoglycosides

Correct Answer: Displace other drugs from plasma proteins increasing free drug levels

Q10. Which laboratory parameter should be monitored due to possible bone marrow suppression by phenylbutazone?

• Serum amylase
• Complete blood count (CBC) with differential
• Fasting blood glucose
• Serum sodium only

Correct Answer: Complete blood count (CBC) with differential

Q11. Phenylbutazone’s analgesic and antipyretic effects are primarily due to decreased synthesis of:

• Bradykinin
• Prostaglandins
• Histamine
• Interleukin-2

Correct Answer: Prostaglandins

Q12. Which adverse skin reaction is a known, though rare, complication of phenylbutazone?

• Psoriasis vulgaris
• Stevens-Johnson syndrome / toxic epidermal necrolysis
• Vitiligo
• Alopecia areata

Correct Answer: Stevens-Johnson syndrome / toxic epidermal necrolysis

Q13. Phenylbutazone’s effect on platelet function is best described as:

• Enhances platelet aggregation via thromboxane A2 synthesis
• No effect on platelets at therapeutic doses
• Impairment of platelet aggregation by COX-1 inhibition
• Stimulates megakaryocyte proliferation

Correct Answer: Impairment of platelet aggregation by COX-1 inhibition

Q14. In patients taking warfarin, co-administration of phenylbutazone is likely to:

• Have no interaction
• Decrease anticoagulant effect by inducing warfarin metabolism
• Increase warfarin effect by displacing it from plasma proteins and inhibiting metabolism
• Convert warfarin to an inactive metabolite directly

Correct Answer: Increase warfarin effect by displacing it from plasma proteins and inhibiting metabolism

Q15. The contraindication for phenylbutazone in pregnancy is due primarily to:

• Risk of uterine contractions and preterm labor
• Closure of fetal ductus arteriosus and bleeding risk
• Severe teratogenic central nervous system defects
• Excessive fetal insulin production

Correct Answer: Closure of fetal ductus arteriosus and bleeding risk

Q16. A metabolite responsible for prolonged activity of phenylbutazone is:

• Acetaminophen
• Oxyphenbutazone
• Sulindac
• Diclofenac

Correct Answer: Oxyphenbutazone

Q17. Which statement about phenylbutazone’s regulatory status is correct?

• It is widely available over-the-counter in most countries
• It has been restricted or withdrawn for human use in many countries due to toxicity
• It is approved for pediatric use for fever management
• It is classified as an antibiotic in many formularies

Correct Answer: It has been restricted or withdrawn for human use in many countries due to toxicity

Q18. The hepatic adverse effects of phenylbutazone most commonly include:

• Cholestatic and hepatocellular injury with elevated liver enzymes
• Complete resistance to hepatotoxins
• Marked stimulation of bile acid synthesis lowering enzymes
• Primary biliary cirrhosis exclusively

Correct Answer: Cholestatic and hepatocellular injury with elevated liver enzymes

Q19. Phenylbutazone may cause which renal electrolyte disturbance by affecting prostaglandin-mediated renal function?

• Hypokalemia due to increased aldosterone secretion
• Sodium and water retention leading to edema and hypertension
• Hypercalcemia from bone resorption
• Hypermagnesemia due to renal retention

Correct Answer: Sodium and water retention leading to edema and hypertension

Q20. Which monitoring is most appropriate when a patient is started on phenylbutazone therapy?

• Weekly ECGs
• Periodic CBC, renal and liver function tests
• Daily chest X-rays
• Fasting lipid profile monthly

Correct Answer: Periodic CBC, renal and liver function tests

Q21. Which population is at highest risk for severe adverse reactions to phenylbutazone?

• Young healthy adults with no comorbidities
• Elderly patients and those with pre-existing renal or hepatic disease
• Individuals with controlled hypothyroidism
• People on topical antifungals exclusively

Correct Answer: Elderly patients and those with pre-existing renal or hepatic disease

Q22. Phenylbutazone’s bioavailability is influenced mainly by:

• Large first-pass hepatic metabolism producing active metabolites
• Renal secretion through active tubular transport only
• Absence of any metabolism
• Exclusively inhalational absorption

Correct Answer: Large first-pass hepatic metabolism producing active metabolites

Q23. Which adverse hematologic sign should prompt immediate discontinuation of phenylbutazone?

• Transient mild eosinophilia
• Sudden onset agranulocytosis or severe leukopenia
• Slightly elevated hemoglobin within normal limits
• Stable platelet count for several months

Correct Answer: Sudden onset agranulocytosis or severe leukopenia

Q24. The major route of elimination for phenylbutazone metabolites is:

• Exhalation via lungs
• Renal excretion after hepatic metabolism and conjugation
• Direct secretion in sweat glands
• Excretion unchanged in bile only

Correct Answer: Renal excretion after hepatic metabolism and conjugation

Q25. Which clinical sign is characteristic of NSAID-induced renal papillary necrosis that may occur with phenylbutazone?

• Progressive polyuria without hematuria
• Acute flank pain with hematuria and possible obstruction
• Sudden onset visual loss
• Chronic constipation unresponsive to laxatives

Correct Answer: Acute flank pain with hematuria and possible obstruction

Q26. Which statement about phenylbutazone and pregnancy is true?

• Safe throughout all trimesters
• Contraindicated, especially in the third trimester due to fetal risks
• Recommended for labor induction
• Used to increase fetal lung maturity

Correct Answer: Contraindicated, especially in the third trimester due to fetal risks

Q27. Phenylbutazone’s toxicity can include which hepatic manifestation?

• Severe hepatitis with jaundice
• Immediate regeneration of hepatocytes
• Hypersynthesis of clotting factors lowering INR
• Complete protection against viral hepatitis

Correct Answer: Severe hepatitis with jaundice

Q28. Which enzyme system is primarily responsible for biotransformation of phenylbutazone?

• Renal dehydrogenases exclusively
• Hepatic cytochrome P450-mediated oxidation
• Pancreatic lipases
• Salivary amylase

Correct Answer: Hepatic cytochrome P450-mediated oxidation

Q29. An important counseling point for patients prescribed phenylbutazone historically would be to avoid which other medication?

• Topical emollients only
• Concurrent anticoagulants like warfarin without monitoring
• Vitamin C supplements
• Local anesthetic creams

Correct Answer: Concurrent anticoagulants like warfarin without monitoring

Q30. Which adverse effect related to the gastrointestinal tract is commonly associated with phenylbutazone?

• Constipation with no bleeding risk
• Peptic ulceration and GI bleeding
• Increased appetite and weight gain
• Reduction in gastric acid only without symptoms

Correct Answer: Peptic ulceration and GI bleeding

Q31. The pharmacological classification of phenylbutazone is:

• Opioid analgesic
• Nonsteroidal anti-inflammatory drug (NSAID)
• Antidepressant
• Beta-blocker

Correct Answer: Nonsteroidal anti-inflammatory drug (NSAID)

Q32. Which monitoring parameter would indicate early renal impairment from phenylbutazone?

• Decreasing serum creatinine clearance or rising serum creatinine
• Lowering fasting glucose
• Improved creatine kinase levels
• Elevated anti-dsDNA antibodies

Correct Answer: Decreasing serum creatinine clearance or rising serum creatinine

Q33. Phenylbutazone can potentiate the toxicity of which drug due to reduced renal clearance?

• Metformin
• Lithium
• Insulin
• Propranolol

Correct Answer: Lithium

Q34. Which adverse cardiovascular effect may be seen with prolonged NSAID therapy including phenylbutazone?

• Reduced blood pressure with bradycardia
• Fluid retention, edema and increased blood pressure
• Complete prevention of myocardial infarction
• Immediate atrioventricular block in all patients

Correct Answer: Fluid retention, edema and increased blood pressure

Q35. A pharmacodynamic consequence of COX inhibition by phenylbutazone in the kidney is:

• Increased renal prostaglandin-mediated vasodilation
• Reduced prostaglandin synthesis leading to decreased renal blood flow in compromised patients
• Enhanced natriuresis and diuresis always
• Direct stimulation of renin synthesis increasing GFR universally

Correct Answer: Reduced prostaglandin synthesis leading to decreased renal blood flow in compromised patients

Q36. Which adverse hematological test finding could reflect phenylbutazone-induced bone marrow toxicity?

• Isolated elevation of platelets
• Pancytopenia with low hemoglobin, leukocytes and platelets
• Elevated eosinophil count only
• Persistently high hematocrit without symptoms

Correct Answer: Pancytopenia with low hemoglobin, leukocytes and platelets

Q37. In terms of drug formulation, phenylbutazone has historically been available as:

• Topical transdermal patch only
• Oral tablets and parenteral preparations (historically)
• Inhaler solution
• Intranasal spray exclusively

Correct Answer: Oral tablets and parenteral preparations (historically)

Q38. Which clinical scenario would most strongly contraindicate the use of phenylbutazone?

• Well-controlled seasonal allergies
• History of severe aplastic anemia or blood dyscrasia
• Mild tension headache once a month
• Uncomplicated seasonal viral infection

Correct Answer: History of severe aplastic anemia or blood dyscrasia

Q39. Which of the following best describes phenylbutazone’s effect on fever?

• No antipyretic activity
• Antipyretic by lowering the hypothalamic set-point via prostaglandin inhibition
• Produces fever as a side effect
• Antipyretic by direct cooling of blood

Correct Answer: Antipyretic by lowering the hypothalamic set-point via prostaglandin inhibition

Q40. Which adverse effect is particularly associated with long-term or high-dose phenylbutazone therapy?

• Improved renal function
• Chronic bone marrow suppression and renal damage
• Permanent enhancement of platelet count
• Guaranteed weight loss

Correct Answer: Chronic bone marrow suppression and renal damage

Q41. Which statement about enterohepatic circulation and phenylbutazone is accurate?

• Phenylbutazone is not subject to enterohepatic circulation
• Enterohepatic recirculation of metabolites can prolong its apparent half-life
• Enterohepatic circulation eliminates all adverse effects
• It is directly exhaled without hepatic involvement

Correct Answer: Enterohepatic recirculation of metabolites can prolong its apparent half-life

Q42. In toxicology, chronic overexposure to phenylbutazone may present with which neurologic sign?

• Peripheral neuropathy and confusion in severe cases
• Immediate coma in all exposures
• Improved cognitive function
• Selective aphasia only

Correct Answer: Peripheral neuropathy and confusion in severe cases

Q43. Which acidic functional property of phenylbutazone contributes to its NSAID activity?

• It contains a basic amine that neutralizes prostaglandins
• Its acidic moiety allows interaction with COX active site and prostaglandin synthesis inhibition
• It is a neutral lipid that dissolves membranes
• It acts solely through ionic potassium channels

Correct Answer: Its acidic moiety allows interaction with COX active site and prostaglandin synthesis inhibition

Q44. For B. Pharm students learning pharmacokinetics, phenylbutazone is a good example of a drug that is:

• Poorly protein bound with rapid clearance
• Highly protein bound with potential for drug-drug displacement interactions
• Exclusively renally excreted unchanged
• Not metabolized and inert

Correct Answer: Highly protein bound with potential for drug-drug displacement interactions

Q45. Which adverse immune-mediated reaction can phenylbutazone trigger?

• Serum sickness-like reactions and hypersensitivity vasculitis
• Immediate reversal of autoimmunity
• Permanent suppression of all allergic responses
• Exclusive induction of tolerance to antibiotics

Correct Answer: Serum sickness-like reactions and hypersensitivity vasculitis

Q46. A pharmacological difference between phenylbutazone and aspirin is that:

• Phenylbutazone irreversibly inhibits COX-1, while aspirin is reversible
• Aspirin irreversibly inhibits platelet COX, phenylbutazone is a reversible non-selective inhibitor
• Both are selective COX-2 inhibitors
• Phenylbutazone has no effect on prostaglandin synthesis

Correct Answer: Aspirin irreversibly inhibits platelet COX, phenylbutazone is a reversible non-selective inhibitor

Q47. Which clinical laboratory abnormality might you expect in a patient with phenylbutazone-induced hepatic injury?

• Markedly decreased ALT and AST
• Elevated ALT, AST and bilirubin indicating hepatocellular or cholestatic injury
• Isolated decrease in amylase only
• Exclusive rise in creatine kinase

Correct Answer: Elevated ALT, AST and bilirubin indicating hepatocellular or cholestatic injury

Q48. In pharmacology exams, phenylbutazone is often used as an example of an NSAID primarily restricted because of:

• Low potency in inflammation
• High risk of serious and idiosyncratic toxicities like aplastic anemia and severe GI/renal effects
• Excessively pleasant taste
• Inability to bind plasma proteins

Correct Answer: High risk of serious and idiosyncratic toxicities like aplastic anemia and severe GI/renal effects

Q49. Which precaution is most appropriate before administering phenylbutazone to an animal or, historically, a human?

• Ensure baseline CBC, liver and renal function are assessed
• Skip all baseline tests as they are unnecessary
• Only measure blood glucose levels
• Administer simultaneously with methotrexate without concern

Correct Answer: Ensure baseline CBC, liver and renal function are assessed

Q50. Which best summarizes why phenylbutazone remains an important study topic for B. Pharm students despite limited human use?

• It has no clinical relevance and is obsolete
• It exemplifies NSAID pharmacology, severe adverse effect profiles, drug interactions and regulatory considerations
• It is the safest NSAID available for all patients
• It is only relevant for veterinary students and not pharmacists

Correct Answer: It exemplifies NSAID pharmacology, severe adverse effect profiles, drug interactions and regulatory considerations

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com