Anti-inflammatory agents – Diclofenac MCQs With Answer
Diclofenac is a widely used NSAID with potent analgesic and anti-inflammatory properties relevant to B. Pharm students studying pharmacology and therapeutics. This introduction reviews mechanism (COX inhibition), pharmacokinetics (first‑pass metabolism, CYP2C9), formulations (oral, topical, IM, ophthalmic), safety (GI, renal, CV risks), drug interactions (warfarin, ACE inhibitors, SSRIs) and monitoring (LFTs, renal function). Understanding diclofenac’s metabolism, adverse effects and formulation differences (sodium vs potassium salts) is essential for rational prescribing and patient counselling. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Diclofenac is classified as which type of drug?
- Antibiotic
- Nonsteroidal anti-inflammatory drug
- Corticosteroid
- Opioid analgesic
Correct Answer: Nonsteroidal anti-inflammatory drug
Q2. What is the primary molecular mechanism of action of diclofenac?
- Selective β‑adrenergic blockade
- Inhibition of cyclooxygenase-1 and cyclooxygenase-2 with relative COX-2 selectivity
- Activation of mu-opioid receptors
- Antagonism of histamine H1 receptors
Correct Answer: Inhibition of cyclooxygenase-1 and cyclooxygenase-2 with relative COX-2 selectivity
Q3. Which clinical indication is diclofenac commonly used for?
- Type 2 diabetes mellitus
- Osteoarthritis and rheumatoid arthritis pain
- Chronic heart failure
- Epilepsy
Correct Answer: Osteoarthritis and rheumatoid arthritis pain
Q4. Which salt form of diclofenac is known for faster oral absorption?
- Diclofenac sodium
- Diclofenac potassium
- Diclofenac calcium
- Diclofenac magnesium
Correct Answer: Diclofenac potassium
Q5. What is a major reason for lower oral bioavailability of diclofenac?
- Poor lipid solubility
- Significant first‑pass hepatic metabolism
- Extensive renal excretion unchanged
- Inactivation in stomach acid
Correct Answer: Significant first‑pass hepatic metabolism
Q6. Diclofenac is primarily metabolized by which cytochrome P450 enzyme?
- CYP3A4
- CYP2C9
- CYP1A2
- CYP2D6
Correct Answer: CYP2C9
Q7. Which of the following best describes diclofenac’s plasma protein binding?
- Less than 10% bound
- Approximately 30–40% bound
- Approximately 60–70% bound
- Greater than 99% bound
Correct Answer: Greater than 99% bound
Q8. What adverse cardiovascular risk is associated with diclofenac?
- Reduced risk of myocardial infarction
- No cardiovascular effects
- Increased risk of thrombotic events and hypertension
- Direct cardioprotective antioxidant effect
Correct Answer: Increased risk of thrombotic events and hypertension
Q9. Which of the following is a key gastrointestinal risk of diclofenac use?
- Constipation without mucosal injury
- Peptic ulceration and gastrointestinal bleeding
- Pancreatitis due to triglyceride accumulation
- Esophageal spasm
Correct Answer: Peptic ulceration and gastrointestinal bleeding
Q10. Diclofenac can precipitate renal adverse effects primarily by:
- Direct tubular necrosis independent of prostaglandins
- Reducing renal prostaglandin synthesis leading to decreased renal blood flow
- Causing urinary tract infection
- Enhancing aldosterone secretion
Correct Answer: Reducing renal prostaglandin synthesis leading to decreased renal blood flow
Q11. Which patient population is diclofenac contraindicated in due to risk of premature ductus arteriosus closure?
- First trimester pregnancy
- Second trimester pregnancy
- Third trimester pregnancy
- Men over 65 years
Correct Answer: Third trimester pregnancy
Q12. Which laboratory tests should be monitored during prolonged diclofenac therapy?
- Blood glucose and HbA1c
- Liver function tests, renal function and complete blood count
- Thyroid function tests
- Serum amylase and lipase only
Correct Answer: Liver function tests, renal function and complete blood count
Q13. Which interaction is clinically significant with diclofenac leading to increased bleeding risk?
- Co-administration with statins
- Co-administration with warfarin or other anticoagulants
- Co-administration with insulin
- Co-administration with levothyroxine
Correct Answer: Co-administration with warfarin or other anticoagulants
Q14. Diclofenac’s analgesic effect is mainly due to decreased formation of which mediators?
- Histamines
- Prostaglandins
- Cytokines like TNF-α directly
- Bradykinin exclusively
Correct Answer: Prostaglandins
Q15. Which statement about topical diclofenac formulations is TRUE?
- Topical diclofenac has higher systemic exposure than oral diclofenac
- Topical diclofenac eliminates all cardiovascular risk
- Topical diclofenac provides local effect with reduced systemic adverse effects
- Topical diclofenac is ineffective for musculoskeletal pain
Correct Answer: Topical diclofenac provides local effect with reduced systemic adverse effects
Q16. The half-life of diclofenac in plasma is approximately:
- 24–48 hours
- 1–2 hours
- 12–16 hours
- 72 hours
Correct Answer: 1–2 hours
Q17. Diclofenac undergoes enterohepatic recirculation. This phenomenon can lead to:
- Complete renal excretion unchanged
- Secondary plasma concentration peaks and prolonged tissue exposure
- Immediate elimination without side effects
- Reduced therapeutic effect due to inactivation
Correct Answer: Secondary plasma concentration peaks and prolonged tissue exposure
Q18. Which metabolic pathway contributes to diclofenac hepatotoxicity via reactive metabolites?
- Glutathione conjugation exclusively
- CYP‑mediated formation of reactive quinone‑imine metabolites
- Direct glycosylation in plasma
- Reduction by gut bacteria only
Correct Answer: CYP‑mediated formation of reactive quinone‑imine metabolites
Q19. Diclofenac’s effect on platelet aggregation is best described as:
- Irreversible inhibition similar to aspirin
- Reversible inhibition of platelet aggregation
- Potent stimulation of platelet aggregation
- No effect on platelets
Correct Answer: Reversible inhibition of platelet aggregation
Q20. Which adverse reaction is characteristic of NSAID hypersensitivity to diclofenac?
- Urticaria, angioedema and bronchospasm in aspirin-sensitive individuals
- Primary hypothyroidism
- Hyperglycemia with ketoacidosis
- Neutropenia without allergic features
Correct Answer: Urticaria, angioedema and bronchospasm in aspirin-sensitive individuals
Q21. Which drug interaction may reduce the antihypertensive effect of ACE inhibitors when combined with diclofenac?
- Diuretics only
- Nonsteroidal anti-inflammatory drugs via prostaglandin inhibition
- Statins via CYP3A4 inhibition
- Antacids via pH change
Correct Answer: Nonsteroidal anti-inflammatory drugs via prostaglandin inhibition
Q22. Diclofenac is contraindicated in patients with which gastrointestinal condition?
- Chronic constipation only
- Active peptic ulcer disease or gastrointestinal bleeding
- Asymptomatic hemorrhoids
- Mild gastritis without erosion
Correct Answer: Active peptic ulcer disease or gastrointestinal bleeding
Q23. Which formulation of diclofenac is specifically used for ocular inflammation?
- Diclofenac oral enteric-coated tablet
- Diclofenac ophthalmic solution
- Diclofenac topical gel 1%
- Diclofenac intramuscular injection
Correct Answer: Diclofenac ophthalmic solution
Q24. In overdose of diclofenac, the most appropriate initial management is:
- No treatment required; wait for spontaneous recovery
- Gastric decontamination with activated charcoal if recent ingestion and supportive care
- Immediate hemodialysis as first-line
- Administer flumazenil
Correct Answer: Gastric decontamination with activated charcoal if recent ingestion and supportive care
Q25. Diclofenac chemical name includes which functional group?
- Phenylacetic acid derivative
- Beta-lactam ring
- Sulfonylurea moiety
- Benzodiazepine ring
Correct Answer: Phenylacetic acid derivative
Q26. Which CYP polymorphism would most likely increase diclofenac plasma concentrations and toxicity?
- CYP2C9 poor metabolizer genotype
- CYP3A4 ultra-rapid metabolizer genotype
- CYP1A1 loss-of-function genotype
- CYP2D6 ultra-rapid metabolizer genotype
Correct Answer: CYP2C9 poor metabolizer genotype
Q27. Diclofenac typical maximum daily dose for adults (oral) is approximately:
- 10 mg/day
- 50 mg/day
- 150 mg/day
- 500 mg/day
Correct Answer: 150 mg/day
Q28. Which statement about diclofenac and aspirin co-administration is correct?
- Aspirin prevents diclofenac’s hepatotoxicity
- Co-administration increases gastrointestinal bleeding risk
- Diclofenac and aspirin have no additive risks
- Diclofenac potentiates aspirin’s irreversible platelet inhibition
Correct Answer: Co-administration increases gastrointestinal bleeding risk
Q29. Diclofenac is most likely to cause which pattern of liver enzyme abnormality?
- Cholestatic pattern only without transaminase elevation
- Mild to moderate transaminase elevation (hepatocellular pattern)
- Isolated bilirubin increase without enzyme change
- No change in liver enzymes ever
Correct Answer: Mild to moderate transaminase elevation (hepatocellular pattern)
Q30. Which statement about diclofenac and asthma is correct?
- Diclofenac is safe in all asthma patients
- NSAIDs like diclofenac can precipitate bronchospasm in aspirin-sensitive asthmatics
- Diclofenac cures aspirin-induced asthma
- Diclofenac has no effect on leukotriene pathways
Correct Answer: NSAIDs like diclofenac can precipitate bronchospasm in aspirin-sensitive asthmatics
Q31. Which of the following metabolites are major routes of diclofenac elimination?
- Unchanged drug excreted in breath
- Hydroxylated metabolites and conjugated glucuronides excreted in urine and bile
- Parent drug exclusively excreted in feces
- Excretion as sulfate only through sweat
Correct Answer: Hydroxylated metabolites and conjugated glucuronides excreted in urine and bile
Q32. How does diclofenac differ from naproxen in COX selectivity?
- Diclofenac is more COX-2 selective compared to naproxen
- Diclofenac is a selective COX-1 inhibitor only
- Diclofenac has identical COX selectivity to naproxen
- Diclofenac does not inhibit cyclooxygenase enzymes
Correct Answer: Diclofenac is more COX-2 selective compared to naproxen
Q33. Which patient counselling point is important for diclofenac oral tablets?
- Take on an empty stomach to avoid interactions
- Take with food or milk to reduce gastrointestinal upset
- Avoid drinking water with the tablet
- Crush enteric-coated tablets for faster effect
Correct Answer: Take with food or milk to reduce gastrointestinal upset
Q34. Diclofenac is considered which of the following regarding stereochemistry?
- Chiral with clinically used enantiomeric mixture
- Achiral molecule without stereoisomers
- Racemic mixture of two active enantiomers
- Optically active with only S‑enantiomer used
Correct Answer: Achiral molecule without stereoisomers
Q35. Which of the following is an advantage of enteric-coated diclofenac formulations?
- Faster onset than immediate-release potassium salt
- Reduced gastric irritation by delaying release until intestine
- Increased peak plasma concentration compared to all formulations
- Eliminates renal adverse effects
Correct Answer: Reduced gastric irritation by delaying release until intestine
Q36. Diclofenac use with which class of antidepressants increases bleeding risk?
- Tricyclic antidepressants with anticholinergic activity only
- Selective serotonin reuptake inhibitors (SSRIs)
- Monoamine oxidase inhibitors only
- Bupropion exclusively
Correct Answer: Selective serotonin reuptake inhibitors (SSRIs)
Q37. A notable safety warning for diclofenac concerns which organ system most relevant to long‑term use?
- Endocrine system with adrenal suppression
- Cardiovascular system with increased thrombotic risk
- Reproductive system with infertility
- Auditory system with hearing loss
Correct Answer: Cardiovascular system with increased thrombotic risk
Q38. Which pharmacokinetic property explains why single-dose diclofenac effect may outlast its plasma half-life?
- Extensive protein binding prevents distribution
- Enterohepatic recirculation and tissue accumulation
- Poor oral absorption leading to depot effect
- Irreversible receptor binding
Correct Answer: Enterohepatic recirculation and tissue accumulation
Q39. In patients on chronic diclofenac therapy, which symptom warrants immediate discontinuation and evaluation?
- Mild headache after dosing
- Dark tarry stools or signs of gastrointestinal bleeding
- Occasional dry mouth
- Mild transient dizziness
Correct Answer: Dark tarry stools or signs of gastrointestinal bleeding
Q40. Which of the following is a dermatologic adverse effect associated with diclofenac?
- Photosensitivity and rash including rare severe skin reactions
- Permanent skin hyperpigmentation in all users
- Psoriasis cure after discontinuation
- Universal hair loss
Correct Answer: Photosensitivity and rash including rare severe skin reactions
Q41. For acute gouty arthritis, diclofenac is used because it:
- Directly reduces uric acid synthesis
- Provides rapid anti-inflammatory and analgesic effects
- Acts as uricosuric agent
- Stimulates renal urate excretion exclusively
Correct Answer: Provides rapid anti-inflammatory and analgesic effects
Q42. Which of the following best describes diclofenac’s acid‑base property relevant to absorption?
- Strong base with pKa >9
- Weak acid with pKa around 4, largely ionized at physiological pH
- Neutral compound irrespective of pH
- Zwitterion with two pKa values
Correct Answer: Weak acid with pKa around 4, largely ionized at physiological pH
Q43. Which monitoring is particularly important when diclofenac is combined with ACE inhibitors in elderly patients?
- Serum magnesium only
- Renal function and serum potassium
- Fasting blood glucose hourly
- Pulmonary function tests
Correct Answer: Renal function and serum potassium
Q44. Which statement about diclofenac suppositories is correct?
- Suppositories are always contraindicated due to erratic absorption
- Rectal administration can be used when oral route is not feasible
- Suppositories provide permanent tissue deposition
- They are inactive and serve as placebo
Correct Answer: Rectal administration can be used when oral route is not feasible
Q45. Which analgesic property distinguishes diclofenac from acetaminophen (paracetamol)?
- Diclofenac has significant anti-inflammatory effect while acetaminophen has minimal peripheral anti-inflammatory action
- Diclofenac has no analgesic effect
- Acetaminophen causes more GI bleeding than diclofenac
- Both are identical in mechanism and side effects
Correct Answer: Diclofenac has significant anti-inflammatory effect while acetaminophen has minimal peripheral anti-inflammatory action
Q46. Which clinical scenario requires caution or avoidance of diclofenac?
- Young healthy adult with a sprain and no comorbidities
- Patient with severe hypovolemia or heart failure risk who relies on prostaglandin-mediated renal perfusion
- Short-term postoperative pain in low-risk individuals
- Topical use for localized bursitis in a healthy adult
Correct Answer: Patient with severe hypovolemia or heart failure risk who relies on prostaglandin-mediated renal perfusion
Q47. Which pharmacodynamic interaction increases the risk of diclofenac-induced renal impairment?
- Co-administration with probiotics
- Concurrent use of diuretics and ACE inhibitors (triple whammy)
- Use with topical emollients only
- Use with calcium supplements exclusively
Correct Answer: Concurrent use of diuretics and ACE inhibitors (triple whammy)
Q48. Which safety advice is important before performing elective surgery?
- Continue diclofenac up to the time of surgery to control pain
- Stop diclofenac several days before surgery to reduce bleeding risk
- Switch to higher dose the day before surgery
- No need to inform the surgeon about NSAID use
Correct Answer: Stop diclofenac several days before surgery to reduce bleeding risk
Q49. Which statement about diclofenac and hepatic injury is TRUE?
- Hepatotoxicity never occurs with diclofenac
- Hepatotoxicity can occur idiosyncratically and LFT monitoring is recommended during prolonged therapy
- Only patients with pre-existing hepatitis can develop hepatic injury
- Hepatotoxicity is dose-independent and always predictable
Correct Answer: Hepatotoxicity can occur idiosyncratically and LFT monitoring is recommended during prolonged therapy
Q50. Which is an evidence-based clinical advantage of using topical diclofenac gel over oral diclofenac?
- Topical diclofenac uniformly cures systemic inflammatory disease
- Topical diclofenac provides comparable local pain relief with lower systemic exposure and fewer GI adverse events
- Topical diclofenac has faster systemic onset and higher plasma levels
- Topical diclofenac causes more renal toxicity than oral forms
Correct Answer: Topical diclofenac provides comparable local pain relief with lower systemic exposure and fewer GI adverse events
