Norfloxacin and Enoxacin MCQs With Answer

Norfloxacin and Enoxacin MCQs With Answer

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Norfloxacin and Enoxacin MCQs With Answer provides B.Pharm students a focused review of two older fluoroquinolones emphasizing pharmacology, mechanism of action, clinical uses, pharmacokinetics, adverse effects, drug interactions and resistance. This set covers DNA gyrase/topoisomerase IV inhibition, spectrum (especially urinary pathogens), renal elimination, dosing considerations, chelation with divalent cations, tendon toxicity, QT prolongation and CYP interactions. Designed for exam preparation and concept reinforcement, the questions explore practical prescribing cautions, monitoring parameters and molecular bases of resistance. Keywords: Norfloxacin, Enoxacin, fluoroquinolones, DNA gyrase, UTI, pharmacokinetics, adverse effects, drug interactions, resistance. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which is the primary mechanism of action of norfloxacin and enoxacin?

  • Inhibition of cell wall synthesis by binding to PBPs
  • Disruption of bacterial protein synthesis at the 30S ribosomal subunit
  • Inhibition of bacterial DNA gyrase and topoisomerase IV
  • Interference with folate synthesis by inhibiting dihydropteroate synthase

Correct Answer: Inhibition of bacterial DNA gyrase and topoisomerase IV

Q2. To which antibiotic class do norfloxacin and enoxacin belong?

  • Beta-lactams
  • Macrolides
  • Fluoroquinolones
  • Aminoglycosides

Correct Answer: Fluoroquinolones

Q3. Which of the following best describes the antibacterial spectrum of norfloxacin?

  • Primarily Gram-positive cocci only
  • Broad anaerobic coverage including Bacteroides
  • Primarily Gram-negative bacteria including Pseudomonas aeruginosa
  • Antitubercular activity against Mycobacterium tuberculosis

Correct Answer: Primarily Gram-negative bacteria including Pseudomonas aeruginosa

Q4. The most common clinical indication of norfloxacin in B.Pharm practice is:

  • Severe community-acquired pneumonia
  • Uncomplicated urinary tract infections
  • Skin and soft tissue MRSA infections
  • Chronic hepatitis B

Correct Answer: Uncomplicated urinary tract infections

Q5. Which adverse effect is classically associated with fluoroquinolones such as norfloxacin and enoxacin?

  • Ototoxicity leading to permanent hearing loss
  • Tendonitis and tendon rupture
  • Severe hypoglycemia in all patients
  • Massive hemolysis in G6PD deficiency exclusively

Correct Answer: Tendonitis and tendon rupture

Q6. Co-administration of norfloxacin with which of the following will most reduce its oral absorption?

  • Oral corticosteroids
  • Antacids containing aluminium or magnesium
  • Acetaminophen
  • Subcutaneous insulin

Correct Answer: Antacids containing aluminium or magnesium

Q7. In which patient group are norfloxacin and enoxacin generally contraindicated due to potential cartilage damage?

  • Pregnant women and children
  • Adults over 65 years of age
  • Patients with controlled hypertension
  • Patients receiving antiviral therapy

Correct Answer: Pregnant women and children

Q8. Which statement about the oral bioavailability of norfloxacin and enoxacin is true?

  • They have negligible oral absorption and are only given intravenously
  • They have good oral bioavailability suitable for oral therapy
  • They are only absorbed when administered with fatty meals
  • They are inactivated by gastric acid and must be enteric-coated

Correct Answer: They have good oral bioavailability suitable for oral therapy

Q9. What is the principal route of elimination for norfloxacin?

  • Hepatic metabolism to inactive metabolites followed by biliary excretion
  • Renal excretion of unchanged drug
  • Exhalation via lungs as volatile metabolites
  • Extensive enterohepatic recirculation prolongs half-life

Correct Answer: Renal excretion of unchanged drug

Q10. A common genetic mechanism by which bacteria acquire resistance to norfloxacin is:

  • Plasmid-mediated inactivation by beta-lactamases
  • Mutation in the gyrA gene encoding DNA gyrase
  • Increased uptake through porin channels
  • Overproduction of peptidoglycan

Correct Answer: Mutation in the gyrA gene encoding DNA gyrase

Q11. Which cardiac adverse effect can be caused by fluoroquinolones including norfloxacin/enoxacin?

  • Severe bradycardia requiring pacemaker
  • QT interval prolongation leading to arrhythmia risk
  • Immediate myocardial infarction in young adults
  • Complete heart block in all patients

Correct Answer: QT interval prolongation leading to arrhythmia risk

Q12. Which dermatologic adverse reaction is associated with enoxacin and other fluoroquinolones?

  • Immunobullous disease like pemphigus vulgaris
  • Marked photosensitivity and phototoxic reactions
  • Selective loss of skin pigmentation
  • Petechial rash due to platelet consumption

Correct Answer: Marked photosensitivity and phototoxic reactions

Q13. Norfloxacin is commonly used in the oral treatment of which prostatic condition?

  • Acute bacterial prostatitis
  • Benign prostatic hyperplasia (as primary therapy)
  • Prostate cancer
  • Nonbacterial chronic pelvic pain syndrome only

Correct Answer: Acute bacterial prostatitis

Q14. Which agents form chelates with norfloxacin/enoxacin and reduce their absorption?

  • Loop diuretics such as furosemide
  • Iron supplements, milk, and antacids with divalent cations
  • Topical corticosteroids
  • Oral antiemetics like ondansetron

Correct Answer: Iron supplements, milk, and antacids with divalent cations

Q15. Before prescribing norfloxacin for UTI, which baseline test is most important for dose adjustment?

  • Serum amylase
  • Renal function tests (serum creatinine, creatinine clearance)
  • Chest X-ray
  • Fasting blood glucose

Correct Answer: Renal function tests (serum creatinine, creatinine clearance)

Q16. Which fluoroquinolone is known to inhibit CYP1A2 and cause interactions with theophylline and caffeine?

  • Penicillin G
  • Enoxacin
  • Vancomycin
  • Amoxicillin

Correct Answer: Enoxacin

Q17. Which central nervous system adverse effect may be precipitated by fluoroquinolones in susceptible patients?

  • Enhanced seizure risk and other neuropsychiatric effects
  • Immediate and permanent visual loss
  • Chronic demyelinating polyneuropathy
  • Complete paralysis of cranial nerves

Correct Answer: Enhanced seizure risk and other neuropsychiatric effects

Q18. The bactericidal activity of norfloxacin and enoxacin is primarily due to:

  • Disruption of cytoplasmic membrane integrity like detergents
  • Inhibition of metabolic folate pathways leading to static effect
  • Stabilization of DNA-enzyme complexes causing double-strand DNA breaks
  • Interference with peptidoglycan cross-linking

Correct Answer: Stabilization of DNA-enzyme complexes causing double-strand DNA breaks

Q19. Enoxacin is most appropriately used in which of the following infections?

  • Uncomplicated urinary tract infections and prostatitis
  • Fungal candidiasis
  • Viral influenza A infection
  • Latent tuberculosis prophylaxis

Correct Answer: Uncomplicated urinary tract infections and prostatitis

Q20. In patients with reduced creatinine clearance, what is the recommendation for norfloxacin dosing?

  • No adjustment needed regardless of renal function
  • Increase the dose to overcome reduced renal clearance
  • Reduce dose or extend dosing interval according to renal function
  • Stop drug and switch to topical therapy only

Correct Answer: Reduce dose or extend dosing interval according to renal function

Q21. Fluoroquinolones like norfloxacin are generally classified as:

  • Bacteriostatic agents
  • Bactericidal agents
  • Antifungal agents
  • Antiviral agents

Correct Answer: Bactericidal agents

Q22. Which concomitant medication increases the risk of tendon rupture when taken with norfloxacin?

  • ACE inhibitors
  • Systemic corticosteroids
  • Topical antihistamines
  • Inhaled bronchodilators only

Correct Answer: Systemic corticosteroids

Q23. The most commonly reported adverse effects of norfloxacin and enoxacin are:

  • Severe nephrotoxicity in all patients
  • Gastrointestinal disturbances like nausea and diarrhea
  • Persistent severe bleeding from mucous membranes
  • Immediate anaphylactic shock in 50% of users

Correct Answer: Gastrointestinal disturbances like nausea and diarrhea

Q24. Which monitoring modality is most useful to detect fluoroquinolone-induced QT prolongation?

  • Complete blood count (CBC)
  • Electrocardiogram (ECG)
  • Chest X-ray
  • Serum amylase

Correct Answer: Electrocardiogram (ECG)

Q25. Fluoroquinolones such as norfloxacin have relatively poor activity against which type of organisms?

  • Gram-negative bacilli like E. coli
  • Pseudomonas species
  • Anaerobic bacteria such as Bacteroides fragilis
  • Enterobacteriaceae family

Correct Answer: Anaerobic bacteria such as Bacteroides fragilis

Q26. The presence of a fluorine atom at the C-6 position of fluoroquinolones primarily confers:

  • Increased protein binding with no antibacterial effect
  • Enhanced antibacterial potency and cell penetration
  • Specific anti-fungal activity
  • Selective action against protozoa

Correct Answer: Enhanced antibacterial potency and cell penetration

Q27. Taking norfloxacin with milk reduces its absorption primarily because:

  • Lactose in milk induces hepatic enzymes that degrade the drug
  • Calcium in milk chelates the drug forming insoluble complexes
  • Milk accelerates transit time preventing absorption
  • Milk contains proteases that inactivate norfloxacin

Correct Answer: Calcium in milk chelates the drug forming insoluble complexes

Q28. Besides target-site mutation, another major bacterial resistance mechanism to norfloxacin is:

  • Production of beta-lactamases
  • Active efflux pumps removing the drug from the cell
  • Overexpression of folate pathway enzymes
  • Increased ribosomal methylation

Correct Answer: Active efflux pumps removing the drug from the cell

Q29. Which clinical sign requires immediate discontinuation of norfloxacin or enoxacin?

  • Mild transient headache
  • Sudden onset of severe tendon pain suggestive of tendon rupture
  • Temporary metallic taste in the mouth
  • Asymptomatic slight elevation of liver enzymes

Correct Answer: Sudden onset of severe tendon pain suggestive of tendon rupture

Q30. Regarding use in pregnancy, the recommended advice for norfloxacin and enoxacin is:

  • They are first-line agents for urinary infections in pregnancy
  • Use only if benefits clearly outweigh risks due to potential fetal cartilage damage
  • Safe in all trimesters with no fetal risk
  • Require double the usual dose in pregnant women

Correct Answer: Use only if benefits clearly outweigh risks due to potential fetal cartilage damage

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