Introduction: Antimicrobials: Iodine and Preparations MCQs With Answer is a focused study aid for B. Pharm students covering iodine chemistry, iodophors (like povidone‑iodine), tinctures, mechanisms of action, formulations, stability, assays, clinical uses, safety and resistance. This SEO-friendly guide highlights key keywords — iodine, povidone-iodine, iodophors, antiseptics, antimicrobial agents, formulations, mechanism of action, and B. Pharm MCQs — to help deepen understanding and improve exam readiness. Questions range from basic concepts to formulation specifics, pharmacology and quality control considerations relevant to pharmacy practice. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which form of iodine is primarily responsible for antimicrobial activity?
- Molecular iodine (I2)
- Iodide ion (I-)
Correct Answer: Molecular iodine (I2)
Q2. Povidone-iodine is best described as which of the following?
- A simple aqueous solution of elemental iodine
- An iodophor: a complex of polyvinylpyrrolidone and iodine
Correct Answer: An iodophor: a complex of polyvinylpyrrolidone and iodine
Q3. What is the primary mechanism by which iodine exerts antimicrobial effects?
Correct Answer: Oxidation and iodination of proteins and nucleic acids
Q4. Which of the following preparations is NOT an iodophor?
- Povidone-iodine
Correct Answer: Tincture of iodine
Q5. A commercially common concentration of povidone-iodine used for skin antisepsis is:
- 0.5% povidone-iodine
- 2% povidone-iodine
- 10% povidone-iodine
- 50% povidone-iodine
Correct Answer: 10% povidone-iodine
Q6. Compared with tincture of iodine, iodophors such as povidone-iodine generally offer which advantage?
- Faster immediate release of iodine
- Less staining and reduced local irritation
- Higher volatility and stronger odor
- Greater alcohol content for drying effect
Correct Answer: Less staining and reduced local irritation
Q7. Dilution of povidone-iodine with water typically causes which change in available antimicrobial iodine?
- Immediate increase in free iodine concentration
- Decrease in available free iodine over time
- Conversion to iodide without antimicrobial effect
- Precipitation of elemental iodine
Correct Answer: Decrease in available free iodine over time
Q8. Iodine-based antiseptics are broadly active against which group of organisms?
- Gram-positive bacteria only
- Bacteria, fungi and many viruses
- Prions exclusively
- Only anaerobic bacteria
Correct Answer: Bacteria, fungi and many viruses
Q9. Topical overuse or systemic absorption of iodine can most directly affect which organ system?
- Renal system
Correct Answer: Thyroid gland
Q10. Which patient group requires special caution when using topical iodine preparations due to risk of systemic absorption and thyroid effects?
Correct Answer: Pregnant women and neonates
Q11. Tincture of iodine commonly contains which solvent that contributes to its irritation on skin?
Correct Answer: Ethanol (alcohol)
Q12. Lugol’s iodine is a standardized preparation typically containing which components?
Correct Answer: Iodine and potassium iodide in water
Q13. The term “available iodine” in iodophor formulations refers to:
Correct Answer: The free molecular iodine released from the complex
Q14. How does solution pH generally influence the release of free iodine from povidone-iodine?
Correct Answer: Lower (acidic) pH increases free iodine release
Q15. A visible characteristic of povidone-iodine solution commonly observed on skin is:
Correct Answer: Brownish staining of skin
Q16. Which chemical group in microbial proteins is especially susceptible to iodine-mediated oxidation?
Correct Answer: Sulfhydryl (thiol) groups
Q17. Which agent is commonly used to neutralize residual iodine in clinical and laboratory settings?
Correct Answer: Sodium thiosulfate
Q18. The presence of organic matter (blood, pus) typically has what effect on iodine antiseptic activity?
- Converts iodine to a more active form
Correct Answer: Decreases activity by consuming free iodine
Q19. Which laboratory method is commonly used to evaluate antiseptic activity of iodine preparations on agar?
Correct Answer: Disk diffusion (zone of inhibition) assay
Q20. For a surgical skin preparation using povidone-iodine scrub, an often-recommended minimum contact time is approximately:
- 5 seconds
- 30 seconds
- 2 minutes
- 24 hours
Correct Answer: 2 minutes
Q21. Which statement correctly differentiates an antiseptic from a disinfectant?
Correct Answer: Antiseptics are suitable for use on living tissue; disinfectants are for surfaces
Q22. Compared with chlorhexidine, iodine antiseptics generally have which relative characteristic?
- Greater persistent residual activity
- Faster onset but less substantivity
- More selective for Gram-negative bacteria only
- No action against viruses
Correct Answer: Faster onset but less substantivity
Q23. Which iodine formulation is most appropriate for use on mucous membranes (e.g., oral cavity or conjunctiva)?
Correct Answer: Povidone-iodine aqueous solution
Q24. A commonly used concentration of povidone-iodine surgical scrub solution is:
- 0.05%
- 0.5%
- 7.5%
- 25%
Correct Answer: 7.5%
Q25. Which species forms in solution when iodine reacts with excess iodide to increase solubility?
Correct Answer: Triiodide (I3-)
Q26. The functional difference between iodophors and tinctures is primarily that iodophors:
Correct Answer: Release iodine slowly from a carrier complex for controlled action
Q27. Which statement about staining caused by povidone-iodine is correct?
- Staining is irreversible and permanent
Correct Answer: Staining is usually temporary and can be removed with appropriate cleaning or neutralization
Q28. Which analytical method is commonly used to determine available iodine content in formulations?
Correct Answer: Iodometric titration
Q29. The increased solubility of iodine in aqueous media in the presence of iodide is due to formation of:
Correct Answer: Triiodide complex (I3-)
Q30. Significant systemic absorption of topical iodine is most likely to occur when applied to:
- Intact skin in small area
Correct Answer: Large burns or extensive denuded skin
Q31. Which microbial form is relatively more resistant to iodine antiseptics?
Correct Answer: Bacterial spores
Q32. Symptoms such as metallic taste, increased salivation, and mouth burning after exposure to iodine indicate which condition?
Correct Answer: Iodism (iodine poisoning/overexposure)
Q33. For ophthalmic antisepsis prior to ocular surgery, which povidone-iodine concentration is commonly used?
- 0.05% povidone-iodine
- 1% povidone-iodine
- 5% povidone-iodine
- 20% povidone-iodine
Correct Answer: 5% povidone-iodine
Q34. Mixing iodine antiseptics with which class of chemicals is generally NOT recommended due to neutralization or reaction?
Correct Answer: Reducing agents like sodium thiosulfate
Q35. Proper storage to minimize photodegradation of iodine solutions is to keep them in:
- Clear glass bottles exposed to sunlight
Correct Answer: Amber or opaque containers away from light
Q36. The term “iodophor” specifically refers to:
Correct Answer: An iodine complex with a solubilizing carrier that releases iodine slowly
Q37. Which characteristic is true for tincture of iodine compared with povidone-iodine?
Correct Answer: Higher alcohol content leading to greater irritation
Q38. In povidone-iodine, polyvinylpyrrolidone (povidone) primarily acts as a:
Correct Answer: Carrier and solubilizing agent for iodine
Q39. Which laboratory assay measures the rate at which an antiseptic kills organisms over time?
Correct Answer: Time-kill assay
Q40. A major disadvantage of tincture of iodine for routine skin antisepsis is:
Correct Answer: Its high potential to cause skin irritation and staining
Q41. Povidone-iodine displays virucidal activity that is especially effective against which type of viruses?
Correct Answer: Enveloped viruses
Q42. Which factor is LEAST likely to directly affect the in vitro antimicrobial efficacy of an iodine solution?
Correct Answer: Patient age
Q43. In an iodometric titration for iodine content, which chemical is typically used as the titrant?
Correct Answer: Sodium thiosulfate
Q44. Which formulation type of povidone-iodine tends to provide longer contact time at the application site?
Correct Answer: Gel formulation
Q45. For removing povidone-iodine stains from skin, a practical first-line method is:
Correct Answer: Cleaning with soap and water or alcohol swab
Q46. Blood and heavy proteinaceous matter affect povidone-iodine activity primarily by:
- Enhancing free iodine release
- Binding and inactivating free iodine
- Raising pH to alkaline levels
Correct Answer: Binding and inactivating free iodine
Q47. The term that describes an antiseptic’s ability to persist on skin and provide prolonged activity is:
- Bactericidal index
Correct Answer: Substantivity
Q48. Which salt is commonly added to iodine preparations to increase iodine solubility in water?
Correct Answer: Potassium iodide (KI)
Q49. One of the principal approved clinical uses of povidone-iodine is:
Correct Answer: Preoperative skin antisepsis
Q50. When handling concentrated iodine solutions in the lab, an important safety precaution is to:
Correct Answer: Wear gloves and eye protection to prevent skin and eye exposure
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