Definition and preparation of mouthwashes MCQs With Answer

Definition and preparation of mouthwashes MCQs With Answer — This concise introduction covers the definition, classification, formulation principles and practical aspects of mouthwash preparation for B.Pharm students. You will learn key topics such as active antiseptics (chlorhexidine, cetylpyridinium chloride), fluoride and essential oils, excipients (solvents, cosolvents, surfactants, preservatives, flavors), pH and stability issues, manufacturing steps (dissolution, filtration, pH adjustment, packaging) and quality control tests (organoleptic, pH, assay, microbial limits). Emphasis is on formulation strategy, safety, patient use and regulatory considerations to prepare you for examinations and practical lab work. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary definition of a mouthwash (oral rinse) in pharmaceutical terms?

• A liquid preparation intended for topical application to oral mucosa for cleansing, antisepsis or other therapeutic effects
• A liquid intended for ingestion to treat gastrointestinal disorders
• An injectable antiseptic for dental surgery
• A solid tablet that dissolves in saliva to freshen breath

Correct Answer: A liquid preparation intended for topical application to oral mucosa for cleansing, antisepsis or other therapeutic effects

Q2. Which classification correctly distinguishes therapeutic from cosmetic mouthwashes?

• Therapeutic mouthwashes contain active antimicrobial or fluoride agents; cosmetic mouthwashes mainly mask odor and improve taste
• Therapeutic mouthwashes are always alcohol-free; cosmetic ones always contain alcohol
• Therapeutic mouthwashes are only in tablet form; cosmetic ones are liquids
• Therapeutic mouthwashes are used for children only; cosmetic ones are for adults

Correct Answer: Therapeutic mouthwashes contain active antimicrobial or fluoride agents; cosmetic mouthwashes mainly mask odor and improve taste

Q3. Which of the following is a commonly used cationic antiseptic in mouthwash formulations?

• Chlorhexidine gluconate
• Sodium lauryl sulfate
• Sodium fluoride
• Benzoic acid

Correct Answer: Chlorhexidine gluconate

Q4. What is the typical concentration range of chlorhexidine used clinically in therapeutic mouthwashes?

• 0.12% to 0.2%
• 5% to 10%
• 0.001% to 0.01%
• 2% to 4%

Correct Answer: 0.12% to 0.2%

Q5. Which excipient is primarily used as a cosolvent to dissolve essential oils in mouthwash formulations?

• Polysorbate 20 (Tween 20)
• Sodium chloride
• Hydroxypropyl cellulose
• Magnesium stearate

Correct Answer: Polysorbate 20 (Tween 20)

Q6. Cetylpyridinium chloride (CPC) belongs to which chemical class?

• Quaternary ammonium compound
• Phenolic compound
• Fluoride salt
• Bisbiguanide

Correct Answer: Quaternary ammonium compound

Q7. Which preservative is commonly used in acidic mouthwash formulations?

• Sodium benzoate
• Paraffin oil
• Calcium carbonate
• Chlorhexidine

Correct Answer: Sodium benzoate

Q8. What is the role of a buffer system in mouthwash formulation?

• To maintain pH for active stability and oral compatibility
• To act as the main preservative
• To increase foaming during use
• To provide sweetness

Correct Answer: To maintain pH for active stability and oral compatibility

Q9. Which test is essential to assess microbial safety of a non-sterile mouthwash?

• Microbial limit test (total viable count and specified organisms)
• Sterility test under aseptic conditions
• Endotoxin assay
• Pyrogen test

Correct Answer: Microbial limit test (total viable count and specified organisms)

Q10. Which surfactant is often avoided or used cautiously in mouthwashes due to potential mucosal irritation and interference with some actives?

• Sodium lauryl sulfate (SLS)
• Polysorbate 80
• Cetylpyridinium chloride
• Glycerin

Correct Answer: Sodium lauryl sulfate (SLS)

Q11. For essential oil-containing mouthwashes, what formulation approach improves solubilization and clarity?

• Use of nonionic surfactants or cosolvents (e.g., polysorbates, ethanol)
• Addition of calcium ions
• Increasing water hardness
• Adding powdered calcium carbonate

Correct Answer: Use of nonionic surfactants or cosolvents (e.g., polysorbates, ethanol)

Q12. Which quality control parameter evaluates taste and appearance of a mouthwash?

• Organoleptic evaluation
• Assay by HPLC
• pH meter reading
• Viscosity measurement

Correct Answer: Organoleptic evaluation

Q13. Which ingredient is primarily responsible for caries prevention when included in mouthwashes?

• Fluoride (e.g., sodium fluoride, sodium monofluorophosphate)
• Menthol
• Alcohol
• Parabens

Correct Answer: Fluoride (e.g., sodium fluoride, sodium monofluorophosphate)

Q14. Which statement about alcohol in mouthwashes is correct?

• Alcohol acts as a solvent for hydrophobic agents and as a preservative/antiseptic adjunct
• Alcohol is never used because it destabilizes all actives
• Alcohol is the primary active fluoride source
• Alcohol is required for foaming action only

Correct Answer: Alcohol acts as a solvent for hydrophobic agents and as a preservative/antiseptic adjunct

Q15. Which packaging requirement is most appropriate for an essential oil-containing mouthwash?

• Amber or opaque, tight-sealing containers to protect from light and volatilization
• Perforated cardboard to allow evaporation
• Loose caps to allow gas exchange
• Metallic open-top jars

Correct Answer: Amber or opaque, tight-sealing containers to protect from light and volatilization

Q16. During manufacture, what is the correct sequence for preparing a typical mouthwash?

• Dissolve water-soluble actives, add cosolvents/surfactants and flavors, adjust pH, add preservative, filter and fill
• Sterilize final product then add active ingredients
• Mix oils and solids dry, then add to glass containers
• Add preservative last without pH adjustment

Correct Answer: Dissolve water-soluble actives, add cosolvents/surfactants and flavors, adjust pH, add preservative, filter and fill

Q17. Which mechanism best describes how chlorhexidine provides antibacterial action?

• Disruption of bacterial cell membranes leading to leakage of intracellular components
• Inhibition of bacterial DNA gyrase only
• Chelation of calcium in plaque without membrane effects
• Competitive inhibition of fluoride uptake

Correct Answer: Disruption of bacterial cell membranes leading to leakage of intracellular components

Q18. Why is mouthwash generally not classified as sterile product?

• It is a non-sterile topical preparation intended for mucosal application and not for aseptic sites
• Sterility is impossible in any liquid preparation
• Mouthwashes must contain live probiotic organisms
• Regulations forbid sterile labeling

Correct Answer: It is a non-sterile topical preparation intended for mucosal application and not for aseptic sites

Q19. What is the main advantage of alcohol-free mouthwash formulations?

• Reduced mucosal irritation and suitability for alcohol-averse patients
• Improved foaming compared to alcohol-containing products
• Increased antimicrobial potency from alcohol removal
• Guaranteed permanent flavor retention

Correct Answer: Reduced mucosal irritation and suitability for alcohol-averse patients

Q20. Which test evaluates the concentration of active ingredient in mouthwash during QC?

• Assay by validated analytical method (e.g., HPLC, UV spectrophotometry)
• Foam index test
• Viscosity by capillary flow
• Density gradient separation

Correct Answer: Assay by validated analytical method (e.g., HPLC, UV spectrophotometry)

Q21. For pediatric safety, what precaution is typically advised for mouthwash use in young children?

• Avoid routine use in children under 6 years due to swallowing risk
• Children should use adult-strength chlorhexidine daily
• Mouthwash must be heat-sterilized before use by children
• Children can safely swallow small volumes of fluoride mouthwash

Correct Answer: Avoid routine use in children under 6 years due to swallowing risk

Q22. What is the role of glycerin in mouthwash formulations?

• Humectant to improve mouthfeel and solubilize some actives
• Primary preservative
• Strong antiseptic agent
• Thickening agent to form gels only

Correct Answer: Humectant to improve mouthfeel and solubilize some actives

Q23. Which of the following is a common side effect associated with prolonged chlorhexidine mouthwash use?

• Extrinsic tooth staining
• Enamel erosion within one day
• Permanent loss of taste receptors within hours
• Immediate systemic toxicity at therapeutic doses

Correct Answer: Extrinsic tooth staining

Q24. Which buffer system is suitable for maintaining near-neutral pH in mouthwash?

• Phosphate buffer
• Hydrochloric acid alone
• Strong alkaline solution without buffer
• Concentrated acetic acid only

Correct Answer: Phosphate buffer

Q25. In formulation, which ingredient class most directly controls foaming of a mouthwash?

• Surfactants
• Preservatives
• Flavors
• Salts

Correct Answer: Surfactants

Q26. Which preservative efficacy test is relevant to mouthwash quality assurance?

• Challenge test (preservative efficacy test) to monitor microbial kill over time
• Acute oral toxicity test in rodents
• Chromatographic fingerprinting only
• Patch test on skin only

Correct Answer: Challenge test (preservative efficacy test) to monitor microbial kill over time

Q27. Which additive is used primarily to mask bitterness and improve patient acceptance?

• Sweeteners and flavoring agents (e.g., sorbitol, saccharin, mint flavor)
• Calcium carbonate for buffering
• Strong acids to denature taste buds
• Heavy metals to increase weight

Correct Answer: Sweeteners and flavoring agents (e.g., sorbitol, saccharin, mint flavor)

Q28. Why must compatibility studies be performed when formulating a mouthwash?

• To ensure no interactions occur between actives and excipients affecting stability or efficacy
• To increase the product’s water hardness intentionally
• To guarantee the product foams indefinitely
• To make the product sterile without filtration

Correct Answer: To ensure no interactions occur between actives and excipients affecting stability or efficacy

Q29. Which statement about fluoride mouthrinses is correct?

• Low-concentration daily rinses (e.g., 0.05% NaF) reduce caries risk; higher concentrations are for specific prescriptions
• Fluoride is only effective if swallowed
• All fluoride mouthrinses must contain alcohol
• Fluoride destabilizes all other mouthwash actives and cannot be combined

Correct Answer: Low-concentration daily rinses (e.g., 0.05% NaF) reduce caries risk; higher concentrations are for specific prescriptions

Q30. Which regulatory/documentation aspect is essential when releasing a batch of manufactured mouthwash?

• Batch record review including QC test results, stability data and certificate of analysis
• Only a visual inspection is required
• No documentation is needed for OTC mouthwashes
• A verbal approval by production staff is sufficient

Correct Answer: Batch record review including QC test results, stability data and certificate of analysis

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