Preparation of tonics and bleaches MCQs With Answer

Preparation of tonics and bleaches is a focused topic in the Herbal Cosmetics syllabus that combines traditional botanical knowledge with modern formulation science. This quiz set targets M.Pharm students, reviewing principles of formulation, selection of active herbal and chemical bleaching agents, stability considerations, safety and regulatory aspects, and evaluation methods. Questions emphasize mechanisms of action (e.g., inhibition of tyrosinase), excipient roles (vehicles, preservatives, antioxidants, chelators), practical formulation steps, incompatibilities, and standard tests used in development and QC. Use these MCQs to consolidate conceptual understanding and prepare for practical formulation problems and viva voce examinations in cosmeceutical product development.

Q1. Which statement best describes the primary difference between a cosmetic tonic and a skin bleaching preparation?

• A tonic is intended to alter skin pigmentation permanently while a bleach cleanses the skin
• A tonic primarily conditions or stimulates (e.g., scalp or skin), whereas a bleaching preparation is designed to reduce melanin or lighten hyperpigmentation
• A tonic always contains alcohol but bleaches never contain active ingredients
• Tonic formulations are sterile whereas bleaches are non-sterile

Correct Answer: A tonic primarily conditions or stimulates (e.g., scalp or skin), whereas a bleaching preparation is designed to reduce melanin or lighten hyperpigmentation

Q2. What is the principal biochemical mechanism by which hydroquinone produces skin lightening?

• Stimulates melanocyte proliferation to dilute pigment
• Accelerates epidermal turnover without affecting melanin synthesis
• Inhibits tyrosinase and interferes with melanin synthesis in melanocytes
• Acts as a physical barrier preventing UV penetration

Correct Answer: Inhibits tyrosinase and interferes with melanin synthesis in melanocytes

Q3. Which concentration range of hydroquinone is commonly used in OTC topical skin-bleaching products in many jurisdictions?

• 0.01–0.1%
• 0.5–1%
• 2–4%
• 10–15%

Correct Answer: 2–4%

Q4. Kojic acid, a popular skin-lightening agent from fungal fermentation, acts primarily by which mechanism?

• Blocking UV radiation through physical scattering
• Chelating copper at the active site of tyrosinase and inhibiting the enzyme
• Promoting melanosome transfer to keratinocytes
• Irreversibly destroying melanocytes

Correct Answer: Chelating copper at the active site of tyrosinase and inhibiting the enzyme

Q5. Arbutin used in herbal-derivative bleaches is best described as:

• A synthetic peroxide used to remove pigment
• A glycosylated hydroquinone (natural hydroquinone derivative) that inhibits melanin synthesis
• A volatile oil that exfoliates the stratum corneum
• A proteolytic enzyme that digests melanin

Correct Answer: A glycosylated hydroquinone (natural hydroquinone derivative) that inhibits melanin synthesis

Q6. What pH range is generally considered optimal for formulating hydroquinone-containing topical preparations to maximize stability?

• pH 2.0–3.0
• pH 4.0–6.0
• pH 7.0–8.5
• pH 9.0–10.5

Correct Answer: pH 4.0–6.0

Q7. In bleaching or tonic formulations, what is the main role of chelating agents such as disodium EDTA?

• Act as primary preservatives against microbes
• Enhance fragrance stability by binding volatile molecules
• Sequester metal ions that catalyze oxidation of actives and discoloration
• Raise formulation pH for better skin penetration

Correct Answer: Sequester metal ions that catalyze oxidation of actives and discoloration

Q8. Why are antioxidants (e.g., ascorbic acid, tocopherol) commonly included in bleach and tonic formulations?

• To increase product viscosity
• To prevent oxidative degradation of active whitening agents and extend shelf life
• To enhance foaming and cleansing action
• To neutralize the product odor

Correct Answer: To prevent oxidative degradation of active whitening agents and extend shelf life

Q9. Which vehicle is most commonly used for alcohol-based hair tonics to dissolve botanical actives and provide a cooling/antiseptic effect?

• Mineral oil
• Isopropyl myristate
• Ethanol (ethanol/water mix)
• Squalane

Correct Answer: Ethanol (ethanol/water mix)

Q10. For aqueous herbal tonics with broad-spectrum activity, which preservative is often selected due to efficacy and regulatory acceptance?

• Formaldehyde
• Phenoxyethanol
• Mercuric chloride
• Vitamin C (ascorbic acid) alone

Correct Answer: Phenoxyethanol

Q11. Which chronic adverse effect has been associated with prolonged topical hydroquinone use?

• Exogenous ochronosis (paradoxical hyperpigmentation and skin darkening)
• Permanent loss of hair follicles
• Systemic immunosuppression leading to infections
• Immediate photosensitivity without pigmentary change

Correct Answer: Exogenous ochronosis (paradoxical hyperpigmentation and skin darkening)

Q12. Which regulatory statement is true regarding hydroquinone in many countries?

• Hydroquinone is universally approved for over-the-counter use without limits
• Hydroquinone is banned or restricted in several countries and may be prescription-only due to safety concerns
• Hydroquinone is only used in oral pharmaceuticals, not topical products
• Hydroquinone requires no stability testing before marketing

Correct Answer: Hydroquinone is banned or restricted in several countries and may be prescription-only due to safety concerns

Q13. Which analytical method is commonly used to quantify melanin reduction or whitening efficacy in clinical/formulation studies?

• Reflectance spectrophotometry or colorimetry (e.g., Mexameter, reflectance measurements)
• Gram staining of skin scrapings
• Chirality analysis by polarimetry
• Gas chromatography-flame ionization detection (GC-FID)

Correct Answer: Reflectance spectrophotometry or colorimetry (e.g., Mexameter, reflectance measurements)

Q14. Which ingredient commonly used in tonics acts as both a humectant and a penetration enhancer to improve delivery of actives?

• Clay
• Propylene glycol
• Calcium carbonate
• Sodium lauryl sulfate

Correct Answer: Propylene glycol

Q15. Which combination is known to be chemically incompatible in topical acne/bleaching regimens and can cause increased oxidation or inactivation of actives?

• Hydroquinone combined with benzoyl peroxide
• Kojic acid combined with glycerin
• Arbutin combined with water
• Niacinamide combined with emollients

Correct Answer: Hydroquinone combined with benzoyl peroxide

Q16. Which active commonly used in bleaches is particularly sensitive to light and requires opaque packaging to maintain stability?

• Zinc oxide
• Hydroquinone
• Shea butter
• Magnesium sulfate

Correct Answer: Hydroquinone

Q17. When formulating an oil-in-water lotion tonic, which class of emulsifier is generally preferred for good skin feel and compatibility with herbal actives?

• Anionic surfactants like sodium lauryl sulfate
• Nonionic emulsifiers such as polysorbates or sorbitan esters
• Cationic quaternary ammonium salts as primary emulsifiers
• Metal soaps only (e.g., aluminum stearate)

Correct Answer: Nonionic emulsifiers such as polysorbates or sorbitan esters

Q18. Which herbal ingredient is classically used in hair tonics for promoting hair health and commonly included in M.Pharm herbal tonic formulations?

• Bhringraj (Eclipta alba) extract
• Penicillin
• Synthetic retinoic acid
• Potassium permanganate

Correct Answer: Bhringraj (Eclipta alba) extract

Q19. What is the usual preparation method for alcohol-based herbal hair tonics to preserve volatile actives and avoid thermal degradation?

• Hot homogenization at >80°C
• Cold or room-temperature mixing (cold process)
• Autoclaving the final product
• Spray-drying the tonic into a powder

Correct Answer: Cold or room-temperature mixing (cold process)

Q20. Which human test is commonly used during development to assess skin sensitization or irritation potential of a topical tonic or bleach?

• Acute oral toxicity (LD50) in rodents
• Human Repeat Insult Patch Test (HRIPT)
• In vitro dissolution testing for tablets
• Aerobic plate count of the product

Correct Answer: Human Repeat Insult Patch Test (HRIPT)

Download