Structure and uses of cetostearyl alcohol MCQs With Answer

Cetostearyl alcohol is a common pharmaceutical excipient composed of a mixture of cetyl (C16) and stearyl (C18) fatty alcohols. For B. Pharm students, understanding the structure, physicochemical properties and multifunctional uses—emulsifier, emollient, thickening agent and co-emulsifier—is essential for rational formulation design. Key topics include molecular structure and functional groups, chain length effects, melting point range, HLB behavior, typical concentrations in creams and lotions, compatibility with surfactants and preservatives, and pharmacopoeial/INCI nomenclature. You will also learn stability considerations, analytical methods (IR, GC, HPLC) and quality control tests used in pharmaceutical practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the correct description of cetostearyl alcohol?

• A pure single-chain fatty alcohol with 18 carbons
• A mixture of cetyl and stearyl fatty alcohols
• A polyethylene glycol derivative
• An anionic surfactant

Correct Answer: A mixture of cetyl and stearyl fatty alcohols

Q2. Which functional group is characteristic of cetostearyl alcohol?

• Carboxylic acid
• Aldehyde
• Primary alcohol
• Ether

Correct Answer: Primary alcohol

Q3. The INCI name commonly used for cetostearyl alcohol is:

• Cetyl palmitate
• Cetostearyl Alcohol or Cetyl Stearyl Alcohol
• Sodium lauryl sulfate
• Stearic acid

Correct Answer: Cetostearyl Alcohol or Cetyl Stearyl Alcohol

Q4. Typical pharmaceutical use of cetostearyl alcohol in topical creams is primarily as a:

• Preservative
• Co-emulsifier and emollient
• Active pharmaceutical ingredient
• pH indicator

Correct Answer: Co-emulsifier and emollient

Q5. Which property of cetostearyl alcohol helps to stabilize oil-in-water emulsions?

• High ionic charge
• Nonionic amphiphilic character and waxy consistency
• Strong acidity
• Volatility

Correct Answer: Nonionic amphiphilic character and waxy consistency

Q6. Cetostearyl alcohol is most compatible with which type of surfactant in topical formulations?

• Strongly cationic surfactants (e.g., benzalkonium chloride)
• Nonionic surfactants (e.g., polysorbates)
• Strongly anionic surfactants only
• Oxidizing surfactants

Correct Answer: Nonionic surfactants (e.g., polysorbates)

Q7. Which statement about the melting point of cetostearyl alcohol is most accurate?

• It is a low-melting liquid at room temperature
• It has a broad melting range usually around 50–60°C
• It sublimes below 20°C
• It decomposes at 30°C

Correct Answer: It has a broad melting range usually around 50–60°C

Q8. In emulsion formulations, cetostearyl alcohol is typically used at what concentration range?

• 50–70% w/w
• 0.01–0.1% w/w
• 1–10% w/w
• 90–100% w/w

Correct Answer: 1–10% w/w

Q9. Which analytical technique is commonly used to confirm the presence of long-chain alcohols like cetostearyl alcohol?

• FTIR spectroscopy
• Visible spectrophotometry at 450 nm
• Flame photometry for sodium
• pH meter measurement

Correct Answer: FTIR spectroscopy

Q10. The primary chemical difference between cetyl alcohol and stearyl alcohol is:

• One has an ester group, the other an alcohol
• Different chain length: cetyl C16 and stearyl C18
• Cetyl is aromatic while stearyl is aliphatic
• Stearyl is water-soluble while cetyl is not

Correct Answer: Different chain length: cetyl C16 and stearyl C18

Q11. Which formulation attribute is improved by adding cetostearyl alcohol to a cream?

• Decreased viscosity and runny texture
• Improved viscosity, body and skin feel
• Increased aqueous phase volatility
• Enhanced antimicrobial activity

Correct Answer: Improved viscosity, body and skin feel

Q12. Cetostearyl alcohol acts as an emollient by:

• Forming an occlusive layer reducing transepidermal water loss
• Increasing skin acidity dramatically
• Acting as a systemic analgesic
• Rapidly evaporating from skin

Correct Answer: Forming an occlusive layer reducing transepidermal water loss

Q13. Which regulatory designation commonly applies to cetostearyl alcohol in cosmetics and pharmaceuticals?

• Explosive substance
• INCI-listed cosmetic ingredient; generally recognized as safe excipient
• Controlled narcotic
• Radioactive compound

Correct Answer: INCI-listed cosmetic ingredient; generally recognized as safe excipient

Q14. Cetostearyl alcohol is most likely to be classified as which type of excipient?

• Surfactant and co-emulsifier
• Antioxidant
• Active antimicrobial
• Solvent for polar drugs

Correct Answer: Surfactant and co-emulsifier

Q15. A common advantage of using cetostearyl alcohol in creams is:

• It dramatically lowers formulation pH
• It provides structural stability and enhances consistency
• It increases water solubility of actives
• It acts as an oxidizing preservative

Correct Answer: It provides structural stability and enhances consistency

Q16. Which test is important in quality control of cetostearyl alcohol to detect free fatty acids or contaminants?

• Acid value or saponification value determination
• Measuring turbidity at 700 nm
• Determination of chloride by titration
• Flame test for potassium

Correct Answer: Acid value or saponification value determination

Q17. When designing an oil-in-water cream, cetostearyl alcohol is often combined with:

• Anionic surfactants exclusively
• Nonionic emulsifiers such as polysorbate and sorbitan esters
• Strong acids to neutralize it
• Only hydrophilic polymers

Correct Answer: Nonionic emulsifiers such as polysorbate and sorbitan esters

Q18. Which property of cetostearyl alcohol contributes to its effect as a thickening agent?

• High water solubility
• Waxy solid nature and crystalline network formation
• Strong ionic charge creating electrostatic gel
• Low molecular weight and volatility

Correct Answer: Waxy solid nature and crystalline network formation

Q19. In stability studies, excessive heating of cetostearyl-containing cream may cause:

• Permanent solidification of water
• Phase separation and coalescence if emulsifier balance is disturbed
• Instant sterilization and extended shelf life
• Loss of fragrance only

Correct Answer: Phase separation and coalescence if emulsifier balance is disturbed

Q20. Which statement about the solubility of cetostearyl alcohol is true?

• It is freely soluble in water
• Sparingly soluble in water, soluble in oils and some organic solvents
• Only soluble in strong acids
• Soluble in saline but not in organic solvents

Correct Answer: Sparingly soluble in water, soluble in oils and some organic solvents

Q21. Which test method would help quantify individual components (cetyl vs stearyl) in cetostearyl alcohol?

• Gas chromatography (GC) or GC-MS after derivatization
• pH titration
• Simple visual inspection
• Colorimetric starch-iodine test

Correct Answer: Gas chromatography (GC) or GC-MS after derivatization

Q22. Cetostearyl alcohol can react with acids to form esters; this transformation is called:

• Saponification
• Esterification
• Hydrogenation
• Halogenation

Correct Answer: Esterification

Q23. Which of the following is a potential disadvantage of using too high concentration of cetostearyl alcohol in a topical product?

• Excessive greasiness and heavy skin feel
• Significant antimicrobial action
• Increased water evaporation increasing dryness
• Becoming fully aqueous solution

Correct Answer: Excessive greasiness and heavy skin feel

Q24. Cetostearyl alcohol contributes to which HLB-related effect in emulsions?

• Acts as a high-HLB hydrophilic surfactant only
• Acts as a low-HLB oily co-emulsifier modifying interfacial film
• Neutralizes HLB of water
• Destroys surfactant action completely

Correct Answer: Acts as a low-HLB oily co-emulsifier modifying interfacial film

Q25. When stored improperly, cetostearyl alcohol may show which instability sign?

• Polymerization to long chains
• Rancidity from residual fatty acids and odor development
• Instant dissolution in air
• Reduction in carbon number

Correct Answer: Rancidity from residual fatty acids and odor development

Q26. Which is the main reason cetostearyl alcohol is preferred over pure cetyl or stearyl alcohol in some formulations?

• Lower cost, combined properties and improved consistency
• It is a powerful preservative
• It is water-soluble while the others are not
• It has aromatic rings improving fragrance

Correct Answer: Lower cost, combined properties and improved consistency

Q27. Cetostearyl alcohol is classified pharmaceutically as which type of excipient for ointments?

• Hydrophilic gel former
• Hydrophobic base modifier and emollient
• Systemic steroid enhancer
• Oral disintegrant

Correct Answer: Hydrophobic base modifier and emollient

Q28. What precaution is important when using cetostearyl alcohol with cationic active ingredients?

• No precaution; they always form stable complexes
• Potential incompatibility due to adsorption or interaction; compatibility testing needed
• They form salts that enhance solubility invariably
• Cetostearyl inactivates cationic actives by oxidation

Correct Answer: Potential incompatibility due to adsorption or interaction; compatibility testing needed

Q29. Which pharmacopoeial parameter is commonly specified for cetostearyl alcohol quality?

• Radioactivity limit
• Melting range, acid value and identification tests
• Chloride content only
• Optical rotation exclusively

Correct Answer: Melting range, acid value and identification tests

Q30. In emulsification, cetostearyl alcohol primarily affects:

• Drug’s chemical structure
• Interfacial film strength and cream viscosity
• Sterilization requirements
• Salt formation with alkalis

Correct Answer: Interfacial film strength and cream viscosity

Q31. Which of the following is a correct IUPAC-related statement for cetostearyl alcohol?

• It is a single chemical with a single IUPAC name
• It is a mixture; individual components have IUPAC names (hexadecanol, octadecanol)
• It has no chemical name and is only trade-named
• It is an ether, so no alcohol nomenclature applies

Correct Answer: It is a mixture; individual components have IUPAC names (hexadecanol, octadecanol)

Q32. Which sensory property of a topical product is enhanced by cetostearyl alcohol?

• Sandy texture and graininess
• Silky, non-greasy or semi-occlusive skin feel depending on concentration
• Extremely sticky residue
• Sharp cooling sensation

Correct Answer: Silky, non-greasy or semi-occlusive skin feel depending on concentration

Q33. For sterile ophthalmic ointments, using cetostearyl alcohol would be:

• Common practice without further validation
• Possible but requires strict purification and compatibility/stability validation
• Impossible because it’s explosive
• Mandated by pharmacopeia for all ophthalmic bases

Correct Answer: Possible but requires strict purification and compatibility/stability validation

Q34. Which safety statement about topical use of cetostearyl alcohol is most accurate?

• Highly toxic and systemically absorbed at low doses
• Generally safe topically; may cause mild irritation in sensitive individuals
• Always causes severe allergic reactions
• Must not be used on human skin

Correct Answer: Generally safe topically; may cause mild irritation in sensitive individuals

Q35. Which manufacturing consideration is important when melting cetostearyl alcohol into an oil phase?

• Heat above decomposition temperature (>200°C) to ensure mixing
• Melt gently below decomposition temperature, typically 60–70°C, with controlled mixing to avoid oxidation
• Keep at room temperature and stir vigorously
• Use strong acids to dissolve it

Correct Answer: Melt gently below decomposition temperature, typically 60–70°C, with controlled mixing to avoid oxidation

Q36. Cetostearyl alcohol can be used to improve the stability of which type of emulsion?

• Only water-in-oil emulsions, never oil-in-water
• Both oil-in-water and water-in-oil emulsions as a co-emulsifier depending on formulation
• Only foams
• Only intravenous emulsions

Correct Answer: Both oil-in-water and water-in-oil emulsions as a co-emulsifier depending on formulation

Q37. What is the expected effect of cetostearyl alcohol on the rheology of a lotion?

• It decreases viscosity making the lotion runny
• It increases viscosity and imparts body to the lotion
• It causes the lotion to become gaseous
• It converts the lotion into a crystalline solid instantly

Correct Answer: It increases viscosity and imparts body to the lotion

Q38. Which is an appropriate preservative compatibility consideration when formulating with cetostearyl alcohol?

• Preservatives always become inactive in its presence
• Check solubility and partitioning of preservative between phases as cetostearyl can partition preservatives into oil phase
• All preservatives are fully miscible and unaffected
• Preservatives are unnecessary when cetostearyl alcohol is present

Correct Answer: Check solubility and partitioning of preservative between phases as cetostearyl can partition preservatives into oil phase

Q39. Which is a typical organoleptic description of cetostearyl alcohol at room temperature?

• Clear, volatile liquid with strong odor
• White to pale yellow waxy solid with mild fatty odor
• Bright red powder
• Dark brown syrupy liquid

Correct Answer: White to pale yellow waxy solid with mild fatty odor

Q40. The role of cetostearyl alcohol in an ointment base like white soft paraffin is to:

• Act as the main hydrophilic phase
• Modify texture, improve spreadability and skin feel
• Reduce oil content to zero
• Make the base water-miscible

Correct Answer: Modify texture, improve spreadability and skin feel

Q41. Which degradation pathway is most likely for cetostearyl alcohol on prolonged exposure to light and air?

• Polymerization to polyethylene
• Oxidation of residual unsaturations or impurities producing off-odors
• Becoming ionic and water-soluble
• Spontaneous conversion to amino alcohols

Correct Answer: Oxidation of residual unsaturations or impurities producing off-odors

Q42. In cold process emulsification, using cetostearyl alcohol without heat will likely result in:

• Immediate homogeneous emulsion
• Poor dissolution into oil phase and unstable emulsion unless pre-melted
• Complete solubilization in water
• Instant sterilization

Correct Answer: Poor dissolution into oil phase and unstable emulsion unless pre-melted

Q43. Which excipient class does cetostearyl alcohol NOT belong to?

• Emollient
• Co-emulsifier
• Hydrophilic solvent for polar actives
• Viscosity modifier

Correct Answer: Hydrophilic solvent for polar actives

Q44. Which analytical identification test specifically indicates the presence of long-chain alcohols?

• Molisch test for carbohydrates
• FTIR peak around 3300 cm−1 for O–H and C–H stretching in long chain
• Biuret test for proteins
• Starch iodine blue complex

Correct Answer: FTIR peak around 3300 cm−1 for O–H and C–H stretching in long chain

Q45. When formulating an aqueous lotion, adding cetostearyl alcohol without adequate emulsifier can cause:

• Enhanced solubilization of hydrophilic drugs
• Phase separation and waxy particles in the lotion
• Complete clarification of the lotion
• Increased microbial resistance without preservative

Correct Answer: Phase separation and waxy particles in the lotion

Q46. Which raw material attribute should be checked on the certificate of analysis for cetostearyl alcohol?

• Color, melting point range, acid value and assay
• Radio frequency emission
• Number of aromatic rings
• Presence of transition metals only

Correct Answer: Color, melting point range, acid value and assay

Q47. Which is an appropriate storage condition for cetostearyl alcohol raw material?

• Open to air at high temperature and sunlight
• Cool, dry, well-sealed container away from light to minimize oxidation
• Immersed in water
• Stored with strong oxidizers

Correct Answer: Cool, dry, well-sealed container away from light to minimize oxidation

Q48. Which derivative formed from cetostearyl alcohol is commonly used as a PEGylated emulsifier?

• Cetostearyl sulfate
• Cetostearyl polyethylene glycol ether (e.g., cetostearyl PEG-100 ether)
• Cetostearyl chloride
• Cetostearyl nitrate

Correct Answer: Cetostearyl polyethylene glycol ether (e.g., cetostearyl PEG-100 ether)

Q49. In topical delivery, cetostearyl alcohol may influence drug release by:

• Transforming the active into a gas
• Modifying the matrix and occlusivity, which can slow or alter release kinetics
• Instantly increasing systemic absorption of all actives
• Removing the drug from formulation completely

Correct Answer: Modifying the matrix and occlusivity, which can slow or alter release kinetics

Q50. Which practice ensures reliable performance of cetostearyl alcohol in a new formulation?

• Ignoring compatibility testing because it is always inert
• Performing pre-formulation compatibility, stability and preservative efficacy tests with intended actives and excipients
• Assuming any supplier material is identical and skipping quality checks
• Using it at extremely high concentrations (≥80%) for all formulations

Correct Answer: Performing pre-formulation compatibility, stability and preservative efficacy tests with intended actives and excipients

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com