Preparation of pastes and creams MCQs With Answer

As B.Pharm students, mastering the preparation of pastes and creams is essential for topical formulation design, manufacturing, and quality control. This introduction highlights key concepts such as bases (hydrocarbon, absorption, water‑washable, water‑soluble), emulsions (O/W, W/O), excipients (emulsifiers, humectants, stiffening agents), methods (fusion, levigation, homogenization), and critical parameters like rheology, stability, preservative selection, and percutaneous absorption. Understanding particle size, occlusivity, HLB theory, and analytical tests (viscosity, spreadability, microbial limits) enables rational formulation and troubleshooting. Practical knowledge bridges theory and industry practice for safe, effective topical products. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which statement best differentiates pastes from creams?

• Pastes are less viscous and contain high water content compared to creams.
• Pastes contain a high proportion of insoluble solids and are stiffer than creams.
• Creams always are water‑in‑oil emulsions while pastes are oil‑in‑water.
• Pastes are intended for systemic delivery whereas creams are only cosmetic.

Correct Answer: Pastes contain a high proportion of insoluble solids and are stiffer than creams.

Q2. Which cream base is most occlusive and useful for dry, scaly lesions?

• Oil‑in‑water (O/W) cream
• Water‑soluble cream
• Water‑in‑oil (W/O) cream
• Hydrophilic ointment

Correct Answer: Water‑in‑oil (W/O) cream

Q3. The fusion method in semisolid preparation is best described as:

• Incorporating dry powders into a cold vehicle without heating.
• Melting and mixing miscible solid and liquid components followed by cooling.
• Shearing components at high speed to reduce particle size without heat.
• Preparing an emulsion by adding water to surfactant slowly.

Correct Answer: Melting and mixing miscible solid and liquid components followed by cooling.

Q4. Which HLB value is generally required for an oil‑in‑water (O/W) emulsifier?

• HLB 3–6
• HLB 8–18
• HLB 0–2
• HLB 20–30

Correct Answer: HLB 8–18

Q5. What is the primary purpose of levigation during paste or cream manufacture?

• To sterilize the formulation before packaging.
• To chemically preserve the components.
• To reduce particle size of insoluble solids and improve wettability.
• To convert W/O to O/W emulsions.

Correct Answer: To reduce particle size of insoluble solids and improve wettability.

Q6. Carbomers are commonly used in creams because they:

• Act as strong anionic preservatives.
• Function as pH‑dependent gelling agents requiring neutralization.
• Are nonionic surfactants that form W/O emulsions.
• Provide occlusivity by forming a hydrophobic film.

Correct Answer: Function as pH‑dependent gelling agents requiring neutralization.

Q7. Which preservative is widely used in creams for broad antifungal and antibacterial activity?

• Methylparaben and propylparaben combination
• Benzalkonium chloride alone
• Pure glycerin at 5% concentration
• Sodium chloride as preservative

Correct Answer: Methylparaben and propylparaben combination

Q8. Spreadability testing of a cream primarily assesses:

• The microbial load after storage.
• The extrudability from a tube.
• The ease with which a formulation spreads on the skin.
• The pH change under stress conditions.

Correct Answer: The ease with which a formulation spreads on the skin.

Q9. Phase inversion in emulsions is commonly triggered by:

• Adding solid fillers to the external phase only.
• Changing temperature, composition, or surfactant HLB balance.
• Decreasing water activity by adding humectants.
• Sterilizing by filtration.

Correct Answer: Changing temperature, composition, or surfactant HLB balance.

Q10. How does particle size of dispersed solids affect sensory properties of a paste?

• Larger particles reduce grittiness and improve smoothness.
• Smaller particles increase grittiness perceptibly.
• Smaller particles reduce grittiness and enhance smooth feel.
• Particle size has no effect on sensory properties.

Correct Answer: Smaller particles reduce grittiness and enhance smooth feel.

Q11. Increasing occlusivity of a topical cream generally causes which effect on drug absorption?

• Decreases hydration and decreases absorption.
• Has no effect on percutaneous absorption.
• Enhances skin hydration and often increases absorption.
• Prevents drug release from the base completely.

Correct Answer: Enhances skin hydration and often increases absorption.

Q12. Which cream type is most easily removed with plain water?

• Water‑in‑oil (W/O) cream
• Ointment base
• Oil‑in‑water (O/W) cream
• Hydrocarbon base

Correct Answer: Oil‑in‑water (O/W) cream

Q13. Which excipient is commonly used as a humectant in creams and pastes?

• Stearic acid
• Glycerin
• Beeswax
• Cetostearyl alcohol

Correct Answer: Glycerin

Q14. For achieving a fine, uniform emulsion during manufacture of creams, which equipment is most appropriate?

• Low‑speed magnetic stirrer
• Homogenizer or high‑shear mixer
• Simple mortar and pestle only
• Vacuum oven

Correct Answer: Homogenizer or high‑shear mixer

Q15. The continental (dry gum) emulsification method is characterized by:

• Addition of oil to water with continuous stirring.
• Mixing gum with oil first, then adding water rapidly.
• Preparing an emulsion by phase inversion at high temperature.
• Dispersion of powders into molten base only.

Correct Answer: Mixing gum with oil first, then adding water rapidly.

Q16. The antimicrobial efficacy of parabens is most affected by which parameter?

• Presence of heavy metals only
• pH of the formulation
• Color of the packaging
• Ambient light exclusively

Correct Answer: pH of the formulation

Q17. Which antioxidant is commonly used to prevent oxidation of unsaturated oils in creams?

• Butylated hydroxytoluene (BHT)
• Chlorocresol
• Glyceryl monostearate
• Sodium lauryl sulfate

Correct Answer: Butylated hydroxytoluene (BHT)

Q18. Which analytical instrument is typically used to measure the viscosity of creams?

• UV‑Vis spectrophotometer
• Brookfield viscometer
• Flame photometer
• Gas chromatograph

Correct Answer: Brookfield viscometer

Q19. Which of the following is a commonly used permeation enhancer for topical formulations?

• Sucrose
• Dimethyl sulfoxide (DMSO)
• Calcium carbonate
• Silicon dioxide

Correct Answer: Dimethyl sulfoxide (DMSO)

Q20. Emulsifying wax in a cream formulation typically produces which washability property?

• Hydrophobic, water‑insoluble product
• Water‑washable (O/W) cream
• Anhydrous paste with no water content
• Solid bar for topical application

Correct Answer: Water‑washable (O/W) cream

Q21. A low HLB surfactant (HLB 3–6) is most suitable for stabilizing which emulsion type?

• Oil‑in‑water (O/W)
• Water‑in‑oil (W/O)
• Microemulsion with high water content
• Hydroalcoholic aqueous solution

Correct Answer: Water‑in‑oil (W/O)

Q22. Cetyl alcohol added to a cream formulation primarily acts as a:

• Preservative
• Stiffening agent and co‑emulsifier
• Primary surfactant for O/W emulsions
• Solvent for active drug molecules

Correct Answer: Stiffening agent and co‑emulsifier

Q23. Which preservative tends to be inactivated by anionic surfactants and detergents?

• Parabens
• Benzalkonium chloride (a cationic quaternary ammonium)
• Sodium benzoate
• Phenoxyethanol

Correct Answer: Benzalkonium chloride (a cationic quaternary ammonium)

Q24. Extrudability testing of a cream evaluates:

• How much drug is released in vitro over 24 hours.
• The ease or force required to extrude the product from a tube.
• The color stability under UV light.
• The antimicrobial efficacy against fungi.

Correct Answer: The ease or force required to extrude the product from a tube.

Q25. Which microbial quality control test is essential for creams containing significant water?

• Assay of active ingredient only
• Total aerobic microbial count and absence of specific pathogens
• Determination of melting point
• Particle size distribution only

Correct Answer: Total aerobic microbial count and absence of specific pathogens

Q26. A levigating agent commonly used when triturating insoluble powders into ointment bases is:

• Propylene glycol or glycerin
• Distilled water only
• Liquid paraffin exclusively
• Calcium hydroxide

Correct Answer: Propylene glycol or glycerin

Q27. High water content in creams primarily increases the risk of:

• Enhanced chemical stability and no microbial growth
• Microbial contamination unless adequate preservatives are used
• Reduced skin hydration compared to anhydrous bases
• Instant phase inversion to ointments

Correct Answer: Microbial contamination unless adequate preservatives are used

Q28. To protect unsaturated oils in creams from rancidity, formulators commonly add:

• Chelating agents alone without antioxidants
• Antioxidants such as BHT or tocopherols
• High concentrations of sugar
• Neutral salts like sodium chloride

Correct Answer: Antioxidants such as BHT or tocopherols

Q29. Typical concentration range for methylparaben when used as a preservative in creams is approximately:

• 0.001–0.005%
• 0.1–0.3%
• 5–10%
• 20–30%

Correct Answer: 0.1–0.3%

Q30. Which analytical technique is useful for detecting physical‑chemical incompatibilities in cream formulations during preformulation?

• Differential scanning calorimetry (DSC)
• Simple organoleptic inspection only
• Paper chromatography exclusively
• pH paper test without further analysis

Correct Answer: Differential scanning calorimetry (DSC)

Download