Introduction: Excipients used in semisolid dosage forms are non‑active ingredients that determine the performance of ointments, creams and gels. For B.Pharm students it is essential to understand emollients, humectants, emulsifiers, gelling agents, preservatives, antioxidants, penetration enhancers and rheology modifiers. Proper excipient selection affects stability, pH, viscosity, spreadability, percutaneous absorption and formulation compatibility. Knowledge of bases (oleaginous, absorption, water‑removable, water‑soluble), HLB concepts, microbial protection and packaging is critical for safe, effective topical products. This concise guide prepares you for formulation decisions and quality control considerations. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary role of excipients in semisolid dosage forms?
- Only to provide color and fragrance
- To act as the therapeutic active ingredient
- To enhance drug stability, appearance and application
- To sterilize the formulation
Correct Answer: To enhance drug stability, appearance and application
Q2. Which of the following is an occlusive emollient commonly used in ointments?
- Glycerin
- Petrolatum
- Polysorbate 80
- Carbomer
Correct Answer: Petrolatum
Q3. Which excipient functions primarily as a humectant in topical semisolids?
- Methylparaben
- Lanolin
- Glycerin
- Bentonite
Correct Answer: Glycerin
Q4. Which emulsifier is commonly used to formulate oil-in-water creams?
- Span 60 (Sorbitan stearate)
- Polysorbate 80 (Tween 80)
- White petrolatum
- Carbopol 940
Correct Answer: Polysorbate 80 (Tween 80)
Q5. Which gelling agent is a synthetic acrylic polymer widely used in topical gels?
- Xanthan gum
- Carbomer (Carbopol)
- Sodium alginate
- Tragacanth
Correct Answer: Carbomer (Carbopol)
Q6. Which excipient is primarily used to increase viscosity of aqueous semisolids?
- Butylated hydroxytoluene (BHT)
- Carbomer
- Propylene glycol
- Lanolin alcohol
Correct Answer: Carbomer
Q7. Which system is commonly used to maintain pH and buffer topical semisolids?
- Phosphate buffer
- Benzalkonium chloride
- Sorbitan monostearate
- White soft paraffin
Correct Answer: Phosphate buffer
Q8. Which preservative is widely used for broad‑spectrum antimicrobial protection in creams?
- Methylparaben
- Carbomer
- Petrolatum
- Xanthan gum
Correct Answer: Methylparaben
Q9. Which antioxidant is suitable for protecting oils in semisolid formulations?
- Ascorbic acid (water‑soluble)
- Butylated hydroxytoluene (BHT)
- Sodium lauryl sulfate
- Polysorbate 20
Correct Answer: Butylated hydroxytoluene (BHT)
Q10. What is the main purpose of a penetration enhancer in topical products?
- To act as a preservative
- To decrease drug solubility
- To increase percutaneous absorption of the drug
- To neutralize drug activity
Correct Answer: To increase percutaneous absorption of the drug
Q11. A high Hydrophilic‑Lipophilic Balance (HLB) value indicates an emulsifier is more suitable for which type of emulsion?
- Water-in-oil (W/O)
- Oil-in-water (O/W)
- Anhydrous ointment
- Solid dispersion
Correct Answer: Oil-in-water (O/W)
Q12. Which semisolid base is considered water‑washable and readily removed from skin with water?
- Petrolatum (oleaginous base)
- Absorption base
- Oil-in-water cream (water‑washable)
- Anhydrous lanolin
Correct Answer: Oil-in-water cream (water‑washable)
Q13. Which polymer forms thermoreversible gels and is often used for topical and ophthalmic gels?
- Carbomer 934
- Poloxamer (Pluronic) F127
- Hydroxypropyl methylcellulose (HPMC)
- Calcium alginate
Correct Answer: Poloxamer (Pluronic) F127
Q14. Which of the following acts both as a solvent and a penetration enhancer in topical formulations?
- Xanthan gum
- Propylene glycol
- Methylparaben
- White soft paraffin
Correct Answer: Propylene glycol
Q15. Which excipient is used as a chelating agent to improve preservative efficacy by binding metal ions?
- EDTA (disodium edetate)
- Carbomer
- Lanolin
- Glycerin
Correct Answer: EDTA (disodium edetate)
Q16. Which excipient imparts thixotropic behavior and viscosity to topical gels and creams?
- Bentonite
- Sodium chloride
- Methylparaben
- Polysorbate 80
Correct Answer: Bentonite
Q17. Which solvent is frequently used to dissolve poorly water‑soluble drugs in semisolid formulations?
- Water
- Propylene glycol
- Carbomer dispersion
- Sodium lauryl sulfate
Correct Answer: Propylene glycol
Q18. Which excipient is well known to cause contact allergy in some patients?
- Petrolatum
- Lanolin
- Carbomer
- Xanthan gum
Correct Answer: Lanolin
Q19. Which formulation property describes the ease with which a semisolid spreads over the skin?
- Viscosity
- Spreadability
- pH
- Preservative efficacy
Correct Answer: Spreadability
Q20. Which parameter is critical for both preservative efficacy and chemical stability of many topical actives?
- Ambient light only
- Package color only
- pH of the formulation
- Ingredient odor
Correct Answer: pH of the formulation
Q21. Which of the following is a nonionic emulsifier commonly used in topical systems?
- Benzalkonium chloride
- Polysorbate 80 (Tween 80)
- Sodium lauryl sulfate
- EDTA
Correct Answer: Polysorbate 80 (Tween 80)
Q22. Which base type is most greasy and provides strong occlusion to reduce transepidermal water loss?
- Oleaginous (petrolatum) base
- Oil-in-water cream
- Water-soluble PEG base
- Hydrophilic gel
Correct Answer: Oleaginous (petrolatum) base
Q23. Which natural polymer is commonly used as a gelling agent in topical formulations?
- Carbomer
- Xanthan gum
- Poloxamer 407
- Butylated hydroxytoluene
Correct Answer: Xanthan gum
Q24. Which excipient is a widely used humectant and solvent that also stabilizes aqueous systems?
- Lanolin
- Glycerin
- Petrolatum
- Polysorbate 60
Correct Answer: Glycerin
Q25. Which preservative is known to be inactivated by anionic surfactants and soaps?
- Methylparaben
- Benzalkonium chloride (a quaternary ammonium compound)
- Phenoxyethanol
- EDTA
Correct Answer: Benzalkonium chloride (a quaternary ammonium compound)
Q26. Which thermosensitive polymer forms gels upon warming and is used in topical delivery?
- Carbomer 940
- Poloxamer 407 (Pluronic F127)
- Xanthan gum
- Sodium lauryl sulfate
Correct Answer: Poloxamer 407 (Pluronic F127)
Q27. Which excipient is commonly used to adjust viscosity in hydroalcoholic gels for topical use?
- Carbomer
- Butylated hydroxytoluene
- Lanolin
- White soft paraffin
Correct Answer: Carbomer
Q28. Which factor typically increases percutaneous absorption of a drug from a semisolid?
- Decreasing skin hydration (dry skin)
- Occlusion that increases skin hydration
- Using an inert opaque container
- Lowering drug concentration to trace levels
Correct Answer: Occlusion that increases skin hydration
Q29. Which antioxidant is water‑soluble and sometimes used in aqueous semisolid formulations?
- Butylated hydroxytoluene (BHT)
- Ascorbic acid (Vitamin C)
- White soft paraffin
- Polysorbate 80
Correct Answer: Ascorbic acid (Vitamin C)
Q30. Which type of container best limits oxygen ingress and helps protect oxidation‑sensitive semisolids?
- Wide‑mouth jar that is opened frequently
- Airless pump container
- Clear glass jar with loosely fitting lid
- Unsealed polyethylene bag
Correct Answer: Airless pump container
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.
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