Semisolid dosage forms – definition and classification MCQs With Answer

Semisolid dosage forms are topical preparations placed between solids and liquids that deliver drugs to skin or mucous membranes. This introduction covers the definition, primary classification (ointments, creams, gels, pastes, poultices), bases, excipients, physicochemical properties, rheology, stability, and formulation challenges relevant to B. Pharm students. Emphasis is given to topical delivery, occlusion, drug release, penetration enhancers, preservative choice, and quality control tests such as spreadability and in vitro release. Understanding these concepts helps in rational formulation, selection of bases, and troubleshooting. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the best definition of a semisolid dosage form?

• A preparation with fixed shape like a tablet
• A formulation that flows freely like a liquid
• A topical preparation with viscosity between liquid and solid
• An injectable aqueous solution

Correct Answer: A topical preparation with viscosity between liquid and solid

Q2. Which of the following is NOT considered a semisolid dosage form?

• Ointment
• Gel
• Pill
• Paste

Correct Answer: Pill

Q3. Which classification is based on the physical nature of the vehicle?

• Therapeutic classification
• Physical classification
• Legal classification
• Route-based classification

Correct Answer: Physical classification

Q4. Which semisolid base is predominantly hydrocarbon and occlusive?

• Hydrophilic ointment
• Petrolatum (oleaginous) base
• Water-soluble polyethylene glycol base
• Hydrogel

Correct Answer: Petrolatum (oleaginous) base

Q5. Creams are generally classified as:

• Single-phase solutions only
• Emulsions (oil-in-water or water-in-oil)
• Gaseous systems
• Unidirectional patches

Correct Answer: Emulsions (oil-in-water or water-in-oil)

Q6. A gel typically consists of:

• A liquid dispersed in a solid network
• A solid tablet embedded in cream
• An emulsion without a polymer network
• A microemulsion only

Correct Answer: A liquid dispersed in a solid network

Q7. Which rheological property describes decreasing viscosity with increasing shear rate common in many gels?

• Newtonian behavior
• Pseudoplasticity (shear-thinning)
• Dilatancy (shear-thickening)
• Thixotropic recovery

Correct Answer: Pseudoplasticity (shear-thinning)

Q8. Thixotropy in semisolids refers to:

• Permanent hardening on standing
• Time-dependent viscosity decrease under shear and recovery when at rest
• Increase in viscosity with temperature
• Rapid evaporation of solvent

Correct Answer: Time-dependent viscosity decrease under shear and recovery when at rest

Q9. Which parameter is most directly related to spreadability of an ointment?

• pH
• Viscosity
• Drug’s molecular weight
• Color of the base

Correct Answer: Viscosity

Q10. An advantage of water-washable creams (O/W) over oleaginous ointments is:

• Better occlusion
• Greater water solubility and ease of removal
• Longer contact time on skin
• Higher oil content

Correct Answer: Greater water solubility and ease of removal

Q11. Which preservative is commonly used in aqueous semisolids?

• Benzalkonium chloride
• Paraffin wax
• Lanolin
• Sodium lauryl sulfate

Correct Answer: Benzalkonium chloride

Q12. For water-in-oil (W/O) creams, the continuous phase is:

• Water
• Oil
• Alcohol
• Polyethylene glycol

Correct Answer: Oil

Q13. Which factor most increases percutaneous absorption from a semisolid?

• Decreased drug solubility in base
• Use of penetration enhancers
• Higher melting point base
• Lower skin hydration

Correct Answer: Use of penetration enhancers

Q14. Span and Tween surfactants are used to:

• Act as preservatives
• Stabilize emulsions as emulsifying agents
• Provide fragrance
• Increase drug molecular size

Correct Answer: Stabilize emulsions as emulsifying agents

Q15. Which quality control test measures semisolid consistency by the time to flow under fixed weight?

• Spreadability test
• Puncture test
• Penetrometer test
• Loss on drying

Correct Answer: Penetrometer test

Q16. Which base would be preferable for a water-soluble drug requiring non-greasy feel?

• Hydrocarbon base (petrolatum)
• Water-soluble polyethylene glycol base
• Anhydrous paraffin
• Lanolin

Correct Answer: Water-soluble polyethylene glycol base

Q17. Pastes differ from ointments mainly because they:

• Contain a higher proportion of insoluble solids and are stiffer
• Are always aqueous
• Are intended for oral use only
• Evaporate rapidly on skin

Correct Answer: Contain a higher proportion of insoluble solids and are stiffer

Q18. Which semisolid is best described as a suspension of fine particles in a fatty or aqueous vehicle and is used as protective dressing?

• Gel
• Paste
• Tablet
• Solution

Correct Answer: Paste

Q19. The HLB system helps formulators to:

• Determine preservative efficacy
• Select appropriate surfactants for emulsions
• Calculate drug dose
• Measure pH stability

Correct Answer: Select appropriate surfactants for emulsions

Q20. Which of the following tests assesses in vitro drug release from semisolids?

• Disintegration test
• Diffusion cell (Franz cell) study
• Hardness test
• Uniformity of weight

Correct Answer: Diffusion cell (Franz cell) study

Q21. An occlusive base will most likely:

• Enhance skin hydration and drug penetration
• Reduce drug absorption by drying skin
• Always make formulation aqueous
• Prevent microbial growth without preservatives

Correct Answer: Enhance skin hydration and drug penetration

Q22. Which incompatibility is most critical when combining certain drugs with semisolid bases?

• pH-dependent degradation or complexation with ionic excipients
• Color mismatch
• Fragrance preference
• Packaging design

Correct Answer: pH-dependent degradation or complexation with ionic excipients

Q23. Which property of a semisolid affects residence time on mucosal surfaces?

• Surface tension
• Adhesiveness or mucoadhesion
• Electrical conductivity
• Dissolution temperature

Correct Answer: Adhesiveness or mucoadhesion

Q24. Which excipient is commonly used to gel water and form hydrogels?

• Carbomer (carbopol)
• Liquid paraffin
• Lanolin USP
• White petrolatum

Correct Answer: Carbomer (carbopol)

Q25. Microbial contamination in semisolids is controlled primarily by:

• Reducing particle size
• Use of appropriate preservatives and water activity control
• Increasing oil content only
• Avoiding emulsification

Correct Answer: Use of appropriate preservatives and water activity control

Q26. Which regulatory reference often provides monographs and tests for semisolid dosage forms?

• British Pharmacopeia (BP) and United States Pharmacopeia (USP)
• FIFA regulations
• ISO 9001 only
• Local newspaper

Correct Answer: British Pharmacopeia (BP) and United States Pharmacopeia (USP)

Q27. In formulation, a co-solvent is used to:

• Reduce container size
• Increase solubility of lipophilic drugs in semi-aqueous bases
• Act as primary emulsifier
• Increase pH dramatically

Correct Answer: Increase solubility of lipophilic drugs in semi-aqueous bases

Q28. Which statement about lipophilic ointment bases is TRUE?

• They are easily removed with water
• They provide high occlusion and are not water-washable
• They always contain high levels of surfactant
• They are unsuitable for hydrophobic drugs

Correct Answer: They provide high occlusion and are not water-washable

Q29. Pseudoplastic flow combined with thixotropy is desirable because it:

• Makes the product solid under shear
• Allows easy application and returns to higher viscosity at rest
• Prevents any spreading on skin
• Causes irreversible breakdown

Correct Answer: Allows easy application and returns to higher viscosity at rest

Q30. When designing a semisolid for acne with benzoyl peroxide, what must be carefully controlled?

• Light sensitivity and compatibility with oxidizable ingredients
• Flavor of the product
• Magnetic properties
• Radioactivity

Correct Answer: Light sensitivity and compatibility with oxidizable ingredients

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