“Top 20 Interview Questions on Semi-Solid Dosage Forms for Pharma Freshers”

1. What are semi-solid dosage forms?

These are pharmaceutical preparations with a consistency between solid and liquid, designed for topical, transdermal, or rectal application (e.g., ointments, creams, gels).

2. Name the common types of semi-solid dosage forms.

• Ointments
• Creams
• Gels
• Pastes
• Lotions

3. What are the advantages of semi-solid dosage forms?

• Easy application to skin or mucous membranes.
• Localized or systemic drug delivery.
• Reduces systemic side effects compared to oral dosage forms.

4. What is the difference between an ointment and a cream?

• Ointment: Greasy and hydrophobic, used for occlusive effects.
• Cream: Less greasy, contains water, used for moisturizing or less oily applications.

5. What are the key components of a semi-solid dosage form?

• Active pharmaceutical ingredient (API)
• Base (e.g., petrolatum, lanolin)
• Emulsifiers
• Preservatives
• Stabilizers

6. What is a gel, and how is it different from other semi-solid forms?

A gel is a semi-solid preparation with a jelly-like texture, often transparent, and usually hydrophilic for better absorption.

7. What are the ideal properties of a base used in semi-solid dosage forms?

• Non-irritating and non-toxic.
• Should not interact with the drug.
• Stable and compatible with APIs.
• Easy to spread and washable if required.

8. What are the methods of preparation for semi-solid dosage forms?

• Fusion method – Components are melted and mixed.
• Mechanical mixing – Components are blended without heating.
• Emulsification – Used for creams and emulsions.

9. What is the role of preservatives in semi-solid formulations?

Preservatives prevent microbial contamination and ensure product stability during storage.

10. What is the significance of viscosity in semi-solid dosage forms?

Viscosity determines the spreadability, ease of application, and drug release profile of the formulation.

11. What are some common defects in semi-solid formulations?

• Phase separation in creams.
• Grittiness in ointments or gels.
• Syneresis (liquid separation) in gels.
• Microbial contamination.

12. How do you evaluate the quality of semi-solid dosage forms?

• Spreadability test
• pH measurement
• Drug content uniformity
• Viscosity testing
• Microbial limit test

13. What is the role of emulsifiers in creams?

Emulsifiers stabilize the oil and water phases in creams, preventing separation and ensuring consistency.

14. What are transdermal semi-solid formulations?

These formulations deliver drugs through the skin into the systemic circulation (e.g., medicated gels or patches).

15. What is the difference between a gel and a paste?

• Gel: Contains a higher liquid content, is smooth, and used for localized drug delivery.
• Paste: Thick and contains solid particles, used for protective or absorbent applications.

16. What challenges are associated with semi-solid dosage forms?

• Stability issues (e.g., phase separation, microbial growth).
• Drug release inconsistencies.
• Compatibility between the base and the drug.

17. What is the purpose of pH adjustment in semi-solid formulations?

To match the pH of the skin or application site, ensuring comfort and preventing irritation.

18. What packaging materials are used for semi-solid dosage forms?

• Tubes (aluminum or plastic).
• Jars (glass or plastic).
• Sachets for single-use applications.

19. How are semi-solid dosage forms stored?

Store in cool, dry places, protected from light, and as per labeled storage conditions to maintain stability.

20. What is the regulatory importance of microbial limit testing in semi-solid formulations?

It ensures the product is free from harmful microorganisms, which is critical for patient safety and regulatory compliance.