GPAT Suppositories Displacement Value MCQs with Answers

MCQs on Displacement Value & Evaluation of Suppositories.

Q1. Which of the following best defines the displacement value (DV) of a drug?

A. The weight of the base displaced by 1 gm of the drug

B. The number of grams of base displaced by the drug

C. The number of parts of the drug that displace one part of the base.

D. The volume of base required for the drug

Answer: A

Explanation: Option C is sometimes mentioned as a definition in certain texts. But the standard definition used in compounding (especially suppositories) is option A.

• Displacement Value (DV) is a calculation used in suppository formulation and similar dosage forms.

• It tells us how much of the suppository base is replaced (displaced) when a given amount of drug is incorporated.

• Standard definition: The weight of the base displaced by 1 g of drug.

• Another definition (less common): The weight of a drug that displaces 1 g of base. This is why option C can appear in some contexts. But it is not the primary definition of DV.

Key Points for Students

• Formula relation:

DV = Density of base/Density of drug

• Application: Used to calculate how much base is required when preparing suppositories with an active drug.

• Importance: Ensures accurate dosage consistency and prevents errors in formulation.

2. The primary purpose of calculating the displacement value is

A. To increase dissolution rate
B. To maintain a uniform volume of mould
C. To determine the accurate amount of base required
D. To reduce viscosity

Answer: C

Explanation

• In a suppository formulation, the drug added displaces a certain amount of the base.

• The displacement value tells us how much base is displaced by 1 g of drug.

• By knowing DV, pharmacists can calculate the exact quantity of base needed to maintain the correct weight and dosage of the suppository.

• This ensures uniformity, accuracy, and consistency in drug delivery.

3. The displacement value of a drug is 2; it shows

A. 1 gm drug displaces 2 gm base
B. 2 gm drug displaces 1 gm base
C. 2 gm base displaces 1 gm drug
D. Drug and base are equal

Answer: A

Explanation

• By definition, DV is the weight of base displaced by 1 g of drug.

• If DV = 2, it indicates that 1 g of the drug replaces 2 g of the suppository base.

• This value is crucial in calculating the exact amount of base required when incorporating drugs into suppositories, ensuring accurate dosage and uniformity.

4. Displacement value depends primarily on

A. Base Colour
B. Drug & base Density
C. Suppository Shape
D. Mould Temperature

Answer: B

Trap: DV is density-dependent, not shape-dependent.

Explanation

• DV is a measure of how much base is displaced by a given weight of drug.

• Since displacement is essentially about volume occupied, the densities of both the drug and the base determine how much one replaces the other.

• Factors like base colour, suppository shape, or mould temperature do not directly affect DV. They may influence appearance or manufacturing, but not the displacement calculation.

5. Select the TRUE statement for suppository moulds?

A. Weight is constant, but volume varies
B. Volume is constant, but weight varies
C. Both weight & volume vary
D. Both weight & volume are constant

Answer: B

Explanation

• Suppository moulds are designed to have a fixed cavity volume.

• When different drugs are incorporated, the weight of the suppository changes due to the density of the drug and base.

• Therefore, while the volume remains constant, the weight varies depending on the formulation.

This principle is why displacement value (DV) is so important. It helps to calculate the correct amount of base required when a drug is added. This ensures uniformity in dosage despite weight variations.

6. Which one is NOT required in the calculation of DV?

A. Weight of base-only suppositories
B. Weight of medicated suppositories
C. Density of air
D. Weight of drug

Answer: C

Explanation

• To calculate the displacement value (DV), the following are required:

  • Weight of base-only suppositories (to know the base weight without drug)

  • Weight of medicated suppositories (to see how much base is displaced)

  • Weight of drug (to relate displacement to 1 g of drug)

• The density of air is irrelevant in this calculation. DV is based on the relationship between the drug and the base. Not on environmental factors.

7. The formula to calculate displacement value:

A. DV = Base displaced / Drug
B. DV = Drug / Base displaced
C. DV = Weight variation/drug
D. DV = Base / Drug

Answer: A

Explanation

• DV is defined as the weight of base displaced by 1 g of drug.

• Mathematically:

DV= Weight of base displaced/ Weight of drug OR

• This formula ensures that when incorporating a drug into suppositories, you can calculate how much base is replaced and, therefore, how much base is still required to maintain uniform weight and dosage.

• Option B (drug / base displaced) would be the reciprocal of the definition.

• Some textbooks mention this reciprocal form when explaining DV, but the standard accepted definition in pharmacy is “weight of base displaced by 1 g of drug," which matches option A.

8. Displacement value is MOST important in which method?

A. Spray drying
B. Fusion molding
C. Hand rolling
D. Compression molding

Answer: B

In fusion molding, the base (often a suppository base like cocoa butter or PEG) is melted, and then the drug is incorporated. The mixture is poured into molds. And here’s the catch: the displacement value becomes crucial because the drug displaces part of the base. If you don’t account for this correctly, the mold won’t be filled properly. This leads to inaccurate dosage or incomplete suppositories.

By contrast:

• Spray drying: focuses on particle size and drying efficiency, not displacement.

• Hand rolling: more about shaping and consistency, not precise volume displacement.

• Compression molding: Displacement matters, but less than in fusion molding, because powders are compressed directly into molds without melting bases.

So the most correct answer is actually B. Fusion molding. The displacement value is essential for calculating the exact amount of base needed to fill the mold after the drug is added.

9. Which one has the highest displacement effect?

A. A Drug with a higher density than base
B. A Drug is insoluble in base
C. A Drug with a lower density than the base
D. A Drug with the same density

Answer: A

• Displacement value measures how much base is replaced by a given weight of drug.

• If the drug is denser than the base, a small volume of drug corresponds to a larger weight, meaning it displaces more of the base in the mold.

• If the drug is less dense than the base (Option C), it occupies more volume per unit weight, so the displacement effect is lower.

• Same density (Option D) → no displacement difference, effect is minimal.

• Insoluble drug (Option B) → solubility doesn’t directly affect displacement; it’s about density and volume replacement.

Correct answer: A. A drug with a higher density than base.

10. Displacement factor (f) is linked to DV:

A. As independent
B. As an equal always
C. As directly proportional
D. As inversely proportional

Answer: D

• Displacement value (DV) = the amount of drug that displaces 1 g of base.

• Displacement factor (f) = the reciprocal of DV.

• So, if DV increases, f decreases, and vice versa.

For example:

• If DV = 2 (meaning 2 g of drug displaces 1 g of base), then f = 1/2 = 0.5.

• If DV = 0.5, then f = 1/0.5 = 2.

So the correct answer is D, as inversely proportional.

Calculation-Based MCQs (High Probability)

11. Weight of 10 blank suppositories = 10 gm

Weight of 10 medicated suppositories = 14 gm
Drug present = 4 gm
Base displaced = 2 gm

DV =?

A. 0.5
B. 1.4
C. 2
D. 3.5

Answer: C
(DV = 4/2)

Step by step:

• Weight of 10 blank suppositories = 10 gm. So each blank suppository = 1 gm base.

• Weight of 10 medicated suppositories = 14 gm.

• Drug present = 4 gm total. So each medicated suppository contains 0.4 g of the drug.

• Base displaced = 2 g total. So each medicated suppository has 0.2 g less base.

Definition: Displacement value (DV) = Weight of drug that displaces 1 g of base.

• 4 g drug displaces 2 g base.

• So, DV = (Weight of drug) / (Weight of base displaced) = 4/2=2.

Correct answer: C. 2.

12. If DV increases, the base requirements will:

A. Become zero
B. Remain constant
C. Decrease
D. Increase

Answer: C

Explanation

If the displacement value (DV) increases, it means that a larger amount of drug is required to displace 1 g of base.

Therefore, the base requirements will decrease (Option C) because more drug is replacing the base in the mould.

• DV ↑ : Base ↓

• DV ↓ : Base ↑

Correct answer: C. Decrease.

13. Which test is performed to ensure cracks and pitting are absent?

A. Liquefaction test
B. Dissolution test
C. Mechanical strength test
D. Appearance test

Answer: D

Explanation:

• Appearance test: Checks for visual defects like cracks, pits, air bubbles, or surface irregularities.

• Liquefaction test: Measures melting or softening time.

• Dissolution test: Evaluates drug release rate.

• Mechanical strength test: Assesses hardness and resistance to breakage.

14. The “breaking test” is performed for:

A. Dissolution rate
B. Melting point

C. Drug release
D. Brittleness and strength

Answer: B

• It measures the mechanical resistance of a suppository to breaking under stress.

• This ensures the dosage form can withstand handling, packaging, and administration without crumbling or cracking.

• It is not related to dissolution, melting point, or drug release directly, but rather to physical integrity.

15. The liquefaction time test measures:

A. Softening time at the body temperature of the suppository
B. Melting range of suppository
C. Hardness of suppository
D. Drug content of suppository

Answer: A

• Option A is correct: it checks how long the suppository takes to soften or liquefy once exposed to physiological conditions (around 37 °C).

• Option B (Melting range) → that’s determined by a melting point test, not liquefaction.

• Option C (Hardness) → assessed by mechanical strength or breaking test.

• Option D (Drug content) → measured by assay, not liquefaction.

16. Which one is used to test the melting range?

A. Soxhlet extractor
B. Tablet disintegration apparatus
C. UV spectrophotometer
D. Brookfield viscometer

Answer: B

• Soxhlet extractor (A): Used for the extraction of compounds, not melting range.

• Tablet disintegration apparatus (B): Adapted for suppositories to measure the melting/softening range under controlled conditions.

• UV spectrophotometer (C): Used for drug content analysis, not melting.

• Brookfield viscometer (D): Measures viscosity of liquids/semi-solids, not melting range.

17. Dissolution testing of suppositories is used to measure:

A. Suppositories' shape uniformity
B. Rate of drug release from suppositories
C. suppositories Hardness
D. Base Density

Answer: B

18. The mechanical strength of suppositories should be:

A. Less than 500 g
B. 1.8–2 kg
C. 3.5 kg
D. Not suitable to measure

Answer: B

Mechanical strength testing of suppositories ensures they can withstand handling, packaging, and insertion without breaking. A strength of about 1.8–2 kg is considered appropriate.

• Less than 500 g → too weak, likely to break.

• 3.5 kg → excessively hard, may cause discomfort and poor drug release.

• Not suitable to measure → incorrect, because mechanical strength is a critical quality control parameter.

19. Fat blooming in suppositories indicates:

A. Higher melting point
B. Increased dissolution
C. Drug degradation
D. Surface dullness

Answer: D

Fat blooming in suppositories during the fatty base undergoes polymorphic changes. It is due to improper storage or temperature fluctuations. This leads to a whitish, dull appearance on the suppository surface.

• Higher melting point: Not correct; fat blooming doesn’t raise the melting point.

• Increased dissolution: Incorrect; blooming doesn’t improve drug release.

• Drug degradation: Not directly; it’s a physical change, not chemical degradation.

• Surface dullness: Correct; the main visible sign of fat blooming.

20. For lipophilic suppositories, which test is MOST relevant?

A. pH test
B. Viscosity test
C. Friability test
D. Dissolution using a dialysis cell

Answer: D

For lipophilic suppositories, the most relevant test is dissolution using a dialysis cell. This method helps evaluate how the drug diffuses out of the fatty base into an aqueous medium, simulating in vivo conditions.

• pH test: Not relevant, since lipophilic bases don’t rely on pH changes.

• Viscosity test: Applies more to liquid/semi-solid formulations, not solid suppositories.

• Friability test: Used for tablets, not suppositories.

• Dissolution using a dialysis cell: Correct, as it measures drug release from lipophilic bases

21. Fat blooming in suppositories can be prevented by:

A. Storing suppositories at fluctuating temperatures

B. Rapid cooling of suppositories after molding

C. Using stable polymorphic forms of the base and controlled storage conditions

D. Adding excess drug to the suppository base

Correct Answer: C.

Explanation: Fat blooming occurs due to polymorphic transitions in fatty bases (like cocoa butter). Manufacturers prevent it by:

• Selecting stable polymorphic forms of the base

• Avoiding rapid cooling (which encourages unstable forms)

• Maintaining consistent, cool storage conditions

22. Assertion (A): Displacement value varies for the base used.

Reason (R): The drugs have different densities in different bases.

A. Both true and R explain A
B. Both true, but R is not an explanation
C. A true, R false
D. Both false

Answer: A

• Assertion (A): Displacement value varies for the base used: True. Different suppository bases (lipophilic vs. hydrophilic) have different physical properties, so the displacement value changes.

• Reason (R): The drugs have different densities in different bases: True. The drug density relative to the base determines how much base is displaced when the drug is added.

• Since the reason directly explains the assertion, option A is correct.

This concept is crucial in suppository formulation calculations because the displacement value helps to determine the exact quantity of base required when a drug is added.

23. Assertion (A): The weight variation test is essential for suppositories.

Reason (R): Suppositories are prepared in constant weight moulds.

A. Both true and R explain A
B. Both true, but R is an incorrect explanation
C. A true, R false
D. Both false

Answer: C

Trap: Moulds are constant volume, not weight.

• Assertion (A): The weight variation test is essential for suppositories → This is true, because it ensures uniformity of dose.

• Reason (R): Suppositories are prepared in constant weight moulds → This is false. Moulds are constant in volume, not weight. Since bases and drugs have different densities, the weight can vary even if the mould volume is fixed.

So, Option C (A true, R false) is actually the most accurate choice.

Final Answer: C. A true, R false

This highlights a subtle but important distinction: moulds control volume, but weight variation testing is still necessary to confirm dose uniformity.

24. Match the Following

List I List II

A. Liquefaction test 1. Drug release

B. Dissolution test 2. Softening time

C. Breaking test 3. Mechanical strength

D. Appearance test 4. Surface defects

A. A-2, B-1, C-3, D-4
B. A-1, B-2, C-4, D-3
C. A-3, B-1, C-2, D-4
D. A-2, B-3, C-1, D-4

Answer: A

Explanation:

• Liquefaction test: Softening time (2): Measures how long a suppository takes to soften under specific conditions.

• Dissolution test: Drug release (1): Evaluates the rate and extent of drug release from the base.

• Breaking test: Mechanical strength (3): Assesses the ability of suppositories to withstand handling without breaking.

• Appearance test: Surface defects (4): Checks for visual flaws like cracks, pits, or fat blooming.

Case-Based MCQ

25. A variation in the suppository's weight despite using the same mould. What will be the MOST probable reason?

A. High lubrication
B. Improper cooling process
C. Air bubble entrapment
D. Incorrect calculation of displacement value

Answer: C

Explanation:

• Even though suppositories are made in constant-volume moulds, their weight can vary if air bubbles get trapped during pouring or filling.

• High lubrication affects mould release but not weight.

• Improper cooling can cause polymorphic changes or surface defects, but not major weight variation.

• Incorrect calculation of displacement value affects the drug content/base ratio, but not the weight variation when using the same mould.

So, air bubble entrapment is the key culprit for weight variation in suppositories despite identical moulds.

📌 High-Yield Takeaways

• DV = Drug / Base displaced

• Depends on density + base type

• Mould = constant volume (not weight)

• Key evaluation tests:

  • Appearance

  • Melting range

  • Liquefaction time

  • Breaking test

  • Dissolution

High-Yield Tricks:

1. DV = Drug / Base displaced (most repeated formula)

2. Mould = constant volume (not weight)

3. Lower DV → more base correction

4. Always check the trap: calculated weight vs mould capacity

5. Most numericals test conceptual understanding, not just formula

Questions on DV calculation are most probable in the exam. If you wish for more practice questions on DV calculation, Write it in the comments. I will upload these questions.

Dr Alok Singh