Physicochemical Properties of Drug Substances: Quizzes and Practice Questions

Question 1

The partition coefficient of a drug substance is a measure of its:

Accepted Answer

Lipophilicity

Answer

Solubility in oil

Answer

Polarity

Answer

Solubility in water

Question 2

The hygroscopicity of a drug substance refers to its ability to:

Accepted Answer

Absorb moisture from the air

Answer

Release moisture into the air

Answer

Change color in the presence of moisture

Answer

React chemically with moisture

Question 3

The partition coefficient of a drug substance primarily measures its:

Accepted Answer

Solubility in oil

Answer

Solubility in water

Answer

Ionization constant

Answer

Melting point

Question 4

Which factor is NOT known to influence drug substance stability?

Accepted Answer

Dosage formulation

Answer

Temperature

Answer

Humidity

Answer

Light

Question 5

Which of the following factors **does not** affect the solubility of a drug substance?

Accepted Answer

Molecular weight

Answer

Temperature

Answer

pH

Answer

Crystal form

Question 6

Which of the following techniques can be used to improve the stability of a drug substance?

Accepted Answer

Combination of the above

Answer

pH adjustment

Answer

Encapsulation

Answer

Addition of antioxidants

Question 7

The partition coefficient of a drug substance is a measure of its:

Accepted Answer

Solubility in water and oil

Answer

Acidity or basicity

Answer

Stability in different solvents

Answer

Rate of dissolution

Question 8

Which of the following is **not** a method for determining the purity of a drug substance?

Accepted Answer

Dissolution testing

Answer

Chromatography

Answer

Spectroscopy

Answer

Melting point determination

Question 9

The intrinsic dissolution rate of a drug substance is a measure of its:

Accepted Answer

Dissolution rate in the absence of external factors

Answer

Solubility in water

Answer

Stability in different solvents

Answer

Bioavailability

Question 10

Which factor does NOT influence the solubility of a drug substance?

Accepted Answer

Protein binding

Answer

Molecular size

Answer

Crystal form

Answer

pH of the solvent

Question 11

What is the scientific term describing the rate at which a drug substance dissolves in a solvent?

Accepted Answer

Dissolution rate

Answer

Disintegration rate

Answer

Absorption rate

Answer

Distribution rate

Question 12

Drug stability is primarily impacted by which mechanism?

Accepted Answer

Chemical degradation

Answer

Physical degradation

Answer

Biological degradation

Answer

Photodegradation

Question 13

Which common method is used to determine the partition coefficient of a drug substance?

Accepted Answer

Shake-flask method

Answer

HPLC

Answer

Turbidimetry

Answer

Fluorescence spectroscopy

Question 14

The dissolution rate of a drug is 20% after 30 minutes. What is the dissolution rate constant?

Accepted Answer

0.02 min^-1

Answer

0.002 min^-1

Answer

0.2 min^-1

Answer

2 min^-1

Question 15

Which of the following is the primary technique used to determine the stability of a drug substance?

Accepted Answer

Accelerated stability testing

Answer

Dissolution testing

Answer

X-ray diffraction

Answer

Gas chromatography

Question 16

The pH of a drug solution is adjusted to minimize:

Accepted Answer

Drug degradation

Answer

Drug solubility

Answer

Drug absorption

Answer

Drug safety

Question 17

Why is it important to understand the physicochemical properties of drug substances?

Accepted Answer

To optimize drug product performance

Answer

To predict drug metabolism and excretion

Answer

To ensure patient safety

Answer

To facilitate drug discovery

Question 18

The dissolution rate of a drug is typically affected by all of the following EXCEPT:

Accepted Answer

Surface tension

Answer

Particle shape

Answer

Temperature

Answer

pH

Question 19

Which of the following methods is most commonly used to measure the stability of drug substances?

Accepted Answer

Accelerated stability testing

Answer

Real-time stability testing

Answer

In vitro testing

Answer

In vivo testing

Question 20

The pKa of a drug substance represents its:

Accepted Answer

Acid dissociation constant

Answer

Melting point

Answer

Solubility constant

Answer

Partition coefficient

Question 21

Which of the following techniques is used to determine the crystal structure of a drug substance?

Accepted Answer

X-ray crystallography

Answer

NMR spectroscopy

Answer

HPLC

Answer

DSC

Question 22

The polymorphism of a drug substance refers to its ability to exist in:

Accepted Answer

Multiple solid forms

Answer

Multiple liquid forms

Answer

Multiple gas forms

Answer

Multiple amorphous forms

Question 23

The hygroscopicity of a drug substance indicates its tendency to:

Accepted Answer

Absorb moisture

Answer

Dissolve in water

Answer

Decompose in air