APHA NAPLEX Review Questions
If the pka of a weak acid is 2.5, at which pH will this drug become more ionized?
A. pH 5
B. pH 2.5
C. pH 1.5
D. pH 1 - Answer-A. For a weak acid, a higher pH increases ionization
Which equation describes the rate of drug dissolution from a tablet?
A. Fick's Law
B. Henderson-Hasselbalch equation
C. Michaelis-Menten equation
D. Noyes-Whitney equation - Answer-D. The Noyes-Whitney equation describes the rate of drug
dissolution from a tablet. Fick's first law of diffusion is similar to the Noyes-Whitney equation in that
both equations describe drug movement attributable to a concentration gradient. The Michealis-
Menten equation involves enzyme kinetics, whereas Henderson-Hasselbalch equations are used for
determination of pH of the buffer and the extent of ionization of a drug molecule
The pH of a buffer system can be calculated with
,A. the Henderson-Hasselbalch equation
B. the Noyes-Whitney equation
C. the Michealis-Mention equation
D. Yong's equation - Answer-A. The Henderson-Hasselbalch equation form a weak acid and its salt is
represented as pH = pka + log ([salt]/[acid]), where pka is the negative log of the dissolution constant of
a weak acid, as [salt]/[acid] is the ratio of the molar concentration of salt and acid used to prepare a
buffer
If the pka of a drug is 5, at which of the following pH values do the ionic and nonionic forms of the drug
exist at equal ratio?
A. pH 1
B. pH 5
C. pH 7
D. pH 9 - Answer-B. When the pH = pka, the ratio of ionized to un-ionized becomes the same
What is bioavailability?
A. Bioavailability is the measurement of the rate and extent of active drug that reaches the systemic
circulation
B. It is the relationship between the physical and chemical properties of a drug and its systemic
absorption
C. It is the movement of the drug into body tissues over time
D. It is the dissolution of the drug in the GI tract - Answer-A. Bioavailability is the measurement of the
rate and extent of systemic circulation of an active drug
Which of the following may be used to assess the relative bioavailability of two chemically equivalent
drug products in a crossover study?
,A. Dissolution test
B. Peak concentration
C. Time-to-peak concentration
D. Area under the plasma-level time curve - Answer-D. The plasma drug concentration versus time curve
measures the bioavailability of a drug from a product. The peak plasma drug concentration (Cmax)
relates to the intensity of the pharmacologic response, while the time for peak plasma drug
concentration (Tmax) relates to the rate of systemic absorption
What condition usually increases the rate of drug dissolution for a tablet?
A. Increase the particle size of the drug
B. Decrease the surface area of the drug
C. Use of ionized, or salt, form of the drug
D. Use of the free acid or free base form of the drug - Answer-C. The ionized, or salt, form of a drug is
generally more water soluble and therefore dissolves more rapidly than the nonionized (free acid or free
base) form of the drug. According to the Noyes-Whitney equation, the dissolution rate is directly
proportion to the surface area and inversely proportional to the particle size. Therefore, an increase in
the particle size or a decrease in the surface area slows the dissolution rate
If the pka of a weak base drug is 8.3, at which of the following pH values does this drug become more
ionized?
A. pH 4
B. pH 9
C. pH 10
D. pH 13 - Answer-A. For a weak base, a lower pH value increase ionization of the molecule
Which of the following dosage forms may use surface-active agents in their formulations?
, A. Emulsions
B. Suspensions
C. Colloidal dosage forms
D. Creams
E. All of the Above - Answer-E. Surface active agents facilitate emulsion formation by lowering the
interfacial tension between the oil and water phases. Adsorption of surfactants on insoluble particles
enables these particles to be dispersed in the form of a suspension
Which of the following statements about lyophilic colloidal dispersions is true?
A. They tend to be more sensitive to the addition of electrolytes than do lyophobic systems
B. They tend to be more viscous than lyophobic systems
C. They can be precipitated by prolonged dialysis
D. They separate rapidly - Answer-B. Most lyophilic colloids are organic molecules (including gelatin and
acacia); they spontaneously form colloidal solutions and tend to be viscous. Dispersion of lyophilic
colloids is stable in the presence of electrolytes
Which of the following is not true for tablet formulations?
A. A disintegrating agent promotes granule flow
B. Lubricants prevent adherence of granules to the punch faces of the tableting machine
C. Glidants promote flow of the granules
D. Binding agents are used for adhesion of powder into granules - Answer-A. Disintegrating agents are
added to the tablets to promote breakup of the tablets when placed in the aqueous environment.
Lubricants are required to prevent adherence of the granules to the punch faces and dies. Glidants are
added to tablet formulations to improve the flow properties of the granulations. Binding agents are
added to bind powders together in the granulation process
If the pka of a weak acid is 2.5, at which pH will this drug become more ionized?
A. pH 5
B. pH 2.5
C. pH 1.5
D. pH 1 - Answer-A. For a weak acid, a higher pH increases ionization
Which equation describes the rate of drug dissolution from a tablet?
A. Fick's Law
B. Henderson-Hasselbalch equation
C. Michaelis-Menten equation
D. Noyes-Whitney equation - Answer-D. The Noyes-Whitney equation describes the rate of drug
dissolution from a tablet. Fick's first law of diffusion is similar to the Noyes-Whitney equation in that
both equations describe drug movement attributable to a concentration gradient. The Michealis-
Menten equation involves enzyme kinetics, whereas Henderson-Hasselbalch equations are used for
determination of pH of the buffer and the extent of ionization of a drug molecule
The pH of a buffer system can be calculated with
,A. the Henderson-Hasselbalch equation
B. the Noyes-Whitney equation
C. the Michealis-Mention equation
D. Yong's equation - Answer-A. The Henderson-Hasselbalch equation form a weak acid and its salt is
represented as pH = pka + log ([salt]/[acid]), where pka is the negative log of the dissolution constant of
a weak acid, as [salt]/[acid] is the ratio of the molar concentration of salt and acid used to prepare a
buffer
If the pka of a drug is 5, at which of the following pH values do the ionic and nonionic forms of the drug
exist at equal ratio?
A. pH 1
B. pH 5
C. pH 7
D. pH 9 - Answer-B. When the pH = pka, the ratio of ionized to un-ionized becomes the same
What is bioavailability?
A. Bioavailability is the measurement of the rate and extent of active drug that reaches the systemic
circulation
B. It is the relationship between the physical and chemical properties of a drug and its systemic
absorption
C. It is the movement of the drug into body tissues over time
D. It is the dissolution of the drug in the GI tract - Answer-A. Bioavailability is the measurement of the
rate and extent of systemic circulation of an active drug
Which of the following may be used to assess the relative bioavailability of two chemically equivalent
drug products in a crossover study?
,A. Dissolution test
B. Peak concentration
C. Time-to-peak concentration
D. Area under the plasma-level time curve - Answer-D. The plasma drug concentration versus time curve
measures the bioavailability of a drug from a product. The peak plasma drug concentration (Cmax)
relates to the intensity of the pharmacologic response, while the time for peak plasma drug
concentration (Tmax) relates to the rate of systemic absorption
What condition usually increases the rate of drug dissolution for a tablet?
A. Increase the particle size of the drug
B. Decrease the surface area of the drug
C. Use of ionized, or salt, form of the drug
D. Use of the free acid or free base form of the drug - Answer-C. The ionized, or salt, form of a drug is
generally more water soluble and therefore dissolves more rapidly than the nonionized (free acid or free
base) form of the drug. According to the Noyes-Whitney equation, the dissolution rate is directly
proportion to the surface area and inversely proportional to the particle size. Therefore, an increase in
the particle size or a decrease in the surface area slows the dissolution rate
If the pka of a weak base drug is 8.3, at which of the following pH values does this drug become more
ionized?
A. pH 4
B. pH 9
C. pH 10
D. pH 13 - Answer-A. For a weak base, a lower pH value increase ionization of the molecule
Which of the following dosage forms may use surface-active agents in their formulations?
, A. Emulsions
B. Suspensions
C. Colloidal dosage forms
D. Creams
E. All of the Above - Answer-E. Surface active agents facilitate emulsion formation by lowering the
interfacial tension between the oil and water phases. Adsorption of surfactants on insoluble particles
enables these particles to be dispersed in the form of a suspension
Which of the following statements about lyophilic colloidal dispersions is true?
A. They tend to be more sensitive to the addition of electrolytes than do lyophobic systems
B. They tend to be more viscous than lyophobic systems
C. They can be precipitated by prolonged dialysis
D. They separate rapidly - Answer-B. Most lyophilic colloids are organic molecules (including gelatin and
acacia); they spontaneously form colloidal solutions and tend to be viscous. Dispersion of lyophilic
colloids is stable in the presence of electrolytes
Which of the following is not true for tablet formulations?
A. A disintegrating agent promotes granule flow
B. Lubricants prevent adherence of granules to the punch faces of the tableting machine
C. Glidants promote flow of the granules
D. Binding agents are used for adhesion of powder into granules - Answer-A. Disintegrating agents are
added to the tablets to promote breakup of the tablets when placed in the aqueous environment.
Lubricants are required to prevent adherence of the granules to the punch faces and dies. Glidants are
added to tablet formulations to improve the flow properties of the granulations. Binding agents are
added to bind powders together in the granulation process
