By the definitions from out notes for disperse systems, “Generally, a liquid preparation in which a finely divided, insoluble or immiscible material is distributed throughout a vehicle”, what is the minimum number of phases present in a dispersed system?
1
2
3
The distinction between the terms coarse, fine, colloidal dispersion is based upon what property of the dispersed phase?
Solid state
Particle size
Molecular weight
Chemical structure
Why might a dispersed phase containing drug be formulated in a dispersion medium in which it was insoluble?
To increase the solubility
To mask bitter tastes
To increase the viscosity
To decrease the viscosity
None of the above
Given the equation for Stoke’s law of settling below, by how much you have to increase the viscosity to offset a particle size increase of a factor of two?
Factor of 1/2
Factor of 2
Factor of 4
Given a suspension with a fixed particle size distribution, what would be true if each powder particle displaced its own weight of dispersing phase (i.e. density of dispersed phase = density of dispersion medium)?
The viscosity would be infinite
The settling rate will be very high
The settling rate would be zero
The particle size would approach colloidal dimensions
The primary mechanism of altering dispersion medium properties is modification of:
Density
Viscosity
Dielectric constant
Which of the following characteristics is NOT desirable in the case of suspension dosage forms?
Flocculation with formulation of loosely bound aggregates
Flocculation with formulation of strongly bound aggregates
Formation of loose sediment
An advantage of a shear thinning formulation includes:
Ease of mixing with relatively mild shaking of the container
Lower viscosity on standing to prevent settling
Caking of needle shaped particles
Under what conditions would you compound a suspension using benzyl alcohol or propylene glycol for preemies?
Only for acute usage
Only for antibiotics
Never
You are asked to compound a suspension of a drug normally dispensed as a solid dosage form. Why is it prudent to determine if a liquid dosage form is also commercially available?
You can save the effort and advise the patient they must wait until you can order the commercial dosage form
If a commercial liquid dosage form isn’t available, it may indicate a potential chemical stability problem
If a commercial liquid dosage form isn’t available, it may indicate a potential physical stability problem
Both B and C
Select the choices that correctly fill the blanks in the following statement: the three minimum requirements (i.e., 3 rules) needed for form a stabilized emulsion are 1) ____ 2)____ 3)____.
1) Components forming at least 2 phases, 2) a component to stabilize the interface between the internal and external (continuous) phase, 3) sufficient energy input to break up each phase into droplets.
1) At least one solid component 2) amphiphilic surfactant molecules, 3) adjustment to physiologic pH
1) Component forming liquid crystalline phases, 2) a component to overcome the “double layer between the internal and external (continuous) phase, 3) sufficient energy input to break up each phase into droplets.
All of the above
Which of the following statements is NOT a valid criterion for suspecting an emulsion is physically unstable?
Dispersed phase tends to form aggregates of globules on standing
Aggregates of the dispersed phase may be re-dispersed by shaking
Large globules or aggregates of globules rise to the top or fall to the bottom of container forming a concentrated layer of dispersed phase
All or part of the liquid in the dispersed phase separates to form a distinct layer
Patients should virtually never be instructed to store an emulsion dosage form:
In the refrigerator
At room temperature
In the freezer
The HLB system is primarily useful for matching a non-ionic surfactant system with the oil phase in an emulsion. Given that: HLB Span 60 = 4.7, and HLB of Tween 60 = 14.9 estimated fraction of Span 60 and Tween 60 needed to achieve an HLB of 12 is approximately (to the nearest %):
72 and 28% respectively
28 and 72% respectively
A magma is a:
Two phase gel in which the gel mass does not consists of floccules of small distinct particles
One phase gel in which the gel mass consists of floccules of small distinct particles
Two phase gel in which the gel mass consist of floccules of small distinct particles
In a colloidal dispersion the particle size is:
Much smaller than typical molecule dimensions
Much larger than typical molecule dimensions
The same or smaller than typical molecule dimensions
Which of following is FALSE in case of gel formulation exhibiting syneresis?
A measurable increase in volume of Gel
A non-measurable change in the volume of Gel
A measureable decrease in volume of Gel
A and B
B and C
What is a major function of glycerin in the carboxymethylcellulose based gel formulations?
To prevent drying of Gel
Sweetner
Antioxidant
Which of following if true of aerosol used to provide an airborne mist?
Particle size >50μm
Particle size <50 μm
Particle size <1μm
None of above
A properly prepared pharmaceutical suspension should settle slowly and should readily re dispersed upon gentle shaking on the container
Which of the following excipients should not be used in the formulation of a Carboxymethylcellulose-based gel?
Preservative
Glycerin
Alcohol
Stability is an important consideration in the formulation of emulsions. Which of the following represents an irreversible phenomenon in terms of re-dispersion of emulsion?
Creaming
Coalescence of droplets
Flocculation
Given that the API is soluble in water, which of the following type of emulsion is desirable to formulate?
O/W
W/O
When you decrease the particle size of disperse phase by factor of 10, then the settling velocity will decrease by a factor of:
10
100
1000
What is a primary reason to formulate the powders for suspension?
To facilitate transport and ease of administration
Maintain the stability of API
Improve patient compliance
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