Week 3 Flashcards
Coarse and colloidal disperse systems are [Select all that apply]
- non-homogeneous
- homogeneous
- made of dispersed molecules
- made from dispersed particle
non-homogeneous
made from dispersed particle
Match the type of non-homogeneous disperse system to its composition:
-Suspension
-Emulsion
-Aerosol
Options:
-an immiscible liquid dispersed in a liquid
-an immiscible solid dispersed in a liquid
-an immiscible solid/liquid dispersed in air
suspension : an immiscible solid dispersed in a liquid
emulsion: an immiscible liquid dispersed in a liquid
aerosol: an immiscible solid/liquid dispersed in air
The force causing interfacial or surface tension is due to?
immiscibility of the two surfaces causing molecules on the surface/ interface to pull inward
Interfacial tension occurs between any _________, while surface tension occurs between _______
two surfaces except for air
any surface and air
The kinetic properties that affect a two phase non-homogeneous system are
gravity and Brownian motion
Brownian motion _____ a disperse system stability by causing particles to move __________ in the dispersion medium
decreases
in all directions
Gravity _____ a disperse system stability by causing particles to move ______ in the dispersion medium.
decreases
up or down
Based on the Stokes equation, what happens to the settling rate when the viscosity of the dispersed system increases?
- increases
- decreases
- remains the same
decreases
Based on the Stokes equation, what happens to the settling rate when the particle size of the dispersant decreases?
- increases
- decreases
- remains the same
decreases
Based on the Einstein equation, what happens to the rate of Brownian motion when the particle size of the dispersant increases?
- increases
- decreases
- remains the same
decreases
Based on the Einstein equation, what happens to the Brownian motion displacement when the dispersant’s particle size increases?
- increases
- decreases
- remains the same
decreases
The electric property that effects a two phase non-homogeneous system is?
zeta potential
Zeta potential values of 50 mV indicate _________ between the particles, while 0 mV zeta potential values indicate ____________ between the particles.
high repulsive forces
high attractive forces
Particles that have very high repulsive forces will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse
form strong sediments that do not re-disperse
Particles which have no repulsive forces, very high attractive forces, and 0 mV zeta potential will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse
form strong sediments that do not re-disperse
Particles which have optimized or adjusted zeta potential will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse
form loose sediments that do disperse
Optimizing the zeta potential means adjusting the zeta potential to have: low attractive forces to form flocs high attractive forces to form flocs high repulsive forces to form flocs no attractive forces to form flocs
low attractive forces to form flocs
Examples of irreversible phase separation in non-homogeneous two-phase dispersions include: Caking and cracking Caking and creaming Floc formation and cracking Floc formation and creaming
Caking and cracking
Reducing which of the following will improve the stability of non-homogeneous 2 –phase disperse systems? Select all that apply.
- Interfacial tension
- Particle aggregation
- Particle deaggregation
- Floc formation
Interfacial tension
Particle aggregation
Match the colloid type with its stabilization mechanism in non-homogeneous two-phase dispersions. Soluble colloids Association colloids Particulate colloids options: Steric and/or Electrostatic stabilization Steric stabilization Electrostatic stabilization
Soluble colloids: Steric stabilization
Association colloids: Steric and/or Electrostatic stabilization
Particulate colloids: Electrostatic stabilization
Which of the following colloid(s) enhance stability without affecting the viscosity of the dispersion medium?
Soluble colloids
Association colloids
Particulate colloids
Association colloids
Zwitterionic surfactants or association colloids exhibit? negative charges positive charges both negative and positive charges neither negative nor positive charges
both negative and positive charges
HLB is the system of rating surfactants in terms of their ________ which helps identify their function in various disperse systems.
hydrophilicity and lipophilicity
Viscosity is defined as the rate of?
flow of fluids
Viscosity of Newtonian fluids:
changes with changes in shear rate
changes with changes in shear stress
does not change with changes in shear rate
cannot be predicted based on shear stress
does not change with changes in shear rate
The viscosity of pseudoplastic fluids:
decreases with a reduction in shear rate
increases with a reduction in shear rate
decreases with an increase in shear rate
increases with an increase in shear rate
decreases with an increase in shear rate
Which type of rheology is usually avoided in the pharmaceutical setting? Newtonian Plastic Thixotropic Dilatant
Dilatant
Components of an emulsion include an \_\_\_\_\_ dispersed in an \_\_\_\_\_\_ using an \_\_\_\_\_\_\_ options: internal phase emulsifier external phase
internal phase, external phase, emulsifier
Emulsions typically contain? two immiscible solids a liquid in an immiscible solid two immiscible liquid a solid in an immiscible liquid
two immiscible liquid
Emulsions can be characterized based on. [Select all that apply] their phases the size of the dispersed particles the viscosity of the external phase the type of emulsifier used
their phases
the size of the dispersed particles
The external phase in an O/W emulsion is?
oil
water
wetting agent
water
Colloidal emulsions have dispersed phase sizes that are?
10-200 nm
The dominant force in coarse emulsions is ___________ due to the size of the _____________.
gravity; dispersed particle
Microemulsions tend to have higher/lower stability due to higher/lower surfactant concentration.
higher; higher
T/F Emulsions can sometimes be used to deliver only in the internal phase
true
T/F Emulsions can carry high drug concentrations
false
A lipophilic drug delivered in an emulsion requires an ___ as the internal phase of the formulation
oil
A surfactant with an HLB of _____________ is needed to prepare an O/W emulsion.
8-19
Which type of colloids must be used in an emulsion to stabilize the interface and reduce interfacial tension?
soluble colloids
association colloids
particulate colloids
association colloids
Which type of excipient will promote flocculation in emulsions? Preservative Antioxidant Particulate hydrocolloid Tonicity agent
Particulate hydrocolloid
Reversible physical stability issues with emulsions include\_\_\_\_\_\_\_\_\_\_\_. [Select all that apply] flocculation cracking creaming coalescence
flocculation and creaming
Oxidation in emulsions is commonly associated with?
oil
T/F All coarse emulsions can be administered parenterally by the IV route.
false
A major concern with microemulsion use parenterally is \_\_\_\_\_\_\_\_\_\_\_. options: low stability due to gravity high surfactant concentration risk of pulmonary embolisms risk of microbial contamination
high surfactant concentration
Drug E is available as a W/O emulsion. Drug E has a MW of 310 Da and a log Ko/w of 0.5. What will be the rate limiting step for Drug E in this dosage form?
Diffusion coefficient
Both diffusion coefficient & partition coefficient
Partition coefficient
Neither diffusion coefficient & partition coefficient
Partition coefficient
