Methods of formulation Flashcards
To be classified as a colloid, the particles must not settle under gravity. True or false?
True
What is the difference between a disperse system, a colloidal suspension and a coarse suspension?
a dispersed system is made from a dispersed/internal phase (particles or droplets) dispersed in another component ( continuous phase), a colloidal suspension is used between 1nm- 1um & coarse suspension above 1um
What are the 3 purification methods of disperse systems?
dialysis, ultrafiltration & electrodialysis
What is a sol?
A colloid suspension of solid particles in a liquid
An emulsion is a mixture of two solids. True or false?
False
Two liquids
How is a foam formed?
when many gas particles are trapped in a liquid or solid
An aerosol contains small particles of liquid or solid dispersed in a gas, True or false?
True
What is meant by a lyophobic colloid?
solvent hating
What is meant by a lyophilic colloid?
Solvent loving
Lyophilic sols exhibit low viscosity. True or false?
False
High viscosity
Are the particles in a lyophilic sol symmetrical or asymmetrical?
asymmetrical
Lyophilic particles are stable to addition of electrolytes. True or false?
True
Lyophobic sols exhibit high viscosity. True or false?
False
Low viscosity
Lyophobic sols contain symmetrical particles. True or false?
True
Lyophobic sols are sensitive to the addition of electrolytes. True or false?
True
How are lyophobic dispersion systems formed?
The dispersion of oil in water
What is meant by dispersion?
The breakdown of coarse material by colloid mills or ultrasonic treatment
What is the stability of an emulsion assessed by and how can it be increased?
visualization & by monitoring particle size over time. Can be increased by reducing droplet size, decreasing density differences & increasing viscosity of continuous phase
Condensation involves the slow production of a supersaturated solution of the colloidal material under conditions that cause formation of colloidal particles and not a precipitate. True or false?
False
Fast production
What are random zig zag collisions a result of?
X
At what size will particles sediment under gravity?
0.5 micrometres or more
Particles less than 0.5 micrometres have to be sedimented by centrifugation. True or false?
True
What are flocs?
Aggregates with an open structure
Majority of gels are formed by aggregation of colloidal sol particles. True or false?
True
What is a gel containing no liquid called?
A xerogel composed of charged particles and form gels by flocculation
Bentonite is a clay. What are clays composed of and how do they turn into gels?
Composed of charged particles and form gels by flocculation
Which type of bonds hold type 1 gels together?
Covalent
Which type of bonds hold type 2 gels together?
Weak bonds like H bonds
Type 1 gels are heat reversible. True or false?
False, irreversible
Type 1 gels swell in water and dissolve. True or false?
false, do not dissolve due to stabilizing links
Type 2 gels are heat reversible. What is meant by this?
On heating or cooling there is a transition from sol to gel and vice versa
As temperature is increased, the solubility of type 2 gels increases. True or false?
False
Decreases
Why does the solubility of type 2 gels decrease as temperature is increased?
Because type 2 gels form micelles and upon warming, more and more micelles form. The micelles are formed so closely together that movement is prevented and a gel phase is formed
A surfactant is an amphipathic molecule. What is meant by this?
It contains both hydrophilic groups and hydrophobic
CMC decreases as length of hydrocarbon chain increases. True or false?
True
How can the stability of an emulsion be increased?
Reduce globlet size, Decrease density difference, Increase viscosity of continuous phase
What particle size is needed for good penetration into the airways?
1 - 5 micrometres
Aerosol particles above 20 micrometres are deposited in the mouth and throat. True or false?
False
More than 10
What happens if the aerosol particles are less than 0.5 micrometres?
They may be exhaled
What is a foam?
Dispersion of a gas in a liquid
Surfactants are required for the formation of foams and emulsions. True or false?
True
What are the two ways in which an aerosol can be prepared?
- dispersion (a pressurized container, active ingredients contained within liquified propellant or additional solvent)
- condensation (sample of vapour-saturated gas is subjected to rapid volume expansion, which lowers temp and causes supersaturation)
Drugs for treatment of erectile dysfunction can be taken through nasal delivery formulations. True or false?
True
Give 2 examples of drugs delivered via nasal drug delivery
Antihistamines and corticosteroids
Give 2 examples of drugs delivered via pulmonary drug delivery
bronchodilators (local delivery) & sodium cromoglicate and Isoprenaline (systemic)
How long is the nasal cavity?
12-14 cm long
In the nasal cavity, cilia of the nasal vestibule filter out particles of which diameter?
Over 10 micrometres
What is the main drug absorption site in the nasal cavity?
The epithelium of the nasal turbinates
Particles of which diameter are deposited in the nasal cavity?
5-10 micrometres
What is PecFent and what is it used for?
Nasal spray with API Fentanyl used for breakthrough pain in people already receiving opioids on a regular basis
All drugs which are orally administered can be given rectally. True or false?
True but may not be as effective
What are some disadvantages of rectal delivery systems?
Not favoured by patients Development of proctitis Slow and sometimes incomplete absorption of drug
Problems with insertion
Short shelf life
