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M102 > W5 Disperse systems- Dosage forms > Flashcards

W5 Disperse systems- Dosage forms Flashcards

1
Q

What is a colloid/colloidal dispersion?

A

A two phase system of matter; a type of mixture intermediate between homogenous and heterogenous mixtures. (size <1 micron)

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2
Q

What is a phase colloid?

A

Small droplets or particles of one substance are dispersed in another

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3
Q

What is a molecular colloid?

A

Macromolecules are dispersed in a continuous phase

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4
Q

What is a disperse system?

A

One phase is distributed throughout a second phase
( a continuous phase or dispersant)
(two immiscible phases in contact)

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5
Q

What is electrophoresis?

A

Migration of charged particles
Surface dependent

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6
Q

What is thixotropy?

A

Exhibits stable form at rest
Becomes fluid with shear/agitated
E.g. paint

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7
Q

What does lyophobic and lyophilic mean?

A

Solvent hating (hydrophobic)
Solvent liking (hydrophilic)
(lyo means solvent)

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8
Q

Calcium phosphate (in toothpaste) is lyophobic or lyophilic?

A

Lyophobic

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9
Q

Starch and gelatine are lyophobic or lyophilic?

A

Lyophilic

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10
Q

What is a sol?
examples?

A

A colloidal suspension of small, solid particles in a continuous liquid medium e.g. paint, mud
(solid in a liquid)

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11
Q

What is a gel?

A

A colloidal suspension in which the liquid medium has become viscous enough to behave more or less as a solid.

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12
Q

How can you identify if a gel is a two phase system? (lyophobic)

A

Flocculated particles in a two-phase gel
Network of elongated particles or rods forming a gel structure
(particles are attached)
Usually opaque, not as stable as single phase

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13
Q

How can you identify if a gel is a one phase system? (lyophilic)

A

Matted fibres as found in soap
Crystalline and amorphous regions in a gel of carboxymethylcellulose
Clear or translucent, with no definite boundaries between the dispersed macromolecules and the liquid.
Can be dispersed in water to provide a range of bases from mobile liquids to solids

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14
Q

What are foams?
how are they formed?

A
  • Gases dispersed in a liquid/solid
  • Formed by trapping many gas bubbles
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15
Q

What instruction is given for most liquid dosage forms

A

‘Shake well before use’

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16
Q

Types of defoamer/antifoaming agents

How do they work?

A

Foam breakers and preventers
- Act as small droplets forming in the foam lamellae
- Displaces surfactants at the air-water interface
e.g. silicone fluids

17
Q

What type of emulsion is cod liver oil?

A

An oil in water dispersion

18
Q

Is a suspension a colloid?

A

No.
As they are generally larger than 1 micron/micrometer

19
Q

What are suspensions?

A

Insoluble particles are dispersed within a liquid medium which is usually aqueous
e.g. ibuprofen or paracetamol oral suspension

20
Q

Which is bigger?
Suspension, Colloid or Solution?

A

Suspension.

21
Q

What are the properties of colloids?

A

Tyndall effect
Brownian motion
Adsorption
Dialysis
Electrophoresis
Thixotropy

22
Q

What is an emulsion?

A

A liquid in a liquid e.g. a cream

23
Q

What is a foam?

A

A gas in a liquid

24
Q

What happens when dissolving a solute into a solvent? (6)

A

Molecular dispersion
Contains small particles (ions or molecules)
Transparent
Do not separate
Cannot be filtered
Do not scatter light

25
Q

What are 3 examples of everydaysolutions?

A

Saline solution
Multi-purpose contact lens solution
Hydrogen peroxide contact lens solution
Makeup toner

26
Q

What are 3 examples of disperse systems?

A

Droplets of pine oil dissolved in active germ killing ingredient
Face cream
Nail polish

27
Q

What is an example of a pharmaceutical solution?

A

Mouth wash (Chlorhexidine gluconate)
Feminine wash
Saline laxative (constipation relief)

28
Q

What are examples of pharmaceutical disperse systems?

A

Amoxicillin oral suspensions
Aveeno lotion
Pfizer solution

29
Q

What is the Tyndall effect?

A

Colloids scatter light
(light beam path through colloid is visible due to light scatter)

30
Q

What is Brownian motion?

A

Under a microscope, the molecules of the liquid are in motion
Because of the motion, the larger particles of the colloid are being constantly bombarded by the smaller particles of the liquid

31
Q

What is adsorption?

A

A chemical is associated to the surface of a second agent
Often reversible
Can lead to conformational changes
Manipulate physiochemical properties

32
Q

What is dialysis? (in colloids)

A

Separation of suspended colloidal particles from dissolved ions or molecules of small dimensions
By means of their unequal rates of diffusion through the pores of semi-permeable membranes

33
Q

What is the formulation (ingredients) of gels?

A

Gelling agents, semisynthetic materials, synthetic, humectants, preservatives, water

34
Q

Why can foams pose as a problem?

A

The foam forms on shaking and might be too much so a defoamer should be added

M102 (42 decks)

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