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Performulation Flashcards

(81 cards)

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1
Q

Factors affecting solubility

A
  • temp
  • pressure
  • molecular structure of solute
  • solvent characteristics
  • crystal characteristic
  • pH
  • common ion effect
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2
Q

How is solubility affected in endothermic reaction

A

Temp increases so solubility increases (kinetic energy increase with temp)

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3
Q

What happens when pH increases with weak acids

A

Ionisation increases

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4
Q

What happens when pH increases with weak bases

A

Ionisation decreases

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5
Q

How soluble is Amorphous ?

A

Very soluble

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6
Q

How to assess solubility ?

A

XS solute in solvent to dissolve
Removed undissolved solid
Molecules with e- absorb light
Amount of light absorbed proportional to analytical conc.

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7
Q

What is surface tension depended on?

A

Temperature

Impurities (surfactants)

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8
Q

What to use to measure surface tension?

A

Wilhelmy plate

Du Noüy ring (interfacial tension too)

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9
Q

How does wetting happen?

A

Result of intermolecular interactions at the S-L interface

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10
Q

Surfactant ceutical uses?

A
  • detergent
  • emulsifying agent
  • wetting agents
  • foaming agent
  • flocculating agent
  • solubilising agent
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11
Q

What happens when the surfactant concentration too much?

A

No more surface for surfactant molecules to line thus form micelles

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12
Q

Critical micelle concentration

A

Surfactant conc. above micelles form

  • in water, CMC decreases with increases molecular size of surfactant
  • bulkier surfactant =less molecules fit in give SA so lower CMC
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13
Q

What administration can emulsions be given in?

A

Oral
Parenteral
Topical

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14
Q

Single emulsion

A

Liquid droplets (disperse phase) in another liquid (continuous phase)

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15
Q

Double emulsion

A

Primary emulsion droplets in another liquid

EG: O/W/O Emulsion

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16
Q

Most emulsifiers are?

A

Surfactants and therefore amphipilic

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17
Q

What to emulsifiers mediate?

A

Molecular interactions at the interface between disperse and continuous phase

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18
Q

Stable emulsions called?

A

Meta stable

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19
Q

Different types on emulsion instability?

A

Flocculation
Creaming
Sedimentation
Cracking

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20
Q

Flocculation

A

Electrical double layer around particles

Flocs May fuse = coalescence

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21
Q

How can floc interactions be altered

A

With additives

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22
Q

Sedimentation and creaming

A

Patrick’s sink in continuous phase under opposing forces

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23
Q

Sedimentation rate increases with?

A
  • larger droplet size
  • lowkey fluid viscosity
  • greater density differences between droplet and continuous phase
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24
Q

If emulsifier is more soluble in water, what type of emulsion?

A

O/W emulsion

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25
If emulsifier more soluble in oil, what type of emulsion?
W/O emulsion formed
26
What is crystalline structure?
Thermodynamically stable, sharp MPT
27
Polymorphism of same substance can differ in terms of:
``` MPT Density Chemical reactivity Mechanical properties Dissolution rate ```
28
Polymorphs absorption
Is different and bioavailability despite identical formulation
29
What undergoes glass transition?
Amphorous
30
Compaction cycle
1-filling in die cavity 2-compression -die volume decreases 3-ejection - tablet pushed (lubrication)
31
Compression results in:
Reduced porosity Reduced bulk volume Increases bulk density
32
Mechanical properties required for compaction
Plasticity - deformed particles when compressed = greater cohesion Brittleness - particles fragment = increase SA and surface energy = greater cohesion
33
What is tensile strength
Stress needed to fracture tablet. Reflects strength of inter-particle bonding
34
If compaction pressure increases ?
Tensile strength increases
35
If tablets are flat it convex ?
Lower tensile strength
36
If the polymorph is stable?
Lower tensile strength
37
Driving forces
Gravitational force, mechanical agitation
38
Retardant forces
Cohesion /adhesion, friction, mechanical interlocking
39
What does adhesion attract
2 chemically different surfaces
40
What does cohesion attract?
Attractive forces between 2 chemically similar surfaces
41
Example of adhesion/cohesion forces?
- VDW - electrostatic attraction - capillarity forces (liquid bridges)
42
How do VDW forces increase?
With particle size and proximity | Dominant effect on fine particles over gravity
43
What do capillary forces do?
Adsorb moisture on particle surface, forming liquid bridges
44
What are the factors affecting particle size? (To favour flow)
``` Large particle size Spherical particle SA of particle = small High density Looser packing geometry Moderate moisture content ```
45
What happens when there too much moisture with particles?
They clump together
46
What is the angle of repose and how does it come about?
Cohesive powders flow less well and also pile up higher | =steeper slope, larger angle of repose = lower flowability
47
Product quality aims from mixing?
Uniformity of mass Reproducibility Therapeutic efficacy Patient safety
48
What is a positive mixture ?
Approaches perfect mixture (eg: alcohol and water)
49
What is a negative mixture?
Energy input required to mix components and maintain mixture (Eg:emulsion)
50
Neutral mixture ?
Energy input required to mix/segregate eg:powders/pastes
51
Random mixture?
Group of particles adjacent to one another | Free flowing primary particles
52
Ordered mixture (cohesive particles)?
Micronised particles adsorbed on surface of larger carrier particles
53
When is segregation likely?
Particle size non-uniform Particle density non-uniform Spherical shape (free flowing)
54
Demixing - percolation separation
Small particles fall through voids
55
Demixing - trajectory segregation
Larger particles go further as they have more mass
56
Demixing - elutriation segregation
‘Dusting out’ - fine particles settle on top after motion has stopped
57
How to minimise segregation ?
Select suitable particle size range Select excipients to similar density Reduce vibration
58
What is adsorption due to?
- physical bonding between adsorbent and adsorbate (weak VDW, H-bonds) - chemical bonding called chemisorption (via strong covalent bonds)
59
Thin layer chromatography phases?
Stationary - silica (polar) | Mobile - liquid mixture of solvents
60
High performance liquid chromatography (HPLC) phases?
Mobile - runs through column of solid stationary phase at high pressure
61
Gas chromatography phases?
Mobil - has | Stationary - either liquid/solid
62
Alfa tor’s affecting adsorption
Temperature (increase temp, decrease adsorption) Concentration Nature of solvent Solute 2nd solid present pH - many materials ionisable/tendency to interact greatly if exist as polar ions
63
Example of good adsorbent and it’s use?
Activated charcoal for overdose/poisoning | -large SA (50-100g adult)
64
What is koalin drug?
Adsorb toxins and often used for mild diarrhoea
65
What is chemisorption?
When chemical bonding between adsorbent and adsorbate on the monolayer on the surface -irreversible, only arise when chemical bonds (Eg ammonia synthesis)
66
What is dissolution?
Transfer of molecules/ions from solid state into a solution (thermodynamically favourable)
67
What is solubility?
Capacity of absolute to dissolve in a solvent
68
Dissolution rate controlled by?
Speed of removal of particles from solid surface Diffusion rate through boundary layer Stirring/agitation decrease diffusion gradient
69
What happens when a drug has limited water solubility?
Dissolution is rate-limiting step to absorption
70
Why is dissolution testing carried out?
For quality control - consistency | Predictive testing - assess product stability
71
How much drug needs to dissolve in QC dissolution testing?
More than or equal to 80%
72
Dissolution testing apparatus
Basket Paddle Flow through cell Reciprocating cylinder
73
Properties of dissolution medium
Mustn’t affect drug stability Easy to prepare Preferable inorganic (Eg 0.1M HCL for weakly basic drugs)
74
Class I
Soluble at 250mL More than 90% absorption (Dissolution >85% in 30mins)
75
Class II
Not soluble in 250mL | Absorption >90%
76
Class III
Dose soluble in 250mL | Absorption <90%
77
Class IV
Not soluble in 250mL | Absorption <90%
78
Class I rate limiting step?
Gastric emptying
79
Class II rate limiting step?
Dissolution rate or solubility
80
Class III rate limiting step?
Membrane permeability + physiology
81
Class IV rate limiting step?
Various, including dissolution rate

Pharmacy (11 decks)

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