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Medicines design II - solid dosage forms > L7&8 Excipients > Flashcards

L7&8 Excipients Flashcards

0
Q

Why formulate a dose?

A

Patients unlikely to be able to measure accurately. (Especially with low dose)
High doses may be have poor flow/compressibility to make into a tablet.

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1
Q

Why not administer a pure drug? (6)

A
  • Dose control
  • taste
  • physical properties (partitioning, solubility, BA, stability)
  • to control rate of absorption
  • allow admin via specific route
  • handelling, transportation on and marketing
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2
Q

Taste… Many drugs taste… Can’t be improved by…

A

Very bitter

Film coating

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3
Q

Panafon actifast claims

A

Paracetamol
Very rapid dissolution therefore rapid adsorption
Less GI problems, suitable for asthmatics
Fast acting pain relief

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4
Q

Talc is used as

A

A flow agent

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5
Q

Steric acid is used as…

A

A lubricant

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6
Q

Potassium sorb ate is used as

A

A sweetener

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7
Q

Starch is used as

A

Disintergrants

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8
Q

Triacetic and Hydroxpropymethylcellulose (HPMC) is used as…

A

Film coating

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9
Q

Sodium bicarbonate is uses as

A

Super disintergrant

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10
Q

Excipients definition

A

All components of the formulation other than the drug

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11
Q

Excipients require

A

Appropriate evaluation for safety

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12
Q

Excipients should be

A

Chemically and physiologically inert

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13
Q

Eg or a moral or religious objection to excipients

A

Genetic

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14
Q

Function of excipients (3)

A
  • provide identification
  • enhance BA, solubility and acceptability
  • aid processing of the system during manufacture
  • enhance other attributes of overall safety and effectiveness of drug during storage and use
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15
Q

Lactose and microcrystalline cellulose are used as…

A

Diluents and compressive

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16
Q

Colloidal sillica used as

A

Flow agent

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17
Q

Magnesium sterate is used as

A

Lubricant

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18
Q

Fumed sillica is used as

A

Adsorbers

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19
Q

What can be adversely affected by excipients?

What is particularly troublesome?

A

Rate of adsorption

Tableting lubricants

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20
Q

Example of excipients inhibiting solubility

A

Magnesium sterate is insoluble and inparts hydrophobicity to formulation

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21
Q

If posible …. To avoid dissolution proplems

A

Minimise percentage of excipient in solid dosage forms

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22
Q

Duleunts or bulking agents are…

A

Added to make tablet a reasonable size

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23
Q

Principle deluant used is…. Why?

A

Lactose

Pleasant taste, dissolves in water, not hygroscopic

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24
Q

Dicalcium phosphate is used as….

properties…

A

Deluant particularly in wet granulation
Insoluble in water
less hygroscopic
Cheap

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25
Q

Starches are use…. Property…

A 
Deluant
Very hygroscopic (>14% moisture uptake)
Good disintegration properties
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26
Q

Micro crystalline cellulose (MCC) is used as… Properties…

A

Direct compression diluent
Excellent compression properties
Some disintergrant ion properties

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27
Q

Starch is used as …. Properties …

A

Diluent
Sweet tasting but
Very hydroscopic

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28
Q

MCC is produced by

A

Partial hydrolysis of cellulose

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29
Q

MCC gives…. Tablet strength from… Compression forces

A

High tablet strength from low compression forces

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30
Q

MCC has good/poor flow

A

Poor flow as particles a naturally 50micrometers

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31
Q

T/f MCC is sensitive to lubricant?

A

T - lubricant hinders formation of strong bonds between layers (weakens tablet)

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32
Q

T/f - MCC is sensitive to moisture?

A

T-5% uptake

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33
Q

Cheaper grades of MCC obtained from

A

Wood pulp

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34
Q

Lower moisture grade MCC has the disadvantage of

A

Reduced compression

35
Q

High bulk density MCC …

A

Aids blending

36
Q

Low bulk density MMC

A

Increases tablet strength

37
Q

Lubricant function

A

Prevent adherence of formulation to punches and dies and ensure smooth ejection from these.

38
Q

How do lubricants work?

A

Form a film of low shear strength between tablet and surface of punch

39
Q

Some lubricants also act as 2

A

Antiadherance and flow aids

40
Q

2 popular lubricants for punches

A

Talc and magnesium sterate

41
Q

Popular die lubricant

A

Steric acid

42
Q

How is magnesium sterate put into things?

A

Encorporate into dry granules prior to compression

Concentration up to 1%

43
Q

Lubricants in weaponised anthrax?

A

It’s hard to get a small thing into the lung but if you coat it in lubricant it’s much easier

44
Q

If you coated a sugar cube in mg sterate and dissovled it you would get a shell. Why?

A

Very hydrophobic

45
Q

Disadvantages of mg sterate
Increased concentration decreases disintegration time, drug dissolution and weakens bond forces (soft tablets) due to hydrophobic nature
Incompatibility with many drugs
Ethical problems.

A

Requires additional steps

I

46
Q

Mg sterate incompatible with eg…

A

Aspirin

47
Q

Ethical problem of mg sterate

A

Derived from cow fat although plant sources are now available.

48
Q

Gildants are also known as

A

Flow agents

49
Q

Purpose of flow agent

A

Added to formulation to improve the flow of granules

50
Q

Flow agents act by

A

Reducing inter particulate friction

51
Q

Most commonly used and effective flow agent is

A

Fumed Sillica

52
Q

But what actually is fumed sillica

A

Amorphous colloidal silicon dioxide

53
Q

What concerntraion of fumes sillica is required

A

Less than 0.1%

54
Q

Action of flow agents

A

Reduction of contact area between granules reduces inter particulate cohesion / adhesion and that increases flow ability
This is the opposite of geckos sticking to walls

55
Q

Main forces reduced by use of flow agents

A

Van der waals

56
Q

Sillicified MCC is a combination of

A

MCC and silicon dioxide
During spray drying colloidal sillica is added
10-15nm

57
Q

Advantage of the two in one sillicified MCC

A

Reduced burden of lubricants
Dramatically increases flow
Better blending
Increases tablet strength

58
Q

Disadvantage of sillicified MCC.?

A

One supplier, very expensive

59
Q

For effervescent formulations what sort of flow agent do you need?

A

A soluble one

60
Q

Self lubrication…

A

I think… Is where it stays in the punch after a number of cycles and then remains consistently lubed

61
Q

People like lubricants as the give

A

Smooth tablet texture

62
Q

Ideal antifriction agent for decreasing ejection force is

A

Oil such as Hvo

63
Q

Disintergrants are added to

A

Promote break up of tablets in vivo

64
Q

Disintergrants are particularly important in 2

A

Break up of insoluble drugs particularly those of high dose

65
Q

Disintergrants work by

A

Increasing the surface area of the formed de aggregates by various methods. Thus promoting rapid release of drug.

66
Q

Why do we granulate?

A

To make sure concentration of drug is consistency throughout tablet,

67
Q

Main Mechanismof disintergrant action

A

Swelling

Takes in stomach fluid and expands

68
Q

Other mechanisms of disintergrants action

A

1Porosity and capillary action - draws in fluid which ruptures inter particulate bonds
2Deformation
3Gas production
An inter relationship probably occurs in most formulations.

69
Q

Most common disintergrant?

A

Starch

70
Q

PVP, modified starches and cellulose are used as…

A

Disintergrants

71
Q

Venalafaxine Xl works by

A

At certain pH everything inside swells up so drug is pushed out through the tiny whole

72
Q

Super disintergrants - for when starch isn’t enough eg

A

Modified starch -rapid and extensive swelling with minima gelling

73
Q

Modified starch advantage

A

More effective at lower concentrations.

Reduces problems with compressibility and flows biliary of stach

74
Q

Disadvantaged of modified starch

A

Hygroscopic

75
Q

Binders are also known as

A

Adhesives

76
Q

Two methods of adding binders

A

Slugging (as a powder into the formulation)
And
As a solution to mixed powders in wet granulation

77
Q

Binding agents function

A

Bind powders together in wet granulation process or granules during direct compression

78
Q

What must be removed prior to compression

A

Liquid additives

79
Q

Binder disadvantage

A

Can effect dissolution rate

80
Q

Typical binding agents 2

A

starch mucilage and gelatin.

81
Q

Most important binder is… Because…

A

PVP. Soluble in water and alcohol and releases drug rapidly

82
Q

Typical concentrations of PVP binder

A

2-10%

83
Q

Function of adsorbants

A

Hold quantity of fluid in apparently dry state

84
Q

What sort of fluids do we use adsorbants to add

A

Liquid flavourings, fluid extracts. Oils

85
Q

Commonly used adsorbants

A

Fumed silica, microcrystalline cellulose, kaolin and magnesium carbonate are commonly employed adsorbents.

86
Q

Why is fumed silica used as adsorbant?

A

Porus

Medicines design II - solid dosage forms (11 decks)

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