Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gary's lecture (Pharmaceutics) > Stability and stability testing of pharmaceuticals > Flashcards

Stability and stability testing of pharmaceuticals Flashcards

1
Q

How is quality measured?

A
  • By the content of the active substance in the product
  • By the purity of active substance in the product
  • By the physico-chemical properties of the product
  • By the microbiological properties of the product
  • By the organoleptic and aesthetic properties of the product
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is hydrolyxis frequently catalized by?

A

-By hydrogen ions or hydroxyl ions and by acidic or basic species (buffers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Give examples of the main classes of drugs that susceptible to hydrolysis?

A

“Known as labile carbonyls”

  • Esters e.g aspirin , cocaine
  • Amides e.g Dibucaine
  • Lactones e.g Pilocarpine
  • Lactams e.g Penicillins, nitrazepam
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do we prevent or reduce hydrolysis?

A
  • Minimise contact - removal of moisture (water, humidity)
  • Control manufacturing envrionement
  • Introduce solid dosage form
  • Adjust pH - reduces acid base catalysed hydrolysis
  • Reduce solubility - if drug is not in solution it cannot be hydrolysed
  • Form complexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main cause of drug degradation?

A

Oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is drug degradation influenced by?

A

Light and heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What functional groups are prone to oxidation?

A
  • Phenols
  • Ethers
  • Thiols
  • carboxylic acids
  • Aldehydes
  • Catechols
  • Thioethers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is chemical oxidation?

A

It is the removal or the addition of an electropositive or an electronegative atom, radical or electron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Oxidation is essentially the loss of electrons without th addition of oxygen. TRUE OR FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are free radicals?

A

They are chemicals containing alteast one unpaired electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Free radicals are highyl unstable and highly reactive, TRUE OR FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is auto-oxidation?

A

It is the spontaneous oxidation of a compound in air or in the presence of oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Many pharmaceutical oxidations are irreversible chain reactions proceeding slowly under the influence of atmospheric oxygen. TRUE OR FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Oxidation reactions over does not occur several years. TRUE OR FALSE?

A

FALSE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The shelf life is dependent on the suitability of the dosage form. TRUE OR FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Oxidation involves the formation of free radicals. TRUE OR FALSE?

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three steps in the chain reaction during an oxidation reaction?

A
  • Initiation
  • Propagation
  • Termination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What occurs during the initiation reaction?

A

-Free radicals formed by the action of light, heat or trace of metals (such as iron - which comes form the formulation itself)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What occurs during propagation reaction?

A
  • Formation of peroxy radical

- Removal of H from organic molecule to form hydroperoxide and a new free radical.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Propagation step is the chain reaction step. TRUE OR FALSE?

A

TRUE

21
Q

What occurs in the termination step?

A

-Free radicals combine to form inactive (new) product

22
Q

How do antioxidants work?

A

-They interrupt propagation by interaction with free radicals; which leads to the formation of an antioxidatant free radicals which is not sufficiently reactive to maintain the chain reaction.

23
Q

How do we prevent or reduce oxidation?

A
  • Precautions during manufacture
  • Avoid contact of drug with heavy metals ions
  • Replace oxygen in container with nitrogen
  • Well filled containers less room for oxygen
  • Store at reduced temperatures
24
Q

What are the formulaton approaches of reducing and or preventing oxidation?

A
  • Use antioxidants
  • Use chelating agents e.g EDTA
  • Adjust pH
25
Q

What do primary antioxidants do?

A

-They interfere with propagation step

26
Q

What do synergists do?

A

-They promote activity of primary antioxidants

27
Q

Reducing agents have a lower redox potential than the drug, so are therefore more likely to be oxidised than the drug. TRUE OR FALSE?

A

TRUE

28
Q

Decreasing pH often increases REDOX potential. TRUE OR FALSE?

A

TRUE

29
Q

What is REDOX potential?

A

-The tendency of a chemical to acquire electrons and therefore be reduced and increases resistance to oxidation

30
Q

The higher the REDOX potential to more likely to be reduced. TRUE OR FALSE?

A

TRUE

31
Q

In adrenaline solution, decreasing the pH from 6 to 4 results in a 2 fold increase in chemcal stability. TRUE OR FALSE?

A

TRUE

32
Q

Give examples of commonly used antixidants?

A
  • Gallic acid
  • Butylated hydroxyanisole
  • Butylated hydroxytoluene
  • Tocopherols
33
Q

What photochemical degradation (photolysis)?

A

-The seperation or degradation of a molecule by the action of light

34
Q

What occurs during photolysis?

A
  • Molecules exposed to electromagnetic radiation, absorb light at characteristic wavelengths, causing an increase in energy state of the compound that can lead to:
  • Decomposition
  • Conversion to heat
  • Emission of light at a new wavelength
35
Q

What does photolysis result in?

A
  • A change of colour in product

- Fading of colouring agents

36
Q

How do we prevent or reduce Photochemical degradation?

A
  • Storage and packages - amber bottles/boxes
  • Darkness
  • Store at cool temperatures
  • UV absorbers
37
Q

How do UV absorbers work and provide an example?

A

-They absorb harmful light radiation and dissipate the energy as heat of flourescence or in a reversible chemical reaction. e.g benzophenones

38
Q

What is isomerisation?

A

Conversion of a drug to its optical or geometric isomer

39
Q

What is an epimerisation?

A

-An epimer is one of a pair of stereoisomers. The two isomers differ in configuration at only one stereogenic center

40
Q

What is polymerisation and provide a drug example?

A

-The process by which two or more identical molecules form a complex e.g ampicillin

41
Q

What is dehydration and provide an?

A

-The breaking of a covalent bond to eliminate a water molecule from the structure e.g tetracycline

42
Q

What is decarboxylation and provide an example?

A

-The elimination of carbon dioxide from a compound e.g when parenteral solutions of sodium bicarbonate are autoclaved

43
Q

What are chemical incompatibilities?

A

When two chemicals rae mixed in a formulation and react, which is usually seen by precipitation from a solution

44
Q

Provide example of physical degradations for tablets and capsules?

A
  • Dissoultion rate
  • Appearance
  • Odour
  • Friability - durability of drug during transit
  • Hardness
45
Q

Provide example of physical degradations for ointments and creams?

A
  • Appearance
  • Odour
  • Viscosity
  • Particle size distribution
46
Q

Provide example of physical degradations for transdermal patches?

A
  • Appearance
  • Rate of drug release
  • Adhesive strength
47
Q

Provide some examples of forms of physical instability?

A
  • Loss of water
  • Change in product colour
  • Change in product odour
  • Crystal growth
  • Polymorphic changes
  • Caking of suspensions
48
Q

How can physical instability be prevented?

A
  • Formulation
  • Manufacture
  • Packaging
  • Storage

Gary's lecture (Pharmaceutics) (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions