Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

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

Stability and stability testing of pharmaceuticals Flashcards

(48 cards)

Start Studying
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?

21
Q

What occurs in the termination step?

Study These Flashcards
A

-Free radicals combine to form inactive (new) product

22
Q

How do antioxidants work?

Study These Flashcards
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?

Study These Flashcards
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?

Study These Flashcards
A
  • Use antioxidants
  • Use chelating agents e.g EDTA
  • Adjust pH
25
What do primary antioxidants do?
-They interfere with propagation step
26
What do synergists do?
-They promote activity of primary antioxidants
27
Reducing agents have a lower redox potential than the drug, so are therefore more likely to be oxidised than the drug. TRUE OR FALSE?
TRUE
28
Decreasing pH often increases REDOX potential. TRUE OR FALSE?
TRUE
29
What is REDOX potential?
-The tendency of a chemical to acquire electrons and therefore be reduced and increases resistance to oxidation
30
The higher the REDOX potential to more likely to be reduced. TRUE OR FALSE?
TRUE
31
In adrenaline solution, decreasing the pH from 6 to 4 results in a 2 fold increase in chemcal stability. TRUE OR FALSE?
TRUE
32
Give examples of commonly used antixidants?
- Gallic acid - Butylated hydroxyanisole - Butylated hydroxytoluene - Tocopherols
33
What photochemical degradation (photolysis)?
-The seperation or degradation of a molecule by the action of light
34
What occurs during photolysis?
- 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
What does photolysis result in?
- A change of colour in product | - Fading of colouring agents
36
How do we prevent or reduce Photochemical degradation?
- Storage and packages - amber bottles/boxes - Darkness - Store at cool temperatures - UV absorbers
37
How do UV absorbers work and provide an example?
-They absorb harmful light radiation and dissipate the energy as heat of flourescence or in a reversible chemical reaction. e.g benzophenones
38
What is isomerisation?
Conversion of a drug to its optical or geometric isomer
39
What is an epimerisation?
-An epimer is one of a pair of stereoisomers. The two isomers differ in configuration at only one stereogenic center
40
What is polymerisation and provide a drug example?
-The process by which two or more identical molecules form a complex e.g ampicillin
41
What is dehydration and provide an?
-The breaking of a covalent bond to eliminate a water molecule from the structure e.g tetracycline
42
What is decarboxylation and provide an example?
-The elimination of carbon dioxide from a compound e.g when parenteral solutions of sodium bicarbonate are autoclaved
43
What are chemical incompatibilities?
When two chemicals rae mixed in a formulation and react, which is usually seen by precipitation from a solution
44
Provide example of physical degradations for tablets and capsules?
- Dissoultion rate - Appearance - Odour - Friability - durability of drug during transit - Hardness
45
Provide example of physical degradations for ointments and creams?
- Appearance - Odour - Viscosity - Particle size distribution
46
Provide example of physical degradations for transdermal patches?
- Appearance - Rate of drug release - Adhesive strength
47
Provide some examples of forms of physical instability?
- Loss of water - Change in product colour - Change in product odour - Crystal growth - Polymorphic changes - Caking of suspensions
48
How can physical instability be prevented?
- Formulation - Manufacture - Packaging - Storage

Gary's lecture (Pharmaceutics) (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions