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Stability Testing > Practical experiments questions > Flashcards

Practical experiments questions Flashcards

1
Q

Why are direct UV measurements and titration only limited for stability testing analysis

A

Both methods are not specific enough for the quantificantion of both DP and DS
in the case of UV, structure of the both degradation and drug product should be similar. Therefore absorbing in a similar range, but the DP could have a higher extinction coefficient

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2
Q

What are two characteristic which are importnat for precise stability data in a analystial method
define both characteristic

A

Specific and senstitv
Specific enough to determine the drug substance, the impuries and degradation products
Sensitiv enough to determine smallest amount

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3
Q

Why is the TCL method for the purity of essential oils still in the pharmacopioa

A

Due to the complex composition of the essential oils, its not easy to used analytical methods such as HPLC or GC to detect the degradation products of essential oils

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4
Q

Which methods are possible

A

HPLC with refractive index detecor or photodiade array detectors (DAD)
GC-MS as detector

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5
Q

Container colusre system for essential oils

A

amber or opague, with low oxgen transmission

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6
Q

Why are the stability of essential oils important

A

Essential oils are used as medinical products.

also in food as antioxidance and preservatives

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7
Q

Importance of the acid value

A

it is a physicochemical property of essential oils

An incremnet in the amount of free aicd is indicative hof hydrolysis, more amount of KOH, NaOH.

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8
Q

What happend to essential oils when not well stored?

A

Its degrades to free acids, through oxidation , polymerisation of resignication reaction.

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9
Q

Used of acid value

A

it is to assess the quality of the product and suitability for the oil

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10
Q

What are typical DP functional groups of essential oils?

A

Alcohols, keton, aldehye epoxis

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11
Q

What is refractive index?

A

it is used to dtermine the speed of light when passing through the oils

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12
Q

In which development phase stability studies are carried out and why they get more important?

A

In all development phases, starting from the drug susbtance itself ( stage 1), preformulation and formulation for toxicology and clinical studies (tage 2), then with the selected formulation (stage 3).
stabiliyt studies with registration batch and production batch and as well with the continous production (4,5,6)
After aproval there is a post aprroval changes study (7)

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13
Q

What is an incompatibilities

A

it is a physical and chemical interactions between two or more components of a preparation which can have an influence on the stability of the formulation

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14
Q

Why stability studies must be carried out

A

it is to provide evidance on how the quality of a drug susbstance or DP varies with time under influence of a varity of enviromental factors such as temperature, humidity and light

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15
Q

what is a Maillard reaction?

A

API with primary amine, which are incompactibale with mono and dissacharides (e.g lactose)

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16
Q

Ester hydrolysis

A

AAS with magnesium hydroxide

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17
Q

Whats the aim of stability test

A

it serve to determine the period during which the drug product retains its specification (expiry date)

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18
Q

Which stability study is the most important one during development

A

Studies witth the resistration application, only results that have already been collected should be confirmed

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19
Q

What is based on the results from stage 4

A

the shelf life statements

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20
Q

What is Matrixing?

A

A selection subsets of all stored samples

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21
Q

What is based on the results from stage 4

A

the shelf life statements

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22
Q

What is Matrixing?

A

A selection subsets of all stored samples analysed at an examination date. the results of the subset are representative for all samples at the time of the examination

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23
Q

Which factors can be included Matrixing?

A

different batches, strenght, sizes of the container closure system

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24
Q

Bracketing

A

Only the extrems of certian design factors are tested at all time points. the assumption that non-audited ones show the same stability behaviours as the two extremes

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25
Q

when are structure identification necessary?

A

when degradation product present at a level greater than (>) than the identification threshold

26
Q

When can the Arrhenius plot be used?

A

When storing samples at different temperature and determineing the content of the samples at predefined time point

27
Q

whats emuslifier used for?

A

To reduced the interfacial tension by forming a film at the water/oil interface

28
Q

Creaming

A

Separation of emulsions into its two parts, less dense part(cream) and the other parts.

29
Q

What’s the main characteristics to define emulsions?

A

Droplet size distribution

30
Q

why do we need a emulsifier with a high viscosity

A

it creates a high viscous interfacial films, which reduces coalescence by decreaseing the velocity of the particles

31
Q

Definition of coalescence

A

it is a porcess where the distance between two or more separated groups of miscible particles become smaller, pulling each other to reach the slightest contact

32
Q

Order the formulation syrup, for oral, eye drops , tablets and ointments for cutaneous for microbial contamination

A

Tablets, syrup for oral,ointments, eye drops

33
Q

Ionic interactions in aqueous systems

A

Salt formation leads to decreases dissoziation

34
Q

Why can incompatibilities have influence on the microbial stability?

A

Because the prevervative can lost its effectivness to preserved the formulation..This will lead to grwoth of micro-organismen over time

35
Q

when happend when an anion API is stabiliert with cation surfactant

A

Cation-anion interactions, decreased hydration/solubility

36
Q

When can precipitation occur?

A

of water-soluble compounds by addition of water-miscible solvents (ethanol)

37
Q

When happend with the an aqueous solution in glas as primary packaging material

A

Ion release into aqueous media, this could be alkali and alkaline earth metals, leading to alkalization of aqueous solutions

38
Q

Glas as PP

A

Drug adsorption on the glas surface, important by low-dose and proteins

39
Q

Plastic and metal as PP

A

Migration of APIs into elastromer or the corrosion of metal can cause metal cations to dissolve

40
Q

Urea and water formulation

A

Urea decomposes slowly in the aqueous solution, the reaction is accelerated by a pH increase durig decomposition (Buffer, pH 4-5)

41
Q

Why do we used the MKT?

A

it is used in storage and distribution applications, especially where there can be fluctuations, either because of the climatic zone or the season

42
Q

Why do we used the Degradation product for calibration

A

because the increase of the degradation product, will results to a highe Area under the curve than the decrease in the API itself

43
Q

Why is the Arrhenius equation important?

A

it describe the effect of temperature on the stability of an API. Therefore, once can conduct stress study at higher temperature. And by using the Arrhenius equation, the shelf-life of the product at a giving temperature can be calculated

44
Q

Why is moisture and temperature a critcal parameter for the stability of a drug?

A

Moisture brings moleules closer together and heat icrease the reaction rate

45
Q

What’s the different between drug-excipients and drug-moisture incompatibility?

A

drug-excipients is when the drug interacts with the excipients, where the drug-moisture is cause due to th exposual to high moisture content

46
Q

Why is ASA incompartible with Mg sterarte?

A

Mg sterate has a higher solublity in acetylsaliclylic acid, which leads to the formtion of a buffer, creating a solvated ASA. the created pH enviroment is what is detrimental to the stability of the ASA

47
Q

What about the Polyethylen glycol with ASA

What’s the reaction?

A

ASA as well undergo a pseudo-first order decomposition

Trans-esterification of the slicyclic acide and acetylated PEG

48
Q

the ph value at which a substance precipitates depends on

A

on the pka value, concentration of the substance and the solubility of the compound

49
Q

which equation is used to calculate the protoned state of a compound?

A

Henderson-Hasselbalch equation

50
Q

Why do we better quanify the DP and the API itself?

A

The decrease of the API content will be visualised as a small change in the AUC compared to the increase of content of the DP (1%–>2%). the 100% increase in the AUC is more accuratly rocorded.

51
Q

On what does the elute of the component in the HPLC depends?

A

it’s depends on the component differential affinity between the stationry and mobile phase

52
Q

Example of the stationary phase

A

normal phase, reverse phase column (RP 18)

and reverse phase (RP 8)

53
Q

The responsible of the mobile phase

A

the MP is responsible for eulting the sample components through the column

54
Q

On what does the speed and degree at which the compound moves depends?

A

it depends on its solubility in the mobile phase. Higher solubility in the MB leads to faster elution out of the column

55
Q

What kind of composition of the MP do you know and when are they used?

A

Isocratic and gradient mobile phase.

gradient phase is used when both compound have similar interaction with the SP

56
Q

How does the ph of the MP affects the speration

A

its effect the shape of the peak

57
Q

How does the ph of the MP affects the speration.

explain with ASA and SA?

A

low ph will shift the equilibrium of the SA to the protonated state, wherby higher ph will result in the stabilisation of intar-molecular hydrogen bonds

58
Q

Why is methanol added to the MP

A

it is to reduced the space(time) between the peaks on the chromatogram and speed speration process

59
Q

What are fatty acids?

give an example

A

fatty acids are carboxylic acids with a carbon chain

omage 3 and 6

60
Q

name the three groups of the FA

A
  1. carboxylic acids with long saturated aliphatic carbon chains
  2. carboxylic acids with long unsaturated aliphatic carbon chains
  3. CA with carbon chains which also includes further functional groups

Stability Testing (5 decks)

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