1. STABILITY STUDY PTE 603 ASSIGMENT By Ogoh Adakole Augustine
An M.Sc. Student of Pharmaceutical Technology
University of Jos
Lecturer: Dr J.D Audu-Perer

2. OUTLINE INTRODUCTION OBJECTIVES AND USES
IMPORTANT OF STABILITY STUDIES
TYPE OF STABILITY STUDIES
REAL-TIME STABILITY TESTING
ACCELERATED STABILITY TESTING
RETAINED SAMPLE STABILITY TESTING
ICH HARMONISED TRIPARTITE GUIDELINE
STEPS INVOLVED IN CALCULATING OF SHELF LIFE
REFERENCES

3. INTRODUCTION
Stability of a pharmaceutical drug products is the ability of a drug formulation in a specific container-closure system to remain within its physical, chemical, microbiological, therapeutic and toxicological specifications throughout its shelf life
Biopharmaceutical products in storage change as they age, but they are considered to be stable as long as their characteristics remain within the manufacturer's specifications (Robert, 2003).
The number of days that the product remains stable at the recommended storage conditions is referred to as the shelf life (Robert, 2003).

4. INTRODUCTION CONT’D
A measure of how a pharmaceutical product maintains its quality attributes over time
Stability testing is used to:
Provide valid evidence as to how the quality of drugs changes with time.
Establish shelf life of pharmaceutical drug product or to establish a re-test period for the active pharmaceutical ingredient
For registration purposes
To determine the recommended storage conditions of drug product.
To determine the right container and packaging materials.

5. IMPORTANT OF STABILITY TESTING
Quality assurance to the patient as in regard to good treatment outcomes
Economic considerations.
Legal requirement for regulatory bodies

6. OBJECTIVES AND USES (Thorat et al., 2014)
Type of study
Use
To select adequate formulation & container Closure system .
Accelerated
Development of the product
To determine shelf life &storage condition.
Accelerated& Real time
Development of the product& of the registration dossier
To substantiate the claimed shelf life.
Real time
Registration dossier
To verify that no changes have been introduced in the formulation or manufacturing process that can adversely affect the stability of the product.
Quality assurance in general, including quality control

7. TYPES OF STABILITY TESTING (Thorat et al., 2014)
Real-Time stability testing
Retained sample stability testing
Accelerated stability testing

8. Real-Time stability testing
In real-time stability testing, a product is stored at recommended storage conditions and monitored until it fails the specification (Robert, 2003).
Real-time stability testing is normally performed for longer duration of the test period in order to allow significant product degradation under recommended storage conditions (Thorat et al., 2014).
The period of the test depends upon the stability of the product which should be long enough to indicate clearly that no measurable degradation occurs and must permit one to distinguish degradation from inter-assay variation(conditions (Thorat et al., 2014).

9. Real-Time stability testing cont’d
During the testing, data is collected at an appropriate frequency.
The reliability of data interpretation can be increased by including a single batch of reference material for which stability characteristics have already been established (Thorat et al., 2014)

10. ICH Climatic zone and Long term condition (Thorat et al,2014)
Climatic definition
Major countries Region
Mean annual partial water press
Long term testing condition 1
Temperate
Europe, Russia
<15ºC/,<11hPa
21ºC/45%RH 2
Subtropical&
Mediterranean
Japan ,Southern
Europe
>15ºC-22ºC/>11-
18 hPa
25ºC/60%RH 3
Hot & Dry
Iraq, India
>22ºC>15hPa
30ºC/35%RH 4a
Hot & Humid
Iran ,Egypt
>22ºC>15-27hPa
30ºC/65%RH 4b
Hot & very humid
Brazil, Singapore
>22ºC>27hPa
30ºC/75%RH

11. Retained sample stability testing (Thorat et al.,2014)
This method is normally use for marketed product that require stability study.
In this study, stability samples, for retained storage for at least one batch a year are selected.
If the number of batches marketed exceeds 50, stability samples from two batches are recommended to be taken.
At the time of first introduction of the product in the market, the stability samples of every batch may be taken, which may be decreased to only 2% to5% of marketed batches at a later stage.
In this study, the stability samples are tested at predetermined intervals i.e. if a product has shelf life of years, it is conventional to test samples at 3, 6, 9, 12,18, 24, 36, 48, and 60 months

12. ACCELERATED STABILITY TESTING
All medicinal products decompose with time
Stability study to predict the shelf life of the product, by accelerating the rate of decomposition, preferably by increasing the temperature of reaction conditions.
Studies designed to increase the rate of chemical degradation or physical change of a drug substance or drug product by using exaggerated storage conditions as part of the formal stability studies (ICH, 2003).
In accelerated stability tests, a product is stored at elevated stress conditions (such as temperature, humidity, and pH) (Robert, 2003)

13. ACCELERATED STABILITY TESTING CONT’D (Thorat et al., 2003)
In addition to temperature, stress conditions applied during accelerated stability testing are moisture, light, agitation, gravity, pH and package
In accelerated stability testing the samples are subjected to stress, refrigerated after stressing, and then assayed simultaneously.
comparison of the unstressed product with stressed material is made within the same assay and the stressed sample recovery is expressed

14. ICH HARMONISED TRIPARTITE GUIDELINE (ICH, 2003)
According to International Council for Harmonization(ICH),
The long term study for drug product must be continued for a sufficient period of time beyond 12 months to cover the shelf life of the product.
Intermediate storage condition data are required when a significant change occurs prior to completion of study under the accelerated storage condition.
The accelerated storage condition must be >15º C above the long term study storage conditions.

15. Storage condition (ICH, 2003)
STUDY
Storage condition
Minimum time period covered by data at submission
Long term
25°C ± 2°C/60% RH ± 5% RH or 30°C ± 2°C/65% RH ± 5% RH
12 months
Intermediate
30°C ± 2°C/65% RH ± 5% RH
6 months
Accelerated
40º C ± 2º C
75%RH ± 5%

16. ICH HARMONISED TRIPARTITE GUIDELINE
Selection of Batches
Data from stability studies should be provided on at least three primary batches of the drug product.
The primary batches should be of the same formulation and packaged in the same container closure system as proposed for marketing.

17. Testing Frequency (ICH, 2003)
For Long term testing, during 1st year sampling should be done every 3 months, during 2nd year is 6months and after 2years is once a year.
Accelerated testing should be done at least six months and it suggests sampling points of 0, 3, 6 months.

18. STEPS INVOLVED IN CALCULATING OF SHELF LIFE(Habib et al., 2015)
Based on the principle of chemical kinetics demonstrated by
 Garret and Carper method
 Free and Blythe method
Shelf Life Determination Based on Arrhenius Plot (Garret and Carper method )
The mathematical prediction of shelf life is based on the application of the Arrhenius equation, which indicates the effect of temperature on the rate constant, k, of a chemical reaction of thermodynamic temperature, 1/T, is a straight line

19. ARRHENIUS EQUATION
It explains the effect of temperature on rate of a reaction. According to Arrhenius, for every 10º rise in temperature, the speed of reaction increases about 2-3 times
K=Ae-Ea/RT
Log K=Log A - Ea/2.303*RT
Where, K= rate constant
R= gas constant =1.987 cal/mole
T = absolute temperature
A = frequency factor
Ea = energy of activation
T10% = (2.303/K)*(log100/90)
T90% = (2.303/K)*(log100/10

20. Garret and Carper method
1. Keep several samples of the drug product at atleast three temperatures, such as 40ºC, 50ºC and 60ºC.
2. Determine the drug content at all three storage points by taking a number of samples and take the mean drug content. We do this for a few weeks.
3. At each temperature we plot a graph between time and log percent drug remaining. If the decomposition is first order this gives a straight line. If it is zero order, percent drug remaining versus time will give a straight line.
4. Next we take the log K or log of reaction constant on Y axis and 1/T x 10-3 on X axis and draw a best fit line. This line is the Arrhenius Plot, extrapolate this line to get k at 25ºC and from this we calculate the shelf-life.

21. Arrhenius plot for predicting drug stability at room temp(PLOT 1)

22. PLOT 2
Arrhenius plot for predicting the rate constant at ambient temperature(25ºC

23. Calculation If the reaction is following zero-order
Expiration date at 25 oC = Initial potency – minimum potency / reaction rate at 25 °C tx =Yo - Yx/ Ko
If the reaction is following first order
Expiration date at 25 oC (tx) = Log initial potency – log minimum potency/reaction rate at 25 tx =log Yo – log Yx / K1
Where Yo = initial potency
Yx = final potency
Ko = zero order constant
K1 = first order constant

24. FREE AND BLYTHE METHOD(based on t90)
In this method the fraction life period is plotted against a reciprocal temp. and the time in days required for drug to decompose to some fraction of its original potency at room temp.
The log% of drug remaining is plotted against time and days and the time for the loss line at several temp. to reach 90% of the theoretical potency is noted by the doted line
The log time to 90% is then plotted against 1/T and the time for 10% loss of potency at room temp. can be obtain from the resulting straight line by extrapolation to 25C
Shelf life and expiration date are estimated in this way
This approach clearly illustrate in below figure (plot a and b).

25. Plot a
Plot b

26. SHELF LIFE DETERMINATION BASED ON REAL TIME TESTING(Thorat et al
1. Keep three batches for stability study at least for 1 year at one fixed temperature. 2. Test them at 0, 1, 3, 6, 9, and 12 months for drug content. At each testing time test a number of samples, so that you have a mean and a standard deviation value of the result. 3. Now plot the graph of % drug content on Y axis and time on X axis along with confidence intervals. Where the lower 95% confidence curve intersects minimum potency, there you fix the shelf life.

27. REFERENCES
ICH (2003);International Council for Harmonisation Q1E Report :Evaluation of stability data
Haabib.U.B, Harum.A.R, Moshin.M and Khadija.T.T:An Overview.(2015);Stability study of pharmaceutical products and shelf life predition.European J Bio and Pharm Sci;2.pp30-40.
Robert.T. Magari.(2003); Assessing shelf life using real-time and accelerated stability test. Biopharm International;16(11)
Thorat. P, Warad.S, Solunke. R, Ashok.S, Anagha. B, and Asha.S.(2014);Stability study of dosage form: An inovative step. World J of pharmacy and pharm Sci;3(2) pp