Forced Degradation Studies in Pharmaceuticals: How to Perform
Introduction and outcome: Forced Degradation Studies
Forced degradation studies are an integral part of stress testing and are very helpful in drug development in managing quality, safety and efficacy. It is a costly activity and requires knowledge of chemistry, expertise and a lot of time. That is why I decided to share my skill-based knowledge on this topic. In this article, you will learn about forced degradation procedure, forced degradation condition selection, degradation impurities identification, stability indicating method (SIM), mass balance and analytical work after forced degradation studies.
The Purpose and Advantages of Forced Degradation Study
The following are the main purpose of the forced degradation study:
- It gives information about the intrinsic stability of the molecule
- It tells about the chemical behaviour of the molecule
- To solve stability-related problems of pharmaceuticals
- Helps in structure elucidation of degradation products
- Tells about the degradation pathways
- It gives information about the stability indicative strength of the analytical method
- It tells about the selectivity or specificity of the stability indicating method
- Very helpful in differentiating actual impurities and potential degradation products
- Helps in the selection of formulation
- Helps in deciding storage and packaging condition
- Support regulatory requirements
- Helps in deciding stability study condition
- To know the impact of acid-base (hydrolysis) oxidation, the effect of temperature and humidity on the drug substance and drug product and the formation of the corresponding impurities.
- It is important component of the GLP and required by almost all regulatory agencies
Related topic: Analytical Method Development and Validation in Pharma
Terminology related to Forced Degradations
Forced Degradations Strategy
Forced Degradations Strategy should be vision-based taking the help of brainstorming sessions of all concerned persons. The following are some important components:
Protocol
An approved protocol should be used for the Forced Degradation study
Analytical Method
The analytical method used in the Forced Degradation studies must be stability indicating (SIM)
Standards
Fully characterised primary standards or pharmacopeial standards with valid COA are used for Forced Degradation studies
Samples Selection
Forced Degradation is performed on a single representative batch of the Active pharmaceutical ingredient and Drug product. Forced degradation is not performed on pharmaceuticals raw material used in the synthesis of APIs and intermediates
Chemicals and Reagents
Chemicals and reagents used in forced degradation must be as per the method and with valid COA
Forced Degradation Condition Selection
| FD Components | FD Conditions |
| Effect of temperature on solution or suspension | It should be performed above the accelerated test condition temperature. The temperature should be increased in 10-degree increments like 40oC, 50oC, 60oC, 70oC, 80oC, 90oC, 100oC etc. |
| Oxidation (on solution or suspension) | The solution of the API or its products should be oxidised with hydrogen peroxide at room temperature. The temperature should be increased in 10-degree increments like 30oC, 40oC, 50oC etc, if require |
| Hydrolysis (on solution or suspension) | Both acid and base hydrolysis should be performed across a wide range of pH. The solution of the compound should be hydrolysed with 0.1N hydrochloric acid or 0.1N sodium hydroxide at room temperature. The temperature should be increased in 10-degree increments like 30oC, 40oC, 50oC etc, if require. |
| Humidity (on solid compound) | Humidity should be 80% RH or greater or as applicable for the API |
| Sunlight exposure (on solution or suspension) | The solution or suspension of the API or its products in a colourless transparent borosilicate glass vessel or quartz glass vessel should be placed in the SUNSET cabinet* or Xenon lamp |
| Effect of temperature on a solid sample | It should be performed above the accelerated test condition temperature. The temperature should be increased in 10-degree increments like 40oC, 50oC, 60oC, 70oC, 80oC etc. |
| Sunlight exposure (on solid sample) | Solid compound up to 3 mm layer spread in a borosilicate glass dish or quartz glass dish and the SUNSET cabinet or Xenon lamp (300 – 800 nm) for light exposure |
| Photostability |
Note:
- Each treated sample is diluted (as per method) for Impurity profile, Assay and Peak purity tests
- SUNSET cabinet*:
- 250Wh/m2 for 8.4 hours or less or at most 21.2 hours or
- 765Wh/m2 for 2.7 hours or less or at most 6.9 hours
Sample analysis and Result evaluation of Forced Degradation studies
Each degraded sample is tested or reviewed for the following parameters:
- Visual changes of the stressed solid sample
- Assays
- Degradation impurities
- Peak purity
How much degradation is recommended and why?
Degradation of drug substances between 5% and 20% is recommended. More degradation can lead to degradation of the degradation impurities ( secondary and tertiary degradation) and the same will not give any idea about the actual degradation product. That is why 5% and 20% is recommended is recommended.
What should be done if there is no degradation in any stress conditions?
The degradation does not need to take place in all stressed conditions. The condition in which degradation is not taking place can be terminated.
Role of PDA Detector in Forced Degradation
Many impurities can form during forced degradation studies. It may be possible that two or more impurities may co-elute or the impurity/impurities may merge with the main analyte peak.
Therefore, peak purity testing is required to determine the specificity or homogeneity of peaks. The PDA detector provides information about the homogeneity/purity of the peak.
Note: It is not applicable for degradation impurities that have a similar UV spectrum to the API.
Stability indicating Method (SIM)
A validated analytical procedure that can be used to determine how the stability of drug substances and drug products changes over time is called the SIM or stability signal method. A stability-indicating method accurately measures changes in the concentration of active ingredients without interference from other degradation products, impurities and excipients.
Validation and Forced Degradation
The stability indicating method which is used for Forced Degradation must be validated for precision, detection limit, quantification limit, accuracy, recovery, linearity, stability of solution and robustness. RRF of known degradation impurities should also be calculated. Actual known impurities should be isolated, and characterised and potency should be calculated.
Forced Degradation and Impurities Identification
Impurities above the identification threshold (usually 0.1%) must be isolated, identified, characterized and potency should be calculated before use.
Mass Balance in Forced Degradation Study
Many impurities are generated during forced degradation of any AIP and result in reduced purity and assay. Mass balance gives the relationship between the purity of the degraded sample and the assay.The mass balance states that the amount of impurities formed during degradation must be equal to the loss of assay value of the degraded sample.
Mass balance calculation
Mass balance = Purity -Assay, where purity = (100 – total impurities)
It also tells about the strength of the analytical method. The smaller the mass balance, better the analytical method. The main reason for mass balance may be variation in the f RRF or degradation products.
Guidelines on Forced Degradation Impurities
The following guidelines are widely used in the industries for forced degradation studies:
- ICH Q1A: Stability Testing of New Drug Substances and Products
- ICH Q1B: Photostability Testing of New Drug Substances and Products
- ICH Q2B: Validation of Analytical Procedures and Methodology
Analytical Work After Forced Degradation
- Method optimizations
- Inclusion of actual degradation impurities in the STP and the monograph
- Inclusions of all precautions related to the chromatographic condition, system suitability test acceptance criteria and sample preparation
Role of LC-MS in Forced Degradation Studies
LC-MS is required to identify and characterise the degradation impurities.
Case Studies related to Forced Degradation Studies
- FDA warning letters: There have been several warning letters on stability indicating methods or forced degradation studies by various authorities in the past. In one case forced debridement was not studied and so the FDA gives the following 483:
- Your company failed to conduct Forced Degradation Test for optical purity testing of DRG substance…
- Deficiency letters: There have been several deficiency letters on forced degradation studies indicating stability by various authorities in the past:
- Provide the amount of each degradation product formed in the forced degradation studies
- Provide the mass balance information forced degradation studies
- Report each degradation product having a value ≥ 0.10%
Conclusion
Forced Degradation plays a unique role in pharmaceutical development since It gives knowledge about possible degradation pathways, actual degradation impurities and possible degradation impurities of the active pharmaceutical ingredients (APIs). I hope this article has helped you to understand pharmaceutical degradation and its importance. Now you can independently plan, design and perform the Forced Degradation.
You may also want to check out other articles on my blog, such as:
- How to control impurities in pharmaceuticals?
- Nitrosamine Impurities in Pharmaceuticals: Challenges and Solutions
- What are the applications of TTC in pharmaceuticals?
- How to identify Genotoxic Impurities in pharmaceuticals?
- What is the chemistry behind Genotoxicity?
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FAQs
What is the ICH guideline for forced degradation?
ICH Q1A, QIB
What is the FDA guidance on forced degradation studies?
Degradation of drug substances should be between 5% and 20%
What are the acceptance criteria for forced degradation studies?
Degradation of drug substances should be between 5% and 20%
How do you calculate forced degradation?
Initially forced degradation is calculated by area % or area normalisation method
What is the difference between forced degradation and stress testing?
Forced degradation is carried out under stressed conditions like temperature, acid and alkali hydrolysis, oxidation etc. Hence forced degradation and stress testing are the same.
What is forced degradation in analytical method validation?
A validated analytical procedure that can be used to determine how the stability of drug substances and drug products changes over time is called the SIM or stability signal method. All degradation impurities must be separated in the method.
What is forced degradation of acids?
The solution of the compound is hydrolysed with 0.1N hydrochloric acid at room temperature. The temperature should be increased in 10-degree increments like 30oC, 40oC, 50oC etc, if require.
What is the range of forced degradation?
5% and 20%
How many sample are taken for forced degradation?
One representative sample is used for forced degradation studies
What temperature is needed for forced degradation studies?
Forced degradation studies be performed above the accelerated test condition temperature. The temperature should be increased in 10-degree increments like 40oC, 50oC, 60oC, 70oC, 80oC, 90oC, 100oC etc.
What is the degradation of H2SO4?
The solution of the compound is hydrolysed with 0.1N H2SO4 at room temperature. The temperature should be increased in 10-degree increments like 30oC, 40oC, 50oC etc, if require.
Should Degradation take place in all stress conditions?
Not necessary
What is the role of LC-MS in pharmaceutical forced degradation?
LC-MS is used to identify degradation products forced degradation.
What is the SIM method?
A SIM method is used for degradation products testing during forced degradation studies
What is the acceptance criteria of mass balance in forced degradation?
The difference between assay and purity should be around 5%
Can secondary standards or working standards be used for forced degradation studies?
No
What is the mass balance calculation in analytical method validation?
% of Mass balance = Purity -Assay, where purity = (100 – total impurities)
What is the purpose of the mass balance study?
Many impurities are generated during forced degradation of any AIP and result in reduced purity and assay. Mass balance gives the relationship between the purity of the degraded sample and the assay
What is the principle of mass balance?
The mass balance states that the amount of impurities formed during degradation must be equal to the loss of assay value of the degraded sample
What is difference between routine analytical method/pharmacopeia method and the SIM method?
References
- Journal of Pharmaceutical Sciences
- ICH Q1A, QIB, and Q2B
- FDA warning letters
Abbreviations
- SIM: Stability indicating method