Forced Degradation Study or Stress Testing Procedure

What is Degradation?

Forced Degradation Study before proceeding on it ,first of all  ”Degradation’‘ to be discuss first, This is the act of lowering to some degree or someone to a less respected state or position. A CEO of a multinational company resigning from his office is a degradation. It’s also a downcast state.

The word degradation is very much related to the degrade, which comes from Latin word Degradare. The word “Degradare” comes from “de”-, meaning “down,” & gradus, meaning “Step.” So, it is very much clear that the degradation as a step down, or feeling as though you’re a step below.

Degradation products

It is the unwanted chemicals which can generate during manufacturing, transportation & storage of pharmaceutical drug products & can affect efficacy of pharmaceutical drug products. A small amounts of pharmaceutical degradation products can affect crucial safety because of the potential to cause adverse effects in end user.

Subsequently, it is crucial to focus on formulation, storage conditions, transportation, distribution channel and packaging to prevent the formation of degradation products which can negatively affect quality, safety and efficacy of the pharmaceutical drug products.

To find out the main cause of degradation of the pharmaceutical product is the crucial point, various software and data tracking system can help in this matter. This system can provide useful information during transportation and storage of pharmaceutical products, the route shall be determined to estimate the main cause.

Presence of a genotoxic degradation product shall tend to more assessment if it identified on due time. The chemical structure of the substance shall be determined to identify the toxic alerting structures associated toxic products, products [Compound] without active structure is marked as ordinary impurities.

A risk/benefit analysis shall be done to evaluate the levels of degradation products and most of the nest pharmaceutical call its mandatory. During the development of any type of product either critical or non-critical drug, critical variable of the drug products shall be follow-up which will control the degree of degradation of impurities.

Now a days the impurity profile has been considered as the key point of the product quality. It is the essential part of the quality parameter for the various competent regulatory authority. The toxicological evaluation and impurity profile become the key point of the degradation products to confirm its certain level of efficacy. Various types of test method have been identified to investigate the degradation products, all of them assay method consider the best to all and it’s highlighted to prove its effectivity.

The purity, safety and efficacy of the product depend on the stability of the product and it is the critical parameter of all the parameter. A product must be stable at a certain period of time to prove its efficacy, potency and safety.

A less stable or changes of stability can create serious toxicological effect by forming toxic degradation products and deliver less active or less effective or less potent drugs to the end user. Under these circumstances, this is very crucial to known the actual behavior of the drug products in various surrounding or environmental conditions.

Dissolution test are considering the most quality control tool for the commercial batch to batch product to monitor its consistency over a certain period of time. It also provides significant information during post approval changes of the certain product as changes made in formulation, manufacturing process and different scale up procedure.

To confirm the quality, safety and efficacy, the chemical stability is very important for a pharmaceutical product. This is very important to know the environmental influences of a certain developed product in specific condition such as Heat [Temperature], Humidity [Relative Humidity] & Light [Photostability] and this also regulatory [ICH & FDA] requirements.

Data acquire from stability study denote the shelf life and storage condition of the specific tested drugs, the container closure system [Protective packaging system] also require to satisfy the regulatory expectation.

Different types of method/instruments are available to determine the degradant compounds which are readily present during the forced degradation study period. HPLC-UV [HPLC with UV detector] and HPLC-PDA [ HPLC with Photodiode Array Detector] is the renowned method and extensively used in pharmaceutical company at the time of degradation study and validation and development of various type of method.

LC-MS [HPLC with Mass Detector], GC-MS [Gas Chromatography with Mass Detector] and NMR [Nuclear Magnetic Resonance] spectroscopy are significant methods to detect the degradants’ structure.

What is Forced Degradation Study?

Exposure of specific sample at the unfavorable/stress condition of Heat [Temperature], Humidity [Relative Humidity], Light [Photostability], Oxidation and Acidic/Basic condition; observe/detect the changes of those sample or measure the rate of changes/degradation, mainly in Efficacy, Safety and Potency parameter of drug substance. Forced degradation study is the key point during the development of a specific drug. Determination of the type changes denote the modification or changes of the development process.

Now a days Force Degradation Study become the prerequisite to submit the NDA to regulatory authority and it became the quality parameter for the new product. During the regulatory submission, the Force Degradation Study data shall be submitted to get satisfactory result from FDA. Some of the best application of Force Degradation Study is depicted here-

[][]Developing and validating stability study indicating method as per regulatory guidelines [ICH Guidelines].
[][]To set up specification of degradants or impurities and to identify structure and toxicity.
[][]To set propose shelf life the specific product without performing Realtime stability data.
[][]To avoid incompatibility of drug products and excipients.
[][]Determination of the process related degradation products or impurities.
[][]Provide supporting data to lab investigations/OOS [out-of-specification] analysis.
[][]To provide regulatory compliance documents during submitting of ANDA/NDA to FDA.

It is a useful tool to predict the stability of any Active Pharmaceutical Ingredient (API) or formulation product. It helps to know about the impurities developed during the storage of drug products in various environmental conditions.

Forced degradation is performed by applying artificial methods and a drug is degraded forcefully. It is also known as stress testing. To assume the stability condition of API [Active Pharmaceutical Ingredient] and formulated product Forced degradation study plays an important role. It also helps to identify the impurities generated during storage of drug products in different environment stage.

Why Forced degradation study carried out?

Its play a vital role to develop and validating of stability study signifying method. At the time of developing phase of a new drug product, force degradation study performs to determine the degradation pathways of drug products & drug substances. It is very important to determine impurities of the degradant product, Forced degradation study quantify the number of impurities present on the specific drug substance. It helps to determine the molecular chemistry. Forced degradation study assure the more stable product. Help to develop the degradation profile. Stability related problem can be solved through Forced degradation study. Forced degradation study also highlight the following point of view-

[][]Evaluation of drug products & drug substance in solution.
[][]Determination of structural transformation of drug product & drug substance.
[][]Determination of the concentration of the degradation products.
[][]To identify the non-relevant impurities in the existence of the desired product.
[][]Separation of the product related degradants derived from intact placebo & excipients.
[][]Describe the degradation pathways of the specific drug substance.
[][]To categorize the degradation products which generate spontaneously during storage & use of products.
[][]To generate product related variants & develop analytical methods Forced degradation studies are performed during accelerated and long-term studies.

During the Forced degradation study, the degradation products may or may not be generate but it will show the degradation pathway of the product. This process will help them develop the analytical method of the relevant product and stability indicating analytical procedure. If any degradation occurs during performing of Forced degradation study, the degradation product shall be evaluated if it significant or minute, to robust the developed formulation.

How Forced degradation Study Conducted?

This study of the drug products or substances is generally conducted on the solid and solution stages at the high temperature exceeding accelerated stability condition which is above 40°C. Various condition are consider here as oxidation, hydrolysis, photolysis, polymerization and thermolysis. In Solution hydrolysis condition are investigated in broader pH range and in solid stage high relative humidity taken under consideration.

Control exposure of molecular oxygen or addition of oxidizing agents such as peroxides is use during investigating Oxidation in solution.
Applying heat in solid state effects of thermolysis are usually assessed. Light with wavelengths in the 300-800 nm range are use in Photolysis investigation in solution or the solid state. In an oxygen atmosphere photooxidation can be investigated with light under oxygen atmosphere. Measuring the rate of degradation, Drug substance polymerization can be investigated at the various drug substance concentrations in solution.

List of Analytical Tools to perform Separation & Identification of degradant

A. Sophisticated Techniques

[][]Capillary Electrophoresis- Mass Spectrometry [CE-MS].
[][]Gas chromatography–mass spectrometry [GC-MS].
[][]Liquid chromatography–mass spectrometry [LC-MS].
[][]Liquid Chromatography- Nuclear magnetic Resonance [LC-NMR].
[][]Liquid chromatography-Fourier Transfer Infrared [LC-FTIR].

B. Conservative Techniques:

[][]Thin layer chromatography [TLC].
[][]Solid phase extraction [SPE].
[][]Accelerated solvent extraction [ASE].
[][]Low-pressure LC [LPLC].
[][]Supercritical fluid extraction [SFE].
[][]Mass Spectrometry [MS].
[][]Nuclear Magnetic Resonance [NMR].
[][]High Performance Liquid Chromatography [HPLC].

Extend of degradation

For validation of a chromatographic purity assay, degradation level of 10-15% is adequate to perform the activities. Forced degradation studies are not considered part of the formal stability program though forced degradation studies are a regulatory requirement & scientific necessity during development of a specific product. For conducting studies at the various phases of development the guidance gives various recommendations.

Selection of Forced Degradation Condition

In common industry practice, forced degradation is generally performed in different stress conditions, i.e., thermal, acid, alkali, peroxide, and UV, along with a control sample which also comply with ICH guidelines. There no specific range or rate of degradation in current industry practice but 5 to 30 percent degradation shall be taken into consideration and this can be achievable on any one of the above stress conditions.

Through stress testing, the aim of the degradation to be achieved to implement the control room temperature for the stability conditions. The conditions or concentrations of reagent shall be optimized if higher or lower degradations are observed.

During the degradation study Mass balance shall be demonstrated & it shall be around 100%, taking into attention margins of analytical errors. During mass balance evaluations, all the degradants /impurities must be calculated.

Any batch which is not be the part of regulatory submission can be used for the forced degradation study. For multiple strengths of the same placebos and different amounts, the highest ratio of placebo vs. API [Active pharmaceutical ingredient] shall be use.

Forced degradation of all the strengths shall demonstrate if placebos are different. Placebo & API [Active Pharmaceutical Ingredient] must be demonstrated to identify actual degradation pathways during the drug product force degradation study. All the placebos shall be considered for force degradation study if placebos are different for different strengths of drug product.

Various degradation conditions are depicted on the following table which is accepted by the regulatory authority [FDA] at the time of DMF/ANDA/NDA submission-

Degradation TypeReagent ConcentrationConditions to be appliedTimeRemarks
Acid5N HCL80deg.C1 HourConcentration, condition and time can change to optimize degradation
Alkali5N NaOH80deg.C1 HourDo
Peroxide10% H2O280deg.C1 HourDo
Heat/Thermal80deg.C80deg.C1 HourDo
UVExpose under UV light at 254nm wavelengthAmbient Temperature24 HoursTime can change to optimize degradation

Force Degradation shall be performed in solid or solution form though it is recommended that Force Degradation shall be executed in solution form using the mobile phase/diluent to get a homogeneous effect with better result. Force Degradation studies shall be started with harsh conditions (i.e., high temperature with high concentration of reagent) to shorten time of study.

Milder conditions shall be applied by reducing concentration of reagent with lowering temperature, etc. when degradation found 30% or above. Based on the initial degradation outcome, Degradation conditions can be optimized to achieve a target range.

To extend shelf life of chromatographic column, pH shall be adjusted about 7.0 for acid & alkali degradation. Different reagents & conditions shall be applied, e.g., Zn, H2SO4, etc. If degradation did not find in any of above conditions. A few numbers of molecule designated rock stable molecules as these molecules didn’t degrade any of the above stress condition. During a stability study This kind of molecule will not engender any additional impurities/degradant peaks.

If drug substance or product shows stability for two years at 30 ±2⁰C & 65 ±5% RH & Six months at 40 ±2⁰C & 75 ±5%RH, then the drug substance or product declared stable.
Concentration of the drug that is being tested for the degradation is a great point. For the degradation study 1 mg/ml of drug concentration is recommended though some degradation studies are done at concentration of drug in the final product. Main cause for this type of study is that precise amount of the degradation can be found in final product & their impact can be scrutinized.

Factors Affecting Forced Degradation Studies

Hydrolytic Degradation:

The reaction of chemical with water at different pH values occur in Hydrolysis degradation. In this degradation drug react with water in acidic & basic conditions. According to the stability of the drug substance concentration of the acid or base is selected where pH is 0.1 to 1.0 M HCl [Hydrochloric Acid] or H2SO4[Sulfuric Acid].

HCl & H2SO4 is used to maintain acidic conditions and 0.1 to 1.0M NaOH [Sodium hydroxide] or KOH [Potassium Hydroxide] used to generate basic conditions. Some materials are not readily dissolve/soluble in water freely; in that case other solvent are use to dissolve the water insoluble materials. Solvent shall be selected carefully so that it can’t degrade the selected drug substance.

Descriptive termPart of the solvent require per part of solute
Very solubleLess than 1
Free SolubleFrom 1 to 10
SolubleFrom 10 to 30
Sparingly solubleFrom 30 to 100
Slightly solubleFrom 100 to 1000
Very Slightly solubleFrom 1000 to 10,000
Practically insoluble10,000 and over

Reference: British Pharmacopoeia [BP]

Generally Chemical degradation shall be conduct in room temperature but if no sign of Chemical degradation occur at room temperature then room temperature shall be increase up to 50-60 ⁰C. A seven days timeframe shall be selected to perform the study. To prevent further degradation, Chemical degradation should be terminated using acid, base or buffer solution. Chemical analysis shall be done as soon as possible after completion of the test.

Oxidation Degradation:

in the forced degradation study, H2O2 (Hydrogen peroxide) is a widely used oxidizing agent. Hydrogen peroxide at 0.1% to3.0% solution is used at room temperature for 7 days is the suitable range to perform the activities. When more then20% degradation occur for a certain product, it can be considered abnormal cases.

Photolytic Degradation:

To determine the effect of light on the product during storage in the market Photostability testing of any drug take into consideration. light conditions shall be described during photostability. light source shall be cool white fluorescent lamp & wavelength of light shall be 200-800 nm (UV+ visible) which is also comply ICH guideline. The and the light intensity shall be not less than 200 watt-hours per sq meter and exposure time shall be not less than 1.2 million lux hours. To monitor the condition, a calibrated lux meter shall be use in place.

Result of forced degradation studies

[][]Forced degradation studies help to determine_
[][]Likely/Probable degradants
[][]Degradation paths
[][]Inherent stability of the drug molecule
[][]Validated stability indicating analytical method

When forced degradation studies to be performed?

This is the best practice to perform forced degradation studies at the time of development of new drug substance and new drug product. FDA prefer to perform it at phase III of the regulatory submission which is the best time to do the same. To establish the regular stability study, forced degradation studies can be prerequisite. This study can be done in different pH solution in the presence of light & Oxygen with high temperature & Humidity Level.

Generally, degradation study performs on single batch. There are two types of timeframes are use to perform stability study which Long Term [12 Months] & Short Term [6 Months]. 6 Months are performed at accelerated condition. Moreover, Intermediate Stability Study performed in a condition lesser than accelerated condition.

Force degradation studies are performed at pre-clinical phase or phase I of clinical trial so that sufficient time provides to identifying structure elucidation, degradation products. If forced degradation studies are performed properly, manufacturing process of the new product can be developed properly and stability-indicating analytical procedures can be select more effectively.

What is the regulatory obligation regarding Force Degradation Studies?

Following ICH [International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use] Guidelines has been depicted regarding forced degradation studies but it covers only marketing applications for new products but not for during clinical development.

[][]ICH Q1A: Stability Testing of New Drug Substances and Products.
[][]ICH Q1B: Photo stability Testing of New Drug Substances and Products.
[][]ICH Q2B: Validation of Analytical Procedures: Methodology.

What actually says this guideline?

[][]ICH Q1A (Stress testing): Stability Testing of New Drug Substances and Products.

It implies for the performing of forced degradation studies for drug substances and drug products. The recommended condition is that the result shall be observe temperature above accelerated condition [Temperature>500C) and Humidity [75% relative humidity] including oxidation and photolysis. pH range may be wide for the testing of solution or suspension.

[][]ICH Q1B: Photo stability Testing of New Drug Substances and Products.

It implies the photo stability of drug substances and drug products. Section II and Section III describe the forced degradation conditions condition for drug substance and drug product. Exposure levels are not defined in Forced degradation studies. Photo stability testing can be performed both in Solid or in solution/suspension. Stability indicating method is developed based on this sample result. Some non-experiential degradation products may be formed during stability studies which may not be taken under consideration.

[][]ICH Q2B: Validation of Analytical Procedures: Methodology.

Provide guideline regarding analytical meth validation. Gives guidance to validate the analytical methodology. To demonstrate specificity, in section B1.2.2 (impurities not available) there is a recommendation to utilize samples from the forced degradation studies.


to develop degradation pathways, Forced degradation studies are the prominent way & Forced degradation studies are the prominent way to develop degradation pathways and to detect degradation products of API [Active pharmaceutical Ingredients], further it simplifies elucidation of degradants structure. Forced degradation studies also simplify the chemical & physical stability analysis of drug substances & drug products. To develop manufacturing conditions, storage conditions & determine expiry date of a new drug formulation Forced degradation studies is considered as key studies.

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