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IntroductionThere are several key questions to answer during earlyphase drug development Questions needing answersinclude:

What is the chemical stability of the API? What physical form should be selected for

development? Which salt form should be used? What are the chemical degradation pathways of

the API? Do the major degradation products match the

metabolites of the API? Which formulation should be selected? What are appropriate storage conditions for the

API and formulations?Forced degradation plays an important role in answeringthese questions and determining the ability to develop adrug.

PurposeThe initial purpose of forced degradation studies is toinvestigate stability-related properties of an API and todevelop an understanding of the degradation productsand pathways. These studies should also be used toevaluate the susceptibility of the drug substance tohydrolysis across a wide range of pH values. Forceddegradation studies are also used to provide degradedsamples for the development of stability-indicatinganalytical methods for the API. The information developedfrom a forced degradation study can also be utilized inseveral other areas of development, including analyticalmethods development, formulation development andstorage conditions, manufacturing-processing, safety-toxicological, identification of possible genotoxicdegradants, identification of potential metabolites and APIdesign/discovery.

Carried Out Early in The development ProcessForced degradation studies are most beneficial if doneearly in the drug development process. The reasoning forthis is that these studies yield predictive information onthe nature of the degradants which are valuable whenassessing the appropriate synthesis routes, API saltselection and formulation development. These earlystudies can help provide information needed for thefollowing:

Forced degradation studies are a necessary part of developing an API into a viable drug products. To accomplishthis , four main degradation mechanisms heat, hydrolytic, oxidative [O2] and photolytic degradation need to beinvestigated.

In development of stability-indicating analyticalmethods.

As a predictive tool to help understanddegradation pathways and stability-related issues.

To predict API stability before real-time stabilitydata is available.

Through the use of these early development degradationstudies the focus should be the garnering of as muchinformation as possible about the chemistry of the API.To accomplish this, forced degradation studies are doneon both the solid state and aqueous solution orsuspension forms of the API. Furthermore, the use ofanalysis at multiple time points allows for approximation ofrates of degradation and such testing at early time pointscan provide a distinction between primary and secondarydegradation products. This approach allows for betterdegradation pathway determination

Repeated As NeededForced degradation studies should be repeated asneeded throughout the drug development process. Forexample, when there are changes in API impurity profile,API salt or polymorph form. When carried out in latedevelopment such studies are referred to as confirmatorystudies. Confirmatory studies are quantitative in nature..Full mass accountability of the API, its impurities anddegradation products are generated from these late stagestudies. Furthermore, based upon the outcome of thesestudies, if necessary, new or orthogonal methods mayneed to be developed to account for all observeddegradation. Also, confirmatory studies for API are doneafter finalization of the synthetic route and form of the API.Such studies are typically done in Phase III with one ofthe registration batches of the API. For drug products,confirmatory studies are done when final formulation(s)and packaging are chosen. After the confirmatory studiesare completed, a report on degradation products andpathways is generated and included in or used to supportNDA filings.

Degradation ConditionsThe following are general conditions that should beemployed when conducting forced degradation studies:Solid State

Heat Heat/humidity Light

Technical Guide SeriesForced Degradation Studies

ByJ. Menoutis, Ph.D., F.A.I.C., C.P.C., C.Ch.E. and A. I. Paris

22 Distribution Boulevard | Edison, New Jersey 08817 USA | phone 732.248.3335 | fax 732.248.0912

© 2012 Quantex Laboratories

Solution and/or Suspension Hydrolysis at various pHs Unbuffered HCl, NaOH, water Buffer solutions (used to determine if pH adjustment

needed to attain maximum stability) Oxidative stress testing H2O2 (to mimic possible presence of peroxides in

excipients) Metal ions (to mimic possible exposure during

manufacture) Radical initiators (to mimic autoxidation) Light

The Analytical MethodThe general approach for carrying out the testing of samplesgenerated from forced degradation is through the use ofHPLC (LC) with either a UV or PDA detector. In mostinstances the initial starting method will be some generic LCmethod with an appropriate column to effectuate separation.Over time, this method will be refined or modified so thatcomplete separation of the API and its degradants areachieved.

Once a satisfactory LC method has been developed theprocess of identifying the structure of degradants can begin.This involves transferring the method for use with LC-MS. LC-MS is powerful analytical tool specifically capable of providingstructural elucidation.

Identifying Impurity and Degradation ProductsBy using LC-MS , and where needed LC-NMR, information onthe structure of each impurity and degradation product of anAPI can thus be developed. This information, along with afundamental understanding of the API’s chemistry provides the means for understanding the API’s degradation pathways.In addition, the elucidation and identification of thesestructures allows investigating whether the degradationproducts are known compounds that have been previouslycharacterized or whether they are potential carcinogens orgenotoxins

Having identified the degradation products the results of theforced degradation can be formalized. This formalization mustinclude both the degradation conditions used and theproposed structures of the degradation products observed forthose conditions. A proposed mechanism of degradation thatidentifies potential degradation products and pathways canthus be understood. Armed with this, a stable formulationwith proper packaging and/or storage conditions can thus bedeveloped .

About the authorsJames Menoutis is the CEO of Quantex Laboratories. He hasover 34 years of experience as an analytical chemist, groupleader, researcher, manager and technology executive. Hisexperience includes toxicology, clinical chemistry, methodsdevelopment and analysis of pharmaceuticals and botanicals,analysis and methods development for the analysis of clinicalpharmaceuticals, pesticide residue analyses, occupationalhealth and analytical toxicological. He has an extensiveanalytical background in mass spectrometry which includes, GC-MS, LC-MS and HRGC-HRMS. His research interests includethe development of GC-MS and LC-MS methods for theidentification and measurement of impurities and degradantsincluding those that are carcinogenic and genotoxic. He holdscertification as a Certified Professional Chemist and as aCertified Professional Chemical Engineer from The NationalCertification Commission in Chemistry and ChemicalEngineering and is a Fellow of the American Institute ofChemists. He is a member of a number of professional andscientific societies, and serves as President of the New JerseyInstitute of Chemists and is a member of the Life SciencesAdvisory Board of the New Jersey Technology Council.

Angela I Parisi is the Vice President of Laboratory Operations forQuantex Laboratories. she has over 36 years of experience asan analytical chemist, researcher, senior scientist, manager andR&D executive. Her experience includes methods developmentand analysis of pharmaceuticals and personal care products,analysis and methods development in support of synthesis andprocess development and the development of analyticalmethods for the identification and measurement of genotoxicimpurities. She has an extensive background inchromatographic and mass spectral techniques which includeGC-MS, LC-MS and HRGC-HRMS. Her research interestsinclude the development of chromatographic methods for theidentification and measurement of degradants and impuritiesincluding carcinogenic and genotoxic impurities. She is also amember of a number of professional and scientific societies.

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