Dear Marcos,

Are you in the process of your method development’s forced degradation study.  I look forward to hearing from you.

Kind regards,

Ade Kujore

Marketing

Cecil Instruments Limited

Milton Technical Centre, Cambridge CB24 6AZ

United Kingdom

email:- [email protected]

telephone:- +44 (0) 1223 420821

fax.:- +44 (0) 1223 420475

web site:- www.cecilinstruments.com

Hi Ade.

I am working in a new protocol made by ANVISA ( brazilian regulatory agency) this protocol is based in FDA protocol but ANVISA is making a lot of questions about reactions, mass balance and degradation products toxicology. Have you experience with this studies? Could you help me?

Dear Marcus,

Forced degradation studies entail a large variety of investigations.

Essentially the degradation products of an Active Pharmaceutical Ingredient (API) and its related impurities need to be evaluated.

If the API is a new chemical entity, this information may be entirely lacking.  Tests should be performed to determine the identity of the degradation products and related impurities when the entity is contained within the chosen excipients and also when the entity is stored in its pure form. 

So first, this new chemical entity is stressed.

Stress testing normally involves single or combination exposure of the entity, to heat, humidity, acid/base hydrolysis, oxidation and UV/Visible light.  The exposure time period is often that which is sufficient to force a degradation between some 5 to 20% of the initial entity.  This time period should be sufficient to induce primary degradation products, but not so large as to induce the formation of secondary degradation products.  Please see the attached link to a good paper on the matter.

Once we suspect that our new chemical entity has been sufficiently degraded, it is time to start working out a strategy to analyse for all analytes on an HPLC/IC system.  The choice of detector is the most important at this stage.

Factors to consider in the choice of detector to use, include which physical /chemical property of the analytes may be taken advantage of.  If the analytes are expected to fluoresce, then a fluorescence detector may be considered.  In the case of analytes which have an ionic charge, a conductivity detector may be useful.  If the analytes are able to undergo significant oxidation/reduction reactions in an electrical current, an electrochemical detector may be used.  If the analytes have a UV/Visible chromophore or if a chromophore can be added, a UV/Visible detector may be of enormous value.  If each analyte molecule is large, a refractive index detector or a light scattering detector may be considered.  Use of a charged aerosol detector may be considered for non-volatile analytes.  The use of a mass spectrometer may also be considered for a wide range of analytes.

A scientist must be certain that each HPLC/IC chromatographic peak seen represents a single analyte.  The identity each peak must also be verified.  So samples of the degraded entity should be subjected to identification, using another analytical confirmatory technique, such as a mass spectroscopy technique, X-ray absorption fluorescence, x-ray diffraction and nuclear magnetic resonance etc.

The mass balance calculations link the detected decrease of the API, to the detected increase in the quantity of the degradation products.  Please see the other attached link to a good paper on the matter.

Toxicology investigations may also be required on the identified degradation products and impurities.

I understand that if the degradation products and related impurities can be reliably predicted, and pure standards of the entity, impurities and degradation products are available, then full forced degradation testing may be avoided.

I hope that my humble summary is of help.

Kind regards,

Ade Kujore

Marketing

Cecil Instruments Limited

Milton Technical Centre, Cambridge CB24 6AZ

United Kingdom

email:- [email protected]

telephone:- +44 (0) 1223 420821

fax.:- +44 (0) 1223 420475

web site:- www.cecilinstruments.com

http://www.particlesciences.com/docs/Forced_Degradation_Studies-DDT_June2010-rd3.pdf

http://www.sgs.co.uk/~/media/Global/Documents/Technical%20Documents/SGS-LSS-Forced%20Degradation-EN-11.pdf

Hi Ade.

Thank you for your explanation, it's very important for understand the product degradation study. I have more doubt, but i think this points are about ANVISA questions. I don't know if I utilize a mass spectrometer for product degradation identification and quantification. Could I use a triple quadrupole or I need a Q TOF mass spectrometer? About mass balance what is the loss limit? Because I believe it's impossible we have a mass balance with 100% efficiency.

I appreciated your contribution.

Regards