AKTS Software Technical Comments

Prediction of Thermal Stability of Materials by Modified Kinetic and Model Selection Approaches based on Limited Amount of Experimental Points

B. Roduit1, M. Hartmann1, P. Folly2, A. Sarbach2 and R. Baltensperger3

1Advanced Kinetics and Technology Solutions AKTS AG http://www.akts.com, TECHNO-Pôle, 3960 Siders, Switzerland
2armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3University of Applied Sciences of Western Switzerland, http://www.eif.ch, 1705 Fribourg, Switzerland

Abstract

The experimental data collected in the discontinuous mode are often used for the computation of reaction kinetics and, further, for the simulation of the thermal stability of materials. However, the kinetic calculations based on limited amount of sparse points require specific criteria allowing correct choice of the best kinetic model. We present the modified kinetic computations allowing considering one, two or even more reaction stages by applying unlimited amount of combinations of different kinetic models for the best description of the reaction course. The kinetic parameters are calculated using the truncated Šesták-Berggren (SB) approach and further verified by using the Akaike and Bayesian information criteria (AIC and BIC, respectively). The proposed method of kinetic and model selection for elaboration of sparse points were checked by the simulation of generated points with known, arbitrarily chosen kinetic parameters containing some scatter. The verified procedure was applied for the prediction of the thermal stability of energetic (propellant) and biological (vaccine) materials characterized by approximately 30 experimental data points. If your institution has access, you may view this paper at:


View Study : Thermochimica Acta, Vol. 579 (2014), 31-39
http://dx.doi.org/10.1016/j.tca.2014.01.005


 

Biophysical virus particle specific characterization to sharpen the definition of virus stability

Didier Clénet1, Tatiana Vinit2, Damien Soulet2, Claire Maillet2, Françoise Guinet-Morlot3, Aure Saulnier1, 2

1Bioprocess R&D Department, Sanofi Pasteur, Marc l'Étoile, France
2Analytical R&D Department, Sanofi Pasteur, Marc l'Étoile, France
3R&D Traveler Endemic Department, Sanofi Pasteur, Marc l'Étoile, France

Abstract

Vaccine thermostability is key to successful global immunization programs as it may have a significant impact on the continuous cold-chain maintenance logistics, as well as affect vaccine potency. Modern biological and biophysical techniques were combined to in-depth characterize the thermostability of a formulated rabies virus (RABV) in terms of antigenic and genomic titer, virus particle count and aggregation state. Tunable resistive pulse sensing (TRPS) and nanoparticle tracking analysis (NTA) were used to count virus particles while simultaneously determining their size distribution. RABV antigenicity was assessed by NTA using a monoclonal antibody that recognize a rabies glycoprotein (G protein) conformational epitope, enabling to specifically count antigenic rabies viruses. Agreement between antigenicity results from NTA and conventional method, as ELISA, was demonstrated. Additionally, NTA and ELISA showed mirrored loss of RABV antigenicity during forced degradation studies performed between 5°C and 45°C temperature exposure for one month. Concomitant with decreased antigenicity, emergence of RABV particle populations larger than those expected for rabies family viruses was observed, suggesting RABV aggregation induced by thermal stress. Finally, using a kinetic-based modeling approach to explore forced degradation antigenicity data (NTA, ELISA), a two-step model accurately describing antigenicity loss was identified. This model predicted a RABV shelf-life of more than 3 years at 5°C; significant loss of antigenicity was predicted for samples maintained several months at ambient temperature. This thorough characterization of RABV forced degradation study originally provided a time-temperature mapping of RABV stability.


View Study : European Journal of Pharmaceutics and Biopharmaceutics Vol. 132 (2018), 62-69
https://doi.org/10.1016/j.ejpb.2018.08.006


 

Accurate prediction of vaccine stability under real storage conditions and during temperature excursions

D. Clénet

Formulation & Stability Platform, Bioprocess R&D Department, Sanofi Pasteur, 1541 Avenue Marcel Mérieux, 69280 Marcy L'Étoile, France

Abstract

Due to their thermosensitivity, most vaccines must be kept refrigerated from production to use. To successfully carry out global immunization programs, ensuring the stability of vaccines is crucial. In this context, two important issues are critical, namely: (i) predicting vaccine stability and (ii) preventing product damage due to excessive temperature excursions outside of the recommended storage conditions (cold chain break). We applied a combination of advanced kinetics and statistical analyses on vaccine forced degradation data to accurately describe the loss of antigenicity for a multivalent freeze-dried inactivated virus vaccine containing three variants. The screening of large amounts of kinetic models combined with a statistical model selection approach resulted in the identification of two-step kinetic models. Predictions based on kinetic analysis and experimental stability data were in agreement, with approximately five percentage points difference from real values for long-term stability storage conditions, after excursions of temperature and during experimental shipments of freeze-dried products. Results showed that modeling a few months of forced degradation can be used to predict various time and temperature profiles endured by vaccines, i.e. long-term stability, short time excursions outside the labeled storage conditions or shipments at ambient temperature, with high accuracy. Pharmaceutical applications of the presented kinetics-based approach are discussed. If your institution has access, you may view this paper at:

View Study : European Journal of Pharmaceutics and Biopharmaceutics Vol. 125 (2018), 76-84


 

Advanced Kinetic Analysis as a Tool for Formulation Development and Prediction of Vaccine Stability

D. Clénet1,F. Imbert1, P. Probeck1, N. Rahman2 S. F. Ausar2

1Bioprocess Research & Development, Sanofi-Pasteur, 69280 Marcy L'Étoile, France
2Bioprocess Research & Development, Sanofi-Pasteur, Toronto, ON M2R 3T4, Canada

Abstract

We have used a protein-based vaccine, a live virus vaccine, and an experimental adjuvant to evaluate the utility of an advanced kinetic modeling approach for stability prediction. The modeling approach uses a systematic and simple procedure for the selection of the most appropriate kinetic equation to describe the degradation rate of compounds subjected to accelerated conditions. One-step and two-step reactions with unlimited combinations of kinetic models were screened for the three products under evaluation. The most appropriate mathematical model for a given product was chosen based on the values of residual sum of squares and the weight parameter w. A relatively simple n-th order kinetic model best fitted the degradation of an adjuvanted protein vaccine with a prediction error lower than 10%. A more complex two-step model was required to describe inactivation of a live virus vaccine under normal and elevated storage temperatures. Finally, an autocatalytic-type kinetic model best fitted the degradation of an oil-in-water adjuvant formulation. The modeling approach described here could be used for vaccine stability prediction, expiry date estimation, and formulation selection. To the best of our knowledge, this is the first report describing a global kinetic analysis of degradation of vaccine components with high prediction accuracy. If your institution has access, you may view this paper at:

View Study : Wiley Online Library (2014)
http://onlinelibrary.wiley.com/doi/10.1002/jps.24117/abstract


 

Optimization of Modeling of Propellants Aging Investigated According to NATO AOP-48 Ed.2 Test Procedure

Bertrand Roduit1, Marco Hartmann1, Patrick Folly2, Alexandre Sarbach2, Pierre Guillaume3, Laurence Jeunieau4

1AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 3, 3960 Siders, Switzerland
2armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3PB Clermont s.a., Rue de Clermont 176, 4480 Engis, Belgium
4Royal Military Academy, Avenue de la Renaissance 30, 1000 Bruxelles, Belgium


Abstract

The stability test procedure according to NATO-AOP 48 Ed. 2 commonly applied for the explosives and nitrocellulose-based propellants is based on the assumption that the kinetic description of the process of stabilizer depletion can be done by applying the reaction-order (RO) model for the fitting experimental data. In the present paper another procedure is proposed by application more general Prout-Tompkins (PT) model based on the autocatalytic character of the reaction. Presented computer simulations indicate that PT model allows much better fit of the processes which kinetics is not fully determined. Application of proposed model significantly decreases the number of experimental points required for the prediction of the propellant properties at 25°C or after 10 years of storage (t25- and T10-values, respectively). The results of elaboration of experimental data of single- and double- based propellants calculated with RO and PT models are presented.

View study (pdf, 137 KB)

View presentation (pdf, 709 KB)

 


 

Japanese version of AKTS-Thermokinetics Software for ‘discontinuous’ collected data

Sakira Kaneko1

1Palmetrics Co. Ltd, http://www.palmetrics.co.jp, Sayama Laboratory 350-1328, Hirose-dai 2-16-15 Sayama IC2, Sayama city, Japan

http://www.palmetrics.co.jp/_userdata/AKTS_TK_3.80.pdf

Japanese version of AKTS-Thermokinetics Software for ‘discontinuous’ collected data (pdf, 672 KB)

 


 

Technical note in Japanese based on HPLC data (limited amount of data points)

Sakira Kaneko1

1Palmetrics Co. Ltd, http://www.palmetrics.co.jp, Sayama Laboratory, 350-1328, Hirose-dai 2-16-15 Sayama IC2, Sayama city, Japan

http://www.palmetrics.co.jp/_userdata/Technical%20note%20AKTS-01.pdf

Technical note in Japanese based on HPLC data (limited amount of data points) (pdf, 614 KB)