in model Korsmeyer-Peppas the value of n characterizes the release mechanism of drug as described in Table 1. For the case of cylindrical tablets, 0.45 ≤n corresponds to a Fickian diffusion mechanism, 0.45 < n < 0.89 to non-Fickian transport, n = 0.89 to Case II (relaxational) transport, and n > 0.89 to super case II transport.
If the value of n was lower than 0.45 in the Korsmeyer-Peppas model then what si the diffusion regime?
Thanks everyone
http://www.ptfarm.pl/pub/File/Acta_Poloniae/2010/3/217.pdf
In the Korsmeyer-Peppas mode,l for spherical particles a value n – 0.43 is characteristic for Fickian diffusion, But
In the Korsmeyer-Peppas mode,l for spherical particles a value n – 0.43 is characteristic for Fickian diffusion, But for polydisperse systems lower values are possible, down to 0.30. See
P.L. Ritger, N. A. Peppas, A simple equation for description of solute release I. Fickian and non-fickian release from non-swellable devices in the form of slabs, spheres, cylinders or discs, Journal of Controlled Release, 5 (1987) 23-36.
If the value of n is more 2, does it make any sense? If so, how to interpret the outcome?
I've performed some experiments about this topic and we have found interesting results where the pore size distribution of the matrix in hidrophilic matrix tablets is critical, and plays a key role in polydispersity and heterogeneity of the gel layer, giving lower values of n in the Korsmeyer - Peppas equation.
See,
Saurí J, Millán D, Suñé-Negre JM, Colom H, Ticó JR, Miñarro M, Pérez-Lozano P, García-Montoya E. Quality by design approach to understand the physicochemical phenomena involved in controlled release of captopril SR matrix tablets. Int. J. Pharm., 2014; 477: 431-441.
A value of n over 1 would mean an acceleration of the release in time, something similar to an autocatalytic process. Hence the drug release would favor its further release, at a higher rate. I don’t know if this can really happen and why.
Hi, Dear Pro.Horovitz,
I am working on immobilization of enzyme on electrospining fiber, do you think for investigating of enzyme activation this model, Peppas model is good, for studying the rate of release of production.
I was wondering If you would make me informed?was wondering If you would make me informed?was wonderin If you would make me informed? eni fam working oezn immoblization oimmoblization o oimmoblization o
The Korsmeyer-Peppas model was proposed for the the description of the mechanism for drug release, but was subsequently largely used for other processes controlled by diffusion. If the subject of your investigation belongs to this area, you can try to use the model.
Ossi Horovitz if the n value is 0.384 for a sustained release microsphere formulation and it follows fickian diffusion.can it be considered as a good sustained release formulation considering the burst release issues?
Hi, Dear Pro.Horovitz,
If the value of n is between 0.85 and 0.45, but it is much closer to 0.85 (e.g. n = 0.78), can we still discuss a diffusion mechanism, or it will be limited by some other phenomenon, like for example a transport process through a tortuous hydrogel matrix.
As a matter of fact, I have no practical experience in release from polymeric matrices. In literature he n values from 0.45 to 1 are assigned to nonFickian transport, which can be a mixed diffusion and chain relaxation mechanisms.
Hi all,
How about oxygen released from spherical particles instead of drugs? Can I use the Korsmeyer-Peppas model or the Higuchi model?
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