kinfit and mkin provide calculation routines based on the FOCUS Kinetics Report (2006). In kinfit, only kinetic models for simple degradation datasets are included. In mkin, there is no theoretical limit for the number of compartments or metabolites to model. gmkin provides a graphical user interface for mkin.
Please note that no warranty is implied for correctness of results or fitness for a particular purpose. For details, please refer to the GNU public license, under which these packages are made available.
The mkin package which can fit complex degradation models to degradation data has a documentation page which also contains installation instructions.
mkin and gmkin are actively developed on github. The source code of released versions is synced to the R-Forge source code repository.
An overview of the capabilities of the kinfit package (parent only degradation kinetics) is given in the kinfit documentation page.
Please refer to the project homepage for further information on the complete r-forge project.