Chemical reactions best-case scenario

Besides the two most well-known cases, the local bifurcations of the saddle-node and Hopf type, biochemical systems may show a variety of transitions between qualitatively different dynamic behavior [13, 17, 293, 294, 297 301]. Transitions between different regimes, induced by variation of kinetic parameters, are usually depicted in a bifurcation diagram. Within the chemical literature, a substantial number of articles seek to identify the possible bifurcation of a chemical system. Two prominent frameworks are Chemical Reaction Network Theory (CRNT), developed mainly by M. Feinberg [79, 80], and Stoichiometric Network Analysis (SNA), developed by B. L. Clarke [81 83]. An analysis of the (local) bifurcations of metabolic networks, as determinants of the dynamic behavior of metabolic states, constitutes the main topic of Section VIII. In addition to the scenarios discussed above, more complicated quasiperiodic or chaotic dynamics is sometimes reported for models of metabolic pathways [302 304]. However, apart from few special cases, the possible relevance of such complicated dynamics is, at best, unclear. Quite on the contrary, at least for central metabolism, we observe a striking absence of complicated dynamic phenomena. To what extent this might be an inherent feature of (bio)chemical systems, or brought about by evolutionary adaption, will be briefly discussed in Section IX. 

Drugs sometimes have quite complicated chemical structures and are, by definition, biologically active compounds. It should not, therefore, come as a surprise that these reactive molecules undergo chemical reactions that result in their decomposition and deterioration, and that these processes begin as soon as the drug is synthesised or the medicine is formulated. Decomposition reactions of this type lead to, at best, drugs and medicines that are less active than intended (i.e. of low efficacy)-, in the worst-case scenario, decomposition can lead to drugs that are actually toxic to the patient. This is clearly bad news to all except lawyers, so the processes of decomposition and deterioration must be understood in order to minimise the risk to patients. 

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