Apologies, I should have clarified. More specifically, concomitant DCI administrations are what are known as 'peripheral decarboxylase inhibitors' - or, in other words, opposing the decarboxylation of L-DOPA to Dopamine in peripheral tissues. This is a necessary adjuvent in order to avoid dyskinesia (motor function fluctuations) as well as neuro-degradative effects (over expression of Dopaminergic transmission leads to post-synaptic degradation; Dopamine 'floods' the Substantia Nigra, so to speak, and cannot be deaminated at a normal rate).
In terms of inherent DCIs, the postulate is that MP contains a DCI such as entacapone or carbidopa; an additional postulate is that MP contains independent, non-DCI L-DOPA enhancing agents. In any respect, the centralization of Dopaminergic transmission and synthesis noted in MP clinical trials leads one to believe that peripheral transmission is not occurring, by whatever mechanism.