In humans, conversion of -DOPA to dopamine does not only occur within the central nervous system. Cells in the peripheral nervous system perform the same task. Thus administering -DOPA alone will lead to increased dopamine signaling in the periphery as well. Excessive peripheral dopamine signaling is undesirable as it causes many of the adverse side effects seen with sole L-DOPA administration. To bypass these effects, it is standard clinical practice to coadminister (with -DOPA) a peripheral DOPA decarboxylase inhibitor (DDCI) such as carbidopa (medicines containing carbidopa, either alone or in combination with -DOPA, are branded as Lodosyn (Aton Pharma) Sinemet (Merck Sharp & Dohme Limited), Pharmacopa (Jazz Pharmaceuticals), Atamet (UCB), Syndopa and Stalevo (Orion Corporation) or with a benserazide (combination medicines are branded Madopar or Prolopa), to prevent the peripheral synthesis of dopamine from -DOPA).