Levodopa and carbidopa

The 2D structures of levodopa and carbidopa

Levodopa-carbidopa (LCD, also known as co-careldopa; brand names: Duodopa, Kinson, Sinemet), is a combination is designed to prevent the metabolism of levodopa in the periphery via the enzyme aromatic L-amino acid decarboxylase (AADC), so as to maximize the amount of unchanged levodopa that makes its way to the CNS. It works because carbidopa cannot cross the BBB. It also reduces the frequency of various peripheral side effects such as: nausea, vomiting and light-headedness.[1]

It turns out that this combination is so effective in reducing the incidence of peripheral side effects and increasing the efficacy of the treatment that in Australia levodopa is only available in combination with an AADC inhibitor like carbidopa.[1] LCD basically increases the production of dopamine in the CNS by serving as a precursor to the neurotransmitter. Consequently it increases basal levels of dopamine in the CNS, potentially reducing the craving, by cocaine addicts, to artificially raise this level with cocaine. Unfortunately, LCD’s use, in the long-term, is limited by its potential to cause hallucinations and delusions which can be persistent. This is likely due to the fact that dopamine is implicated in the aetiology of hallucinations in schizophrenia and other psychotic disorders.[2]

In a recent meta-analysis LCD was not found efficacious in the treatment of cocaine dependence.[3]

Reference listEdit

  1. 1.0 1.1 Brayfield, A, ed. (13 May 2014). "Levodopa". Martindale: The Complete Drug Reference. London, UK: Pharmaceutical Press. Retrieved 28 July 2014.
  2. Guillin, O; Abi-Dargham, A; Laruelle, M (2007). "Neurobiology of dopamine in schizophrenia.". International Review of Neurobiology 78: 1–39. doi:10.1016/S0074-7742(06)78001-1. PMID 17349856.
  3. Amato, L; Minozzi, S; Pani, PP; Solimini, R; Vecchi, S; Zuccaro, P; Davoli, M (December 2011). "Dopamine agonists for the treatment of cocaine dependence.". The Cochrane Database of Systematic Reviews (12): CD003352. doi:10.1002/14651858.CD003352.pub3. PMID 22161376.