PSC 433 Chapter Notes - Chapter 8: Melanin, Decarboxylation, L-Dopa
17 Feb 2019
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Treatment of neurodegenerative diseases: anti-parkinson drugs: amantadine, benztropine, biperiden, bromocriptine, carbidopa, Entacapone, levodopa, pergolide, pramipexole, ropinirole, selegline (deprenyl), tolcapone, Trihexyphenidyl: anti-alzheimer drugs: donezepil, galantamine, memantine, rivastigmine, tacrine. Carbidopa diminishes the metabolism of levodopa in the gi tract and peripheral tissues, and, thus, increases the availability of levodopa to the cns: levodopa decreases the rigidity, tremors, and other symptoms of parkinsonism. In approximately 2/3 of patients with parkinson disease, levodopa-carbidopa treatment substantially diminishes the severity of the disease for the first few years of treatment. Patients then typically experience a decline in response during the third to fifth year of therapy (wearing- off phenomenon): levodopa has an extremely short half life (one to two hours), which causes fluctuations in plasma concentration. Interactions: concomitant administration of levodopa and mao inhibitors, such as phenelzine, can produce a hypertensive crisis caused by enhanced catecholamine production, pyridoxine (b6) diminishes the effect of levodopa due to increased peripheral metabolism.
