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L-多巴几乎是治疗震颤麻痹最有效的药物。但其副作用——开始用药时的恶心和呕吐、长期治疗时的异常运动——使其应用受限制。若在使用L-多巴的同时并用多巴脱羧酶抑制剂,则比单用L-多巴更好。口服L-多巴后,只有很小一部分到达脑内代谢成多巴胺。大部分L-多巴从胃肠道吸收后在脑组织以外即被脱羧,因而起不到治疗作用。故需很大剂量才能使脑组织中达到治疗浓度。一些属于肼类和羟基胺类的物质,能有力地抑制多巴脱羧酶——一种使多巴转变为多巴胺的酶。这些抑制剂限制多巴胺的形成。
L-dopa is almost the most effective treatment of paralysis paralysis drugs. But its side effects - nausea and vomiting at the start of medication and abnormal exercise over long periods of treatment - limit its use. If using L-dopa in combination with dopa decarboxylase inhibitors, than L-dopa alone better. After oral administration of L-dopa, only a small fraction reaches the brain and metabolizes to dopamine. Most L-dopa is absorbed from the gastrointestinal tract and is decarboxylated outside of the brain tissue, thus failing to have a therapeutic effect. It takes a lot of dosage to reach the therapeutic concentration in brain tissue. Some substances belonging to hydrazines and hydroxyamines strongly inhibit dopa decarboxylase, an enzyme that converts dopa into dopamine. These inhibitors limit the formation of dopamine.