<unk>  has demonstrated significant liver toxicity (hepatotoxicity) that limits the drug's utility. Entacapone is an alternative, largely since it has a more favorable toxicity profile. The hepatotoxicity can be related to elevated levels of transaminases, but studies have shown that minimal risk exists for those without preexisting liver conditions when their enzyme levels were being monitored. No clear mechanism is implicated, but it has been hypothesized that it has something to do with abnormal mitochondrial respiration due to the uncoupling of oxidative phosphorylation. Other side effects regard the increase in dopaminergic activity, including digestive symptoms. Treatment with<unk>  runs the risk of eliciting or prolonging dyskinesia; this can be counteracted by decreasing the dose of levodopa. This occurs because the administration of<unk>  results in the accumulation of the biological methyl donor S-adenosyl-L-methionine (SAM) in the striatum that induces Parkinson symptoms. Digestive symptoms include nausea and diarrhea; further dopaminergic side effects include orthostatic hypotension, dry mouth, sweating and dizziness.<unk>  causes more severe diarrhea than entacapone; this was the most common reason for therapy termination in studies. Urine discoloration comes from yellow<unk>  metabolites being excreted in the urine and is harmless.
Tolcapone
Dimethazan
Acolbifene
Lorcaserin
Pretomanid
Quinagolide
Olsalazine
Entropion