Levodopa interaction with other drugs

A growing number of drugs are used that affect the many neurotransmitters in the brain benzodiazepines and others act on GABAergic transmission antidepressants, such as monoamine oxidase inhibitors and tricyclic antidepressants, are thought to increase the concentration of transmitter amines in the brain and so elevate mood—these will also act at peripheral nerve terminals, so interactions with them are a combination of peripheral and central actions. Levodopa (L-dopa) increases central as well as peripheral dopamine, and the newer class of psychoactive drugs, the selective serotonin reuptake inhibitors (SSRIs) of which the ubiquitous fluoxetine (Prozac) is best known, act in a similar way on serotonergic pathways. 

Bupropion Hydrochloride Bupropion interacts with levodopa, nicotine, alcohol, and drugs that affect hepatic metabolic enzymes. It lowers the seizure threshold and potentiates the seizure threshold-lowering effect of other antidepressants.135... 

Many other infrequent symptoms and abnormal laboratory findings have been associated with levodopa treatment. Metabolites cause the urine to turn reddish and then black. Many drug interactions are possible few are confirmed, but this possibility should be watched. Some monoamine oxidase inhibitors reported effective in Parkinson s disease caused hypertensive reactions in combination with levodopa, but tricyclic antidepressants... 

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