Doesn’t the Half-Life of C/L apply only to, while in the bloodstream and once Levodopa crosses the BBB it is stored until used?

[Gcf51]

I posed a question in a comment and have not received an answer.

I am thinking that once L-dopa crosses the BBB it is stored until used (maybe as dopamine). And, Half-Life is how long it stays in your Blood Stream.

The plasma half-life of levodopa is about 50 minutes, without carbidopa. When carbidopa and levodopa are administered together, the half-life of levodopa is increased to about 1.5 hours. dailymed.nlm.nih.gov/dailym...

Note because I change title I repost. My experience is a link to a changed title will take you to page not found,

[park_bear]

This is a good topic. Personally I have found that the effects of levodopa medication last a lot longer than the duration in the plasma.

[Gcf51 in reply to park_bear]

Probability the reason you can take B6 within hours of taking C/L and not have problems.

[WinnieThePoo]

No. Normally levadopa is decarboxylated in the brain and the body. Peripheral levadopa conversion to dopamine is at best wasteful, at worst toxic. Levadopa has a half life of 1-3 hours. If it is combined with a DDCI like Carbidopa, it is inhibited from conversion to dopamine in its presence. Carbidopa is incapable of crossing the BBB and so allows more levadopa to cross into the brain, where it is converted at the same rate. But dopamine is also incapable of crossing the BBB - it's a 2 way thing, so the dopamine made in the brain stays there until used. That is why the effects of taking oral L/C last longer than levadopas half life.

[Boscoejean in reply to WinnieThePoo]

I guess what I find puzzling is that when my husband takes the compounded carbidopa with mucuna one time in the morning he seems to have benefits pretty much throughout the day and does not have to experience symptoms that are so often mentioned that are associated with having the standard carbidopa/levodopa medication wear off- maybe we are just lucky in this respect and not sure how long this will be helpful but the naturopath we saw mentioned that one of her patients was able to maintain on this combination for over 8 years and then eventually started using the standard medication