This is a very interesting and detailed article by a group who have considerable ressources and skills. The space given to in "Science" magazine shows the importance of finding better ways to deliver levodopa. Unfortunately in my opinion, and based on the modest research I've done on the metabolism of levodopa with zero ressources (I'm retired) this article totally misses the point. The biggest barrier to getting more levodopa to the brain is the very common, very potent and extesively studied enzyme CYP3A4. I now have the the evidence for this which I posted in my Researchgate space two days ago as experimental results. I can't yet post that link as I'm still only a junior member here ( it's the only place I'm junior). For those of you who want to know more, read my post on " The metabolism of levodopa " and the reply by Johnt who posted a link for me on an earlier paper that gives the science that you need to know to understand why I'm so convinced that CYP3A4 should be our real target.
This link gets you to that space where I've posted the latest experimental data. Those who want to will find it and will get a like for posting the link.
John and I are now working to get numerical data on the inhibition of CYP3A4 and we now have the first results that are very promising indeed. We need many more people like John to join us on this project. There's a lot of work to be done on this and it will only get done by PwP, for reasons that become very clear when you read my articles, but I'm convinced it will make a massive difference for us. It's up to us to get the research done that matters to us.
There, I've had my rant, and I feel better for it.