UW Spinoff Impel Neuropharma Passes Key Nose-to-Brain Clinical Trial
 

wow, no idea if just hype though.
and they tested a peptide, made up of amino acids.
http://www.xconomy.com/seattle/2013/...linical-trial/

Six years later ... an update on Impel Neuropharma's nasal dlivery system (levodopa)
 

An update from AANAM 2019 (via PNT):

#AANAM - L-DOPA Nasal Delivery May Help Manage PD OFF Episodes

I'm sure there must be a more-recent thread that I could have used, but this is the only one that came up when I searched for Impel Neuropharma.