I'd like to put this out there and see what others think:
https://pdfs.semanti...ba0ead808ed.pdf
"Permeability of water through the buccal mucosa was approximately 10 times higher, whilst in floor of the mouth the permeability was approximately 20 times higher than skin . Drugs can be transported across epithelial membranes by passive diffusion, carrier-mediated active transport or other specialized mechanisms. Most studies of buccal absorption indicate that the predominant mechanism is passive diffusion across lipid membranes via either the paracellular or transcellular pathways .although these may actually be the same pathway. The hydrophilic nature of the paracellular spaces and cytoplasm provides a permeability barrier to lipophilic drugs but can be favorable for hydrophilic drugs. In contrast, the transcellular pathway involves drugs penetrating through one cell and the next until entering the systemic circulation. The lipophilic cell membrane offers a preferable route for lipophilic drugs compared to hydrophilic compounds . Drugs can transverse both pathways simultaneously although one route could be predominant depending on the physicochemical properties of the drug .Although passive diffusion is the predominant mechanism of absorption from the oral mucosa, specialized transport mechanisms have also been reported for a few drugs and nutrients. "
If this is the case then I was completely wrong about the hydrophilicity of the molecule making it less efficient for for sublingual administration. And furthermore, a solubilized preparation may be effective for sublingual administration also, either in water or aqueous ethanol perhaps.
We still have the question Michael brought up: "absorbed intact into the circulation" but otherwise this seems positive.
Edited by TMNMK, 08 April 2018 - 03:07 PM.