First off Loperamide is formulated with Magnesium Stearate which is highly insoluble in water. Stearates break down on exposure to even mild acids & heat.
Alot of people think you can grind up Lomotil & water extract the atropine. (Keep in mind atropine is less commonly used along with PTC in bitter principle taste-tests) Not only is a water extract of 60 Lomotil tabs (2 mg atropine) tasteless but it has nil-to-no anticholinergic effects.
Now if you take that Lomotil soln. mix with a small amount of hcl or vinegar and microwave to heat to ~180°F you go from having a flocculent solution of large hydrophobic white particles to a solution where the particles appear to have 'unfolded' and are nearly transparent and obviously interacting with water. And of course the solution is very bitter. Separating the 2 compounds is another issue.
(
http://opioids.com/loperamide/index.html)
It was concluded that in its present form, i.e., capsules containing loperamide mixed with magnesium stearate, loperamide poses little threat of potential abuse.
As for Cimetidine - Loperamide is metabolized by Cyp3A4 and Cyp2C8 it is actively effluxed by PGP in the gut and brain. Quercetin blocks 40% of N-Demethyl. (2C8) and Ketoconazole blocks up to 90% (3A4)
Probably the most readily available inhibitor of Cyp3A4 and P-glycoprotein is Piperine in black pepper. This will only block 3A4 and PGP in the gut/liver and will not enable you to get high - though it may help with peripherally mediated opiate receptor withdrawal effects.
As for getting Loperamide across the BBB the best, easiest, and most readily available chemical is
HPßCD - HydroxyPropyl Beta CycloDextrin. Unlike coating nanoparticles and crap all you have to do with HPßCD is mix in an aqueous solution and agitate for several hour/days(?). HPßCD is mentioned along with loperamide in a few patents as being well suited for enhancing solubility & bioavailability. HPßCD is reasonably readily available (alot of places that deal with both mind and muscle use it.)
Oh and insuffalating Stearate complexed loperamide is not very bioavailable, you'd need to break it down as detailed above, extract and adjust the pH back to normal. The nasal cavity has PGP, too although it takes a very low (hundreds of times lower conc.) of an inhibitor to block it here.
