0.3%. this is what according to Wikipedia you get in the bloodstream after the oral dose. Blood-brain barrier is another obstacle to cross. Quinidine taken wit

0.3%. this is what according to Wikipedia you get in the bloodstream after the oral dose. Blood-brain barrier is another obstacle to cross. Quinidine taken with loperamide blocks transport protein P-glycoprotein and causing loperamide to have opioid like effects in the brain.