The present invention provides a method of treating a respiratory illness in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a compound comprising a reaction product of a reaction mixture comprising: a) N-phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]propanamide or a derivative thereof; and b) dimethyl sulfoxide. Also provided are methods of alleviating opioid addiction while suppressing withdrawal symptoms and alleviating inflammation and visceral pain with minimal risk of addiction in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the compound described above.