- Unpermitted concomitant medication defined as any medicine with a potential interaction with alpha lipoic acid or with the effect of alpha lipoic acid were excluded as concomitant medication. These included aldose reductase inhibitors, substances promoting blood flow, anticoagulants apart from acetylsalicylic acid 500 mg/day and short-term treatment of diseases with the normal dose of acetylsalicylic acid, chronically and systemically administered corticosteroids, hormonal contraceptives