What exactly is complamina (xanthinol nicotinate)?

Vasodialator niacin. Its a form of Niacin - and acts as a vasodialator - it seems to be a german or indian brand name and promoted as a memory aid - however there can be side effects such as flushing at low doses and more serious side effects when doses are excessive - not all supplements are benign and more is not always better. When in doubt consult a physician or a pharmacist.