Difrarel is a complex preparation containing anthocyanosides from bilberry (Vaccinium myrtillus) and other compounds (phenobarbital, nicotinic acid, papaverine, beta-carotene). Vaccinium myrtillus anthocyanosides can reduce microvascular impairments (notably those due to ischemia reperfusion injury) to preserve the endothelium and to improve capillary perfusion. They play a role in the redistribution of microvascular blood flow and interstitial fluid formation. The preparation, given orally, is endowed with significant vasoprotective and antioedema properties, and was recommended to treat arterial hypertension and vascular disease.
The drug remains in use today in some countries to treat high blood pressure, cataracts, age related macular degeneration, and other diseases. Notably, bilberry has been recommended to delay cataract progression, by reducing eye inflammation and eye nerve damages caused by free radicals for example. Bilberry fruit anthocyanin-rich extracts can be found in different medicinal preparations used today. Such bilberry extracts can also provide protection from the cardiotoxic effects of anthracyclines anticancer drugs.