Vitamin B-12 1000 mcg Prolonged-Release Tablets, 100 ct, QC96591 Sale! This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Vitamin B12 (Cyanocobalamin) supports the body's nerves and blood cells. Prolonged release vitamins slowly release nutrients into the body over an extended period of time. No added sugar, salt, yeast, preservatives, artificial flavors or colors, and gluten-free.