Phytonadione (Vitamin K1)
Phytonadione (Vitamin K1) is an analogue of Vitamin K; but it has the quickest onset of action, the most prolonged duration, and is the most potent of all the Vitamin K forms. It is also safer than menadione (K3) to use on newborns. K3 is the only one that could cause toxicity, causing hemolytic anemia. Hemolytic anemia happens when the RBC's die more quickly than the body can reproduce. In addition, it speeds liver damage, producing jaundice, deafness, and severe neurological problems, including retardation in infants. There is no record that the other two forms have produced toxic levels. Care must be taken with IV injections of Vitamin K, since they can cause facial flushing, excessive perspirations, chest tightness, cyanosis, vascular collapse, and shock as well as anaphylaxis.
Vitamin K1 was named phylloquinone since it is an indirect product of photosynthesis in plant leaves where it occurs in chloroplasts and participates in the overall photosynthetic process. The methyl naphthoquinone ring has a phytyl side chain (partially saturated polyisoprenoid alcohol). Anticoagulant rodenticides interfere with the vitamin K-dependent carboxylation of factors II, VII, IX and X by inhibiting the epoxide-reductase enzyme necessary for the recycling of vitamin K, thus depleting body stores of vitamin K. As a result, only nonfunctional precursors of the vitamin K-dependent factors are synthesized. Coumarin compounds including warfarin, coumafuryl, brodifacoum, and bromadiolone have a half-life of up to 55 hours. In contrast, indanedione compounds (pindone, valone, diphacinone and chlorophacinone) have a half-life as long as 4 to 5 days and can affect hemostasis for as long as 30 days. In addition, the indanedione compounds may interfere with exocrine pancreatic function resulting in reduced intestinal absorption of vitamin K. It is insoluble in water, soluble in chloroform and slightly soluble in ethanol. It has a molecular weight of 450.70.
Phytonadione refers to a branch of Vitamin K which is a fat-soluble vitamin required for the normal clotting of the blood. Vitamin K is found in two forms in nature: Phytonadione or Vitamin K1 which is found in plants and Menaquinone or Vitamin K2 which can be synthesized by many bacteria. A manmade form of Vitamin K called menadione or Vitamin K3 is also available. Vitamin K is essential in blood clotting and if it were absent, a small cut would cause continuous bleeding in the body to the point of death. The process of blood clotting begins automatically when a tear in a blood vessel is present. When a tear in a blood vessel is present, a collection of molecules assemble rapidly to form a blood clot. Clotting is dependent on proteins such as Factor II, Factor VII, Factor IX, and Factor X that require vitamin K for synthesis in the body. Besides its blood clotting function, recent medical research has linked Vitamin K with the prevention of osteoporosis, a disease that weakens the bones. This is important as calcium was the only known preventative of this disease. Vitamin K is also produced naturally in the intestines where it assists the conversion of glucose to glycogen which is then stored in the liver.
Phytonadione is present in a number of dietary sources that includes: green leafy vegetables such as spinach; green tea; cabbage; turnip greens; brussels sprouts; alfafa; eggs; soybean oil; canola oil; olive oil; soybeans; cheddar cheese; oats; cauliflower; asparagus; coffee; cow milk; and bacon. Vitamin K is required in only small amounts and little of the vitamins are lost from these dietary sources with ordinary cooking. In instances of Vitamin K deficiency, phytonadione supplements are available. The recommended dosage in newborn infants that are afflicted with Vitamin K deficiency is a single dose of 5 mg of phytonadione. In adults with Vitamin K deficiency, the recommended dosage of phytonadione is 10 mg taken orally per week.
Molecular formula: C31H46O2
Molecular weight: 450.7