Acetomenaphthane, A vitamin K analogue used to treat and prevent hypoprothrombinemia caused by vitamin K deficiency. Also called menadiol diacetate. Hypoprothrombinemia is a blood disorder in which a deficiency of prothrombin results in impaired blood clotting, leading to an increased physiological risk for bleeding, especially in the gastrointestinal system, cranial vault, and superficial integumentary system.