1. Phenylindanedione-induced hypoprothrombinemia is rapidly counteracted by a vitamin K1 emulsion. This hypoprothrombinemia is antagonized at a more rapid rate than that induced by any of the other commonly employed prothrombopenic agents.
2. The optimum dose of the vitamin K1 emulsion in emergency is 5 mg. per Kg. Since a refractoriness to the prothrombopenic action of phenylindanedione ensues, smaller doses should be used in situations where there is to emergency.