Vitamindosage

Anticoagulant-Induced Prothrombin Deficiency: 2.5 mg to 10 mg or up to 25 mg Hypoprothrombinemia Due to Other Causes: 2.5 mg to 25 mg or more Must be given with bile salts when endogenous supply of bile to gastrointestinal track is deficient.

2.1 Dosing Considerations

Avoid the oral route when the clinical disorder would prevent proper absorption. Bile salts must be given with the tablets when the endogenous supply of bile to the gastrointestinal tract is deficient. The coagulant effects of phytonadione tablets are not immediate; improvement of international normalized ratio (INR) may take 1 to 8 hours. Interim use of whole blood or component therapy may also be necessary if bleeding is severe. Phytonadione tablets will not counteract the anticoagulant action of heparin. When phytonadione tablets are used to correct excessive anticoagulant-induced hypoprothrombinemia, anticoagulant therapy still being indicated, the patient is again faced with the clotting hazards existing prior to starting the anticoagulant therapy. Phytonadione is not a clotting agent, but overzealous therapy with vitamin K1 may restore conditions which originally permitted thromboembolic phenomena. Dosage should be kept as low as possible, and prothrombin time should be checked regularly as clinical conditions indicate.

2.2 Recommended

Dosage Anticoagulant-Induced Prothrombin Deficiency in Adults The recommended dose to correct excessively prolonged prothrombin times caused by oral anticoagulant therapy is, 2.5 to 10 mg or up to 25 mg initially. In some instances 50 mg may be required. Frequency and amount of subsequent doses should be determined by prothrombin time response or clinical condition. If, in 12 to 48 hours after oral administration, the prothrombin time has not been shortened satisfactorily, repeat the dose. Repeated large doses of phytonadione tablets are not warranted in liver disease if the response to initial use of the vitamin is unsatisfactory. Failure to respond to phytonadione tablets may indicate a congenital coagulation defect or that the condition being treated is unresponsive to vitamin K. Hypoprothrombinemia Due to Other Causes in Adults If possible, discontinuation or reduction of the dosage of drugs interfering with coagulation mechanisms (such as salicylates, antibiotics) is suggested as an alternative to administering concurrent phytonadione tablets. The severity of the coagulation disorder should determine whether the immediate administration of phytonadione tablets is required in addition to discontinuation or reduction of interfering drugs. The recommended dose is 2.5 mg to 25 mg or more (sometimes up to 50 mg). Evaluate INR after 6 to 8 hours, and repeat dose if INR remains prolonged. Modify subsequent dosage (amount and frequency) based upon the INR or clinical condition.