Phytonadione (K₁; Phylloquinone; Methylphytyl Naphthoquinone)

A to Z Drug Facts

 Action Promotes hepatic synthesis of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX) and Stuart factor (factor X).

 Indications Management of coagulation disorders due to faulty formation of factors II, VII, IX and X when due to vitamin K deficiency or interference with vitamin K activity.

Oral/Parenteral: Treatment of anticoagulant-induced prothrombin deficiency; treatment of hypoprothrombinemia secondary to salicylates or antibacterial therapy or secondary to obstructive jaundice and biliary fistulas, provided bile salts are also given. Parenteral: Treatment of hypoprothrombinemia secondary to conditions limiting absorption or synthesis of vitamin K prophylaxis and therapy of hemorrhagic disease of the newborn.

 Contraindications Standard considerations.

 Route/Dosage

ADULTS & CHILDREN: PO/SC/IM 2.5 to 10 mg (in adults, up to 25 mg for serious bleeding; rarely, 50 mg), may repeat oral dose based on response in 6 to 8 hr or 12 to 48 hr; avoid oral route when disorder would prevent adequate absorption.

Hemorrhagic Disease (Prophylaxis)

NEONATES IM Single dose 0.5 to 1 mg within 1 hr of birth. INFANTS: PO/SC/IM 2 mg.

Hemorrhagic Disease (Treatment)

NEONATES SC/IM 1 mg accompanied by laboratory evaluation.

 Interactions

Oral anticoagulants: Effects are antagonized by vitamin K, particularly in patients with advanced liver disease.

 Lab Test Interferences Paradoxical prolongation of prothrombin time (PT) after maximum doses of vitamin K.

 Adverse Reactions

CV: Hypotension; cyanosis. CNS: Headache; dizziness. DERM: Pruritic erythematous plaques at IM injection site; rash; urticaria. HEPA: Hyperbilirubinemia, including kernicterus, in newborns. OTHER: Anaphylactoid reactions; pain, swelling and tenderness at injection site; death after IV injection.

 Precautions

Pregnancy: Category C. Lactation: Vitamin K excreted in breast milk. Anticoagulation: Patient may be refractory to oral anticoagulants, particularly large doses. Bleeding: Giving vitamin K has no immediate coagulant effect. Management of bleeding involves standard measures (eg, transfusions). Hypersensitivity: Rash and urticaria; anaphylactoid reactions. Impaired hepatic function: Giving vitamin K to correct hypoprothrombinemia associated with severe hepatitis or cirrhosis may further depress prothrombin concentration. IV administration: Deaths have occurred; restrict this route to situations in which other routes of administration are not feasible.

 Administration/Storage

• After initial dose, determine subsequent doses by PT response or clinical condition. If in 6 to 8 hr after parenteral administration or 12 to 48 hr after oral administration, PT has not been shortened satisfactorily, repeat dose.
• Give SC or IM when possible. For adults and older children, inject IM in upper outer quadrant of buttocks. In infants and young children, anterolateral aspect of thigh or deltoid region is preferred.
• Protect from light at all times.
• Avoid IV route unless risk outweighs benefit. If IV administration is unavoidable, inject very slowly, not exceeding 1 mg/min.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• When given for oral anticoagulant-induced hypoprothrombinemia, remember that phytonadione promotes synthesis of prothrombin by liver, but does not directly counteract effects of oral anticoagulants. Do not expect immediate coagulant effect; it takes minimum of 1 to 2 hr for measurable improvement in PT.
• Check PT prior to and after treatment with phytonadione.
• For prophylaxis or treatment of hemorrhagic disease of newborn, phytonadione (vitamin K ₁) is safer than menadiol sodium diphosphate (vitamin K ₄). A prompt response (shortening of the PT in 2 to 4 hr) is usually diagnostic of hemorrhagic disease of newborn; failure to respond indicates another diagnosis or coagulation disorder.

 Patient/Family Education

• Explain that patient may experience temporary “flushing sensations” and “peculiar” sensations of taste. Rarely dizziness, rapid weak pulse, profuse sweating, or difficulty breathing may occur. Another rare occurrence is pain, swelling, or tenderness at injection site.
• Remind patients on anticoagulant and phytonadione therapy of importance of regular lab work to check PT. Anticoagulant effects are antagonized by vitamin K so temporary resistance to oral anticoagulants may result, especially when larger doses are used.
• Instruct patient to report any symptoms of bleeding.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts