Phytonadione

Pronunciation
( K 1 ; Phylloquinone ; Methylphytyl Naphthoquinone )

Pronunciation: fye-TOE-na-DYE-one
Class: Vitamin K, Blood modifier

Trade Names

Mephyton
- Tablets, oral 5 mg

Phytonadione
- Tablets, oral 100 mcg
- Injection 2 mg/mL
- Injection 10 mg/mL

Pharmacology

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

Slideshow: View Frightful (But Dead Serious) Drug Side Effects

Pharmacokinetics

Absorption

Phytonadione is adequately absorbed from the GI tract only if bile salts are present. Phytonadione is rapidly absorbed following IM administration.

Distribution

Following absorption, phytonadione is concentrated in the liver and the concentration rapidly declines. Very little vitamin K accumulates in tissues.

Metabolism

Very little is known about the metabolic fate of vitamin K.

Elimination

Almost no free unmetabolized vitamin K appears in the bile or urine.

Onset

6 to 10 h (oral) and 1 to 2 h (parenteral); controls hemorrhage in approximately 3 to 6 h.

Indications and Usage

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

Oral

Factors limiting absorption or synthesis of vitamin K (eg, biliary fistulas, obstructive jaundice, sprue, ulcerative colitis) provided bile salts are given concurrently.

Oral/Parenteral

Treatment of anticoagulant-induced prothrombin deficiency; treatment of hypoprothrombinemia secondary to salicylates or antibacterial therapy; dietary supplement.

Parenteral

Treatment of hypoprothrombinemia secondary to conditions limiting absorption or synthesis of vitamin K; prophylaxis and therapy of hemorrhagic disease of the newborn.

Contraindications

None well documented.

Dosage and Administration

Anticoagulant-Induced Prothrombin Deficiency
Adults

PO / Subcutaneous / IM / IV 2.5 to 25 mg (rarely up to 50 mg). The dose may be repeated in 12 to 48 h after oral administration or 6 to 8 h after parenteral administration if the PT has not been shortened satisfactorily.

Dietary Supplement

PO 100 mcg daily, or as directed.

Hypoprothrombinemia Due to Other Causes
Adults

PO / Subcutaneous / IM / IV 2.5 to 25 mg (rarely up to 50 mg). When possible, discontinue or reduce the dosage of drugs interfering with coagulation mechanics (eg, salicylates, antibiotics) as an alternative to administering phytonadione.

Hemorrhagic Disease (Prophylaxis)
Newborns

IM Single dose of 0.5 to 1 mg within 1 h of birth.

Hemorrhagic Disease (Treatment)
Newborns

Subcutaneous / IM 1 mg accompanied by laboratory evaluation.

General Advice

  • Give subcutaneously 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.
  • Avoid IV route unless risk outweighs benefit. If IV administration is unavoidable, inject very slowly, not exceeding 1 mg/min.
  • Avoid oral route when the clinical disorder would prevent proper absorption.
  • Bile salts must be given when endogenous supply of bile to GI tract is deficient.
  • The dose and route should be determined by severity of the condition and response obtained.
  • Benzyl alcohol has been associated with toxicity in newborns; therefore, dilutions for newborns should be preservative free.

Storage/Stability

Store tablets between 59° and 86°F. Always protect from light. Store injection between 68° and 77°F. Protect from light until time to use.

Drug Interactions

Oral anticoagulants

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

Laboratory Test Interactions

Paradoxical prolongation of PT after max doses of vitamin K.

Adverse Reactions

Cardiovascular

Cyanosis, hypotension, rapid and weak pulse.

CNS

Dizziness.

Dermatologic

Profuse sweating, transient flushing.

GI

Peculiar taste sensations with parenteral administration.

Hepatic

Hyperbilirubinemia in newborns following parenteral administration.

Hypersensitivity

Severe hypersensitivity reactions, including anaphylactoid reactions and death following parenteral administration.

Local

Erythematous, indurated pruritic plaques that rarely may progress to scleroderma-like lesions; pain, swelling, and tenderness at injection site.

Respiratory

Dyspnea.

Precautions

Warnings

Injection

Severe reactions, including death, have occurred during and immediately after IV injection. Severe reactions have resembled hypersensitivity or anaphylaxis, including shock and cardiac and/or respiratory arrest. Events have occurred even when appropriate dilution was used to avoid rapid infusion. Some patients have exhibited symptoms on first administration of the drug. Thus, restrict IV and IM use for situations where other routes are not feasible and benefit/risk ratio is assessed.


Monitor

Prothrombin time should be checked regularly as clinical conditions indicate.


Pregnancy

Category C .

Lactation

Undetermined.

Children

Oral: Safety and efficacy not established.

Elderly

Use with caution, usually starting at the low end of the dosage range, because of the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Hypersensitivity

Rash, urticaria, or anaphylactoid reactions may occur.

Renal Function

Patients with impaired kidney function, including premature neonates, who receive parenteral levels of aluminum at more than 4 to 5 mcg/kg/day accumulate aluminum at levels associated with CNS and bone toxicity.

Hepatic Function

Giving vitamin K to correct hypoprothrombinemia associated with severe hepatitis or cirrhosis may further depress prothrombin concentration.

Anticoagulation

Patients 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).

Heparin

Anticoagulant effect will not be counteracted by phytonadione.

Overdosage

Symptoms

No data available.

Patient Information

  • 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; therefore, temporary resistance to oral anticoagulants may result, especially when larger doses are used.
  • Instruct patient to report any symptoms of bleeding.

Copyright © 2009 Wolters Kluwer Health.

Hide
(web3)