PHYTONADIONE (VITAMIN K1)

PHYTONADIONE (VITAMIN K1)
(fye-toe-na-dye'one)
Mephyton
Classifications: vitamin k; antidote;
Therapeutic: vitamin k, antidote

Pregnancy Category: C

Availability

5 mg tablets; 2 mg/mL, 10 mg/mL injection

Action

Fat-soluble substance chemically identical to and with similar activity as naturally occurring vitamin K. Vitamin K is essential for hepatic biosynthesis of blood clotting Factors II, VII, IX, and X.

Therapeutic Effect

Promotes liver synthesis of clotting factors.

Uses

Drug of choice as antidote for overdosage of coumarin and indandione oral anticoagulants. Also reverses hypoprothrombinemia secondary to administration of oral antibiotics, quinidine, quinine, salicylates, sulfonamides, excessive vitamin A, and secondary to inadequate absorption and synthesis of vitamin K (as in obstructive jaundice, biliary fistula, ulcerative colitis, intestinal resection, prolonged hyperalimentation). Also prophylaxis of and therapy for neonatal hemorrhagic disease.

Contraindications

Hypersensitivity to phytonadione, benzyl alcohol or castor oil; severe liver disease; pregnancy (category C).

Cautious Use

Biliary tract disease, obstructive jaundice; elderly (IV use).

Route & Dosage

Anticoagulant Overdose
Adult: PO/SC/IM 2.5–10 mg; rarely up to 50 mg/d, may repeat parenteral dose after 6–8 h if needed or PO dose after 12–24 h IV Emergency only: 10–15 mg at a rate of ≤1 mg/min, may be repeated in 4 h if bleeding continues

Hemorrhagic Disease of Newborns
Infant: IM/SC 0.5–1 mg immediately after delivery, may repeat in 6–8 h if necessary

Other Prothrombin Deficiencies
Adult: IM/SC/IV 2–25 mg
Child/Infant: IM/SC/IV 0.5–5 mg

Administration

Intramuscular

Note: Konakion, which contains a phenol preservative, is intended ONLY for IM use. AquaMEPHYTON may be given SC, IM, or IV as prescribed.

  • Give IM injection in adults and older children in upper outer quadrant of buttocks. For infants and young children, anterolateral aspect of thigh or deltoid region is preferred.
  • Aspirate carefully to avoid intravascular injection.
  • Apply gentle pressure to site following injection. Swelling (internal bleeding) and pain sometimes occur with SC or IM administration.
Intravenous
  • Note: Reserve IV route only for emergencies.

PREPARE: Direct: Dilute a single dose in 10 mL D5W, NS, or D5/NS.  

ADMINISTER: Direct: Give solution immediately after dilution at a rate not to exceed 1 mg/min.  

INCOMPATIBILITIES Solution/additive: Ascorbic acid, cephalothin, dobutamine, doxycycline, magnesium sulfate, nitrofurantoin, phenobarbital, ranitidine, thiopental, vancomycin, warfarin. Y-site: Dobutamine.

  • Protect infusion solution from light by wrapping container with aluminum foil or other opaque material.
  • Discard unused solution and contents in open ampul.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity or anaphylaxis-like reaction: facial flushing, cramp-like pains, convulsive movements, chills, fever, diaphoresis, weakness, dizziness, shock, cardiac arrest. CNS: Headache (after oral dose), brain damage, death. GI: Gastric upset. Hematologic: Paradoxic hypoprothrombinemia (patients with severe liver disease), severe hemolytic anemia. Metabolic: Hyperbilirubinemia, kernicterus. Respiratory: Bronchospasm, dyspnea, sensation of chest constriction, respiratory arrest. Skin: Pain at injection site, hematoma, and nodule formation, erythematous skin eruptions (with repeated injections). Special Senses: Peculiar taste sensation.

Diagnostic Test Interference

Falsely elevated urine steroids (by modifications of Reddy, Jenkins, Thorn procedure).

Interactions

Drug: Antagonizes effects of warfarin; cholestyramine, colestipol, mineral oil decrease absorption of oral phytonadione.

Pharmacokinetics

Absorption: Readily from intestinal lymph if bile is present. Onset: 6–12 h PO; 1–2 h IM/SC; 15 min IV. Peak: Hemorrhage usually controlled within 3–8 h; normal prothrombin time may be obtained in 12–14 h after administration. Distribution: Concentrates briefly in liver after absorption; crosses placenta; distributed into breast milk. Metabolism: Rapidly in liver. Elimination: In urine and bile.

Nursing Implications

Assessment & Drug Effects

  • Monitor patient constantly. Severe reactions, including fatalities, have occurred during and immediately after IV injection (see ADVERSE EFFECTS).
  • Lab tests: Baseline and frequent PT/INR.
  • Frequency, dose, and therapy duration are guided by PT/INR clinical response.
  • Monitor therapeutic effectiveness which is indicated by shortened PT, INR, bleeding, and clotting times, as well as decreased hemorrhagic tendencies.
  • Be aware that patients on large doses may develop temporary resistance to coumarin-type anticoagulants. If oral anticoagulant is reinstituted, larger than former doses may be needed. Some patients may require change to heparin.

Patient & Family Education

  • Maintain consistency in diet and avoid significant increases in daily intake of vitamin K–rich foods when drug regimen is stabilized. Know sources rich in vitamin K: Asparagus, broccoli, cabbage, lettuce, turnip greens, pork or beef liver, green tea, spinach, watercress, and tomatoes.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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