AQUAMEPHYTON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AQUAMEPHYTON (AQUAMEPHYTON).
Phytonadione (vitamin K1) is a cofactor for hepatic synthesis of clotting factors II, VII, IX, and X. It promotes the carboxylation of glutamate residues on these factors, enabling calcium binding and coagulation activity.
| Metabolism | Primarily hepatic via CYP4F2 and other enzymes; undergoes glucuronidation and oxidation. |
| Excretion | Renal: minimal (<10% as unchanged drug); biliary/fecal: ~50% as metabolites; enterohepatic circulation occurs. |
| Half-life | Terminal half-life: ~1.5-2.5 hours (adults); clinical context: short half-life requires repeated dosing for vitamin K deficiency correction; prolonged in liver disease (up to 5-7 hours). |
| Protein binding | Highly bound to serum albumin (~90% bound; minor binding to lipoproteins). |
| Volume of Distribution | Approximately 0.3-0.5 L/kg in adults; clinical meaning: distributes primarily into extracellular fluid and liver; high hepatic uptake. |
| Bioavailability | Oral: ~50% (range 40-80%) due to saturable absorption and first-pass metabolism; IM: nearly 100% (extensive absorption); IV: 100% (bypasses absorption). |
| Onset of Action | IV: within 1-2 hours for reversal of anticoagulation (INR decreases); IM: 3-6 hours; oral: 6-10 hours; subcutaneous: variable, 6-12 hours. |
| Duration of Action | Reversal of anticoagulation: 12-24 hours after IV/IM; may require repeated dosing for sustained effect; vitamin K-dependent clotting factor synthesis normalization persists 24-48 hours after adequate dose. |
Phytonadione (vitamin K1) 10 mg IV or IM, once; for non-urgent reversal of anticoagulation, 2.5-5 mg oral, once.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for any degree of renal impairment. |
| Liver impairment | No standardized Child-Pugh based adjustments; use with caution in severe hepatic impairment as vitamin K dependency may be altered. |
| Pediatric use | Neonates: 0.5-1 mg IM once at birth. Infants/Children: 1-5 mg IM/SC/IV for deficiency or reversal; for overdose, 0.5-1 mg IV/IM. |
| Geriatric use | No specific dose adjustment; use lower end of dosing range due to potential for increased sensitivity and adverse reactions. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AQUAMEPHYTON (AQUAMEPHYTON).
| Breastfeeding | Compatible with breastfeeding. Vitamin K is naturally present in breast milk; supplemental doses are not excreted in significant amounts. M/P ratio not established. |
| Teratogenic Risk | Pregnancy category C. First trimester: no evidence of teratogenicity in animal studies, but human data limited. Second and third trimesters: no known fetal risks at therapeutic doses; however, synthetic vitamin K (menadione) is contraindicated due to hemolytic anemia and kernicterus risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
Intravenous administration has been associated with severe reactions including anaphylaxis, cardiac arrest, and death. Reserve IV use for serious or life-threatening situations and administer by slow infusion with resuscitation equipment available.
| Serious Effects |
["Hypersensitivity to phytonadione or any component of the formulation","Severe liver disease (relative, as response may be impaired)"]
| Precautions | ["Severe hypersensitivity reactions, including anaphylaxis, especially with IV administration","Hemolysis in neonates with glucose-6-phosphate dehydrogenase (G6PD) deficiency","Hyperbilirubinemia in premature infants (large doses may increase risk of kernicterus)","Not effective for hereditary hypoprothrombinemia or hemophilia","Monitor INR or PT when reversing anticoagulation"] |
| Food/Dietary | No known food interactions. Oral absorption is enhanced by dietary fat; advise taking with a fatty meal if oral form is used. No specific dietary restrictions. |
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| Monitor maternal prothrombin time and INR in those with coagulation disorders. Neonates should receive prophylactic vitamin K at birth. |
| Fertility Effects | No known adverse effects on fertility. Vitamin K is essential for reproductive function; deficiency may impair fertility. |
| Clinical Pearls | For neonates: administer IM (not IV) to avoid risk of anaphylaxis; IV route reserved for adults with severe bleeding. Note that Aquamephyton (phytonadione) is a fat-soluble vitamin; monitor INR response closely in patients on warfarin. Phytonadione restores hepatic synthesis of clotting factors II, VII, IX, X within 6-12 hours. |
| Patient Advice | Take this medication exactly as prescribed; do not increase dose or frequency. · Report any signs of bleeding (e.g., unusual bruising, blood in urine/stool) or severe injection site reactions immediately. · For oral form: take with a meal containing fat to enhance absorption. · Keep all appointments for blood tests (INR) to monitor effect. · Inform all healthcare providers you are taking phytonadione. |