Phytonadione (Vitamin K1)
Phytonadione supplies vitamin K1 for hepatic synthesis of functional clotting factors. It treats vitamin K antagonist coagulopathy but does not immediately replace circulating clotting factors.
Group
Vitamin K antagonist antidote
Mechanism of Action
Restores the vitamin K cofactor needed to activate coagulation factors II, VII, IX and X.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Short-acting anticoagulant toxicosis | 1 mg/kg | PO, SC | Every 24 h | Up to 14 days; Listed course 10–14 days; extend or stop based on anticoagulant identity and coagulation response. |
| Long-acting anticoagulant toxicosis | 2.5–5 mg/kg | PO, SC | Every 24 h | Up to 42 days; Listed course 3–4 weeks; may require up to 6 weeks. Total listed daily amount. IM risks hematoma in actively coagulopathic patients. |
| Long-acting anticoagulant toxicosis | 2.5–5 mg/kg | IM | Every 24 h | Up to 42 days; Do not use in: Active severe coagulopathy for IM administration; Listed course 3–4 weeks; may require up to 6 weeks. Total listed daily amount. IM risks hematoma in actively coagulopathic patients. |
| Short-acting anticoagulant IM alternative | Reference only | IM | The vitamin K monograph additionally lists 1 mg/kg/day IM for 10–14 days; IM hematoma risk makes oral or appropriate SC treatment preferable in a bleeding patient. | |
| Vitamin K adjunct in acute liver failure | 1–5 mg/kg | PO, SC | Every 24 h | May help if vitamin K deficiency contributes; does not correct clotting-factor failure from severe hepatocellular damage. |
| Nonbleeding anticoagulant rodenticide exposure | 1.25–2.5 mg/kg | PO | Every 12 h | Up to 28 days; With a fatty meal for a listed 2–4 week course when exposure warrants treatment; duration depends on compound and post-treatment coagulation testing. |
| Bleeding anticoagulant rodenticide toxicosis | 2.5 mg/kg | PO | Every 12 h | Treat at least 4 weeks with a fatty meal; plasma and/or whole blood may be required for immediate clotting-factor or red-cell replacement. |
| Anticoagulant toxicosis oral loading — Loading | 2.5–5 mg/kg | PO | Once | Symptomatic-patient loading alternative; follow a separately selected maintenance schedule, not every listed course. |
| Alternative divided daily anticoagulant course | 1.5–2.5 mg/kg | PO | Every 12 h | Derived from 3–5 mg/kg TOTAL PER DAY divided into two equal doses. First-generation course about 14 days; second-generation or unknown compounds at least 30 days; duration guided by PT after stopping. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Short-acting anticoagulant toxicosis | 1 mg/kg | PO, SC | Every 24 h | Up to 14 days; Listed course 10–14 days; extend or stop based on anticoagulant identity and coagulation response. |
| Long-acting anticoagulant toxicosis | 2.5–5 mg/kg | PO, SC | Every 24 h | Up to 42 days; Listed course 3–4 weeks; may require up to 6 weeks. Total listed daily amount. IM risks hematoma in actively coagulopathic patients. |
| Long-acting anticoagulant toxicosis | 2.5–5 mg/kg | IM | Every 24 h | Up to 42 days; Do not use in: Active severe coagulopathy for IM administration; Listed course 3–4 weeks; may require up to 6 weeks. Total listed daily amount. IM risks hematoma in actively coagulopathic patients. |
| Short-acting anticoagulant IM alternative | Reference only | IM | The vitamin K monograph additionally lists 1 mg/kg/day IM for 10–14 days; IM hematoma risk makes oral or appropriate SC treatment preferable in a bleeding patient. | |
| Vitamin K adjunct in acute liver failure | 1–5 mg/kg | PO, SC | Every 24 h | May help if vitamin K deficiency contributes; does not correct clotting-factor failure from severe hepatocellular damage. |
| Nonbleeding anticoagulant rodenticide exposure | 1.25–2.5 mg/kg | PO | Every 12 h | Up to 28 days; With a fatty meal for a listed 2–4 week course when exposure warrants treatment; duration depends on compound and post-treatment coagulation testing. |
| Bleeding anticoagulant rodenticide toxicosis | 2.5 mg/kg | PO | Every 12 h | Treat at least 4 weeks with a fatty meal; plasma and/or whole blood may be required for immediate clotting-factor or red-cell replacement. |
| Anticoagulant toxicosis oral loading — Loading | 2.5–5 mg/kg | PO | Once | Symptomatic-patient loading alternative; follow a separately selected maintenance schedule, not every listed course. |
| Alternative divided daily anticoagulant course | 1.5–2.5 mg/kg | PO | Every 12 h | Derived from 3–5 mg/kg TOTAL PER DAY divided into two equal doses. First-generation course about 14 days; second-generation or unknown compounds at least 30 days; duration guided by PT after stopping. |
Birds
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anticoagulant toxicosis | 2.5–5 mg/kg | PO, SC, IM | Every 24 h | Up to 28 days; Listed course 14–28 days; oral or suitable SC administration avoids IM hematoma in coagulopathy. |
| Anticipated perioperative hemorrhage | 2.5–5 mg/kg | IM | Equivalent to 0.25–0.5 mL/kg of the 10 mg/mL injection; repeat timing is not specified. Assess IM bleeding risk. | |
| Alternative hemorrhagic disorder regimen | 0.2–2.5 mg/kg | IM | As needed | Usually only 1–2 injections are described; may also be used with amprolium or sulfa treatment when indicated. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Vitamin K antagonist coagulopathy | 0.5–2.5 mg/kg | SC, IM | No repeat interval is specified for this amount. Includes calves under cattle; determine schedule from coagulation response. | |
| Sweet-clover or lespedeza coagulopathy | 1–1.5 mg/kg | SC | Described for several days without a defined repeat interval. Remove the offending feed and avoid stress or injury. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Vitamin K antagonist coagulopathy | 0.5–2.5 mg/kg | SC, IM | No repeat interval is specified for this amount. Includes calves under cattle; determine schedule from coagulation response. | |
| Anticoagulant toxicosis fixed regimen | 500 mg/animal | SC | Every 4–6 h | Until one-stage prothrombin time returns to control. Blood/plasma may be needed initially; alternative to weight-based courses. |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Vitamin K antagonist coagulopathy | 0.5–2.5 mg/kg | SC, IM | No repeat interval is specified for this amount. Includes calves under cattle; determine schedule from coagulation response. |
Goats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Vitamin K antagonist coagulopathy | 0.5–2.5 mg/kg | SC, IM | No repeat interval is specified for this amount. Includes calves under cattle; determine schedule from coagulation response. |
Rabbits
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anticoagulant toxicosis oral loading — Loading | 2.5–5 mg/kg | PO | Once | Small-mammal empirical protocol; severely affected patients may need blood products. |
| Divided anticoagulant maintenance — Maintenance | 1.5–2.5 mg/kg | PO | Every 12 h | Per administration after dividing 3–5 mg/kg/day into two equal doses. First-generation course approximately 14 days; second-generation or unknown at least 30 days, with post-treatment coagulation testing. |
| Alternative divided 5 mg/kg daily course | Reference only | PO | A TOTAL of 5 mg/kg/day can be divided every 8 or 12 hours using an appropriate oral preparation. Choose one division schedule; do not administer 5 mg/kg at every interval. |
Ferrets
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anticoagulant toxicosis oral loading — Loading | 2.5–5 mg/kg | PO | Once | Small-mammal empirical protocol; severely affected patients may need blood products. |
| Divided anticoagulant maintenance — Maintenance | 1.5–2.5 mg/kg | PO | Every 12 h | Per administration after dividing 3–5 mg/kg/day into two equal doses. First-generation course approximately 14 days; second-generation or unknown at least 30 days, with post-treatment coagulation testing. |
| Alternative divided 5 mg/kg daily course | Reference only | PO | A TOTAL of 5 mg/kg/day can be divided every 8 or 12 hours using an appropriate oral preparation. Choose one division schedule; do not administer 5 mg/kg at every interval. |
Pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Vitamin K antagonist coagulopathy | 0.5–2.5 mg/kg | IM | No repeat interval is specified; avoid routine IV administration. |
Indications
- Anticoagulant rodenticide toxicosis
- Sweet-clover anticoagulant coagulopathy
Contraindications
- Hypersensitivity
- Routine IV administration because of severe anaphylactoid risk
Interactions
- Cephalosporins and other medicines affecting vitamin K-dependent coagulation may alter response.
- Oral mineral oil can reduce vitamin K absorption.
Adverse effects
- Injection-site reactions
- IM hematoma in a coagulopathic patient
- Severe reaction with IV administration
Toxicity
Rapid IV exposure can cause life-threatening reactions. Do not substitute menadione (vitamin K3) for phytonadione.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Mephyton tablets 5 mg | Tablet | 5 mg / tablet | PO |
| Veta-K1 capsules 25 mg | Capsule | 25 mg / capsule | PO |
| Phytonadione injection 2 mg/mL Use a formulation suitable for the selected route. Protect from light; avoid routine IV administration. IM can cause hematoma in coagulopathy. | Injection | 2 mg / mL | SC, IM |
| Phytonadione injection 10 mg/mL Use a formulation suitable for the selected route. Protect from light; avoid routine IV administration. IM can cause hematoma in coagulopathy. | Injection | 10 mg / mL | SC, IM |
| Phytonadione chewable tablets 25 mg Vitamin K1, not menadione; verify species and excipients of the actual product. | Tablet | 25 mg / tablet | PO |
| Phytonadione chewable tablets 50 mg Vitamin K1, not menadione; verify species and excipients of the actual product. | Tablet | 50 mg / tablet | PO |
Monitoring and Administration
Give oral vitamin K1 with a fat-containing meal. Identify the anticoagulant where possible; duration depends on its persistence.
Check coagulation response, especially prothrombin time, and assess again after treatment is stopped. Severe active bleeding may also require plasma or blood products.
Prefer oral treatment when feasible; IM injection in active coagulopathy risks hematoma. Use an appropriate SC preparation when parenteral treatment is selected.
Protect from light; do not freeze. Only compatible diluents and formulation-specific instructions should be used for injections.
Oral or SC absorption may be unreliable in hypovolemia. New clotting-factor synthesis can take 6–12 hours, so vitamin K alone is insufficient for immediate control of major hemorrhage.
Recheck PT or an appropriate coagulation test about 48 hours after stopping treatment; some protocols specify 2–3 days. If prolonged, reinstitute the selected course and reassess after stopping again.
Historical cattle IV courses used 0.5–2.5 mg/kg with maximum administration rates of 5–10 mg/min; these remain non-routine rescue descriptions because the same sources warn against IV anaphylactoid reactions. Small-gauge needles reduce injection trauma.