Warfarina Sódica
Warfarin Sodium
También conocido como: Coumadin · Jantoven · Panwarfin · sodium warfarin · warfarinum natricum
Revisado por el equipo veterinario de VetSheetActualizado 5 abr 2026Referencia veterinaria basada en la evidencia
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Dosis por especie
🌎 NA — North America🌍 EU — Europe
Perros
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Adjunctive maintenance therapy for venous thrombosis with or without pulmonary thromboembolism (PTE) | 0.22 mg/kg | PO | q12h | — | 🌎 NA |
| Adjunctive therapy of thromboemboli | 0.22 mg/kg | PO | q12h | — | 🌎 NA |
| Prophylactic use in patients with glomerular disease and severe proteinuria | 0.22 mg/kg | PO | once daily | — | 🌎 NA |
- Adjunctive maintenance therapy for venous thrombosis with or without pulmonary thromboembolism (PTE): Initially, then adjusted to achieve a PT prolongation of 1.25 to 1.5 times the pretreatment value.
- Adjunctive therapy of thromboemboli: Target dosage to prolong PT by 1.25-1.5 times the pretreatment value.
- Prophylactic use in patients with glomerular disease and severe proteinuria: Initially. Monitor PT and adjust dose so that PT is maintained at 1.5 times normal.
Gatos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Adjunctive maintenance therapy for venous thrombosis with or without pulmonary thromboembolism (PTE) | 0.5 mg (total dose per cat) | PO | once daily | — | 🌎 NA |
| Maintenance therapy for feline arterial thromboembolism | 0.06 to 0.09 mg/kg/day | PO | once daily | — | 🌎 NA |
| Long-term thromboprophylaxis | 0.06-0.09 mg/kg per day | PO | once daily | — | 🌎 NA |
| Adjunctive therapy of thromboembolism | 0.25-0.5 mg (total dose) per cat | PO | once daily | — | 🌎 NA |
| Cardiogenic arterial thromboembolism | 0.25-0.5 mg total dose per cat | PO | q24h | — | 🌎 NA |
- Adjunctive maintenance therapy for venous thrombosis with or without pulmonary thromboembolism (PTE): Initially, then adjusted to achieve a PT prolongation of 1.25 to 1.5 times the pretreatment value.
- Maintenance therapy for feline arterial thromboembolism: Heparinization is recommended during the first 5 to 7 days that warfarin is administered.
- Long-term thromboprophylaxis: Initially. Tablets should be crushed and mixed well due to unequal drug distribution. Overlap heparin and warfarin therapy by at least 4-5 days.
- Adjunctive therapy of thromboembolism: Initially. Adjust dosage to prolong PT to twice normal value, or INR to be between 2-3. Overlap therapy with heparin.
- Cardiogenic arterial thromboembolism: Heparin (150-250 Units/kg SC q8h) should be administered concurrently during the first 4-6 days. Target PT range is 1.3-1.6 times baseline, or INR 2.0-3.0.
Caballos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Adjunctive treatment of laminitis | 0.0198 mg/kg | PO | once daily | — | 🌎 NA |
| Anticoagulant | Initially, 0.018 mg/kg PO once daily and increase dose by 20% every day until baseline PT is doubled. Final dose rates may be from 0.012 mg/kg to 0.57 mg/kg daily. | PO | once daily | — | 🌎 NA |
- Adjunctive treatment of laminitis: Monitor OSPT (one-step prothrombin time) until prolonged 2-4 seconds beyond baseline.
- Anticoagulant: ARCI UCGFS Class 5 Drug.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
La warfarina es un anticoagulante derivado de la cumarina utilizado principalmente para el tratamiento o la prevención a largo plazo de afecciones trombóticas en pacientes veterinarios, como gatos, perros y caballos.
Debido a su estrecho índice terapéutico, el potencial de hemorragia potencialmente mortal y la necesidad de un control de la coagulación frecuente y costoso, su uso en medicina veterinaria es algo controvertido y a menudo se reserva para casos específicos donde otros anticoagulantes no son viables.
Perlas clínicas:
- La warfarina se administra como una mezcla racémica de enantiómeros S(+) y R(-), siendo el enantiómero S significativamente más potente.
- Debido a que solo inhibe la síntesis de nuevos factores de coagulación, existe un tiempo de latencia característico de 2-5 días antes de observar los efectos anticoagulantes completos, ya que los factores circulantes preexistentes deben degradarse primero.
- La warfarina es el ingrediente activo en muchos rodenticidas anticoagulantes de primera generación; la toxicidad se presenta de manera idéntica a una sobredosis clínica.
Mecanismo de acción
Warfarin acts as an indirect anticoagulant by antagonizing Vitamin K.
- It competitively inhibits the enzyme Vitamin K epoxide reductase (VKORC1).
- This inhibition prevents the conversion of inactive Vitamin K epoxide back into its active form (Vitamin K hydroquinone).
- Active Vitamin K is an essential cofactor for the γ-carboxylation (activation) of coagulation factors II, VII, IX, and X, as well as the endogenous anticoagulant proteins C and S.
- Pathway: VKORC1 inhibition → Depletion of active Vitamin K → Production of inactive, undercarboxylated clotting factors (PIVKA) → Prolonged clotting times and anticoagulation.
Seguridad y advertencias
Contraindicaciones
- Preexistent hemorrhagic tendencies or diseases
- Patients undergoing or contemplating eye or CNS surgery
- Major regional lumbar block anesthesia
- Surgery of large, open surfaces
- Active bleeding from the GI, respiratory, or GU tract
- Aneurysm
- Acute nephritis
- Cerebrovascular hemorrhage
- Blood dyscrasias
- Uncontrolled or malignant hypertension
- Hepatic insufficiency
- Pericardial effusion
- Pregnancy (Teratogenic - FDA Category X / Papich Class D)
- Visceral carcinomas
Efectos adversos
- Dose-related hemorrhage (primary adverse effect)
- Anemia
- Thrombocytopenia
- Weakness
- Hematomas and ecchymoses
- Epistaxis (nosebleeds)
- Hematemesis (vomiting blood)
- Hematuria (blood in urine)
- Melena (dark, tarry stools)
- Hematochezia (fresh blood in stools)
- Hemarthrosis (bleeding into joints)
- Hemothorax
- Intracranial hemorrhage
- Pericardial hemorrhage
- Death
Precauciones
Strict Monitoring Required: Warfarin has a narrow therapeutic index. Frequent monitoring of coagulation status (PT/INR) is mandatory to prevent fatal hemorrhage.
- Teratogenicity: Warfarin is embryotoxic and causes congenital malformations. It is strictly contraindicated in pregnancy. Low-dose heparin is preferred if anticoagulation is required during pregnancy.
- Nursing: Use with caution in nursing patients; prolonged prothrombin times have been reported in some breast-fed human infants.
- Dietary Changes: Sudden changes in diet (especially foods high in Vitamin K) can alter the efficacy of warfarin.
- Laboratory Interference: May cause falsely decreased theophylline values if using the Schack and Waxler ultraviolet method.
Interacciones farmacológicas
May increase anticoagulant response (via protein displacement or platelet inhibition); increases bleeding risk.
May increase anticoagulant response (often via inhibition of hepatic metabolism).
May increase anticoagulant response.
May increase anticoagulant response.
May increase anticoagulant response.
Increases anticoagulant response; often used concurrently during the initial overlap phase but requires careful monitoring.
May decrease anticoagulant response (via induction of hepatic metabolizing enzymes).
May decrease anticoagulant response.
Directly antagonizes warfarin, decreasing its anticoagulant response (used as an antidote for overdose).
Monitorización
- Prothrombin Time (PT) - Target usually 1.25 to 1.5x (or up to 2x) normal depending on protocol
- International Normalized Ratio (INR) - Target usually 2.0 to 3.0 (Note: not fully validated for veterinary patients)
- PIVKA (Proteins Induced by Vitamin K Antagonists) - May be more sensitive than PT
- Platelet counts and hematocrit (PCV)
- Occult blood in stool and urine
- Physical observations for bleeding (mucous membranes, bruising, epistaxis)
- Clinical efficacy (resolution/prevention of thromboembolism)
Farmacocinética
Vida media
Absorción
Rapidly and completely absorbed after oral administration in humans and cats.
Distribución
Highly bound to plasma proteins (approximately 99% in humans, >96% in cats). Wide species variation exists; horses have a higher free (unbound) fraction than rats, sheep, or swine. Only the free fraction is active. Does not enter milk in humans.
Metabolismo
Principally metabolized in the liver to inactive metabolites.
Eliminación
Metabolites are excreted in urine and bile (then reabsorbed and excreted in the urine).
Sobredosis
Acute overdosages of warfarin may result in life-threatening hemorrhage.
- Toxic Doses: In dogs and cats, single doses of 5-50 mg/kg have been associated with toxicity. Cumulative toxic doses are reported as 1-5 mg/kg for 5-15 days in dogs, and 1 mg/kg for 7 days in cats.
- Lag Time: A lag time of 2-5 days may occur before clinical signs of toxicity manifest. Animals must be monitored closely during this period.
- Treatment: If detected early, prevent absorption from the gut using standard decontamination protocols (emesis, activated charcoal). If clinical signs of bleeding are noted, treat with blood products (plasma/whole blood to replace active clotting factors) and Vitamin K1 (phytonadione).
Productos disponibles
Formulaciones
- Oral tablets
- Powder for injection (lyophilized)
Veterinario
- None (ARCI Class 5 substance for racing)
Etiquetado para humanos
- Warfarin Sodium Oral Tablets (scored): 1 mg, 2 mg, 2.5 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7.5 mg & 10 mg (Coumadin, Jantoven, generic)
- Warfarin Sodium Powder for Injection, lyophilized: 5.4 mg (2 mg/mL when reconstituted) preservative-free in 5 mg vials (Coumadin)
Estado regulador
Sin datos reguladores para: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Tablets should be stored in tight, light-resistant containers at temperatures less than 40°C, preferably at room temperature. Powder for injection should be protected from light and used immediately after reconstituting.
Información para el cliente
Advertencia crítica: La warfarina es un anticoagulante potente. Es absolutamente esencial seguir estrictamente el programa de dosificación prescrito. No omita dosis ni administre dosis adicionales sin consultar a su veterinario.
- Esté atento a hemorragias: Informe inmediatamente a su veterinario sobre cualquier signo de sangrado. Esto incluye encías pálidas, hematomas inusuales, hemorragias nasales, sangre en la orina o heces (que pueden verse negras y alquitranadas), vómitos con sangre, tos con sangre o debilidad/letargo repentinos.
- Prevenga traumatismos: Mantenga a las mascotas (especialmente a los gatos) en interiores y limite el juego brusco para minimizar el riesgo de lesiones traumáticas, que podrían provocar una hemorragia grave.
- Interacciones medicamentosas: No le dé a su mascota ningún medicamento nuevo, suplemento o fármaco de venta libre (especialmente aspirina u otros analgésicos) sin consultar a su veterinario, ya que muchos medicamentos interactúan peligrosamente con la warfarina.
- Dieta: Mantenga constante la dieta de su mascota, ya que los cambios repentinos en la alimentación (especialmente aquellos que contienen vitamina K) pueden alterar la forma en que funciona el medicamento.
La referencia de medicamentos de VetSheet está destinada a profesionales veterinarios autorizados como ayuda para la toma de decisiones clínicas, no como sustituto del criterio profesional ni del prospecto actual del fabricante.