Azatioprina
Azathioprine
Azathioprine / Azathioprine Sodium
También conocido como: Imuran · Azasan · Azathioprinum · BW-57322 · NSC-39084
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 |
|---|---|---|---|---|---|
| Inflammatory bowel disease | Initially 2 mg/kg PO once daily for 2 weeks, then tapered to 2 mg/kg PO every other day for 2-4 weeks, then 1 mg/kg PO every other day. | PO | q24h then tapered | Long-term | 🌎 NA |
| Immune-mediated anemia, colitis, immune-mediated skin disease, and acquired myasthenia gravis | 2 mg/kg PO once daily (q24h); long-term therapy 0.5-1 mg/kg PO every other day | PO | q24h then q48h | Long-term | 🌎 NA |
| Adjunctive therapy in myasthenia gravis in non-responsive patients | Initially, 1 mg/kg PO once daily. If neutrophil and platelet counts are normal after 2 weeks, dose is increased to 2 mg/kg PO once daily. | PO | q24h | Until clinical remission | 🌎 NA |
| Lymphoplasmacytic enteritis (if poor response to prednisolone) | 2 mg/kg PO once daily for 5 days, then on alternate days to prednisolone | PO | q24h then q48h | Long-term | 🌎 NA |
| Severe cases of immune-mediated hemolytic anemia (IMHA) | 2.2 mg/kg PO once daily (q24h) | PO | q24h | Long-term | 🌎 NA |
| Acute immune-mediated hemolytic anemia (IMHA) with glucocorticoids | 1-2 mg/kg PO once daily | PO | q24h | Long-term maintenance | 🌎 NA |
| Severe and refractory inflammatory bowel disease | 2.2 mg/kg PO once daily | PO | q24h | Long-term | 🌎 NA |
| Adjunctive treatment of ocular fibrous histiocytomas | 2 mg/kg PO daily for 2 weeks, reevaluate, and reduce to 1 mg/kg every other day for 2 weeks, then 1 mg/kg once weekly for 1 month | PO | Tapering schedule | 10 weeks | 🌎 NA |
| Prevention of rejection of MHCmatched renal allografts (with cyclosporine) | 1-5 mg/kg PO every other day | PO | q48h | Long-term | 🌎 NA |
| Perianal fistulas (anal furunculosis) | Initially 2 mg/kg PO once daily (q24h)... Then reduce to 2 mg/kg PO every other day (q48h) and continued for 12 weeks... After 12 weeks, reduce dose to 1 mg/kg PO every other day (q48h) | PO | Tapering schedule | 12 months | 🌎 NA |
| Glomerulonephritis | 2 mg/kg PO once daily | PO | q24h | Unspecified | 🌎 NA |
| Chronic hepatitis (to reduce inflammation) | 2.2 mg/kg PO once daily in combination with corticosteroids... Azathioprine dose is given every other day after 1-2 weeks. | PO | q24h then q48h | Long-term | 🌎 NA |
| Immune-mediated diseases (e.g., IMHA, polyarthritis) | 2 mg/kg p.o. q24h for a maximum of 2-3 weeks, then 0.5-2 mg/kg p.o. q48h | PO | q24h initially, then q48h | Max 2-3 weeks for initial q24h dosing, then maintenance | 🌍 EU |
- Inflammatory bowel disease: May take 2-6 weeks before beneficial effects are seen.
- Immune-mediated anemia, colitis, immune-mediated skin disease, and acquired myasthenia gravis: With prednisolone administered on the alternate days.
- Adjunctive therapy in myasthenia gravis in non-responsive patients: Taper to every other day when clinical remission occurs. Discontinue if WBC <4,000 cells/mcL or neutrophils <1,000 cells/mcL.
- Severe cases of immune-mediated hemolytic anemia (IMHA): In addition to prednisone. Tapered gradually.
- Acute immune-mediated hemolytic anemia (IMHA) with glucocorticoids: Used for long-term maintenance as steroid side effects become intolerable.
- Severe and refractory inflammatory bowel disease: A lag time of 3-5 weeks is expected before clinical improvement is noted.
- Perianal fistulas (anal furunculosis): Dose reduced based on clinical response or myelosuppression markers.
- Glomerulonephritis: Immunosuppressive treatment is controversial.
- Immune-mediated diseases (e.g., IMHA, polyarthritis): Often used in conjunction with corticosteroids. Clinical response may take up to 6 weeks.
Gatos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Severe and refractory inflammatory bowel disease | 0.3 mg/kg PO once every other day | PO | q48h | Long-term | 🌎 NA |
| Immune-mediated diseases | Not recommended | PO | Not recommended | Not recommended | 🌍 EU |
- Severe and refractory inflammatory bowel disease: Must be used with extreme caution due to myelotoxicity. May take 3-5 weeks for beneficial effects.
- Immune-mediated diseases: Cats often develop severe, non-responsive fatal leucopenia and thrombocytopenia.
Hurones
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Inflammatory bowel disease | 0.9 mg/kg PO q24-72h | PO | q24-72h | Unspecified | 🌎 NA |
- Inflammatory bowel disease: Used alongside prednisone and dietary management.
Caballos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Immunosuppressive | 3 mg/kg PO q24h | PO | q24h | Unspecified | 🌎 NA |
| Autoimmune skin diseases (e.g., pemphigus foliaceous) | 13 mg/kg PO q24h for 1 month, then every other day (q48h) | PO | q24h then q48h | Long-term | 🌎 NA |
- Immunosuppressive: Appears to be a relatively safe immunosuppressive treatment in the horse.
- Autoimmune skin diseases (e.g., pemphigus foliaceous): Used as a steroid-sparing drug. May cause thrombocytopenia.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
Azatioprina es un potente agente inmunosupresor antagonista de las purinas ampliamente utilizado en medicina veterinaria, principalmente en perros, para tratar una variedad de enfermedades inmunomediadas y autoinmunes (p. ej., anemia hemolítica inmunomediada [IMHA], enfermedad inflamatoria intestinal [IBD], miastenia gravis y pénfigo).
Perlas clínicas clave:
- Efecto ahorrador de esteroides: Se administra frecuentemente junto con corticosteroides (como prednisona o prednisolona). Esta combinación permite una reducción gradual de la dosis de corticosteroides, minimizando los efectos adversos a largo plazo de los esteroides mientras se mantiene la remisión de la enfermedad.
- Inicio de acción retardado: La azatioprina no es de acción rápida. Por lo general, requiere de 2 a 6 semanas para lograr una eficacia clínica inmunosupresora completa. Por lo tanto, no es adecuada como agente único para crisis autoinmunes agudas que amenacen la vida.
- Sensibilidad de especie: Los gatos son extremadamente sensibles a la supresión de la médula ósea inducida por azatioprina debido a los niveles naturalmente bajos de la enzima tiopurina metiltransferasa (TPMT). Su uso en felinos es altamente controvertido y generalmente se evita.
- Riesgos de toxicidad: El efecto adverso más significativo es la mielosupresión (leucopenia, anemia, trombocitopenia). La hepatotoxicidad y la pancreatitis aguda también son riesgos notables en perros.
Mecanismo de acción
Azathioprine is a prodrug that must be metabolized to exert its effects.
- Pathway: Azathioprine is rapidly converted in the body (primarily in erythrocytes and the liver) to 6-mercaptopurine (6-MP).
- 6-MP is further metabolized into active thioguanine nucleotides (TGNs).
- Mechanism: These active metabolites act as purine antagonists. They are falsely incorporated into cellular DNA and RNA, which inhibits purine metabolism, RNA/DNA synthesis, and cellular mitosis.
- Immunological Effect: Because lymphocytes (T-cells and B-cells) lack a salvage pathway for purine synthesis and rely heavily on de novo synthesis, they are profoundly affected. This leads to a marked suppression of delayed hypersensitivity and cellular immunity, with a lesser effect on humoral antibody responses.
Seguridad y advertencias
Contraindicaciones
- Known hypersensitivity to azathioprine
- Cats (generally contraindicated due to severe, potentially fatal myelotoxicity)
Efectos adversos
- Bone marrow suppression (leukopenia, anemia, thrombocytopenia)
- Gastrointestinal distress (vomiting, diarrhea, anorexia)
- Acute pancreatitis
- Hepatotoxicity
- Poor hair growth
- Increased susceptibility to secondary infections
- Increased risk of neoplastic illnesses with long-term use
Precauciones
Black Box Warning Equivalent: Azathioprine is a known mutagen and teratogen. Pregnant women or those trying to conceive should avoid handling this medication. If handling is necessary, strict use of protective gloves is required.
- Hepatic Dysfunction: Use with extreme caution in patients with pre-existing liver disease, as hepatotoxicity is a known adverse effect.
- Thiopurine Methyltransferase (TPMT) Deficiency: Dogs have variable TPMT activity (similar to humans). Dogs with low TPMT activity are at a significantly higher risk for severe bone marrow suppression.
- Tapering: In recovering patients (e.g., IMHA), withdrawal of the drug must be tapered very slowly over several months. Rapid withdrawal can trigger a rebound hyperimmune response and fatal relapse.
- Pregnancy/Nursing: FDA Category D (human). Distributed into milk; use milk replacer if the dam is treated.
Interacciones farmacológicas
Increased potential for hematologic toxicity
Decreases hepatic metabolism of azathioprine; significantly increases toxicity risk. Dose of azathioprine must be reduced to 1/4 to 1/3 of the usual dose if used concurrently.
Increased risk for azathioprine toxicity
Neuromuscular blocking activity may be inhibited or reversed by azathioprine
Often used together intentionally, but carries a greater potential risk for overall toxicity development
Increased potential for hematologic toxicity (additive bone marrow suppression)
Potential for reduced anticoagulant effect
Increased risk of azathioprine toxicity.
May increase the potential for haematological adverse events (e.g., severe anaemia or leucopenia).
Monitorización
- Hemograms (CBC including platelets): Monitor closely; initially every 1-2 weeks, then every 1-2 months on maintenance therapy. Reduce dose by 25% if WBC drops to 5,000-7,000 cells/mcL. Discontinue if WBC < 5,000 cells/mcL until resolved.
- Liver function tests (ALT, AST, ALP, Bilirubin)
- Serum amylase/lipase (if pancreatitis is suspected)
- Clinical efficacy and signs of secondary infection
Farmacocinética
Absorción
Poorly absorbed from the gastrointestinal tract.
Distribución
Rapidly taken up by lymphocytes and erythrocytes. Distributed into milk.
Metabolismo
Rapidly metabolized to mercaptopurine (6-MP). Mercaptopurine is further metabolized to several other compounds via pathways including thiopurine methyltransferase (TPMT). Cats have naturally low TPMT activity, making them highly susceptible to toxicity.
Eliminación
Metabolites are excreted primarily by the kidneys. Only minimal amounts of azathioprine or mercaptopurine are excreted unchanged.
Sobredosis
There is limited specific information regarding acute overdose of azathioprine in veterinary patients.
- Decontamination: If ingestion was recent, use standard protocols to empty the GI tract (emesis induction, activated charcoal).
- Treatment: Provide aggressive supportive care. Monitor hematologic parameters closely for delayed bone marrow suppression.
- Consultation: Contact an animal poison control center for the most up-to-date guidance.
Productos disponibles
Formulaciones
- Tablets
- Injection (powder for reconstitution)
- Compounded oral suspension
Etiquetado para humanos
- Azathioprine Tablets: 50 mg, 75 mg & 100 mg (Azasan®, Imuran®, generic)
- Azathioprine Sodium Injection: 100 mg (as sodium)/vial in 20 mL vials (generic)
Estado regulador
POM (Prescription Only Medicine). Handled under cascade using human formulations.
POM-V / POM. Handled under the prescribing cascade.
Sin datos reguladores para: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Tablets should be stored at room temperature in well-closed containers and protected from light. Sodium powder for injection should be stored at room temperature and protected from light; after reconstitution, it must be used within 24 hours as it contains no preservatives. Compounded oral suspensions have optimal stability between pH 5.5 and 6.5 and should be protected from light.
Información para el cliente
Información importante para los propietarios de mascotas:
- La paciencia es clave: Este medicamento tarda en hacer efecto. Pueden pasar varias semanas antes de que note una mejoría en la condición de su mascota. No deje de administrar el medicamento sin consultar a su veterinario.
- Seguridad y manipulación: La azatioprina es un fármaco potente que puede afectar el ADN humano. Lávese bien las manos después de manipular las tabletas. Si está embarazada, intentando quedar embarazada o amamantando, no manipule este medicamento o use guantes protectores si es estrictamente necesario.
- Esté atento a los efectos secundarios: Debido a que este fármaco suprime el sistema inmunológico y puede afectar la médula ósea, su mascota tiene un mayor riesgo de infecciones y sangrado.
- Cuándo llamar al veterinario: Contacte a su veterinario inmediatamente si su mascota muestra signos de sangrado anormal, hematomas inexplicables, encías pálidas, fiebre, pérdida de apetito, vómitos, diarrea o letargo.
- Monitoreo estricto: Su mascota necesitará análisis de sangre frecuentes (especialmente en los primeros meses) para asegurar que el fármaco no esté dañando su médula ósea o hígado. Asista a todas las citas de control programadas.
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.