Famotidina
Famotidine
3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N'-sulfamoylpropanimidamide
También conocido como: Pepcid AC · Pepcid RPD · famotidinum · L-643341 · MK-208 · YM-11170 · Famotidina
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 |
|---|---|---|---|---|---|
| To reduce gastric acid production | 0.1-0.2 mg/kg | PO, SC, IM, IV | q12h | — | 🌎 NA |
| To reduce gastric acid production | 0.5 mg/kg | PO, SC, IM, IV | q12-24h | — | 🌎 NA |
| For esophagitis | 0.5-1 mg/kg | PO | q12h | — | 🌎 NA |
| For acute reflex esophagitis | 0.55-1.1 mg/kg | PO | q24h (or q12h if severe) | 2-3 weeks | 🌎 NA |
| Adjunctive treatment (prevent/treat gastric ulcers) of mast cell tumors | 0.5 mg/kg | Not specified | q24h | — | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic kidney disease | 0.5 mg/kg | PO | q24h | — | 🌎 NA |
| All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions) | 0.5-1.0 mg/kg | PO | q12-24h | — | 🌍 EU |
- Adjunctive treatment of GI effects associated with chronic kidney disease: Effective evidence grade: 3
- All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions): Effect on gastric pH diminishes with time when given daily.
Gatos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| To reduce gastric acid production | 0.2 mg/kg | PO, SC, IM, IV | q24h | — | 🌎 NA |
| To reduce gastric acid production | 0.5 mg/kg | PO, SC, IM, IV | q12-24h | — | 🌎 NA |
| For esophagitis | 0.5 mg/kg | PO | q12h | — | 🌎 NA |
| For acute reflex esophagitis | 0.55-1.1 mg/kg | PO | q24h (or q12h if severe) | 2-3 weeks | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic progressive renal disease | 1 mg/kg | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic progressive renal disease | 0.5-1 mg/kg | PO | q12-24h | — | 🌎 NA |
| All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions) | 0.5-1.0 mg/kg | PO | q12-24h | — | 🌍 EU |
- To reduce gastric acid production: See warning about IV use in cats
- All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions): Effect on gastric pH diminishes with time when given daily.
Pequeños mamíferos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Rabbits: For stress induced ulcer prevention once critically ill animal has stabilized | 1 mg/kg | IV | q24h | — | 🌎 NA |
Hurones
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For stress induced ulcers | 0.25-0.5 mg/kg | PO, IV | q24h | — | 🌎 NA |
| In combination with antibiotics for Helicobacter treatment | 0.25-0.5 mg/kg | PO, IV | q24h | — | 🌎 NA |
Caballos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| As an adjunct in ulcer treatment | 0.23 mg/kg or 0.35 mg/kg | IV | q8h (for 0.23 mg/kg) or q12h (for 0.35 mg/kg) | — | 🌎 NA |
| As an adjunct in ulcer treatment | 1.88 mg/kg or 2.8 mg/kg | PO | q8h (for 1.88 mg/kg) or q12h (for 2.8 mg/kg) | — | 🌎 NA |
- As an adjunct in ulcer treatment: 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 famotidina es un antagonista potente y de acción prolongada de los receptores H2 de histamina, utilizado ampliamente en medicina veterinaria para suprimir la producción de ácido gástrico y tratar o prevenir úlceras gástricas/duodenales, gastritis y esofagitis.
En comparación con la cimetidina, la famotidina es significativamente más potente, requiere una dosificación menos frecuente y, fundamentalmente, no inhibe el sistema enzimático del citocromo P450 hepático, lo que la hace libre de muchas interacciones medicamentosas comunes.
Perla clínica: Aunque es eficaz para la supresión ácida leve o la profilaxis rutinaria, los inhibidores de la bomba de protones (IBP) como el omeprazol generalmente se consideran superiores para tratar úlceras activas, prevenir la gastritis inducida por el ejercicio o controlar la esofagitis grave. Además, la famotidina es propensa a la tolerancia farmacológica (taquifilaxia) dentro de los 3 a 14 días de uso continuo en perros y gatos, lo que disminuye su eficacia supresora de ácido con el tiempo.
Mecanismo de acción
Famotidine acts as a competitive, reversible antagonist at the H2 receptors located on the basolateral membrane of gastric parietal cells.
By blocking histamine binding, it prevents the activation of adenylate cyclase → decreases intracellular cAMP levels → reduces the activation of the H+/K+-ATPase proton pump. This effectively blunts both basal gastric acid secretion and secretion stimulated by food, pentagastrin, or insulin. By decreasing the total volume of gastric juice produced, H2-blockers also indirectly decrease the amount of pepsin secreted. It does not alter gastric emptying time, biliary secretion, or lower esophageal sphincter pressure.
Seguridad y advertencias
Contraindicaciones
- Known hypersensitivity to H2 blockers
- Known hypersensitivity to famotidine or other H2 receptor antagonists
Efectos adversos
- Bradycardia (if infused too rapidly IV)
- GI effects (anorexia, vomiting, diarrhea)
- Headache
- Dry mouth or skin
- Intravascular hemolysis (rare, anecdotally reported in cats given IV)
- Transient increase in serum gastrin (returns to baseline by 14 days)
- Generally has a very good safety profile with fewer side effects than cimetidine
Precauciones
Use cautiously in geriatric patients and those with significantly impaired hepatic or renal function; consider dosage reduction in patients with significant renal dysfunction. Famotidine may have negative inotropic effects and some cardioarrhythmogenic properties; use with caution in patients with cardiac disease. When administering IV to cats, infuse slowly (over 5 minutes) to minimize the rare risk of intravascular hemolysis.
Interacciones farmacológicas
Famotidine raises gastric pH, which may decrease the absorption of these agents. Administer the azole one hour prior to famotidine.
Famotidine may decrease the absorption of these cephalosporins. Taking with food may alleviate this effect.
Famotidine may decrease the absorption of oral iron. Administer iron at least one hour prior to famotidine.
Monitorización
- Clinical efficacy (decrease in symptomatology, endoscopic examination, resolution of blood in feces)
- Adverse effects
- Clinical signs of GI ulceration or bleeding (vomiting, melena, anorexia)
- Gastric pH (if clinically indicated and feasible)
Farmacocinética
Vida media
Absorción
Incompletely absorbed after oral administration with minimal first-pass metabolism. Systemic bioavailability is ~40-50% in humans. Bioavailability is low in horses (13%).
Distribución
Concentrates in the liver, pancreas, kidney, and submandibular gland (in rats). Only ~15-20% is bound to plasma proteins. Does not cross the blood-brain barrier or placenta in rats. Distributed into milk. Volume of distribution in horses is 4.28 L/kg.
Metabolismo
Primarily metabolized in the liver.
Eliminación
Excreted in the urine. After oral dosing, ~1/3 is excreted unchanged; after IV dosing, ~2/3 is excreted unchanged.
Sobredosis
Famotidine has a wide margin of safety. The minimum acute lethal dose in dogs is reported to be >2 grams/kg for oral doses and approximately 300 mg/kg for intravenous doses.
IV doses in dogs ranging from 5-200 mg/kg caused vomiting, restlessness, mucous membrane pallor, and redness of the mouth and ears. Higher doses caused hypotension, tachycardia, and collapse.
Most overdoses require only monitoring. In massive oral overdoses, gut-emptying protocols should be considered and supportive therapy initiated when warranted.
Productos disponibles
Formulaciones
- Oral tablets (plain, film-coated, chewable, orally disintegrating)
- Powder for oral suspension
- Injection
- 20 mg tablets
- 40 mg tablets
Etiquetado para humanos
- Famotidine Oral Tablets (plain, film-coated, chewable & orally disintegrating) & Gelcaps: 10 mg, 20 mg, & 40 mg (Pepcid®, Pepcid AC®, generic)
- Famotidine Powder for Oral Suspension: 8 mg/mL when reconstituted (Pepcid®)
- Famotidine Injection: 10 mg/mL in vials; 20 mg/50 mL premixed containers (generic)
- 20 mg tablets
- 40 mg tablets
Estado regulador
Human authorized product used off-label under the cascade. Cimetidine is the only H2 antagonist with veterinary authorization.
Human authorized product used off-label under the cascade (POM).
Sin datos reguladores para: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Tablets should be stored in well-closed, light-resistant containers at room temperature. Powder for oral suspension should be stored <40°C; after reconstitution, it is stable for 30 days when stored <30°C (do not freeze). Injection should be stored in the refrigerator (2-8°C).
Información para el cliente
- Administración: Administre este medicamento exactamente como lo recetó su veterinario. Para maximizar su efecto bloqueador de ácido, a menudo es mejor administrarlo con el estómago vacío, unos 30-60 minutos antes de una comida.
- Consistencia: No omita dosis. Los signos clínicos de reflujo ácido o úlceras pueden reaparecer si se omiten las dosis.
- Formulaciones líquidas: Si utiliza una suspensión líquida compuesta, agítela bien antes de cada uso y guárdela en el refrigerador. Deseche cualquier porción no utilizada después de 30 días.
- Interacciones: Informe a su veterinario sobre cualquier otro medicamento o suplemento que esté tomando su mascota. Si su mascota toma suplementos de hierro orales o ciertos medicamentos antimicóticos, deben administrarse con al menos una hora de diferencia de la famotidina.
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.