Tolazolina
Tolazoline
Tolazoline hydrochloride
También conocido como: Tolazine · Priscoline · Vaso-Dilatan · benzazoline hydrochloride · tolazolinium chloratum
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 |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second | IV | once | — | 🌎 NA |
- For reversal of xylazine effects: High concentration (100 mg/mL) makes accurate dosing difficult; yohimbine or human-labeled tolazoline (25 mg/mL) may be safer alternatives. Not FDA-approved for dogs.
Gatos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second | IV | once | — | 🌎 NA |
- For reversal of xylazine effects: High concentration (100 mg/mL) makes accurate dosing difficult; yohimbine or human-labeled tolazoline (25 mg/mL) may be safer alternatives. Not FDA-approved for cats.
Aves
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| As a reversal agent for alpha2-adrenergic agonists (e.g., xylazine, detomidine, etc.) | 15 mg/kg IV | IV | once | — | 🌎 NA |
Caballos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second | IV | once | — | 🌎 NA |
- For reversal of xylazine effects: FDA-approved for use in horses.
Ganado
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 2-4 mg/kg slow IV ; titrate to effect | IV | once | — | 🌎 NA |
| For reversal of xylazine effects (Emergency) | 2 mg/kg IM | IM | once | — | 🌎 NA |
- For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.
- For reversal of xylazine effects (Emergency): Should not be administered IV rapidly as this can result in cardiac asystole. Effects of reversal should start to become evident about 10 minutes following IM administration.
Ovejas
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 2-4 mg/kg slow IV ; titrate to effect | IV | once | — | 🌎 NA |
| For reversal of xylazine effects | 1-2 mg /kg IM. Give 50% of initial dose slow IV or IM and then determine if more is needed. | IM/IV | once | — | 🌎 NA |
- For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.
Cabras
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| For reversal of xylazine effects | 2-4 mg/kg slow IV ; titrate to effect | IV | once | — | 🌎 NA |
| For reversal of xylazine effects | 1-2 mg /kg IM. Give 50% of initial dose slow IV or IM and then determine if more is needed. | IM/IV | once | — | 🌎 NA |
- For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
La tolazolina es un antagonista alfa-adrenérgico competitivo no selectivo utilizado principalmente en medicina veterinaria para revertir los efectos sedantes, analgésicos y cardiovasculares de la xylazine, particularmente en la práctica equina y de rumiantes.
- Perla clínica: Aunque es altamente efectiva para revertir la xylazine, la tolazolina generalmente se considera menos específica y menos efectiva para los α2-agonistas más nuevos y altamente selectivos como la dexmedetomidina o la detomidina (donde el atipamezol es el agente de reversión preferido).
- Debido a que bloquea tanto los receptores α1 como los α2 y posee propiedades vasodilatadoras directas, sus efectos cardiovasculares pueden ser complejos y a veces impredecibles, lo que requiere una administración lenta y cuidadosa.
Mecanismo de acción
Tolazoline acts as a competitive antagonist at both α1- and α2-adrenergic receptors.
- Central & Peripheral α2 Blockade → Reverses the sedation, analgesia, and bradycardia induced by α2-agonists (like xylazine).
- Direct Smooth Muscle Relaxation → Exerts a direct relaxant effect on vascular smooth muscle → peripheral vasodilation → decreases total peripheral resistance.
- Onset: Rapid acting (usually within 5 minutes of IV administration), but has a short duration of action, meaning repeat doses may occasionally be required if re-sedation occurs.
Seguridad y advertencias
Contraindicaciones
- Horses exhibiting signs of stress, debilitation, or shock
- Cardiac disease or coronary artery disease
- Sympathetic blockage
- Hypovolemia
- Cerebrovascular disease
- Known hypersensitivity to the drug
- Foals (relative contraindication; adverse reactions and fatalities reported)
Efectos adversos
- Transient tachycardia
- Peripheral vasodilation (sweating, injected mucous membranes of gingiva and conjunctiva)
- Hyperalgesia of the lips (licking, flipping of lips)
- Piloerection
- Clear lacrimal and nasal discharge
- Muscle fasciculations
- Apprehensiveness and anxiety
- Gastrointestinal hypermotility (flatulence, diarrhea, mild colic)
Precauciones
WARNING: Rapid IV Administration Acute death and cardiac asystole have been reported after rapid IV administration of tolazoline at high dosages, particularly in camelids and cattle. Always administer IV slowly (e.g., 1 mL/second) or consider the IM route.
- High Concentration Risk: The veterinary formulation is highly concentrated (100 mg/mL), making accurate dosing difficult in small animals (dogs/cats). Yohimbine or atipamezole are generally safer alternatives for small animals.
- Human Safety: Humans with coronary artery or cerebrovascular disease should use extra caution when handling this agent.
Interacciones farmacológicas
Accumulation of acetaldehyde can occur if tolazoline and alcohol are given simultaneously.
If large doses of tolazoline are given with epinephrine, a paradoxical drop in blood pressure can occur followed by a precipitous increase in blood pressure.
If large doses of tolazoline are given with norepinephrine, a paradoxical drop in blood pressure can occur followed by a precipitous increase in blood pressure.
Monitorización
- Reversal effects (efficacy of waking up/recovery)
- Heart rate and rhythm
- Blood pressure
- Adverse effects (sweating, GI hypermotility, anxiety)
Farmacocinética
Vida media
Absorción
Rapid acting after IV administration (usually within 5 minutes).
Distribución
Widely distributed. Animal studies have demonstrated that tolazoline is concentrated in the liver and kidneys.
Sobredosis
Overdoses can cause severe cardiovascular and gastrointestinal disturbances.
- Horses (5X overdose): Gastrointestinal hypermotility resulting in flatulence, defecation, mild colic, and transient diarrhea. Intraventricular conduction may be slowed (prolongation of the QRS-complex). Ventricular arrhythmias and death may occur at higher overdoses.
- Camelids (5X overdose in a llama): Anxiety, hyperesthesia, profuse salivation, GI tract hypermotility, diarrhea, convulsions, hypotension, and tachypnea. Successfully treated with IV diazepam, phenylephrine, IV fluids, and oxygen.
- Human Treatment Note: Ephedrine (NOT epinephrine or norepinephrine) has been recommended to treat serious tolazoline-induced hypotension.
Productos disponibles
Formulaciones
- Injection: 100 mg/mL (Veterinary)
- Injection: 25 mg/mL (Human-labeled, historically)
Veterinario
- Tolazoline HCl Injection: 100 mg/mL in 100 mL multi-dose vials (Tolazine®)
Estado regulador
Sin datos reguladores para: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Commercially available injection products should be stored between 15-30°C and protected from light. Reportedly physically compatible with commonly used IV solutions.
Información para el cliente
La tolazolina es un medicamento administrado exclusivamente por profesionales veterinarios para "despertar" (revertir la sedación) a su animal después de un procedimiento o examen.
- Qué esperar: A medida que su animal despierte, es posible que note efectos secundarios temporales como sudoración, chasquidos o lamido de labios, ansiedad o espasmos musculares.
- Duración: Estos efectos son generalmente leves y deberían disminuir y desaparecer dentro de las 2 horas posteriores a la administración.
- Seguridad: Debido a los cambios rápidos en la frecuencia cardíaca y la presión arterial que pueden ocurrir, su animal será monitoreado de cerca por el equipo veterinario durante el período de recuperación.
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.