Morfina
Morphine
Morphine sulfate
También conocido como: Astramorph PF · Avinza · DepoDur · Infumorph · Kadian · MSIR · MS Contin · Oramorph SR · RMS · Roxanol · Morphini sulfas · Morphine sulfate · Morphine hydrochloride
Revisado por el equipo veterinario de VetSheetActualizado 5 abr 2026Referencia veterinaria basada en la evidencia
Evidencia posológica v13 auditada
Evidencia estructurada para el cálculoAnalgesia (extra-label) — CRI dosing
Requiere verificación veterinaria
NA
Contexto clínico obligatorio (5)
- 1. Preservative-free morphine formulations should be used for epidural administration.
- 2. Do not confuse CRI dosages listed as mg/kg/hour with those listed as µg/kg/minute.
- 3. For additional dosages/protocols for using morphine in combination with other drugs (eg, ketamine, lidocaine, dexmedetomidine) for pain/sedation in dogs or cats, see the dosages and their accompanying references in the Dexmedetomidine, Ketamine, and Lidocaine monographs.
- Analgesia (extra-label):
- Morphine injection should be stored at room temperature (20°C-25°F [68°F-77°F]), protected from light; do not freeze. 19 Morphine gradually darkens in color when exposed to light. Morphine does not appear to adsorb to plastic or polyvinyl chloride (PVC) syringes, tubing, or bags.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
La morfina es el analgésico opiáceo prototípico utilizado en medicina veterinaria para el tratamiento del dolor agudo de moderado a severo. Es un agonista puro de los receptores mu-opioides de origen natural derivado del opio.
Perlas clínicas y diferencias entre especies:
- Perros y primates: La morfina típicamente causa depresión del SNC, sedación y analgesia predecibles. Es un emético potente en perros debido a la estimulación directa de la zona gatillo quimiorreceptora (CTZ). Los perros a menudo defecan inmediatamente después de una dosis inicial, seguido de una disminución de la motilidad gastrointestinal.
- Gatos, caballos y rumiantes: Estas especies pueden exhibir excitación del SNC paradójica (disforia, manía, caminar en círculos) en lugar de depresión, especialmente si se administra sin un sedante o tranquilizante concurrente (como acepromacina o un agonista alfa-2). Los gatos requieren dosis significativamente más altas que los perros para inducir el vómito.
- Liberación de histamina: La morfina causa la liberación de histamina no inmunológica de los mastocitos. La administración intravenosa debe realizarse lentamente para evitar hipotensión severa, vasodilatación y broncoconstricción.
- Termorregulación: La morfina puede causar hipotermia en perros y conejos, pero hipertermia en gatos, caballos, ganado vacuno y cabras.
Mecanismo de acción
Morphine acts primarily as a full agonist at the mu (μ) opioid receptors in the central nervous system, with some secondary activity at delta receptors.
- Mechanism: Binding to the G-protein coupled mu-receptor → inhibits adenylate cyclase → decreases intracellular cAMP.
- Presynaptic effect: Closes voltage-gated calcium channels → decreases the release of excitatory nociceptive neurotransmitters (e.g., Substance P, glutamate).
- Postsynaptic effect: Opens inward-rectifying potassium channels → hyperpolarizes the neuron → inhibits ascending pain transmission pathways.
- Secondary effects: Direct stimulation of the chemoreceptor trigger zone (CTZ) causes emesis. Central vagal stimulation leads to bradycardia. Increased anti-diuretic hormone (ADH) release can reduce urine production.
Seguridad y advertencias
Contraindicaciones
- Hypersensitivity to narcotic analgesics
- Patients receiving monoamine oxidase inhibitors (MAOIs)
- Diarrhea caused by a toxic ingestion (until toxin is eliminated)
- Scorpion envenomation (Centruroides spp. - potentiates venom)
- Conditions where vomiting is contraindicated (e.g., raised intraocular pressure)
Efectos adversos
- Histamine release (hypotension, vasodilation)
- Bronchoconstriction
- CNS depression (dogs, primates) or excitation (cats, horses, ruminants)
- Physical dependence (with chronic use)
- Hyperthermia (cattle, goats, horses, cats)
- Hypothermia (dogs, rabbits)
- Nausea and vomiting
- Decreased intestinal peristalsis and constipation
- Initial defecation (dogs)
- Panting (dogs)
- Bradycardia or tachycardia
- Histamine release (if given rapidly IV)
- Vomiting (common in non-painful pre-operative patients)
- Transient excitation (IV administration)
- Respiratory depression (especially under general anaesthesia)
- Constriction of gastrointestinal sphincters (e.g., pyloric sphincter)
- Reduction in gastrointestinal motility (with prolonged use)
- Neonatal sedation (crosses the placenta)
Precauciones
Extreme Caution: Patients with head injuries, increased intracranial pressure, acute abdominal conditions (e.g., colic - may mask clinical signs), and respiratory disease or acute respiratory dysfunction.
Caution: Hypothyroidism, severe renal insufficiency (acute uremia), adrenocortical insufficiency (Addison's), and geriatric or severely debilitated patients.
Important Notes:
- IV Administration: Must be given slowly to avoid significant hypotension and histamine release.
- Envenomation: Avoid in envenomation situations, as clinical signs associated with histamine-release can be confused with anaphylaxis.
- Uremia: Because of its effects on vasopressin (ADH), urine flow can decrease by up to 90% in dogs given large doses.
Interacciones farmacológicas
May cause increased CNS or respiratory depression when used with morphine.
Opiates may decrease diuretic efficacy in congestive heart failure patients.
Use with extreme caution; contraindicated in humans due to risk of severe opiate overdose signs.
Morphine may enhance neuromuscular blockade.
Morphine may exacerbate the effects of tricyclic antidepressants.
Opiates may potentiate anticoagulant activity.
Increased CNS or respiratory depression
Monitorización
- CNS level of depression or excitation
- Blood pressure (especially with IV use)
- Analgesic activity
- Respiratory rate and depth (especially under general anaesthesia)
- Pain scores (to assess individual efficacy)
- Signs of histamine release (hypotension, tachycardia) during IV administration
- Gastrointestinal motility
Farmacocinética
Vida media
Absorción
Absorbed when given by IV, IM, SC, and rectal routes. Very low oral bioavailability (<20%) in dogs due to a high first-pass effect, limiting the clinical usefulness of oral morphine in canines.
Distribución
Concentrates in the kidney, liver, and lungs; lower levels are found in the CNS. The majority of free morphine is found in skeletal muscle. Crosses the placenta and distributes into maternal milk. Volume of distribution in dogs is ~7.5 L/kg.
Metabolismo
Major route of elimination is by metabolism in the liver, primarily by glucuronidation. Cats are deficient in this metabolic pathway, leading to prolonged half-lives.
Eliminación
The active glucuronidated metabolite (M6G) is excreted by the kidney. Clearance in dogs is approximately 83 mL/min/kg.
Sobredosis
Signs of Toxicity: Overdosage may produce profound respiratory and/or CNS depression in most species. Newborns are more susceptible. Parenteral doses >100 mg/kg are thought to be fatal in dogs. Other toxic effects include cardiovascular collapse, hypothermia, and skeletal muscle hypotonia. Horses, cats, swine, and cattle may demonstrate CNS excitability (hyperreflexia, tremors) and seizures at high doses or if given rapidly intravenously.
Treatment:
- Naloxone is the agent of choice for treating respiratory depression. Doses may need to be repeated as naloxone's effects might diminish before sub-toxic levels of morphine are attained.
- Mechanical respiratory support should be considered in severe cases.
- Pentobarbital has been suggested for CNS excitement and seizures in cats, but extreme caution is required as barbiturates and narcotics have additive respiratory depressant effects.
Productos disponibles
Formulaciones
- Morphine Sulfate for Injection (1-50 mg/mL)
- Liposomal Extended-release Injection (10 mg/mL)
- Preservative-free Injection (0.5-25 mg/mL)
- Soluble Tablets for Injection
- Oral Tablets (15 mg, 30 mg)
- Extended/Controlled Release Tablets (15-200 mg)
- Extended/Sustained Release Capsules (20-200 mg)
- Oral Solution (2-20 mg/mL)
- Rectal Suppositories (5-30 mg)
- Injectable solution: 10 mg/ml, 15 mg/ml, 20 mg/ml, 30 mg/ml
- Oral tablets: 10 mg, 30 mg, 60 mg, 100 mg
- Oral suspensions
- Slow-release capsules
- Granules
Etiquetado para humanos
- Morphine Sulfate for Injection (1 mg/mL to 50 mg/mL)
- Morphine Sulfate Liposomal Extended-release Injection (DepoDur, 10 mg/mL)
- Morphine Sulfate for Injection, preservative-free (Infumorph, Astramorph PF, 0.5 mg/mL to 25 mg/mL)
- Morphine Sulfate Soluble Tablets for Injection (10 mg, 15 mg, 30 mg)
- Morphine Sulfate Oral Tablets (15 mg, 30 mg)
- Morphine Sulfate Extended/Controlled Release Tablets (MS Contin, Oramorph SR, 15 mg to 200 mg)
- Morphine Sulfate Extended/Sustained Release Capsules (Avinza, Kadian, 20 mg to 200 mg)
- Morphine Sulfate Oral Solution (MSIR, Roxanol, 2 mg/mL to 20 mg/mL)
- Morphine Sulfate Rectal Suppositories (RMS, 5 mg to 30 mg)
- Morphine sulfate injectable solutions
- Morphine sulfate tablets and slow-release capsules
- Morphine suppositories
Estado regulador
Methadone is the licensed alternative preferred for bolus administration.
Controlled Drug Schedule 2. Methadone is the licensed alternative.
Sin datos reguladores para: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Oral morphine products should be stored in tight, light-resistant containers at room temperature unless otherwise labeled. Morphine injection should be stored at room temperature, protected from light; do not freeze. Morphine gradually darkens in color when exposed to light; protect from prolonged exposure to bright light.
Información para el cliente
La morfina es un medicamento analgésico potente y altamente regulado que normalmente se administra en un entorno hospitalario bajo supervisión veterinaria directa.
- Qué esperar: Su mascota puede parecer sedada, somnolienta o inusualmente tranquila. Los perros a menudo jadean intensamente y pueden vomitar o defecar poco después de recibir el medicamento.
- Gatos y caballos: A veces pueden parecer inquietos, caminar de un lado a otro o tener los ojos muy abiertos en lugar de parecer somnolientos. Esta es una diferencia conocida entre especies.
- Cuidados en casa: Si su mascota es enviada a casa con morfina oral, manténgala estrictamente fuera del alcance de niños y otros animales. Es una sustancia altamente controlada (Lista II). No ajuste la dosis sin consultar a su veterinario.
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.