Metazolamida
Methazolamide
N-(4-methyl-2-sulfamoyl-Δ2-1,3,4-thiadiazolin-5-ylidene)acetamide
También conocido como: Neptazane · GlaucTabs · Glaumetax · MZM · Methazolamidum
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 |
|---|---|---|---|---|---|
| Medical treatment of glaucoma | 2.5-5 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 NA |
| Medical treatment of glaucoma | 2-4 mg/kg PO two to three times a day | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 3-5 mg/kg divided q12h PO | PO | q12h | — | 🌎 NA |
| Medical treatment of glaucoma | 2-5 mg/kg PO two to three times a day | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 2.2-4.4 mg/kg PO two to three times a day. | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 2-10 mg/kg PO two to three times a day. | PO | two to three times a day | — | 🌎 NA |
Gatos
| Indicación | Dosis | Vía | Frecuencia | Duración | Región |
|---|---|---|---|---|---|
| Medical treatment of glaucoma | 3-4 mg/kg PO twice a day. | PO | twice a day | — | 🌎 NA |
| Medical treatment of glaucoma | 1-2 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 NA |
- Medical treatment of glaucoma: Cats may not tolerate oral carbonic anhydrase inhibitors (CAIs) as well as dogs. Reported side effects include lethargy, inappetence, vomiting. Topical CAIs may be better tolerated.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
Metazolamida es un inhibidor de la anhidrasa carbónica (IAC) de administración oral utilizado principalmente en medicina veterinaria para el manejo médico del glaucoma de ángulo abierto.
Históricamente, los IAC sistémicos como la metazolamida fueron el pilar para reducir la presión intraocular (PIO), pero han sido desplazados en gran medida por formulaciones tópicas (p. ej., dorzolamida, brinzolamida). Los agentes tópicos ofrecen una reducción de la PIO comparable con una incidencia significativamente menor de efectos adversos sistémicos.
Puntos clínicos clave:
- Efectos sistémicos: Debido a que se administra por vía oral, la metazolamida afecta a la anhidrasa carbónica en todo el cuerpo, lo que puede provocar acidosis metabólica y desequilibrios electrolíticos (especialmente hipopotasemia).
- Utilidad clínica: Por lo general, se reserva para casos de glaucoma refractarios a terapias tópicas o cuando la administración tópica no es factible.
- Sensibilidad de especie: Los gatos son particularmente sensibles a los efectos adversos de los IAC orales y pueden presentar letargo profundo y anorexia.
Mecanismo de acción
Methazolamide acts via noncompetitive, reversible inhibition of the enzyme carbonic anhydrase (CA), specifically the CA-II isoenzyme.
- In the Eye (Ciliary Body): Inhibition of CA → reduces the formation of hydrogen (H+) and bicarbonate (HCO3-) ions from carbon dioxide and water → decreases the availability of these ions for active transport into the posterior chamber → decreased aqueous humor production → reduced intraocular pressure (IOP).
- In the Kidneys (Proximal Tubule): Inhibition of CA → increased renal tubular secretion of sodium (Na+), potassium (K+), and bicarbonate (HCO3-) → increased urine alkalinity and volume, often resulting in a mild hyperchloremic metabolic acidosis.
- In the CNS: Exhibits anticonvulsant activity independent of its diuretic effects, potentially due to localized CA inhibition in the brain or secondary to systemic metabolic acidosis.
Seguridad y advertencias
Contraindicaciones
- Significant hepatic disease (may precipitate hepatic coma)
- Renal or adrenocortical insufficiency
- Hyponatremia or hypokalemia
- Hyperchloremic acidosis or severe electrolyte imbalance
- Severe pulmonary obstruction (inability to increase alveolar ventilation to compensate for metabolic acidosis)
- Hypersensitivity to carbonic anhydrase inhibitors or sulfonamides
- Chronic, noncongestive, angle-closure glaucoma (long-term use may mask the condition by lowering IOP while angle closure progresses)
Efectos adversos
- GI disturbances (vomiting, diarrhea, inappetence)
- Metabolic acidosis (often manifesting as heavy panting in dogs)
- CNS effects (sedation, depression, disorientation, excitement)
- Hematologic effects (bone marrow depression, thrombocytopenia)
- Renal effects (crystalluria, dysuria, renal colic, polyuria, polydipsia)
- Hypokalemia
- Hyperglycemia
- Hyponatremia
- Hyperuricemia
- Hepatic insufficiency
- Dermatologic effects (rash)
- Hypersensitivity reactions
- Weakness or cardiac arrhythmias (secondary to electrolyte imbalances)
Precauciones
Laboratory Interferences: By alkalinizing the urine, carbonic anhydrase inhibitors may cause false-positive results in determining urine protein using bromphenol blue reagent, sulfosalicylic acid, nitric acid ring test, or heat and acetic acid test methods. They may also decrease iodine uptake by the thyroid gland in hyperthyroid or euthyroid patients.
- Use with caution in pregnant animals (FDA Category C in humans; animal studies show adverse fetal effects).
- Combining oral methazolamide with topical dorzolamide does not yield additive reductions in IOP and may increase adverse effects.
- Monitor closely for signs of hypokalemia and metabolic acidosis, especially in cats.
Interacciones farmacológicas
Alkaline urine caused by methazolamide may decrease excretion of tricyclic antidepressants.
Increased risk of methazolamide accumulation and toxicity; increased risk for metabolic acidosis; methazolamide increases salicylate excretion.
Methazolamide may cause hypokalemia, leading to an increased risk for digoxin toxicity.
Rarely, carbonic anhydrase inhibitors may interfere with the hypoglycemic effects of insulin.
Methazolamide alkalinizes urine, which may negate the urinary antiseptic effects of methenamine.
Concomitant use may exacerbate potassium depletion and hypokalemia.
Increased urinary excretion due to alkaline urine, which may reduce phenobarbital serum levels.
May result in decreased primidone concentrations.
Alkaline urine caused by methazolamide may decrease quinidine excretion.
Monitorización
- Intraocular pressure (IOP) / tonometry
- Serum electrolytes (especially potassium and sodium)
- Blood pH / acid-base status
- Baseline CBC with differential, and periodic retests if using chronically
- Clinical signs of adverse effects (lethargy, GI upset, heavy panting)
Farmacocinética
Absorción
Absorbed from the GI tract, albeit more slowly than acetazolamide.
Distribución
Distributed throughout the body, including the cerebrospinal fluid (CSF) and aqueous humor.
Metabolismo
At least partially metabolized in the liver.
Eliminación
Excreted primarily via the kidneys, leading to increased urine alkalinity.
Sobredosis
Information regarding acute overdosage of methazolamide in veterinary species is limited.
Clinical Signs: Expected signs of toxicity include severe electrolyte imbalances (hypokalemia, hyponatremia), profound metabolic acidosis, CNS depression or disorientation, and dehydration secondary to diuresis.
Management:
- Monitor serum electrolytes, blood gases (for acidosis), volume status, and CNS status.
- Treat symptomatically and supportively.
- Administer intravenous fluids to correct dehydration and electrolyte deficits (especially potassium supplementation if indicated).
- Correct severe metabolic acidosis with sodium bicarbonate if necessary, based on blood gas analysis.
Productos disponibles
Formulaciones
- Tablets
Etiquetado para humanos
- Methazolamide Tablets: 25 mg & 50 mg (generic, Rx)
Estado regulador
Sin datos reguladores para: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
Methazolamide tablets should be stored at room temperature in well-closed containers. Tablets typically have an expiration date of 5 years after manufacture.
Información para el cliente
Entendiendo el medicamento: La metazolamida se utiliza para disminuir la presión dentro del ojo (o los ojos) de su mascota causada por el glaucoma. Funciona reduciendo la cantidad de líquido que produce el ojo.
Administración:
- Administrar con comida: Si este medicamento causa malestar estomacal (vómitos o pérdida de apetito), administrarlo con una comida puede ayudar.
- No triturar ni masticar a menos que su veterinario indique lo contrario.
Qué observar:
- Jadeo intenso: Este fármaco puede causar un cambio leve en la acidez de la sangre (acidosis metabólica), que los perros a menudo intentan corregir jadeando intensamente. Contacte a su veterinario si esto parece excesivo.
- Letargo y esconderse: Los gatos son especialmente sensibles a este medicamento y pueden volverse muy apáticos o dejar de comer.
- Aumento de la sed y la micción: Puede notar que su mascota bebe y orina más de lo habitual.
- Busque atención veterinaria inmediata si nota sangrado o hematomas anormales, debilidad severa, temblores musculares o erupciones cutáneas.
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.