Fludrocortisone Acetate
Fludrocortisone acetate is a potent, orally administered **synthetic corticosteroid** primarily utilized in veterinary medicine for its profound **mineralocorticoid** properties. * **Primary Indication:** It is a mainstay treatment for **adrenocortical insufficiency (Addison's disease)** in dogs and cats, serving as an oral alternative to injectable desoxycorticosterone pivalate (DOCP). * **Dual Action:** While used for its mineralocorticoid effects (125 times more potent than hydrocortisone), it also possesses significant **glucocorticoid activity** (10-15 times that of hydrocortisone). * **Clinical Pearl:** Because of its inherent glucocorticoid activity, approximately 50% of dogs managed on fludrocortisone do not require additional daily prednisone/prednisolone supplementation, unlike those treated with DOCP. However, this same glucocorticoid activity can lead to iatrogenic hyperadrenocorticism signs (PU/PD, polyphagia) at higher doses.
Mecanismo: Fludrocortisone acts as a potent agonist at mineralocorticoid receptors. * Binds to **cytosolic mineralocorticoid receptors** in the principal cells of the **renal distal tubules** and **collecting ducts** → translocates to the nucleus. * Upregulates the transcription of **epithelial sodium channels (ENaC)** on the apical membrane and **Na+/K+-ATPase pumps** on the basolateral membrane. * This mechanism → promotes active **sodium reabsorption** (and obligate water retention) while accelerating the excretion of **potassium** and **hydrogen ions** into the tubular lumen. * Also binds to **glucocorticoid receptors**, contributing to anti-inflammatory and metabolic effects (gluconeogenesis, protein catabolism).
Dosificación por especie
- Maintenance therapy of hypoadrenocorticism · 0.02 mg/kg PO once daily · PO · once daily · Prednisone or prednisolone (1.25 mg per cat PO once daily) can be used for glucocorticoid replacement.
- Maintenance therapy of hypoadrenocorticism · 0.1 mg total dose/cat PO once daily · PO · once daily · Administer with prednisolone (0.2 mg/kg PO once daily).
- Hypoadrenocorticism · 0.05-0.1 mg/kg PO q24h or divided q12h · PO · q24h or divided q12h · For those animals that still exhibit Addisonian signs even with prednisone therapy.
- Hypoadrenocorticism · Initial dose of 0.01 mg/kg PO twice daily · PO · twice daily · Adjust dose based on monitoring serum electrolyte concentrations every 1-2 weeks until stable. Once stable, recheck every 3-4 months. Addition of NaCl (0.1 g/kg/day) can be useful in reducing the dose of fludrocortisone and reducing PU/PD.
- Maintenance of hypoadrenocorticism · Initially, 0.01-0.02 mg/kg/day PO and adjusted by 0.05-0.1 mg (total dose) increments · PO · daily · Adjust based on serial electrolyte determinations. Most dogs will ultimately require 0.02-0.03 mg/kg/day.
- Hypoadrenocorticism · 0.01 mg/kg PO twice daily · PO · twice daily · Titrate dose to effect; typically dose needs to be increased over time. Only 50% of dogs on fludrocortisone require supplemental prednisone.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- Known hypersensitivity to fludrocortisone
Efectos adversos
- Polyuria (PU)
- Polydipsia (PD)
- Hypertension
- Edema
- Hypokalemia
- Hypernatremia
- Signs of iatrogenic Cushing's syndrome (due to glucocorticoid effects)
Interacciones farmacológicas
- Amphotericin B · Patients may develop hypokalemia if administered concomitantly.
- Aspirin · Fludrocortisone may reduce salicylate levels.
- Potassium-depleting diuretics (e.g., thiazides, furosemide) · May cause hypokalemia; diuretics can cause sodium loss, counteracting the effects of fludrocortisone.
- Insulin · Potentially increases the insulin requirements of diabetic patients.
Monitoreo
- Serum electrolytes (Sodium, Potassium)
- BUN and Creatinine
- Body weight
- Physical examination for signs of edema or hypertension
- Clinical signs of PU/PD
Sobredosis
Overdosage is typically characterized by excessive mineralocorticoid effects: * **Clinical Signs:** Hypertension, edema, severe hypokalemia, and hypernatremia. Excessive glucocorticoid signs (severe PU/PD, panting) may also occur. * **Management:** Discontinue the drug until clinical signs associated with overdosage have resolved. Electrolytes should be aggressively monitored. Potassium supplementation may be required. Once resolved, restart the drug at a lower dosage.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.