Isoflupredone Acetate
**Isoflupredone acetate** is a potent, fluorinated synthetic glucocorticoid used primarily in large animal medicine (cattle, horses, and swine). * **Potency**: It possesses approximately **17 times** the anti-inflammatory potency of hydrocortisone and **10 times** that of prednisolone. Its glucocorticoid activity is rated at 50 times that of hydrocortisone. * **Clinical Utility**: Commonly utilized for its profound anti-inflammatory and immunosuppressive effects. Labeled indications include adjunctive treatment for bovine ketosis, musculoskeletal inflammation, acute hypersensitivity, overwhelming infections with severe toxicity, and recurrent airway obstruction (RAO) in horses. * **Clinical Pearl**: Unlike dexamethasone or betamethasone, isoflupredone is less likely to induce early parturition, though it should still be avoided in late pregnancy. Notably, it retains significant **mineralocorticoid activity**, making patients highly susceptible to **hypokalemia**, even after a single dose in dairy cattle.
Mechanism: Isoflupredone exerts its effects via classic genomic and non-genomic steroid pathways: * **Anti-inflammatory (Glucocorticoid Receptor - GR)**: Binds to cytosolic **GR** → translocates to the nucleus → induces transcription of **lipocortin-1 (annexin A1)**. Lipocortin-1 inhibits **phospholipase A2**, thereby blocking the release of arachidonic acid and halting the production of inflammatory prostaglandins and leukotrienes. It also transrepresses pro-inflammatory transcription factors like **NF-κB** and **AP-1**. * **Mineralocorticoid Effects (Mineralocorticoid Receptor - MR)**: Binds to **MR** in the distal renal tubules → upregulates Na+/K+ ATPase and ENaC channels → promotes **sodium retention** and **potassium excretion** (leading to hypokalemia). * **Metabolic**: Stimulates hepatic gluconeogenesis (useful in bovine ketosis) and decreases peripheral glucose utilization.
Dosing by species
- Labeled systemic indications · 10-20 mg (total dose) · IM · repeated in 12 to 24 hours if indicated · according to the size of the animal and severity of the condition
- Labeled systemic indications · 5-20 mg (total dose) · IM · repeated as necessary
- Intrasynovial administration · 5-20 mg or more · Intrasynovial · depending on the size of the joint cavity
- Intraarticular administration · 4-20 mg · Intraarticular · has a short to medium duration of action
- Treatment of 'heaves' (RAO) · 10-14 mg (total dose) · IM · once daily · for a horse weighing between 450-500 kg
- Treatment of recurrent airway obstruction (RAO) · 0.03 mg/kg · IM · once daily · 14 days · Patients developed significant decreases in serum potassium
- Labeled systemic indications · 5 mg (total dose) · IM · for a 300 lb. animal. Adjust dose proportionally for a smaller or larger animal.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Systemic fungal infections (unless used for Addison's replacement)
- Idiopathic thrombocytopenia (when administered IM)
- Hypersensitivity to the compound
- Downer cows or animals susceptible to hypokalemia
- Calves to be processed into veal
- Late stages of pregnancy (relative contraindication)
Adverse effects
- Hypokalemia (even with single doses)
- Reduced milk production
- Delayed wound healing
- Gastrointestinal ulceration
- Increased infection rates
- Diabetes mellitus exacerbation / hyperglycemia
- Pancreatitis
- Hepatopathy
- Renal dysfunction
- Osteoporosis
- Laminitis (horses)
- Hypothyroidism
- Hyperlipidemia
- Decreased growth in young animals
- Premature parturition with retained placenta (if used in late pregnancy)
Drug interactions
- Digitalis glycosides (digoxin) · Increased chance of digitalis toxicity may occur should hypokalemia develop; diligent monitoring of potassium and digitalis glycoside levels is recommended
- Potassium-depleting diuretics (furosemide, thiazides) · Administered concomitantly with glucocorticoids may cause hypokalemia
- Salicylates · Glucocorticoids may reduce salicylate blood levels
- Ulcerogenic drugs (e.g., NSAIDs) · With glucocorticoids may increase the risk of gastrointestinal ulceration
- Vaccines, toxoids, bacterins · A diminished immune response may occur; patients receiving immunosuppressive dosages should generally not receive live attenuated-virus vaccines
Monitoring
- Efficacy and adverse effects
- Serum potassium (highly recommended due to hypokalemia risk)
- Renal and liver function
- CBC
- Blood glucose
- Serum electrolytes
- ACTH stimulation tests (to determine HPA axis suppression)
- Thyroid hormone monitoring (if use is prolonged)
Overdose
A single overdose of isoflupredone is unlikely to cause harmful effects. Should clinical signs require intervention, use supportive treatment. Chronic usage of glucocorticoids can lead to serious adverse effects, generally manifested as signs of hyperadrenocorticism.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.