Ipodate Sodium
Ipodate sodium is an oral radiopaque organic iodine compound originally utilized in human medicine as a contrast agent for cholecystography. In veterinary medicine, it has been repurposed as an alternative **antithyroid agent** for cats suffering from hyperthyroidism, particularly those that cannot tolerate first-line medications like methimazole or carbimazole. While it can be effective in reducing the clinical signs of hyperthyroidism, its use is limited by a few significant factors: * **Transient Efficacy:** Cats often become refractory to the medication after a relatively short period. * **Availability:** There are no commercial veterinary or human products available; it must be formulated by a compounding pharmacy. * **Severity of Disease:** It is generally less effective in cats with severe hyperthyroidism. > **Clinical Pearl:** Because ipodate does not lower serum T4 levels (and may actually increase them due to decreased clearance), therapeutic monitoring must rely on clinical signs and serum **T3 levels**.
Mecanismo: Ipodate acts via a completely different mechanism than thioureylene antithyroid drugs (like methimazole). Its primary effects include: * **5'-deiodinase inhibition:** It potently inhibits the enzyme responsible for the peripheral conversion of thyroxine (T4) → the more biologically active triiodothyronine (T3). * **Receptor Blockade:** It may competitively block **T3 receptors** in target tissues, thereby protecting organs such as the heart from the hypertrophic and thyrotoxic effects of hyperthyroidism. * **TSH Interference:** It may block the actions of Thyroid Stimulating Hormone (TSH).
Dosificación por especie
- Medical treatment of hyperthyroidism in patients who cannot tolerate methimazole and whose owners will not permit surgery or radioiodine therapy · 100-200 mg (total dose; empiric) PO once daily · PO · q24h
- Medical treatment of hyperthyroidism in patients who cannot tolerate methimazole and whose owners will not permit surgery or radioiodine therapy · 50 mg per cat PO twice daily, if 'good' clinical response not obtained, at 2 week intervals may increase dose to 150 mg/day (100 mg AM, 50 mg PM) and then to 200 mg/day (100 mg twice daily) · PO · q12h · Cats with severe hyperthyroidism are less likely to respond.
- For use before surgery · 15 mg/kg PO q12h · PO · q12h
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 ipodate or other iodine compounds
- Pregnancy (risk of congenital hypothyroidism in fetuses)
Efectos adversos
- GI distress (nausea, vomiting, diarrhea, cramping, inappetence)
- Transient efficacy (patients may become refractory)
- Drug-induced pemphigus (rare)
- Skin rashes, itching, dizziness, and headache (reported in humans)
Interacciones farmacológicas
- Radioactive Iodine (I-131) · Ipodate may interfere with radioactive iodine uptake and therapy. It is recommended to discontinue ipodate at least 2 weeks (preferably 3-4 weeks or more) prior to I-131 treatment.
Monitoreo
- Clinical efficacy (heart rate, body weight, resolution of clinical signs)
- Serum T3 levels (Note: T4 levels typically do not decrease and may remain high; T4 is NOT a reliable indicator of efficacy for this specific drug)
Sobredosis
No specific information located regarding acute toxicity. Cats have reportedly tolerated daily doses up to 400 mg without severe acute adverse effects.
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.