HIPPURAN I 131
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HIPPURAN I 131 (HIPPURAN I 131).
HIPPURAN I 131 (iodohippurate sodium I-131) is a radiopharmaceutical that is actively transported by the renal tubules, allowing dynamic imaging of renal function. The I-131 isotope emits beta and gamma radiation, enabling scintigraphic visualization of renal perfusion and excretion.
| Metabolism | Iodohippurate I-131 is primarily excreted unchanged by the kidneys via tubular secretion. It is not significantly metabolized. |
| Excretion | Renal: >95% excreted unchanged in urine via glomerular filtration and tubular secretion; biliary/fecal: <5%. |
| Half-life | Terminal elimination half-life: 2-4 hours in patients with normal renal function; prolonged in renal impairment, up to 20-40 hours in severe impairment. |
| Protein binding | Minimal (<5%), primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg, reflecting distribution primarily in extracellular fluid. |
| Bioavailability | Oral: <10% due to poor absorption; only administered intravenously. |
| Onset of Action | Intravenous: immediate distribution; renal imaging begins 5-10 minutes post-injection. |
| Duration of Action | Sufficient for renal imaging (20-30 minutes for renogram); effective half-life limits diagnostic window to 2-4 hours. |
1 mCi (37 MBq) intravenously for adults; dose adjusted based on clinical indication and imaging protocol.
| Dosage form | INJECTABLE |
| Renal impairment | Hippuran I 131 is contraindicated in patients with severe renal impairment (GFR < 30 mL/min) due to reduced elimination and increased radiation exposure. No standard dose reduction is established; alternative agents should be considered. |
| Liver impairment | No dose adjustment is required for hepatic impairment as the drug is primarily eliminated renally. |
| Pediatric use | Dose is calculated based on body surface area or weight using the formula: Adult dose × (BSA child / 1.73 m²) or 0.05-0.1 mCi/kg (1.85-3.7 MBq/kg) intravenously. |
| Geriatric use | Elderly patients may have reduced renal function; use caution and consider lower doses based on renal assessment (e.g., Cockcroft-Gault equation). No specific geriatric dosing adjustments are established, but monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HIPPURAN I 131 (HIPPURAN I 131).
| Breastfeeding | Iodine-131 is excreted in breast milk; M/P ratio not established. Breastfeeding must be permanently discontinued before administration due to long half-life and risk of thyroid ablation in infant. |
| Teratogenic Risk | Iodine-131 crosses the placenta; fetal thyroid uptake begins at 10-12 weeks. Second and third trimester exposure carries risk of fetal hypothyroidism, neonatal thyroid dysfunction, and potential carcinogenesis. Use is contraindicated in pregnancy unless essential. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Known hypersensitivity to iodine or any component of the formulation.","Pregnancy (unless benefit outweighs risk)."]
| Precautions | ["Radiation exposure: appropriate shielding and handling necessary; cumulative dose considerations.","Hypersensitivity reactions possible.","Use in pregnancy only if clearly needed; consider fetal radiation risk.","Lactation: discontinue breastfeeding temporarily after administration.","Renal impairment may alter kinetics; dose adjustment may be needed."] |
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| Confirm negative pregnancy test before use. Monitor fetal thyroid function (TSH, free T4) if inadvertent exposure occurs. Monitor maternal thyroid function (TSH, T4) post-treatment. |
| Fertility Effects | Iodine-131 may cause temporary or permanent gonadal dysfunction; cumulative dose >400 mCi increases risk of infertility. Sperm banking or oocyte cryopreservation recommended before therapy. |