IOFLUPANE I-123
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IOFLUPANE I-123 (IOFLUPANE I-123).
Ioflupane I-123 is a radiopharmaceutical that binds with high affinity to the dopamine transporter (DAT) in the striatum. It allows visualization of presynaptic dopaminergic neurons via single-photon emission computed tomography (SPECT) imaging.
| Metabolism | Ioflupane I-123 is not metabolized; it is excreted unchanged in urine and feces. The radioactive decay of I-123 (electron capture, half-life 13.2 hours) is independent of metabolic processes. |
| Excretion | Primarily renal; about 60% of administered radioactivity excreted in urine within 24 hours, with 38% as unchanged ioflupane and 22% as metabolites. Fecal excretion accounts for approximately 14% over 48 hours. Additional elimination via biliary route is minimal. |
| Half-life | Terminal elimination half-life of ioflupane I-123 is approximately 25-30 hours. This prolonged half-life allows for imaging up to 6-8 hours post-injection with sustained target-to-background ratio, but requires consideration for radiation safety. |
| Protein binding | Approximately 80% bound to plasma proteins, primarily albumin. Binding is non-saturable over the clinical concentration range. |
| Volume of Distribution | Apparent volume of distribution is approximately 5-7 L/kg, indicating extensive tissue distribution, particularly into brain due to lipophilicity. Large Vd reflects high affinity for dopamine transporter-rich regions. |
| Bioavailability | Administered only as intravenous injection; bioavailability is 100% by this route. No oral or other route formulation exists. |
| Onset of Action | Intravenous injection: Peak brain uptake occurs at 3-6 hours post-injection, with specific binding to dopamine transporters in striatum evident by 2-3 hours. Diagnostic images of clinical quality are typically obtained 3-6 hours after administration. |
| Duration of Action | Duration of adequate diagnostic imaging is approximately 6-8 hours post-injection. Optimal imaging window is 3-6 hours; after 8 hours, count statistics decline significantly. No therapeutic effect; used solely for SPECT imaging. |
Intravenous: 148-185 MBq (4-5 mCi) administered as a single IV bolus injection over 20-30 seconds, followed by saline flush.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment is recommended based on renal function; however, use caution in severe renal impairment (GFR <30 mL/min) due to potential increased radiation exposure. |
| Liver impairment | No formal Child-Pugh based dose adjustments are established; use with caution in severe hepatic impairment due to altered metabolism. |
| Pediatric use | Weight-based dosing: 3.3 MBq/kg (0.09 mCi/kg) IV, with a minimum of 74 MBq (2 mCi) and maximum of 185 MBq (5 mCi). Safety and efficacy not established in children <4 years. |
| Geriatric use | No specific dose adjustment required for elderly; consider slower injection rate to minimize adverse effects; monitor for injection site reactions. No age-related pharmacokinetic changes necessitate dose modification. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IOFLUPANE I-123 (IOFLUPANE I-123).
| Breastfeeding | IofluPAME I-123 is excreted in breast milk. M/P ratio not available. In breastfed infants, potential for thyroid uptake and long-term carcinogenesis. Discontinue breastfeeding for at least 24 hours after administration and discard milk. Consider interrupting breastfeeding for a period based on residual radioactivity. |
| Teratogenic Risk | IofluPAME I-123 is a radiopharmaceutical. Fetal radiation exposure is the primary concern. First trimester: Avoid due to organogenesis; risk of malformations if absorbed dose > 0.1 Gy. Second/third trimester: Avoid unless benefit outweighs risk; potential for fetal thyroid ablation and carcinogenesis. No teratogenicity data in humans. |
■ FDA Black Box Warning
None
| Serious Effects |
Known hypersensitivity to ioflupane or any excipient.
| Precautions | Risk of hypersensitivity reactions including anaphylaxis; radiation exposure risk; pregnancy and lactation; interpretation of imaging results requires correlation with clinical evaluation; thyroid uptake of free iodide can be blocked by administering potassium iodide or perchlorate prior to administration. |
| Food/Dietary | No specific food restrictions. Maintain hydration post-scan to promote renal excretion of iodine-123. |
| Clinical Pearls |
Loading safety data…
| Fetal Monitoring | Monitor maternal thyroid function (TSH, free T4) before and after administration. In pregnancy, if unavoidable, perform fetal dosimetry (estimated absorbed dose). Monitor fetal thyroid via ultrasound if iodine exposure suspected. No specific fetal monitoring required for diagnostic doses. |
| Fertility Effects | IofluPAME I-123 has no known effects on fertility in animal studies. No human data. Radiopharmaceutical exposure may theoretically affect gonadal tissue at high doses, but diagnostic doses are typically below thresholds. |
| Ioflupane I-123 (DaTscan) is a radiopharmaceutical for striatal dopamine transporter visualization via SPECT. Administer thyroid blockade (supersaturated potassium iodide, potassium perchlorate, or potassium iodate) 1 hour before injection to reduce thyroid uptake of free I-123. Image acquisition occurs 3–6 hours post injection. False positives can occur with drugs that block dopamine transporters (e.g., amphetamines, bupropion, cocaine, methylphenidate). Interpret in context of clinical presentation; a normal scan does not rule out Parkinson's disease and an abnormal scan is not diagnostic of Parkinson's disease. |
| Patient Advice | You will receive a thyroid-blocking medication (e.g., iodine drops) about 1 hour before the injection to protect your thyroid. · This drug is radioactive; the radiation exposure is low and similar to many diagnostic X-rays. · You will be injected with the medicine and then need to wait 3–6 hours before the imaging scan. · Tell your doctor about all medications you take, especially stimulants, antidepressants, and cold remedies, as they may affect the test results. · Drink plenty of fluids after the scan to help eliminate the radioactive material from your body. · Avoid prolonged close contact with pregnant women and infants for 24 hours after the scan. |