Ioflupane (123I) is the international nonproprietary name (INN) of a cocaine analogue which is a neuro-imaging radiopharmaceutical drug, used in nuclear medicine for the diagnosis of Parkinson's disease and the differential diagnosis of Parkinson's disease over other disorders presenting similar symptoms. During the DaT scan procedure it is injected into a patient and viewed with a gamma camera in order to acquire SPECT images of the brain with particular respect to the striatum, a subcortical region of the basal ganglia.[7] The drug is sold under the brand name Datscan and is manufactured by GE Healthcare, formerly Amersham plc.
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| Trade names | Datscan, Striascan, Celsunax |
| Other names | Ioflupane (FPCIT); [I-123] N-ω-fluoropropyl- 2β-carbomethoxy- 3β-(4-iodophenyl) nortropane |
| AHFS/Drugs.com | Professional Drug Facts |
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| Routes of administration | Intravenous |
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| Bioavailability | N/A |
| Excretion | Kidney and fecal |
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| Formula | C18H23FINO2 |
| Molar mass | 431.290 g·mol−1 |
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Pharmacology
editDatscan is a solution of ioflupane (123I) for injection into a living test subject.[7]
The iodine introduced during manufacture is a radioactive isotope, iodine-123, and it is the gamma decay of this isotope that is detectable to a gamma camera. 123I has a half-life of approximately 13 hours and a gamma photon energy of 159 keV making it an appropriate radionuclide for medical imaging. The solution also contains 5% ethanol to aid solubility and is supplied sterile since it is intended for intravenous use.[7]
Ioflupane has a high binding affinity for presynaptic dopamine transporters (DAT) in the brains of mammals, in particular the striatal region of the brain. A feature of Parkinson's disease is a marked reduction in dopaminergic neurons in the striatal region. By introducing an agent that binds to the dopamine transporters a quantitative measure and spatial distribution of the transporters can be obtained.
Method of administration
editThe Datscan solution is supplied ready to inject with a certificate stating the calibration activity and time. The nominal injection activity is 185 MBq[7] and a scan should not be performed with less than 111 MBq.
Thyroid blocking via oral administration of 120 mg potassium iodide is recommended to minimize unnecessary excessive uptake of radioiodine.[8] This is typically given 1–4 hours before the injection.[7][9]
The most convenient way to administer the IV dose is via a peripheral intravenous cannula. The scan is carried out 3 to 6 hours post injection.[8][9]
Pharmacokinetics
editBlood clearance of the radionuclide is rapid in healthy volunteers.[10] Radioactivity was 4.5% of the injected amount 5 min after injection of ioflupane (123I), falling to 2.2% at 30 min, 1.9% at 5 h, and declining to 1.3% at 24 h and 1.1% at 48 h after injection. Values were similar in both whole blood and plasma. Excretion was primarily renal.
Risks
editCommon side effects of ioflupane (123I) are headache, vertigo, increased appetite and formication. Less than 1% of patients experience pain at the injection site.[7]
The radiation risks are reported as low. The committed effective dose for a single investigation on a 70 kg individual is 4.6 mSv.[11] Pregnant patients should not undergo the test. It is not known if 123I-ioflupane is secreted in breast milk however it is recommended that breastfeeding be interrupted for three days after administration.[7]
See also
editReferences
edit- ^ "Neurological therapies". Health Canada. 9 May 2018. Retrieved 13 April 2024.
- ^ "Datscan- ioflupane i-123 injection, solution". DailyMed. 31 March 2020. Retrieved 23 April 2021.
- ^ "Removal of [123I]Ioflupane From Schedule II of the Controlled Substances Act". DEA Diversion Control Division. Archived from the original on 13 May 2017. Retrieved 2016-02-09.
- ^ "Datscan EPAR". European Medicines Agency (EMA). 17 September 2018. Retrieved 1 July 2021.
- ^ "Striascan EPAR". European Medicines Agency (EMA). 24 April 2019. Retrieved 1 July 2021.
- ^ "Celsunax EPAR". European Medicines Agency (EMA). 20 April 2021. Retrieved 1 July 2021.
- ^ a b c d e f g "Datscan Summary of Product Characteristics" (PDF). European Medicines Agency. GE Healthcare. 25 July 2019.
- ^ a b Darcourt J, Booij J, Tatsch K, Varrone A, Vander Borght T, Kapucu OL, et al. (February 2010). "EANM procedure guidelines for brain neurotransmission SPECT using (123)I-labelled dopamine transporter ligands, version 2". European Journal of Nuclear Medicine and Molecular Imaging. 37 (2): 443–50. doi:10.1007/s00259-009-1267-x. PMID 19838702.
- ^ a b Djang DS, Janssen MJ, Bohnen N, Booij J, Henderson TA, Herholz K, et al. (January 2012). "SNM practice guideline for dopamine transporter imaging with 123I-ioflupane SPECT 1.0". Journal of Nuclear Medicine. 53 (1): 154–63. doi:10.2967/jnumed.111.100784. PMID 22159160.
- ^ Zhang M, Wang Y, Wang J, Li X, Li B (7 Apr 2023). "Safety, biodistribution and radiation dosimetry of [123I]ioflupane in healthy Chinese volunteers". EJNMMI Res. 13 (1): 30. doi:10.1186/s13550-023-00978-3. PMC 10082142. PMID 37029298.
- ^ "Notes for Guidance on the Clinical Administration of Radiopharmaceuticals and Use of Sealed Radioactive Sources". ARSAC. Public Health England. 13 February 2019.
