Dosing and uses of DaTscan (ioflupane I123)
Adult dosage forms and strengths
intravenous injection: Schedule II
- 185 MBq/2.5mL
Dopamine Transporter Visualization
Radiopharmaceutical indicated for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging to assist in the evaluation of adults with suspected Parkinsonian syndromes (PS)
May be used to help differentiate essential tremor from tremor due to PS (idiopathic Parkinson's disease, multiple system atrophy and progressive supranuclear palsy)
Measure patient dose by a suitable radioactivity calibration system immediately prior to administration
Administer thyroid-blocking agent (eg, potassium iodide oral solution or potassium perchlorate) at least 1 hr before dose
Recommended dose is 111-185 MBq (3-5 mCi)
Begin SPECT imaging between 3 and 6 hr post-injection
Thyroid blockade
- Administer 1 hr before DaTscan dose
- Potassium iodide oral solution (or Lugol’s Solution) equivalent to 100 mg iodide, OR
- Potassium perchlorate 400 mg
Renal Impairment
Excreted by kidneys
Severe renal impairment may increase radiation exposure to patient and alter images
Pediatric dosage forms and strengths
Safety and efficacy not established
Geriatric dosage forms and strengths
In the 2 principal clinical studies, 45% of the subjects were aged 65 yr or older
There were no differences in response compared to younger subjects that would require a dose adjustment
Other reported clinical experience has not identified differences in responses between the elderly and younger patients
DaTscan (ioflupane I123) adverse (side) effects
<1%
Headache
Nausea
Dizziness
Vertigo
Xerostomia
Warnings
Contraindications
Hypersensitivity to active substance, excipients, or iodine
Cautions
Emits radiation and must be handled with safety measures to minimize radiation exposure to clinical personnel and patients
May cause hypersensitivity reactions depicted by skin erythema and pruritus; these reactions may resolve spontaneously or following the administration of corticosteroids and antihistamines
Have medications and medical support to respond to anaphylaxis readily available
Thyroid accumulation may occur; use thyroid blocking drugs before administration; failure to block thyroid uptake of I123 may result in an increased long term risk for thyroid neoplasia; avoid use of potassium iodide oral solution or Lugol's solution in patients sensitive to such products
Bladder protection: To minimize radiation dose to the bladder, encourage hydration prior to and following administration in order to permit frequent voiding; encourage the patient to void frequently for the first 48 hr following administration
Amoxapine, amphetamine, benztropine, bupropion, buspirone, cocaine, mazindol, methamphetamine, methylphenidate, norephedrine, phentermine, phenylpropanolamine, selegiline, sertraline, citalopram and paroxetine may interfere with imaging
Effects of dopamine agonists and antagonists on Datscan imaging have not been established
Pregnancy and lactation
Pregnancy category: C; Like all radiopharmaceuticals, has a potential to cause fetal harm
The likelihood of fetal harm depends on the stage of fetal development, and the magnitude of the radionuclide dose
Administration of DaTscan at a dose of 185 MBq (5 mCi) results in an absorbed radiation dose to the uterus of 0.3 rad (3.0 mGy); radiation doses greater than 15 rad (150 mGy) have been associated with congenital anomalies but doses under 5 rad (50 mGy) generally have not
Radioactive iodine products cross the placenta and can permanently impair fetal thyroid function
Lactation: Excretion in breast milk unknown; based on the physical half-life of iodine 123 (13.2 hr), nursing women may consider interrupting nursing and pumping and discarding breast milk for 6 days after administration in order to minimize risks to a nursing infant
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of DaTscan (ioflupane I123)
Mechanism of action
Binds reversibly to the human recombinant dopamine transporter (DaT) (Ki = 0.62 nM; IC50 = 0.71 nM)
Following administration, radioactive decay of the iodine123 emits gamma radiation which can be detected externally using gamma detectors, allowing visualization of the brain striata through SPECT imaging
Pharmacokinetics
Half-Life: 13.2 hr
Brain uptake: 7% of injected radioactivity at 10 min post-injection; decreased to 3% at 5 hr post-injection
Onset: ~7% of radioactivity in brain within 10 min
Metabolism: Decays to 123Te by electron capture
Excretion: feces (14% by 48 hr), urine (60% by 48 hr)
Administration
IV Preparation
IV injection: Use aseptic procedures and radiation shielding during preparation and administration
Inspect vial prior to administration and do not use it if the vial contains particulate matter or discoloration
IV Administration
Slow IV injection (administered over a period of not less than 15-20 seconds) via an arm vein
Storage
Store within original lead container or equivalent radiation shielding
Do not use after expiration date and time stated on labeL
