Iofetamine hydrochloride I-123 is a radiopharmaceutical for cerebral perfusion imaging. lofetamine is the N-isopropyl derivative of amphetamine with iodine 123(1123) at the para position to serve as the tracer. This configuration was systematically derived by Winchell et al. to provide sufficient brain uptake and retention for brain imaging, which typically requires an acquisition time of 25-40 minutes. After experimental intraarterial injection the drug has a high extraction ratio (> 90 percent) in the brain. Iofetamine hydrochloride I-123 permits cerebral blood perfusion imaging with single photon emission computed tomography (SPECT). Iofetamine is an amphetamine analog that is rapidly taken up by the lungs, then redistributed principally to the liver and brain. The precise mechanism of localization has not been determined, but is believed to result from nonspecific receptor binding. Brain uptake peaks at 30 minutes postinjection and remains relatively constant through 60 minutes. The drug is metabolized and excreted in the urine, with negligible activity remaining at 48 hours. When compared with CT in stroke patients, visualization may be performed sooner after symptom onset and a larger zone of involvement may be evident with iofetamine. Localization of seizure foci and diagnosis of Alzheimer's disease may also be possible. As CT has revolutionized noninvasive imaging of brain anatomy, SPECT with iofetamine permits routine cerebral blood flow imaging. Iofetamine hydrochloride I-123 under the brand name Spectamine was approved for use in the United States as a diagnostic aid in determining the localization of and in the evaluation of non-lacunar stroke and complex partial seizures, as well as in the early diagnosis of Alzheimer's disease in 1987. However it was discontinued in USA.