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Technetium (99mTc) mebrofenin is a diagnostic radiopharmaceutical with no known pharmacologic action at recommended imaging doses. Under the brand name Choletec it is available through Bracco Diagnostic Inc. Supplied as a sterile kit of mebrofenin and dehydrated stannous fluoride. The vial is reconstituted with 1 to 5 mL up to 100 mCi of sodium pertechnetate solution to form the final radio labeled ] mebrofenin.〔Choletec package insert. Princeton, NJ: Bracco Diagnostics Inc, 2007, May.〕 99mTc mebrofenin is indicated for imaging of the liver and the gallblader. Upon intravenous administration, 99mTc mebrofenin bound to plasma proteins is cleared from systemic circulation in approximately 5 minutes by hepatocytes, while maximal liver uptake occurs within 11 minutes. Mechanism of mebrofenin entering the gallbladder is thought to occur with a mechanism similar to bilirubin clearance. Normal adult patient (70 kg) dose with normal serum bilirubin levels of less than 1.5 mg/dL is 2 to 5 mCi. Increased serum bilirubin increases renal clearance, decreases hepatic uptake and increases visualization time, thus a higher dose of 3 to 10 mCi is recommended. Doses higher than 10 mCi are seldom used. Obese patients require increased dose of 2 to 3 mCi compared with the normal adult patient dose to obtain proper visualization.〔 ==Structure== Mebrofenin is a chelate composed of two molecules of an iminodiacetic acid that is a lidocaine analogue, attached to a technetium-99m ion. All of the hepatobiliary visualization agents previous to mebrofenin have the same structural composition with changes only of the substituants on the phenyl ring of the lidocaine analogue molecules. Mebrofenin's fast hepatic excretion (t½=17 minutes) and high hepatic uptake (98.1%) can be contributed to the addition of methyl groups in the ortho position and the addition of a halogen (bromine).〔 To be a good hepatobiliary imaging agent, the chemical structure of mebrofenin has to meet certain requirements: # an organic ion with molecular weight between 300 to 1000 # at least two aromatic rings in the molecule # ability to bind to albumin In normal individuals, uptake of 99mTc mebrofenin by hepatocytes is 100%. Decreased liver uptake is indicative of hepatocyte disease. Once in the hepatocytes, 99mTc mebrofenin is ''secreted'' into the canaliculi and finally ''excreted'' by the bile ducts.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Technetium (99mTc) mebrofenin」の詳細全文を読む スポンサード リンク
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