Kit for the Preparation of Technetium Tc 99m Mebrofenin

INDICATIONS AND USAGE Technetium Tc 99m Mebrofenin is indicated as a hepatobiliary imaging agent.

DOSAGE AND ADMINISTRATION The suggested intravenous dose range of Technetium Tc 99m Mebrofenin in the average patient (70 kg) is: Nonjaundiced patient: 74 - 185 MBq (2-5 mCi) Patient with serum bilirubin level greater than 1.5 mg/dL: 111-370 MBq (3-10 mCi) The patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration. The patient should be in a fasting state, 4 hours is preferable. False positives (non-visualization) may result if the gallbladder has been emptied by ingestion of food. An interval of at least 24 hours should be allowed before repeat examination. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. RADIATION DOSIMETRY The estimated absorbed radiation doses 1,2 to organs and tissues of an average subject (70 kg) from an intravenous injection of 370 MBq (10 millicuries) of Technetium Tc 99m Mebrofenin are shown in Table 4. TABLE 4 Estimated Absorbed Radiation Doses† Normal Subjects* Severely Jaundiced Patients** Tissue mGy/ 370 MBq rads/ 10 mCi mGy/ 370 MBq rads/ 10 mCi Total Body 2.0 0.2 1.7 0.17 Liver 4.7 0.47 8.1 0.81 Gallbladder Wall 13.7 1.37 12.5 1.25 Small Intestine 29.9 2.99 16.0 1.60 Upper Large Intestine Wall 47.4 4.74 24.8 2.48 Lower Large Intestine Wall 36.4 3.64 19.7 1.97 Kidney 2.2 0.22 1.9 0.19 Urinary Bladder Wall 2.9 0.29 24.2 2.42 Ovaries 10.1 1.01 6.4 0.64 Testes 0.5 0.05 1.1 0.11 Red Marrow 3.4 0.34 2.5 0.25 †Method of Calculation: (1) Loberg, M.D., Buddemeyer, E.V.: Application of pharmacokinetic modeling to the radiation dosimetry of hepatobiliary agents. In Third International Radiopharmaceutical Dosimetry Symposium, FDA No. 81-8166, U.S. Department of Health and Human Services, Public Health Service, FDA, Bureau of Radiological Health, Rockville, MD, (1981) pp. 318-332. (2) Values for S: "S", Absorbed Dose per Unit Cumulated Activity for Selected Radionuclides and Organs, MIRD Pamphlet No. 11 (1975). * Bilirubin <1.5 mg/dL Calculations assume that 98% of the injected activity is taken up by the liver; activity not removed in the urine in 24 hours is excreted in the intestines and no enterohepatic circulation of activity. ** Bilirubin >10 mg/dL (mean 21.8 mg/dL) Calculations assume that 66% of the injected activity is taken up by the liver; activity not removed in the urine in 24 hours is excreted in the intestines and no enterohepatic circulation of activity.

WARNINGS The theoretical possibility of allergic reactions should be considered in patients who receive multiple doses.

CONTRAINDICATIONS Hypersensitivity to this compound.

ADVERSE REACTIONS Urticaria and rash have been rarely reported with the use of Technetium Tc 99m Mebrofenin since market introduction. Rare cases of chills and nausea have been reported with related compounds. Infrequently, death has been reported in association with the use of this class of agents.

CLINICAL PHARMACOLOGY Mebrofenin is an iminodiacetic acid (HIDA) derivative with no known pharmacologic action at the recommended doses. Following intravenous administration in normal subjects, Technetium Tc 99m Mebrofenin was rapidly cleared from the circulation. The mean percent injected dose remaining in the blood at 10 minutes was 17%. The injected activity was cleared through the hepatobiliary system with visualization of the liver by 5 minutes and maximum liver uptake occurring at 11 minutes post-injection. Hepatic duct and gallbladder visualization occurred by 10 to 15 minutes and intestinal activity was visualized by 30 to 60 minutes in subjects with normal hepatobiliary function. The mean percent injected dose excreted in the urine during the first 3 hours was 1% (0.4 to 2.0%). Elevated serum bilirubin levels increase renal excretion of Tc 99m HIDA agents. In two studies in which Tc 99m Mebrofenin was administered to patients having mean elevated serum bilirubin levels of 9.8 mg/dL (1.7 to 46.3 mg/dL), the mean percent injected dose excreted in the urine during the first 3 hours was 3% (0.2 to 11.5%). The mean percent injected dose excreted in the urine during 3-24 hours was 14.9% (0.4 to 34.8%). In jaundiced patients, the percent injected dose remaining in the blood at 10 minutes may be twice as high or more than the level in normals. Hepatobiliary transit may be delayed and visualization times increased. As a consequence, the quality of the images obtained frequently diminishes.