Technetium Tc 99m Lidofenin Injection »Technetium Tc 99m Lidofenin Injection is a sterile,clear,colorless solution of lidofenin complexed to radioactive technetium (99mTc)in the form of a chelate.It is suitable for intravenous injection and may contain buffers.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of 99mTc as the lidofenin chelate expressed in megabecquerels (millicuries)per mLat the time indicated in the labeling.Other chemical forms of radioactivity do not exceed 10.0percent of the total radioactivity. Packaging and storage— Preserve in single-dose or multiple-dose containers at a temperature between 2and 8. Labeling— Label it to include the following,in addition to the information specified for Labelingunder Injections á1ñ:the time and date of calibration;the amount of 99mTc as labeled lidofenin expressed as total megabecquerels (millicuries)per mLat the time of calibration;the expiration date and time;the storage temperature and the statement “Caution—Radioactive Material.”The labeling indicates that,in making dosage calculations,correction is to be made for radioactive decay,and also indicates that the radioactive half-life of 99mTc is 6.0hours. USP Reference standards á11ñ USP Endotoxin RS. Bacterial endotoxins á85ñ The limit of endotoxin content is not more than 175/VEndotoxin Units per mLof Injection,in which Vis the maximum recommended total dose,in mL,at the expiration date or time. pHá791ñ: between 3.5and 5.0. Radiochemical purity— Not more than 10.0percent of the total radioactivity is found as free 99mTc pertechnetate (TcO4),hydrolysed 99mTc and 99mTc technetium tin colloid.The presence of these impurities is determined as follows: Unbound pertechnetate— Apply a measured volume of Injection such that it provides a count rate of about 50,000counts per minute,about 15mm from the end of a 100-mm ×10-mm strip of silicic-acid impregnated fiberglass paper.Dry the spot using a gentle stream of nitrogen and develop immediately using a nitrogen-purged saturated solution of sodium chloride until the solvent front has moved four-fifths of the length of the strip.Determine the distribution of radioactivity on the strip by the use of a strip-scanner or other suitable method.Unbound pertechnetate is found at an RFvalue between 0.5and 1.0.Technetium Lidofenin,hydrolysed and colloidal 99mTc technetium remain at the origin. Hydrolysedand reduced 99mTc technetium—Apply a measured volume of Injection such that it provides a count rate of about 50,000counts per minute,about 15mm from the end of a 100-mm ×10-mm strip of silica gel impregnated fiberglass paper.Dry the spot using a gentle stream of nitrogen and develop immediately using a solution consisting of a mixture of acetonitrile and water (3:1)until the solvent front has moved four-fifths of the length of the strip.Determine the distribution of radioactivity on the strip by the use of a strip-scanner or other suitable method.Unbound pertechnetate and Technetium Lidofenin are found at an RFvalue between 0.5and 1.0.Hydrolysed and colloidal 99mTc technetium remain at the origin. Biological distribution— Inject intravenously between 0.75and 1.85MBq (20µCi and 50µCi)of the Injection into the lateral tail vein of each of three 20-g to 25-g mice.Maintain the injected animals in clean cages with free access to food and water for 1hour.Sacrifice the animals by carbon dioxide or ether asphyxiation and withdraw approximately 1mLof blood.Dissect the animals and remove the liver,gallbladder,and small and large intestines.Remove the tail.Weigh the blood sample.Place the blood sample,organs,and tail in separate counting tubes and determine the activity in each.Correct for decay to the time of injection.Determine the percentage of radioactivity in each organ and blood using the formula: 100B/A, in which Bis the net radioactivity in the organ,and Ais the total radioactivity injected.Assume that the total blood weight is 7.0%of total body weight.If more than 5%of the injected dose is found in the tail,disregard the results from that animal.If more than one animal is rejected on this basis,repeat the entire test with three more animals.Not less than 65%of the total radioactivity is found in the gallbladder and intestines,not more than 10%of the total radioactivity is found in the liver and not more than 2%of the total radioactivity is found in the blood in two out of three mice. Other requirements— It meets the requirements of the tests for Radionuclide identificationand Radionuclide purityunder Sodium Pertechnetate Tc 99m Injection.It meets the requirements under Injections á1ñ,except that it may be distributed or dispensed prior to completion of the test for Sterility,the latter test being started on the day of manufacture,and except that it is not subject to the recommendation on Volume in Container. Assay for radioactivity á821ñ Using a suitable counting assembly (see Selection of a Counting Assembly),determine the radioactivity in MBq(µCi)per mL,of Injection by use of a calibrated system. Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents USP28–NF23Page 1856 Phone Number:1-301-816-8305