Specific activity: dependent upon the amount of radioactivity to be inhaled,but not more than 1.23mmoles of carbon monoxide per volume.

Packaging and storage— Dispense the gas either continuously or batchwise,and preserve in a single-dose container that is adequately shielded.It may also be trapped either on activated charcoal at -196or on a molecular sieve at -72.

Labeling— The label must include the following:the time and date of calibration;the amount of 11Cas carbon monoxide expressed as total MBq (mCi)at time of calibration;the expiration time and date;and the statement “Caution—Radioactive Material.”The labeling indicates that in making dosage calculations correction is to be made for radioactive decay,and states that the radioactive half-life of 11Cis 20.39minutes.Each container to hold 11COshall be independently labeled to indicate lot number and/or batch number.The labeling states that a microbiological filter (0.22µm)is to be in place to remove any possible particulate matter that could be carried through to the final product.

Radionuclide identification (see Radioactivity á821ñ)—

Radionuclidic purity— Amultichannel analyzer is used to count all radioactivity from 40to 2,500KeVto determine the absence of radiation,other than at 0.511MeVand 1.022MeV,over a period of 4hours.Possible impurities could be 13N2(t½=9.97min,this gamma ray spectrum is indistinguishable from 11C,(B+)491KeV),10C(t½=19sec,718.3KeV(100%)),14O(t½=70sec,2312.7KeV(99.4%)).[11C]COshould contain no more than 10%impurities at the time of inhalation.

Radiochemical purity and mass determination— [NOTE—This pharmaceutical may be synthesized by different methods and may therefore contain different impurities.Additional validated tests relevant to the synthetic procedure may be necessary in order to assure radiochemical purity of the final product.]Confirm by radio-gas chromatography.The gas stream,either directly from the target,or after initial chemical processing,is directed to an injection loop valve of a gas chromatograph and two precalibrated columns,a molecular sieve that allows separation of carbon monoxide from the different air components (O2,N2,and CH4),and a column containing support S3and of sufficient length to separate CO2from N2and CO(which co-elute)and CO2from NO2at room temperature.Asimple radioactivity detector and a thermal conductivity detector (or equivalent)are required for the mass determination of carbon monoxide.The radiochemical purity is not less than 98%.Mass analysis of the gas-air mixture must demonstrate levels of carbon monoxide less than 1.23mmoles in the entire dose which is the upper limit for a single-bolus inhalation.

Assay for radioactivity— Determine the radioactivity,in MBq (or mCi),by use of a calibrated system as directed under Radioactivity á821ñ.

Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents

USP28–NF23Page 350

Phone Number:1-301-816-8305