Radiopharmacy (practice and discipline)

Radiopharmacy is the pharmacy specialty concerned with the procurement, compounding, quality control, dispensing and record-keeping of radioactive drugs. In the United States its compounding and quality standards are set out in USP General Chapter <825> "Radiopharmaceuticals - Preparation, Compounding, Dispensing, and Repackaging", which requires that prepared or compounded radiopharmaceuticals meet identity, quality and purity standards from manufacturer labelling, USP monographs or other appropriate sources; that non-sterile compounded components undergo a sterilisation step; that components not certified pyrogen-free undergo bacterial endotoxin testing; and that the final dose or ordered amount be radioassayed in a dose calibrator except for unopened manufacturer containers.

A central radiopharmacy concept is the beyond-use date (BUD): the date and time beyond which a compounded, prepared, repackaged or dispensed radiopharmaceutical must not be administered, determined from the stability of quality attributes such as sterility, radiochemical purity and radionuclidic purity. USP <825> sets reference BUDs of 1 hour for immediate-use sterile radiopharmaceuticals and 99mTc-labelled red blood cells, 6 hours for radiolabelled blood components, 10 hours for direct infusion systems, and 24 hours for radiopharmaceuticals prepared and dispensed under classic sterile compounding conditions. Radionuclidic purity requirements also change with time since calibration: for example, USP monographs for 99mTc radiopharmaceuticals cap the 99Mo radionuclidic impurity at 0.15 microcurie of 99Mo per millicurie of 99Tc-99m at the time of administration, which must be recalculated forward because the ratio increases continuously as the shorter-lived 99mTc decays faster than its 99Mo parent.

Day-to-day radiopharmacy practice includes assaying generator eluate for radionuclidic breakthrough (regulated under 10 CFR 35.204), preparing kits under aseptic technique in the hot lab, performing radiochemical purity testing (commonly thin-layer or paper chromatography) before a preparation is released for patient use, and maintaining records of preparation date and time, activity, component lot numbers, quality-control results and final disposition. The discipline sits at the intersection of pharmacy compounding law, NRC/Agreement State radioactive-materials licensing, and nuclear medicine clinical practice.