title: Validation of a technique for the preparation of individual patient doses of 14C-urea.
abstract: A breath test employing 14C-urea is commonly used to detect the presence of Helicobacter pylori in the stomach of patients with peptic ulcer. 14C-urea is not available commercially as a radiopharmaceutical. It is available only as non-pharmaceutical grade material. A technique for preparing individual patient doses was therefore validated and methods for demonstrating the quality of the 14C-urea raw material and final product were developed. Individual patient doses, each containing 100 kBq 14C and 350 mg urea in 1 ml, were prepared and stored at -20 degrees C. Each batch consisted of approximately 400 doses. The activities of samples from each batch were measured by liquid scintillation counting immediately after preparation (99.6 +/- 4.9 kBq) and 6 months later (98.2 +/- 4.7 kBq). The chemical identity of the 14C-urea was demonstrated by a thin-layer chromatographic technique in which the 14C was shown to have the same Rf value as stable urea. The high radiochemical purity of the final product was demonstrated by the presence of only one peak on the thin-layer chromatogram. The radionuclide identity of the 14C-urea was demonstrated by beta-ray spectroscopy. This technique of preparing individual patient doses of 14C-urea results in a product that is stable for at least 6 months.
authors.affiliation: Royal Infirmary of Edinburgh, UK.
authors.forename: A
authors.initials: A
authors.lastname: Clarkson
authors.forename: A M
authors.initials: AM
authors.lastname: Millar
mesh_terms: D001944:Breath Tests; D002250:Carbon Radioisotopes / Q000032:analysis / Q000592:standards; D002855:Chromatography, Thin Layer; D004355:Drug Stability; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori; D006801:Humans; D019275:Radiopharmaceuticals / Q000592:standards; D015203:Reproducibility of Results; D014508:Urea / Q000032:analysis / Q000592:standards
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D014508:Urea