Measurement of platinum in saliva of patients treated with cisplatin

A procedure for the measurement of platinum (Pt) in the saliva of patients treated with cisplatin has been developed. The saliva is collected and solu bilized in hyamine hydroxide before analysis by graphite furnace atomic abs orption spectrometry using assay by standard additions. The method has an a nalytical detection limit of 0.025 mu g/mL and is precise, with coefficient s of variation of 3-10.0% over a range of 0.05-2.0 mu g/mL. Platinum was me asured in saliva collected during an 8-h infusion of cisplatin from live pa tients, at the end of a 30-min infusion in nine, and 24 and 48 h later from a further 15 patients, all of whom were treated with cisplatin for squamou s cell carcinoma of the neck. The platinum concentration in saliva taken at the end of a 30-min infusion was 0.27 +/- 0.23 mu g/mL (mean +/- 1 SD) but was below the detection limit of 0.025 mu g/mL at 24 and 48 h. After an 8- h infusion the salivary Pt was significantly less (0.12 +/- 0.04 mu g/mL; P < 0.05). The plasma Pt concentrations after 30-min and 8-h infusions were 2.98 +/- 1.03 and 2.54 +/- 0.59 mu g/mL, respectively, and were not signifi cantly different. The results indicate higher concentrations of free platin um in plasma after 30 min compared with an 8-h infusion. The monitoring of salivary concentrations of platinum may therefore provide a non-invasive wa y to study the unbound fraction of cisplatin in blood and facilitate optimi zation of cisplatin treatment.