Pharmacokinetics after a single dose of naloxone administered as a nasal spray in healthy volunteers

Background: There is increasing interest in the use of intranasal naloxone to reverse adverse opioid effects during management of procedural pain in children and in adults after overdose. There are limited data on the pharmacokinetics of intranasal naloxone so in this study we aimed to detail the pharmacokinetic profile of the commercially marketed injectable solution of naloxone 0.4 mg/ml when administered as an intranasal spray. Methods: Twenty healthy volunteers received naloxone as an intranasal spray at a dose of 10 mu g/kg. Venous blood sampling was carried out for 90 min after administration to determine the time profile of the plasma concentrations of using tandem mass spectrometry. Pharmacokinetic parameters were calculated using a one-compartment model. Results: Median time to maximum naloxone concentration (Tmax) was 14.5 (95% CI: 9.0-16.5) min, mean maximum naloxone concentration (Cmax) was 1.09 +/- 0.56 ng/ml and mean AUC(0-90 min) was 37.1 +/- 15.0 ng* min/ml. Elimination half-life estimated from the median concentration data was 28.2 min. Conclusion: Our results show a faster uptake of intranasal naloxone to maximum concentration compared with previous studies although with a marked variation in maximum concentration. The findings are consistent with our clinical experience of the time profile for reversing the effects of sufentanil sedation in children.