Salivary levels of oxytocin remain elevated for more than two hours after intranasal oxytocin administration.

OBJECTIVE: This is the first study investigating whether levels of oxytocin in saliva remained elevated after intranasal oxytocin administration for the duration of an experiment (in which neurobehavioral effects of oxytocin were observed) taking more than two hours. METHODS: Oxytocin levels were measured in saliva samples collected from 57 female participants right before (T0), approximately 1¼ h (T1), and approximately 2¼ h (T2) after intranasal administration of 16 IU of oxytocin or a placebo, using a double-blind, within-subjects design. RESULTS: Average levels of oxytocin did not differ between conditions before use of the nasal spray, markedly increased only after oxytocin administration, and were still elevated after 2¼ h. CONCLUSION: Salivary levels of oxytocin remained persistently elevated over the course of our experiment, i.e. for more than two hours after intranasal oxytocin administration and over a time-period in which neurobehavioral effects of oxytocin are commonly observed. This suggests that salivary concentrations may be a valuable biomarker for oxytocin, and may help to explain its effects on brain activity, information processing, and behavior.