Direct nose-to-brain transfer of morphine after nasal administration to rats.

Purpose: The aim of this study was to quantify the olfactory transfer of morphine to the brain hemispheres by comparing brain tissue and plasma morphine levels after nasal administration with those after intravenous administration.

Methods: Morphine (1.0 mg/kg body weight) was administered via the right nostril or intravenously as a 15-min constant-rate infusion to male rats.

Transfer of morphine along the olfactory pathway to the central nervous system after nasal administration to rodents.

The aim of this study was to investigate whether morphine can be transferred along the olfactory pathway to the CNS, thereby circumventing the blood-brain barrier, after nasal administration to rodents. Radiolabelled and unlabelled morphine were administered via the right nostril to mice and rats. Olfactory bulbs, brain tissue and blood samples were collected.