Increased blood-brain barrier permeability of morphine in a patient with severe brain lesions as determined by microdialysis

Intracerebral microdialysis was utilised to obtain information regarding ho w morphine is transported across the blood-brain barrier (BBB). In a patien t with a severe brain injury, we measured simultaneously unbound extracellu lar fluid (ECF) concentrations of morphine in human brain and in subcutaneo us fat tissue, which were compared to morphine levels in arterial blood. Th is report shows an increase in morphine levels near the trauma site in the brain compared to uninjured brain tissue. The half-life of morphine in unin jured and injured brain tissue of 178 min and 169 min, respectively, were c omparable but were longer than in blood (64 min) and adipose tissue (63 min ). This indicates that morphine is retained in brain tissue for a longer ti me than what could be expected from the blood concentration-time profile. T hese results show the potential of the microdialysis technique in providing new information regarding the pharmacokinetics of drug in the human brain close to the trauma site and in macroscopically intact tissue.