Permeability of the blood-brain barrier for protein fractions 50-100 kDa (PF50-100) of Cellex Daily preparation labeled with fluorescent tracer FITC and non-conjugated FITC were compared after intranasal administration of the preparations to healthy rats. Fluorimetrical analysis of the serum and cerebrospinal fluid samples showed that Cellex Daily PF50-100-FITC administered intranasally penetrated into the blood and cerebrospinal fluid with maximum accumulation in 2 h after administration and persists in the circulation for 24 h probably due to binding with plasma proteins. The differences in the kinetic profile of PF50-100-FITC and free FITC indirectly suggest that the major part of the preparation is not degraded within 24 h and FITC is probably not cleaved from the protein components of the preparation. In vivo fluorescence analysis showed significant fluorescent signal in the olfactory bulbs in 6 h after intranasal administration; hence, the preparation administered via this route can bypass the blood-brain barrier. Scanning laser confocal microscopy of rat brain sections confirmed penetration of the high-molecular weight protein fraction PF50-100-FITC into CNS structures. The most pronounced accumulation of the labeled drug was observed in the olfactory bulb in 6 and 12 h after administration. In contrast to free FITC administered in the control group, significant accumulation of PF50-100-FITC in the olfactory cortex and frontal cortex neurons with functionally active nuclei was observed in 6, 12 and 24 h after intranasal administration.
Keywords: Cellex Daily; blood—brain barrier; intranasal introduction; targeted delivery.