Pyrilamine-sensitive proton-coupled organic cation (H⁺/OC) antiporter for brain-specific drug delivery

Blood-brain barrier (BBB) represents the greatest challenge that hampers therapeutic molecules entering the brain. Here, we described a novel brain-specific delivery strategy targeting to pyrilamine-sensitive H⁺/OC antiporter to facilitate therapeutic molecules cross the BBB and penetrate into the brain. In this study, four cyclic tertiary amines were selected as the brain-targeting moieties to modify naproxen (NP), a non-steroidal anti-inflammatory drug. The obtained NP conjugates displayed cell uptake efficiencies over 144-fold higher than that of unmodified NP in endothelial cells. The cell uptake process of the conjugates was primarily driven by pyrilamine-sensitive H⁺/OC antiporter in a pH-dependent, Na⁺-independent, and membrane potential-independent pathway, which could be further inhibited by pyrilamine, propranolol, and imipramine. Moreover, the NP conjugates showed significantly higher AUC_0-t and C_max in the brain compared with unmodified NP, and significantly higher accumulation than NP in the in situ brain perfusion study. Also, the conjugates showed superior neuroprotective effect in vitro and in vivo. Thus, the chemical modification of therapeutics with a cyclic tertiary amine moiety represents a promising and efficient strategy for brain-specific drug delivery via pyrilamine-sensitive H⁺/OC antiporter.