Improved delivery through biological membranes XIV: Brain-specific, sustained delivery of testosterone using a redox chemical delivery system.

The dihydropyridine in equilibrium pyridinium salt redox delivery system was used for the specific delivery and sustained release of testosterone in the brain. Administration of the N-methyl-1,4-dihydro nicotinate ester of testosterone in female rats gave high and sustained brain levels of the corresponding quaternary ester, testosterone trigonellinate. This contrasted with rapid elimination from the general circulation. Release of testosterone "locked into" brain as the quaternary salt was sustained, t1/2 = 20 h.