Tissue binding kinetics of tobramycin. An experimental study in the mouse inner ear in vitro

The tissue-binding capacity of tritiated tobramycin (TM) was analysed in an organ culture system in the embryonic inner ear of the mouse. A rapid and probably irreversible binding of TM occurs within 10 min, showing about 100 micrograms TM per gram protein in the vestibular half and about 75 micrograms TM per gram protein in the cochlear half of the labyrinth. A steady state is reached within 60 min. The TM uptake was then 390 micrograms TM per gram protein in the vestibular part and 270 micrograms in the cochlear part of the inner ear. A minor fraction of TM, of the same magnitude as initially bound, becomes irreversibly bound, whereas the slow accumulation which reaches the steady state level seems reversible.