[Uptake of 5 fluoroquinolones into human polymorphonuclear cells]

A comparative evaluation of the intracellular penetration of norfloxacin, ofloxacin, levofloxacin, fleroxacin and lomefloxacin was carried out in human polymorphonuclear leucocytes (PMNs).

The fluorometric method was used based on the natural fluorescence of some fluoroquinolones.

All the fluoroquinolones accumulated within the human polymorphonuclear leucocytes achieving a quotient of between 4 to 6 in intracellular and extracellular concentration (I/C) with no significant differences being observed between the two. Penetration was rapid and was not saturable within the intervals of extracellular concentrations tested. The intracellular penetration of these fluoroquinolones was dependent on temperature and cell viability was altered in only levofloxacin and norfloxacin. The I/E values obtained significantly decreased when the cells were incubated at 4 degrees C. These values showed an important increase to pH 5 and decreased to pH 9, with this pH being statistically significant only in ofloxacin.

All the fluoroquinolones evaluated penetrated rapidly into the phagocytic cells achieving intracellular concentrations which were several fold higher than the extracellular concentrations, with no notable differences being observed being the two, thus providing an additional advantage for their use in infections produced by microorganisms capable of surviving intracellularly.