Accumulation of Ciprofloxacin and Minocycline by Cultured Human Gingival Fibroblasts

Abstract

Through a mechanism that is unclear, systemic fluoroquinolones and tetracyclines can attain higher levels in gingival fluid than in blood. We hypothesized that gingival fibroblasts take up and accumulate these agents, thereby enhancing their redistribution to the gingiva. Using fluorescence to monitor transport activity, accumulation of fluoroquinolones and tetracyclines was characterized in cultured human gingival fibroblast monolayers. Both were transported in a concentrative, temperature-dependent and saturable manner. Fibroblasts transported ciprofloxacin and minocycline with K m values of 200 and 108 μg/ml, respectively, at maximum velocities of 4.62 and 14.2 ng/min/ μg cell protein, respectively. For both agents, transport was most efficient at pH 7.2 and less efficient at pH 6.2 and 8.2. At steady state, the cellular/extracellular concentration ratio was >8 for ciprofloxacin and >60 for minocycline. Thus, gingival fibroblasts possess active transporters that could potentially contribute to the relatively high levels these agents attain in gingival fluid.

Modulation of Gingival Fibroblast Minocycline Accumulation by Biological Mediators

“…Gingival fibroblasts possess a transport system that allows them to take up tetracyclines and act as reservoirs for these agents. The transporter exhibits characteristics similar to those of the widely distributed organic cation transporter family, and can move tetracyclines in the forward or reverse direction to maintain equilibrium between intracellular and extracellular concentrations (Yang et al, 2002). Forward transport into fibroblasts presumably occurs when tetracycline levels are increasing or peaking in the tissue.…”

“…When taken by the systemic route, tetracyclines attain GCF levels that are approximately 4-to 5-fold higher than serum levels (Ciancio et al, 1980;Pascale et al, 1986). Our recent work has shown that gingival fibroblasts express transporters that allow them to take up extracellular tetracyclines and sequester them in the gingiva (Yang et al, 2002). Although the affinity of transport is relatively low, fibroblasts accumulate remarkable amounts of these agents.…”

Accumulation of Non-steroidal Anti-inflammatory Drugs by Gingival Fibroblasts

“…We used the pattern of alterations produced by these agents to determine the mechanism of inhibition and the inhibition constant (K i ). We measured intracellular volume by equilibrating fibroblast monolayers with [ 3 H]-water (5 μCi/mL, NEN Life Science Products) exactly as described by Yang et al (2002).…”

“…Despite their extensive use, little is known about the factors that govern the distribution of systemic NSAIDs to the tissues of the periodontium. Gingival fibroblasts have been shown to take up tetracyclines and enhance their redistribution from systemic circulation to gingiva (Yang et al, 2002). Fibroblasts are the most prevalent PGE 2 -producing cell in gingival connective tissue and are a logical target for NSAIDs.…”

Concentrations of Gemifloxacin at the Target Site in Healthy Volunteers after a Single Oral Dose

“…One potential explanation for our observation is related to the ability of fluoroquinolones to concentrate intracellularly in human cells (11,22,25). This assumption is confirmed by the higher V of gemifloxacin (Table 1) than of other quinolones.…”