Tissue binding of antimicrobial agents in vitro: a critical study focusing on the concentration of the tissue homogenate used.

In vitro tissue binding of clindamycin, trimethoprim and rifampin to serial dilutions of canine tissue homogenates was studied. For all three drugs tested, the percentage of bound drug tended to be linearly related to the logarithm of the percentage of tissue homogenate. Tissue binding studies of antimicrobials looking at a single concentration or tissue homogenate may give erroneous results that do not reflect tissue binding in vivo.