Determination of extravascular concentrations of doxycycline

Doxycycline concentration in rabbit serum and muscle fluid were studied following a single iv infusion of 10 mg/kg. Maximal levels of doxycycline in muscle tissue fluid were found within 20 min after the end of infusion. Thereafter muscle fluid levels of doxycycline were similar to concurrent serum levels and were eliminated at a similar rate.