Tissue diffusion of doxycycline in rats: a comparison between intravenous bolus injection or drip-infusion.

The aim of the present paper is to investigate the influence of the infusion rate on doxycycline concentrations in rat body fluids (serum and experimental pleural exudate) and tissues (muscle). The same dose of antibiotic (30 mg/kg) was given both as a bolus and by drip-infusion over 30 min. The drug concentrations in serum samples and tissue specimens were measured by a microbiological method. The highest serum levels and the optimal penetration into muscle and pathological fluids were obtained following drip-infusion.