AIM: Linezolid is a member of oxazolidinones, which is a novel class of antibiotics. The study is to determine the absolute bioavailability of linezolid tablets in Chinese healthy male volunteers. METHODS: A randomized, open cross-over study was conducted in 22 healthy male volunteers, a single oral dose of 600 mg linezolid tablets or IV infusion of 600 mg linezolid were given to subjects, respectively. Blood samples were obtained at different time points and sent to American AvTech laboratories. Plasma concentrations of linezolid were determined by high-performance liquid chromatography (HPLC), pharmacokinetic parameters and absolute bioavailability were calculated. RESULTS: After oral and IV infusion administration of 600 mg linezolid, the elimination half-life (t1/2) was (4.3±1.0) h and (4.4±0.9) h, respectively. The area under plasma concentration-time curve (AUC0-∞) of linezolid were (87±20) μg·mL-1·h and (96±21) μg·mL-1·h, respectively. The absolute oral bioavailability was 93%±23% following single oral dose of 600 mg linezolid tablets. Analyses of two one-sided t tests and 90% confidence interval showed that linezolid tablet and IV formulation are equivalent with respect to AUC. No adverse event was found except one volunteer with transitory mild epigastric pain. CONCLUSION: Linezolid tablets can be completely absorbed; it is equivalent in extent of absorption to its IV formulation. AIM: Linezolid is a member of oxazolidinones, which is a novel class of antibiotics. The study is to determine the absolute bioavailability of linezolid tablets in Chinese healthy male volunteers. METHODS: A randomized, open cross-over study was conducted in 22 healthy male volunteers, a single oral dose of 600 mg of linezolid tablets or IV infusion of 600 mg linezolid were given to subjects, respectively. Blood samples were obtained at different time points and sent to American AvTech laboratories. Plasma concentrations of linezolid were determined by high-performance RESULTS: After oral and IV infusion administration of 600 mg linezolid, the elimination half-life (t1 / 2) was (4.3 ± 1.0) h and (4.4 ± 0.9) The area under plasma concentration-time curve (AUC0-∞) of linezolid were (87 ± 20) μg · mL-1 · h and (96 ± 21) μg · mL-1 · h, respectively. The absolute oral bioavailabili ty was 93% ± 23% following single oral dose of 600 mg linezolid tablets. Analyzes of two one-sided t tests and 90% confidence interval showed that linezolid tablet and IV formulation are equivalent with respect to AUC. No adverse event was found except one volunteer with transitory mild epigastric pain. CONCLUSION: Linezolid tablets can be completely absorbed; it is equivalent in extent of absorption to its IV formulation.