Penetration of minocycline hydrochloride (MINO) into lung tissue and sputum was investigated. MINO (100 mg) was intravenously infused over 30 min to 14 patients before lung surgery: the concentration of MINO was determined in 16 lung tissue samples which were collected between 0.25 and 5.0 h after infusion. The mean concentration of MINO in lung tissue sample was 2.92 ± 1.43 μg/g, and the mean lung tissue/plasma ratio of MINO concentration was 3.71 ± 2.36. MINO was infused intravenously over 60 min twice daily to 5 patients with a chronic respiratory disease for 3-7 days. The concentration of MINO in sputum and in serum was determined on day 3. The mean maximum concentration of MINO in sputum sample was 2.12 ± 2.20 μg/g, and the mean sputum/serum ratio of MINO concentration was 0.56 ± 0.47. The concentration of MINO in sputum showed little time-related variation and remained as high as 0.74 μg/g until 10 h after infusion. The concentration of MINO in sputum and in serum after intravenous drip infusion was about twice as high as that after oral administration at the same dose. The breakpoint was 1.88 for MINO, as calculated by the formula established by the Japan Society of Chemotherapy.
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