Twelve patients will be enrolled in this study. Meropenem pharmacokinetic will be carried out during the first and second dose after 1g meropenem administration. Blood samples (approximately 3 ml) will be obtained by direct venepuncture at the following time: 0, 0.25, 0.5, 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 8, 8.5, 9, 9.5, 10, 12, 14 and 16 h.