[Pulmonary diffusion of gentamicin administered by the direct intravenous route]

Gentamicin diffusion in pulmonary parenchyma was studied in 10 adult patients with normal renal functions before undergoing thoracic surgery. This aminoside was given in a one time dose of 120 mg directly and by way of IV route in 10 min time; blood samples from peripheral and pulmonary sources were drawn at regular intervals between the 10 min period and the 8th hr; parenchymal samples were collected 1 and 2 hrs after drug administration. After separation of residual blood by centrifugation at high speed, the tissues are grinded and homogenized. The assay was performed with an immunological method using a fluorescent polarized detection system. Tissue levels were low in all the patients (0.5 to 2.75 micrograms/g of fresh tissue) and this in spite of the high level of blood collected throughout the administration protocol. As a rule, the relation between tissue/blood is lower than those discussed in literature concerning bronchial secretion. Beside this, the concentrations are similar in peripheral and pulmonary blood collected. Practical conclusions are drawn for therapeutic purpose.