Influence of modes of ACNU administration on tissue and blood drug concentration in malignant brain tumors.

The water-soluble nitrosourea compound ACNU is also lipid-soluble at normal physiological pH levels. It lacks toxic effects on vision that nitrosoureas occasionally produce following intra-arterial administration. In 28 cases of both primary and secondary malignant brain tumors, ACNU was administered at surgery or angiography by three different modes: intravenous injection in Group I (10 cases), intra-arterial injection via the carotid artery in Group II (11 cases), and intra-arterial injection via the carotid artery after opening the blood-brain barrier (BBB) by means of mannitol in Group III (seven cases). Tumor tissue and blood samples were taken serially at various time intervals after ACNU injection, and ACNU was measured by high-performance liquid chromatography. The time-concentration curve for ACNU was calculated in each case by the two- and one-compartment open models for determination of ACNU levels in blood and tissue, respectively. Pharmacokinetic parameters including biological half-life, blood and tissue levels (0-t minutes and 0-infinity minutes), total plasma clearance, and distribution volume of the beta phase were compared. Statistical analysis of tissue ACNU levels at 0-t minutes revealed higher concentrations in Group III patients than in Groups II and I: levels in Group II were significantly higher than in Group I. Mean biological half-life was 30.3, 23.0, and 38.5 minutes in Groups I, II, and III, respectively. Levels of ACNU were significantly increased in tumor tissue as well as in peritumoral tissue in one Group III patient with multiple metastatic anaplastic adenocarcinoma. In this series, treatment of malignant brain tumor by intra-arterial administration of ACNU produced significantly higher tissue levels of ACNU than did the systemic intravenous route.