Absorption of iohexol from cerebrospinal fluid to blood: pharmacokinetics in humans.

The absorption of iohexol from the subarachnoid space was studied in 9 patients. Serum concentrations of iohexol were measured for a minimum of 24 hours after injection. Peak serum concentrations were observed after 2.2 (1.7-2.7) hours. The half-life of the subsequent decrease in serum concentrations was 3.4 (2.2-7.9) hours. Concentrations of iohexol in cerebrospinal fluid were 0.29-4.3 mg I/ml 24 hours after injection (7 patients). Serum and cerebrospinal fluid concentrations of iohexol are comparable to those found after intrathecal injection of metrizamide.