Pharmacokinetics of oxiracetam following intravenous and oral administration in healthy volunteers.

The kinetics of oxiracetam after single intravenous and oral doses (2000 mg) were investigated in four healthy volunteers. Following intravenous administration, the decline in serum levels showed a prolonged, rapid phase followed by a delayed terminal phase. Mean residence times ranged from 3.9 to 6.5 h. Volumes of distribution ranged from 0.9 to 1.81 X kg-1, whereas clearance values ranged from 100 to 119 ml X h-1 X kg-1 More than 90% of the intravenous dose was recovered unchanged in the urine within 48 h. Oral administration resulted in peak levels within 1-2 h; thereafter, the decline in serum levels showed a pattern similar to that observed after the intravenous dose--almost 50% of the oral dose was excreted in the urine within 6 h. The absolute availability of oral oxiracetam was 75 +/- 7%.