ABSORPTION OF CLONAZEPAM AFTER INTRANASAL AND BUCCAL ADMINISTRATION

Serum concentrations of clonazepam after intranasal, buccal and intrav enous administration were compared in a cross-over study in seven heal thy male volunteers. Each subject received a 1.0 mg dose of clonazepam intranasally and buccally and 0.5 mg intravenously. A C-max of 6.3 +/ - 1.0 ng ml(-1) (mean; +/- s.d.) was measured 17.5 min (median) (range 15-20 min) after intranasal administration. A second peak (4.6 +/- 1. 3 ng ml(-1)) caused by oral absorption was seen after 1.7 h (range 0.7 -3.0 h). After buccal administration a C-max of 6.0 +/- 3.0 ng ml(-1) was measured after 50 min (range 30-90 min) with a second peak of 6.5 +/- 2.5 ng ml(-1) after 3.0 h (range 2.0-4.0 h). Two minutes after i.v . injection of 0.5 mg clonazepam the serum concentration was 27 +/- 18 ng ml(-1). It is concluded that intranasal clonazepam is an alternati ve to buccal administration. However, the C-max of clonazepam after in tranasal administration is not high enough to recommend the intranasal route as an alternative to intravenous injection.