Pharmacokinetics of DGAVP in plasma following intranasal and oral administration to healthy subjects.

A pharmacokinetic study was carried out to assess the bioavailability of desglycinamide-[Arg8]vasopressin (DGAVP, Org 5667). DGAVP (2 mg) was administered both intranasally and orally to healthy subjects with a treatment interval of 1 week. Blood samples were taken regularly between 15 min before and 210 min after administration and were assayed for DGAVP by radioimmunoassay. In all subjects endogenous vasopressin (AVP) levels were detectable. Peak levels of DGAVP occurred at 15 min after both treatments. The mean absorption half-life was 8.7 and 7.3 min and the mean elimination half-life was 38 and 34.6 min for the intranasal and oral route of administration, respectively. The bioavailability of orally administered DGAVP was low compared with the intranasally administered drug; the relative bioavailability of oral/nasal administration was 0.7%. The results indicate that DGAVP is absorbed rapidly after both oral and intranasal administration, but the intranasal route of administration of DGAVP is 100 times more effective in increasing plasma DGAVP levels.