Bioavailability of dexmedetomidine after intranasal administration

Purpose The aim of this proof-of-concept study was to characterize the pharmacokinetics and pharmacodynamics of intranasal dexmedetomidine compared with its intravenous administration in a small number of healthy volunteers. Methods Single doses of 84 mu g of dexmedetomidine were given once intravenously and once intranasally to seven healthy men. Plasma dexmedetomidine concentrations were measured for 10 h, and pharmacokinetic variables were calculated with standard noncompartmental methods. Heart rate, blood pressure, concentrations of adrenaline and noradrenaline in plasma, and central nervous system drug effects (with the Maddox wing, Bispectral Index, and three visual analog scales) were monitored to assess the pharmacological effects of dexmedetomidine. Results Six individuals were included in the analyses. Following intranasal administration, peak plasma concentrations of dexmedetomidine were reached in 38 (15-60) min and its absolute bioavailability was 65% (35-93%) (medians and ranges). Pharmacological effects were similar with both routes of administration, but their onset was more rapid after intravenous administration. Conclusions Dexmedetomidine is rather rapidly and efficiently absorbed after intranasal administration. Compared with intravenous administration, intranasal administration may be a feasible alternative in patients requiring light sedation.