The aim of this study is to investigate the comparative pharmacokinetics of intranasally and intravenously administered dexmedetomidine in healthy volunteers. The absolute bioavailability of intranasally administered dexmedetomidine will be calculated. In addition, we will report the effects of intranasally and intravenously administered dexmedetomidine on plasma catecholamine levels, systemic blood pressure, heart rate and sedation. We will also monitor the local and systemic safety and tolerability of intranasally administered dexmedetomidine.