Pharmacokinetics and interaction pharmacodynamics of dexmedetomidine in humans

Dexmedetomidine is a potent and highly selective α2-adrenoceptor agonist with a selectivity ratio of 1600:1 (α2:α1). Dexmedetomidine is a highly lipophylic agent that is rapidly distributed to tissues with a distribution half-life (t1/2α) of approximately 6 minutes. It is extensively distributed and rapidly eliminated, with a mean elimination half-life (t1/2) of 2–2.5 hours. This rapid distribution and short elimination kinetics makes dexmedetomidine amenable to frequent titration allowing adjustability of dosage and effects. Generally, dexmedetomidine does not exhibit pharmacokinetic-based interactions; however, dosage modifications of some concomitant medications may be needed to be adjusted due primarily to common pharmacological actions of the two drugs. Dexmedetomidine is eliminated by metabolism to inactive metabolites, primarily glucuronides. Eighty to ninety percent of an administered dose is excreted in the urine and 5%–13% in the faeces.