Dexmedetomidine
Dexmedetomidine. Selective α2-adrenergic agonist — sedation without respiratory depression (preserves arousability). ICU sedation… Intranasal half-life 3.1 h.
Selective α2-adrenergic agonist — sedation without respiratory depression (preserves arousability). ICU sedation alternative to benzodiazepines reduces delirium incidence; procedural sedation. Bradycardia + hypotension (especially with bolus loading).
PK: the citation supports exactly ONE of its five values. Intranasal F 0.65 is verbatim and stands, though it is a MEDIAN with a 35 to 93% range in six subjects. No volume or half-life appears in it at all: the volume is now the sum of three compartment volumes from Dyck 1993 (PMID:8098191), flagged as arithmetic rather than a quoted total but intravenous-derived and therefore safe to pair with a bioavailability, and the half-life is 3.1 h from PMID:7957520. The corrected pair implies a clearance bracketed by two independent intensive-care estimates, so it is not internally contradictory. THE EFFECT-COMPARTMENT VALUE NEEDS TWO CAVEATS IT DID NOT CARRY: its published variability is 165%, so the parameter is essentially unidentified, and it belongs only to the DELAYED SYMPATHOLYTIC limb of a biphasic blood-pressure model whose vasopressor limb is explicitly undelayed — applying it to a generic sedation effect misuses the estimate. ka 3 dropped against a stated time to peak of 38 minutes.
Pharmacokinetics
- IV — t½ 3.1 h · F 100% · Vd 208.8 L
- Intranasal — t½ 3.1 h · F 65% · Vd 208.8 L
Sources: PMID:21318594, PMID:8098191, PMID:7957520