To the Editor: In their randomized trial comparing dexmedetomidine vs midazolam for sedation in critically ill patients, Dr Riker and colleagues1 found dexmedetomidine to be a safe and effective alternative to midazolam. In the study methods, an optional loading dose of dexmedetomidine (up to 1 μg/kg) was allowed at the investigator's discretion, as recommended in the medication prescribing information.2 However, only 20 of 244 dexmedetomidine-treated patients (8.2%) were administered loading doses. Given the relatively low use of a loading dose, it is plausible that the results of the study may have changed if more patients had been administered loading doses. Because of the half life of dexmedetomidine (2 hours),2 without a loading dose it may take up to 10 hours for a patient to reach steady state. Clinically, this correlates with patients in the dexmedetomidine group being administered more open-label midazolam on the first day (43% vs 30%, P = .02).
Paciullo C. Comparing Dexmedetomidine With Midazolam for Sedation of Patients in the ICU. JAMA. 2009;301(23):2439-2442. doi:10.1001/jama.2009.838