Dexmedetomidine is an intravenous alpha-2 agonist used as a sedative infusion.  It has some uniquely useful properties, particularly that it doesn’t suppress respiration (allowing it to be safely used in non-intubated patients).  The main drawbacks of dexmedetomidine are logistic:  it is expensive and can be administered only as an IV infusion within an ED or ICU.  Oral clonidine offers some similar benefits compared to dexmedetomidine, without these logistic constraints.