Selective Alpha 2a agonist is
Clonidine, Tizanidine are selective alpha 2 agonists. But dexmedetomidine is more selective acting on Alpha 2a receptors-cause sedation. Used as pre-anesthetic medication. Ref: H.L. Sharma 3rd ed Pg:179
Tizanidine
Terazosin
Yohimbine
Dexmedetomidine
Cardiovascular system