1 0   m g , ▁ne b iv ol ol ▁los es ▁its ▁card io select ivity ▁and ▁blocks ▁both ▁ β 1 ▁and ▁ β 2 ▁re cept ors . ▁( Wh ile ▁the ▁recommended ▁starting ▁do se ▁of ▁ne b iv ol ol ▁is ▁ 5   m g , ▁sufficient ▁control ▁of ▁blood ▁pressure ▁may ▁require ▁dos es ▁up ▁to ▁ 4 0   m g ). ▁Furthermore , ▁ne b iv ol ol ▁is ▁also ▁not ▁card io select ive ▁when ▁taken ▁by ▁patients ▁with ▁a ▁gen etic ▁make up ▁that ▁makes ▁them ▁" po or ▁met abol izers " ▁of ▁ne b iv ol ol ▁( and ▁other ▁dru gs ) ▁or ▁with ▁C Y P 2 D 6 ▁in hib itors . ▁As ▁many ▁as ▁ 1 ▁in ▁ 1 0 ▁C au cas ian ▁people ▁and ▁even ▁more ▁black ▁people ▁are ▁poor ▁C Y P 2 D 6 ▁met abol izers ▁and ▁therefore ▁might ▁benefit ▁less ▁from ▁ne b iv ol ol ' s ▁card io select ivity ▁although ▁currently ▁there ▁are ▁no ▁directly ▁compar able ▁studies . ▁ ▁Due ▁to ▁en zym atic ▁in hib ition , ▁flu vo x am ine ▁increases ▁the ▁expos ure ▁to ▁ne b iv ol ol ▁and ▁its ▁active ▁hydro x yl ated ▁met abol ite ▁( 4 - OH - ne b iv ol ol ) ▁in ▁health y ▁volunte ers . ▁ ▁Vas od il ator ▁action ▁Neb iv ol ol ▁is ▁unique ▁as ▁a ▁beta