▁ ▁One ▁of ▁the ▁more ▁lip oph il ic ▁bar bit ur ates , ▁but ab ar b ital ▁cross es ▁the ▁blood ▁brain ▁bar rier ▁with ▁relative ▁ease , ▁and ▁is ▁slightly ▁more ▁pot ent ▁then ▁other ▁less ▁lip oph il ic ▁bar bit ur ates ▁such ▁as ▁phen obar b ital . ▁But ab ar b ital , ▁a ▁weak ▁acid , ▁is ▁most ▁commonly ▁admin ister ed ▁or ally ▁in ▁its ▁sod ium ▁salt ▁form . ▁ 3 – 4 ▁hours ▁after ▁or al ▁administration ▁but ab ar b ital ▁sod ium ▁reaches ▁peak ▁pl ama ▁concentr ations ▁of ▁ 2 0 3   ug / m L ▁for ▁sed ation , ▁or ▁ 2 5   ug / m L ▁to ▁indu ce ▁sleep , ▁absor bed ▁via ▁the ▁G I ▁tract . ▁ ▁Once ▁absor bed , ▁but ab ar b ital ’ s ▁effects ▁have ▁a ▁duration ▁of ▁ 6 – 8 ▁hours ▁if ▁or ally ▁admin ister ed , ▁or ▁ 3 – 6 ▁hours ▁following ▁int rav aneous ▁administration . ▁ ▁General ▁cons ensus ▁has ▁it ▁with ▁a ▁half - life ▁of ▁approximately ▁ 1 0 0 hr , ▁however ▁it ▁has ▁also ▁been ▁reported ▁in ▁one ▁study ▁to ▁have ▁a ▁half ▁life ▁of ▁ 3 4 - 4 2 ▁hr . ▁ ▁The ▁primary ▁way ▁the ▁body ▁termin ates ▁activity ▁is ▁by ▁ox id ation ▁of ▁radical s ▁at ▁C 5 , ▁with ▁other ▁bi otr ans form ations ▁contrib uting ▁to ▁a ▁less