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OBJECTIVE	The purpose of this study was to evaluate the efficacy of once-daily guanfacine extended release ( GXR ) monotherapy administered either in the morning or evening , using a modified Conners ' Parent Rating Scale-Revised : Short Form ( CPRS-R : S ) assessed three times/day in children with attention-deficit/hyperactivity disorder ( ADHD ) .
METHODS	This multicenter , double-blind , placebo-controlled study randomized children 6-12 years of age with ADHD into three groups : GXR a.m. ( GXR in the morning and placebo in the evening ) , GXR p.m. ( placebo in the morning and GXR in the evening ) , or twice-daily placebo .
METHODS	The CPRS-R : S , administered in the morning , afternoon , and evening prior to each study visit , was a secondary measure of efficacy .
RESULTS	A total of 333 subjects were included in the analysis population ( GXR a.m. , n = 107 ; GXR p.m. , n = 114 ; placebo , n = 112 ) .
RESULTS	At visit 10 , last observation carried forward ( LOCF ) , subjects receiving GXR demonstrated significantly greater improvement from baseline in the daily mean CPRS-R : S total score , as well as in each of the morning , afternoon , and evening CPRS-R : S assessments , compared with placebo , regardless of the time of GXR administration ( p < 0.001 vs. placebo for GXR a.m. and GXR p.m. ) .
RESULTS	In addition , subjects receiving GXR showed significantly greater improvements from baseline in each subscale score ( oppositional , cognitive problems/inattention , hyperactivity , and ADHD index ) compared with those receiving placebo , regardless of time of administration ( p < 0.003 vs. placebo across all subscales for GXR a.m. and GXR p.m. ) .
CONCLUSIONS	These results provide further support for the demonstrated efficacy of once-daily GXR in reducing ADHD symptoms , and demonstrate that response is consistent throughout the day regardless of the time of administration , with improvement seen in ratings of oppositional as well as of ADHD symptoms .

