▁of ▁any ▁lig and . ▁An ▁ag on ist ▁increases ▁the ▁activity ▁of ▁a ▁re ceptor ▁above ▁its ▁bas al ▁level , ▁whereas ▁an ▁inverse ▁ag on ist ▁decre ases ▁the ▁activity ▁below ▁the ▁bas al ▁level . ▁ ▁The ▁effic acy ▁of ▁a ▁full ▁ag on ist ▁is ▁by ▁definition ▁ 1 0 0 %, ▁a ▁neutral ▁ant agon ist ▁has ▁ 0 % ▁effic acy , ▁and ▁an ▁inverse ▁ag on ist ▁has ▁< ▁ 0 % ▁( i . e ., ▁negative ) ▁effic acy . ▁ ▁Ex amples ▁Re cept ors ▁for ▁which ▁inverse ▁ag on ists ▁have ▁been ▁identified ▁include ▁the ▁G AB AA , ▁mel an oc ort in , ▁mu ▁op io id , ▁hist am ine ▁and ▁beta ▁ad r ener g ic ▁re cept ors . ▁Both ▁end ogen ous ▁and ▁ex ogen ous ▁inverse ▁ag on ists ▁have ▁been ▁identified , ▁as ▁have ▁dru gs ▁at ▁lig and ▁g ated ▁ion ▁channels ▁and ▁at ▁G ▁protein - cou ple d ▁re cept ors . ▁ ▁Lig and ▁g ated ▁ion ▁channel ▁inverse ▁ag on ists ▁ ▁An ▁example ▁of ▁a ▁re ceptor ▁site ▁that ▁poss esses ▁bas al ▁activity ▁and ▁for ▁which ▁inverse ▁ag on ists ▁have ▁been ▁identified ▁is ▁the ▁G AB AA ▁re cept ors . ▁Ag on ists ▁for ▁G AB AA ▁re cept ors ▁( such ▁as ▁mus c im ol ) ▁create ▁a ▁relax ant ▁effect , ▁whereas ▁inverse ▁ag on ists ▁have ▁ag itation ▁effects ▁( for