apparent affinities ( pa2 ) for antagonists , estimated by their capacity to prevent the effects of the opioid agonist alfentanil , were : naltrexone = 8.69 , naloxone = 7.78 , quadazocine = 7.55 , nalorphine = 7.31 and naltrindole = 5.29 .
C0027360
naltrexone
C0027358
naloxone