nal·trex·one 
(năl-trĕksōn)
(năl-trĕksōn)n.
A synthetic opioid antagonist, C20H23NO4, used in its hydrochloride form to treat addiction to alcohol and to opioid drugs such as heroin.
[Blend of NALOXONE and tre- (probably alteration of TRI-, from the three carbon atoms of the propyl group that distinguishes it from naloxone, of which it is a congener).]
- at (one's) expense
- at one's expense
- at (one's) fingertips
- at one's fingertips
- at (one's) leisure
- at one's leisure
- at (one's) wits' end
- at one's wits' end
- at one time
- atonic
- atonicity
- atony
- atop
- atopic
- atopy
- -ator
- atorvastatin
- -atory
- a tough row to hoe
- atovaquone
- atoxic
- ATP
- ATPase
- at peace
- at present