Naltrexone (brand names – Revia, Trexan). Usually given orally as a treatment for opioid and alcohol addictions as it blocks the opioid receptors (μ, κ, δ) that are responsible for the effects of opioids. It is also thought to be partly responsible for the euphoria-invoking effects of alcohol as alcohol induces the release of endorphins which are endogenous opioids. Overdoses can be fatal by means of severe liver injury that is typical of ODs. It should not be confused with naloxone (brand name: Narcan), which is orally inactive, significantly more potent (i.e., lower doses is required to produce the same effect as a dose of naltrexone), shorter in duration and half-life and used in cases of opioid OD.