Yes, Naltrexone can block Suboxone.
Naltrexone (Common Brands are Vivitrol and Revia) is an opioid antagonist (opioid blocker). It binds more strongly to opioid receptors in the brain compared to other opioids, including Suboxone. When administered, it will “kick out” all other opioids in the body. In case of an overdose, Naltrexone quickly reverses the effects of opioids that are causing the overdose. At the same time, it will precipitate withdrawal symptoms which can be unpleasant.
Generally, administration of Naltrexone will help to reverse the effects of Suboxone acutely if someone has overdosed. However, it is highly unusual to overdose on Suboxone alone, especially in patients who are used to opioid medications. Suboxone is sometimes used for other reasons such as alcohol use disorder, or in the treatment of fibromyalgia and other chronic pain conditions, but cannot generally be used in someone who is also on Suboxone.