Some opioid antagonists are not pure antagonists but in fact do produce some weak opioid partial agonist effects, and can produce analgesic effects when administered in high doses to opioid-naive individuals.
Does the US Navy have 10 or 19 Aircraft Carriers? The U.S. Navy operates 19 ships that could be called aircraft carriers, but only considers 10 to be actual carriers. Last week the U.S. Navy accepted USS America, first of the America-class amphibious assault ships, into service.
The USA has the main navy with nuclear-powered aircraft carriers, while both it and Russia have had nuclear-powered cruisers (USA: 9, Russia 4). The USA had built 219 nuclear-powered vessels to mid 2010, and then had five submarines and an aircraft carrier under construction.