Do they gel up? Crush some and add a little water and see if they turn to gel. If so, search around and you might be able to find a method to defeat that but it'll likely take some work. If they do not gel up, then they certainly have a much higher bioavailability using that route than orally so be careful if you've used them orally. Overall, oxymorphone is a very potent opioid so be careful and start low if you aren't used to it.
Using opana/oxymorphone has been covered a lot so please search around and if you still can find the precise information you're looking for, feel free to PM me or post in BDD.