Hey WP, Purdue first efforts to add small amounts of naltrexone, the same drug to reverse opiate overdoses that blocks opate receptors and the same drug put into Talwyn NX that is only released when the medication is tampered with and injected was their first attempt at producing a tamper proof OxyContin tablet. The initial results failed and they have not been able to find a balance of Oxycodone and the opiate antagonist Naltrexone. They found it reduced OxyContins efficacy.So it seemed to be just a matter of working out the proper math equation and proportionate amount of antagonist only to be released when the tablets is crushed.

They have been continuing to work in order to solve the math problem as to how much naltrexone to place in each tab to reduce any euphoric properties of the medication when the release system has been tampered with, and still maintain it's analgesic properties. To date they have not found the proper amount and are no further along then they were 3 years ago when they started the project to add NX to OxyContin.

I just checked Purdues Newsroom and their site is presently down. This was the top heading of the press releases but I was unable to read the article due to website difficulties, The news release is as follows
"Elite Grants Purdue Exclusive Right to Evaluate Its Abuse Resistance Drug Formulation Technology"

Granting another company use of it's technological breakthroughs, needs to be tested, trialed and recieve FDA aproval before marketed, Untill I read the article I wouldn't know what the technology is but simply obtaining the rights and sharing technology doesn't put a product immedietely on the shelf. If this technology works it could take several years to be implemented. The present generic OxySR products are usng the same "Contin" release technolgy that was patented in 1972 and expired years ago.
I'll keep looking but if you can cut and paste the info you found it would be most helpful.
Welcome and take care, Dave