Prescription Painkillers: Companies Attempt Abuse-Proof Opioids

April 27, 2011— -- When the oxycodone brand called OxyContin was introduced in the late 1990s, its maker claimed that the drug's controlled-release mechanism would make it less likely to be abused.

The idea was that if it released its opioid slowly, rather than all at once, abusers wouldn't find the immediate rush they crave.

But it didn't take long for drug seekers to devise a workaround that foiled that plan.

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Chewing the tablet, crushing it, or dissolving and injecting it -- all destroyed the timed-release mechanism, which unpacked the full opioid punch faster than you could say, "Your brain on drugs."

Since that failed attempt at making a "safe" opioid, researchers have been experimenting with ways to make all prescription painkillers "abuse-resistant."

Although OxyContin maker Purdue had its "tamper-proof" version approved last year, few other attempts to abuse-proof these drugs have made it on the market.

In June, however, the FDA is expected to issue a decision about another oxycodone product -- Acurox, Pfizer's attempt (through the acquisition of King Pharmaceuticals) at entry into the abuse-proof market.

And a handful of other companies are pursuing a pharmacological solution to help mitigate what the federal government has described as an epidemic of prescription painkiller abuse.

Some are attempting to prevent abusers not only from inhaling and injecting the drug, but also from taking multiple pills all at once.

What's Out There

When the goal is making an opioid impenetrable to abuse, there are a host of tacks to take -- adding physical barriers to chewing, crushing, or mixing with alcohol or another liquid to separate out the active ingredient is the first line of strategy.

Another option is to combine agonists with antagonists, like adding naltrexone to oxycodone, or combining the opioid with aversive agents, like niacin.

OxyContin version 2.0 is a good example of the physical barrier strategy. It's resin-based, which not only makes it harder to pound into powder, but also makes it tougher to dissolve in water.

Another entry into the abuse-proof market, an agonist-antagonist, is the morphine sulfate-naltrexone combo marketed as Embeda. The antagonist naltrexone -- which blocks opioid receptors -- remains latent if the drug is taken as prescribed, but can reduce the effects of the morphine, or even lead to withdrawal, if crushed.

But Embeda was recently pulled from the market because of stability problems and will likely remain unavailable for many months, according to reports.

A handful of other long-acting opioids, including Tramadol, Exalgo, and Opana use other capsule manufacturing technologies to make pills crush resistant.

Next in Line

With Acurox, Pfizer tried to combine both a physical barrier and an aversive agent.

The barrier was not only designed to make the drug break down into crumbled chunks instead of powder if crushed, but also to make the drug become "sudsy" if it is mixed with liquid and drawn into a syringe, according to Dr. Gail Cawkwell, vice president of medical affairs at Pfizer.

It also contains an irritant that will affect the nose if inhaled, she said.

This is the second go-round for the Pfizer anti-abuse drug.

Last year an FDA advisory committee gave a thumbs-down to a version that also contained niacin as a means of preventing oral abuse.