Friday, October 22, 2010

Anti-Abuse Mechanisms: TIMERx and OxyContin OP

In James Fogle's classic autobigraphical novel Drugstore Cowboy "blues" - Numorphan tablets containing 10mg of oxymorphone - are the Holy Grail of drugstore heists.  Containing few binders, these little azure beauties dissolved easily in water and made for the greatest (and not infrequently the last) rush of a junkie's shooting career.  In 1972 Numorphan tablets were pulled off pharmacy shelves, thanks to a rash of abuse-related deaths.

When Endo Pharmaceuticals decided to re-introduce oxymorphone to the market as Opana ER (Extended Release)®, they employed TIMERx®, a drug delivery system created by Penwest.  TIMERx tablets contain xanthan and locust bean gum. When swallowed, these components become a tight, thick gel which slowly releases oxymorphone into the patient's system.  This allows for steady, gradual dosing. It also makes it nearly impossible to use Opana ER intravenously.  When water is added to the powdered tablet, it becomes a needle-clogging gel which cannot be drawn up into a syringe or injected into a vein.  

Alas, an Opana ER tablet can be insufflated if it is powdered and kept dry: while there will be some gelling in the nose, plenty of oxymorphone will still reach the bloodstream through the sinuses.  And as the gel goes into the stomach via post-nasal drip, it will continue to have an effect.   While oxymorphone has a low oral bioavailability - roughly 90% is digested via "first pass" metabolism before entering the system - it is still twice as powerful milligram for milligram as a comparable dose of oxycodone. Snorted Opana has become very popular amongst many opiate afficionados for its long-lasting and euphoric high: quite a few of said afficionados have found themselves facing a harsh withdrawal when their Opana supply ran out. 

Purdue Pharma is still stinging from the debacle surrounding their "abuse-proof" oxycodone formulation, OxyContin®.  Soon after its release users discovered that one could gain instant access to the active ingredient merely by crushing the pill.  Many took to shooting them up as a supposedly "safer" alternative to street heroin.  (In fact, IV usage of pills is extremely dangerous: talcosis, abscesses and other damage can result). Others snorted them to gain a slightly quicker rate of onset, despite the risks associated with that mode of usage.

The newest formulation of OxyContin, OxyContin OP, is a plastic matrix shot through with oxycodone.  The tablets are nearly impossible to crush and can only be shaved into flakes through hard work with a hose clamp, file or similar object.  They also gel when exposed to water: people who have tried snorting them report near-suffocation as their nose became clogged by a gluey substance with the texture of hot mozzarella cheese. As a result, OPs are not favored by those who use OxyContins recreationally. After their release the price of the original formulation rose to as much as $120 for an OC 80, while OP 80s could be had for $15 to $20. 

Unfortunately, OxyContin OPs have fallen out of favor with many chronic pain patients as well.  Many report the undigestible pills cause serious stomach upset.  Others claim they are considerably less effective for pain management. Many recreational users have put their minds to breaking the polymer matrix by microwaving and freezing, soaking it in Coca Cola,  using chemicals like acetone and MEK, placing them in epsom salts, or other equally ingenious methods. So far the results have been mixed: some users have injured themselves trying to IV the results of their home chemistry experiments, while others have turned to heroin as a cheaper, easily available substitute.

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