Prescription opioid pharmacology: A peek into the addiction paradox
Oxycodone (common brand: OxyContin ®) and buprenorphine (common brand: Subutex ®), two narcotic analgesics implicated in the relief of moderate to severe pain, both interact with the opioid system to elicit therapeutic effects.
Surrounding a healthcare revolution that experienced a 300% increase in the sale of prescription opioids since 1999 but also nurtured a six-fold increase in heroin overdoses in that same time period, what do the pharmacological subtleties of oxycodone and buprenorphine tell us about substance abuse potential? We go over these important questions in this article, and welcome your questions in the designated section at the end of the page.
How did “The War on Drugs” become so cold?
Atlantic County, New Jersey is the epicenter of an abuse epidemic fueled by our “War on Drugs”. However, today’s battle is, simply put, different. The oppressor-versus-defender narrative that is often highlighted in times of war (images of DEA task force storming into backyard storage sheds turned laboratories and overtaking hundreds of grams of methamphetamine and thousands more in cash “for the good guys”) is absent. The Opioid Crisis in America is a very quiet and personal affair.
We carry the War on Drugs in our purses, receive once monthly autographs from the War on Drugs, and we arrange the War on Drugs in our medicine cabinets. In the wake of a healthcare revolution that experienced a 300% increase in the sale of prescription opioids since 1999, but also nurtured a six-fold increase in heroin overdoses in that same time period, how did our War on Drugs become so cold?
The pharmacology of OxyContin and buprenorphine
In an effort to better understand the battle that we fight, I turn to the pharmacology of two drugs that may sit on our shelves.
- The first is marketed as the widely popular OxyContin ®, an oxycodone hydrochloride tablet for oral administration. As an extended-release and controlled-release alternative to morphine, OxyContin ® was introduced in 1996 as a wonder drug in the treatment of moderate to severe pain.
- The second is buprenorphine, which is commonly marketed as Subutex ® or Suboxone ® although the latter is formulated in combination with naloxone. Buprenorphine is available in sublingual tablets that are marketed for the treatment of opioid dependence.
By classification, oxycodone and buprenorphine are both narcotic analgesics. By definition, narcotic analgesics are potent analgesics that are both selective central nervous system (CNS) depressants as well as effective for the relief of severe pain. For the lay public, this may come with some alarm: Is one of our most prevalent treatments for opioid dependence the prescription of another opioid? However, the unique pharmacological profiles of each drug begin to disentangle the paradoxical nature of this relationship.
Oxycodone and buprenorphine act differently in the brain
A relationship between an opioid analgesic’s mechanisms of action exists such that the type of receptor on which an opioid analgesic acts parallels, to some degree, the physiological effects that it conjures.
The opioid family is characterized by three receptor subtypes – mu, delta, and kappa, as well as the opioid-like receptors (ORL). Most opioid analgesics act primarily on mu receptors, and the physical dependence effects of these drugs are thought to be linked to mu receptor activity. While the action of an opioid analgesic is surely more dimensional that activity at a single receptor subtype, it is thought that the incidence of physical dependence could be reduced by shifting activity away from the mu opioid receptor.
The relationship between oxycodone and buprenorphine is ideal to exemplify this point.
Oxycodone is a fairly strong agonist at the mu receptor while buprenorphine exhibits only partial, much weaker agonism at the mu receptor. Moreover, buprenorphine is a fairly potent kappa and delta receptor antagonist and blocks the effect at these receptors entirely. Buprenorphine’s pharmacodynamic profile may help decrease the propensity for substance abuse, although this comes at the expensive of limited potency as an opioid analgesic and a therapeutic agent for pain management.
Opioid maintenance treatment (OMT)
OMT is widely popular nationally, and its purpose “is not to achieve a drug-free state, but to avoid illicit drug use, and to enable the person to live without the disturbances of illicit use,” (Lobmaier et al. 2010).
The pharmacology of buprenorphine has made it ideal for OMT programs because this drug requires little patient control. The turn of the millennium has morphed “illicit use” into “misuse,” and opioid analgesics such as OxyContin are widely abused. However, the unique pharmacological profile of other opioid analgesics such as buprenorphine or the buprenorphine-naloxone combination perpetuates OMT and provides potential therapeutic value to opioid-dependent individuals.
There is a difference between opioid prescription drugs…that matters!
Education on the pharmacological subtleties between different prescription opioids is imperative to dissolving the stigma associated with this class of drugs. While our War on Drug tears on, we must empower lay populations with the ability to identify and discuss the array of prescription opioids that sit on our shelves. With these skills at hand, we may be able to further understand and communicate the misuse and abuse potential of prescription opioids.
Opioid addiction paradox questions
Would you like to learn more about medications used to treat opioid addiction or have questions in mind regarding the prescription opioid epidemic? Feel free to post your questions in the comments section below. We try to provide a personal and prompt response to all legitimate inquiries. If we do not know the answer to your particular question, we will gladly refer you to someone who can help.