Minimizing Opioid Risks: Two Viewpoints

Dr Steven King is commended for sharing in his recent article that benzodiazepines are contraindicated in pain management as well as for stating the merit of minimizing opioid risks by initiating opioids at the smallest possible dose with agents of the lowest potency (CONSULTANT, September 2011, page 605).1

However, Dr King mistakenly reported opioid potencies, indicating that oxymorphone, now generically available, was of low potency. The author also inaccurately reported that hydrocodone (Vicodin) and oxycodone (Percocet) were low potency while reporting that methadone and morphine are categorized as more potent opioids. Finally, the author neglected to report that buprenorphine is a high-potency opioid despite being available commercially in multiple FDA-approved formulations.

These are issues of importance as Dr King appropriately advises initiation of opioid treatment with low doses of low-potency agents to minimize iatrogenic sequelae.

Weak opioids include tramadol, tapentadol (Nucynta), and codeine, as Dr King noted. As the author reported that tapentadol characterized by 1/50th the potency of morphine, the 50 mg smallest size offers 1 mg of morphine. Codeine is felt to exert its effects via 10% biometabolism to the active agent of morphine such that 30 mg size tabs offer approximately 3 mg of morphine.

Stronger opioids of intermediately defined potency include morphine, hydrocodone (Vicodin), oxycodone (Percocet), and methadone.2

The strongest opioids include fentanyl at 60 to 80 times morphine potency, buprenorphine at up to 5000% morphine potency, hydromorphone, reportedly up to 11 times the potency of morphine, and oxymorphone at 10 times the potency of morphine.3

Opioid dose reduction via concomitant prescription of nonopioid analgesics may also diminish addiction. Dr King appropriately reported that benzodiazepines diminish opioid potency, but readers should be aware that depositing local anesthetics in proximity to nerves has been reported to potentiate opioid-mediated pain relief by up to 300%,4 thereby diminishing opioid dosing substantially with attendant minimization of risks for overdose death and addiction.

Prescription controlled drug abuse has been re- ported to be decreased by almost 50%, from 17.8% down to 9%, at abuse-vigilant interventional pain clinics where opioids are supplemental to injection techniques as op- posed to clinics where opioids constitute the sole offering by the clinicians.5

Finally, acetaminophen, similar to nerve block injections, adds to opioid potency while also minimizing abuse (addiction and/or diversion). However, Dr King endorsed the use of pure opioid, stating “you can avoid problems with acetaminophen toxicity by giving the opioid alone.” The statement is paradoxical, as Dr King subsequently appropriately advocated “if a patient requires more than 2 doses per day of an immediate- release opioid for an extended period, consider pre- scribing a long-acting opioid.”1 The incongruity exists as BID dosing of 325 mg of acetaminophen sums 650 mg, considerably lower than the 2009 revised recom- mendations of 3250 mg maximum daily acetaminophen dosing.

Furthermore, readers should appreciate that acet- aminophen-containing products such as Percocet and Vicodin have considerably less abuse potential relative to pure oxycodone or hydromorphone (Dilaudid), the biometabolite of hydrocodone. Opioids are commonly abused via snorting and doing so with acetaminophen induces oronasal fistula,6 palatal perforation,7 soft palate necrosis,8 atypical mycobacterium infection,9 and inva- sive fungal rhinosinusitis10 as potent disincentives to snort acetaminophen-containing opioids. As such, ad- dicts manipulate the unsuspecting clinician with allergy, intolerance, or end-stage hepatic failure fabrications to avoid acetaminophen-containing opioids in favor of pure opioids.

Similarly, criminals intent on diversion will prefer- entially solicit opioids bereft of acetaminophen as more illicit funds can be obtained from purchasing addicts to achieve euphoria without the tissue destruction risks of insufflating acetaminophen. For this reason, the DEA web site and New Hampshire Board of Phar- macy independently verify the higher street value of pure opioids relative to acetaminophen-containing opioid medications.

The evidence is sufficiently substantial to discourage prescribing pure opioids that the June 2010 issue of Practical Pain Management reported that Tennessee Board of Medical Examiner guidelines indicate that pure oxycodone is not recommended to be prescribed.11 Of note, the same published guidelines endorse Dr King’s recommendation to limit short half-life opioids to BID dosing.