Efficacy and safety of oxymorphone immediate release for the treatment of mild to moderate pain after ambulatory orthopedic surgery: results of a randomized, double-blind, placebo-controlled trial

Hydrocodone, Oxycodone, and Morphine Metabolism and Drug-Drug Interactions

Awareness of drug interactions involving opioids is critical for patient treatment as they are common therapeutics used in numerous care settings, including both chronic and disease-related pain. Not only do opioids have narrow therapeutic indexes and are extensively used, but they have the potential to cause severe toxicity. Opioids are the classical pain treatment for patients who suffer from moderate to severe pain. More importantly, opioids are often prescribed in combination with multiple other drugs, especially in patient populations who typically are prescribed a large drug regimen. This review focuses on the current knowledge of common opioid drug-drug interactions (DDIs), focusing specifically on hydrocodone, oxycodone, and morphine DDIs. The DDIs covered in this review include pharmacokinetic DDI arising from enzyme inhibition or induction, primarily due to inhibition of cytochrome p450 enzymes (CYPs). However, opioids such as morphine are metabolized by uridine-5'-diphosphoglucuronosyltransferases (UGTs), principally UGT2B7, and glucuronidation is another important pathway for opioid-drug interactions. This review also covers several pharmacodynamic DDI studies as well as the basics of CYP and UGT metabolism, including detailed opioid metabolism and the potential involvement of metabolizing enzyme gene variation in DDI. Based upon the current literature, further studies are needed to fully investigate and describe the DDI potential with opioids in pain and related disease settings to improve clinical outcomes for patients. SIGNIFICANCE STATEMENT: A review of the literature focusing on drug-drug interactions involving opioids is important because they can be toxic and potentially lethal, occurring through pharmacodynamic interactions as well as pharmacokinetic interactions occurring through inhibition or induction of drug metabolism.

Relative potency of intravenous oxymorphone compared to other µ opioid agonists in humans - pilot study outcomes

AIMS

Intravenous (IV) misuse of the µ opioid analgesic oxymorphone has caused significant public health harms; however, no controlled data on its IV abuse potential are available. The primary aims of this pilot study were to directly compare IV oxymorphone to IV oxycodone, morphine, and hydromorphone on a subjective measure of drug liking and to assess relative potency.

METHODS

Participants (n = 6) with opioid use disorder, physical dependence, and current IV use completed this two-site, within-subject, double-blind, placebo-controlled, inpatient pilot study. During each session, one IV dose (mg/70 kg) was administered: oxymorphone (1.8, 3.2, 5.6, 10, 18, 32), hydromorphone (1.8, 3.2, 5.6, 10, 18), oxycodone (18, 32, 56), morphine (18, 32), and placebo. Data were collected before and for 6 h after dosing. Primary outcomes included safety/physiological effects, subjective reports of drug liking, and relative potency estimates.

RESULTS

All active test drugs produced prototypical, dose-related µ opioid agonist effects (e.g., miosis). Oxymorphone was more potent than the comparator opioids on several measures, including drug liking and respiratory depression (p < 0.05). Across abuse-related subjective outcomes, oxymorphone was 2.3-2.8-fold more potent than hydromorphone and 12.5-14-fold more potent than oxycodone (p < 0.05).

CONCLUSIONS

Despite the relatively small sample size, this pilot study detected robust oxymorphone effects. Oxymorphone was far more potent than the comparator opioids, particularly on abuse potential outcomes. Overall, these findings may help explain surveillance reports that demonstrate, after adjusting for prescription availability, oxymorphone is injected at the highest frequency, relative to other prescription opioids.

Opioid Use Is Reduced in Patients Treated with NSAIDs After Arthroscopic Bankart Repair: A Randomized Controlled Study

Purpose

To evaluate the efficacy of oral nonsteroidal anti-inflammatory drugs (NSAIDs) as the primary postoperative pain medication compared with standard oral opioids after arthroscopic shoulder capsulolabral (Bankart) repair for recurrent anterior shoulder instability.

Methods

This was a single-center, prospective, randomized controlled study. Patients aged 18 to 65 years indicated for arthroscopic shoulder capsulolabral repair for recurrent anterior shoulder instability were included. Postoperatively, patients were prescribed 1 of 2 analgesic regimens: (1) 30 ibuprofen (600 mg every 6 to 8 hours as needed) and 10 tablets of oxycodone/acetaminophen (5/325 mg every 6 hours as needed for breakthrough pain) or (2) 30 tablets oxycodone/acetaminophen (5/325 mg every 6 hours as needed). Subjects completed questionnaires at 24, 48, and 96 hours and 1 week after surgery, which included questions about analgesic medication usage, visual analog scale (VAS) pain score, incidence of adverse events, and patient satisfaction.

Results

Between December 2017 and May 2019, 80 patients (mean age 31.3 ± 10.4 years) were enrolled. Overall there were no significant differences in VAS pain score or patient satisfaction between the 2 groups. Patients in the opioid-only group had a significantly higher mean opioid consumption on postoperative days (PODs) 2 to 4 (5.5 versus 2.9, P = .05) and after 1 week (11.7 versus 7.9 tablets, P = .05) compared with patients in the NSAID group. Of patients in the NSAID group, 17.5% experienced adverse effects, compared with 35% in the opioid-only group.

Conclusions

Use of oral NSAIDs with limited breakthrough opioids results in significantly less opioid use after arthroscopic Bankart repair in the first postoperative week compared with opioids only. Both groups used limited amounts of opioids to control postoperative pain. There were no differences in pain levels at any time point postoperatively or satisfaction between patient groups.

Level of Evidence

II, nonblinded randomized control trial.

The Utility of Oral Nonsteroidal Anti-inflammatory Drugs Compared With Standard Opioids Following Arthroscopic Meniscectomy: A Prospective Observational Study

PURPOSE

To evaluate the efficacy of oral nonsteroidal anti-inflammatory drugs (NSAIDs) as the primary postoperative pain medication compared with standard oral opioids following arthroscopic partial meniscectomy.

METHODS

This was a single-center, prospective, nonrandomized, comparative observational study. Patients ages 18 to 65 years who were indicated for arthroscopic meniscectomy were included. Postoperatively, patients were prescribed 1 of 2 analgesic regimens: (1) ibuprofen (600 mg every 6-8 hours as needed) and 10 tablets of oxycodone/acetaminophen (5/325 mg as needed for breakthrough pain) or (2) 30 to 40 tablets oxycodone/acetaminophen (5/325 mg every 6 hours as needed). Subjects completed questionnaires at 8 hours, 24 hours, 48 hours, and 1 week after surgery, which included medication usage, visual analog scale pain score, incidence of adverse events, and patient satisfaction.

RESULTS

Sixty-eight patients with mean age 51.2 years (±10.4 years) were enrolled between October 2016 and February 2017. Enrollment in the opioid group continued until 30 patients were enrolled in the NSAID group, and at final analysis there were 28 patients in the NSAID group and 40 in the opioid group. There were no significant differences in sex, visual analog scale pain score, or patient satisfaction between the 2 groups at any time point. Patients in the opioid group had a significantly higher mean opioid consumption on postoperative day 1 (1.1 vs 0.5 tablets, P < .03) and postoperative days 3 to 7 (2.6 vs 0.5 tablets, P < .02) compared with NSAID group patients. There was a trend toward greater total (1 week) opioid usage (4.7 vs 2.0 tablets) in the opioid group; however, this was not statistically significant (P < .08). Fifty-three percent of opioid group patients independently chose to forego their opioid medication for an over-the-counter NSAID and/or acetaminophen instead. No patients requested a medication refill.

CONCLUSIONS

We found no significant difference in pain control, satisfaction, and total 1-week opioid use between patients prescribed NSAIDs with opioids and those prescribed opioids alone. All patients used only limited amounts of opioids to control postoperative pain, suggesting we are currently overprescribing opioids after arthroscopic partial meniscectomy.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Oral Oxymorphone for Pain Management

Objective

To describe the pharmacology, safety and efficacy, and rationale for use of oral oxymorphone for the management of acute and chronic moderate-to-severe pain.

Data Sources

A PubMed/MEDLINE search (1966-March 2007) was conducted using the following terms: oral oxymorphone, oxymorphone, EN 3202, EN 3203, Opana, and Opana ER. Manufacturer-provided data (package inserts) and abstracts presented at the American Pain Society meetings (2003–2006) were also reviewed.

Study Selection and Data Extraction

Human studies evaluating the safety and efficacy of oral oxymorphone in pain management were considered; animal and non–English-language data were excluded.

Data Synthesis

Oral oxymorphone is a semisynthetic opioid agonist that is specific for the μ-opioid receptor and approved to treat both acute and chronic pain. Unlike other opioids, such as oxycodone, oxymorphone does not bind to the κ-opioid receptor. Due to extensive liver metabolism, oral oxymorphone is contraindicated in patients with moderate-to-severe hepatic impairment; however, no clinically significant CYP3A4, 2C9, or 2D6 mediated drug-drug interactions have been noted. Elderly patients may experience a 40% increase in plasma concentrations, while renally impaired patients may have a 57–65% increase in bioavailability. Food can increase the rate of absorption by as much as 50%, necessitating dosing either 1 hour before or 2 hours after a meal. Oxymorphone's primary adverse effects are similar to those of other opioids: nausea, vomiting, pruritus, pyrexia, and constipation.

Conclusions

Oxymorphone is an oral therapeutic option approved for the treatment of acute and chronic moderate-to-severe pain. Oxymorphone has a safety and efficacy profile similar to that of other commonly used pure opioids (morphine, oxycodone, hydromorphone). Like oxycodone and morphine, oxymorphone also has immediate-release and extended-re lease formulations. Since cost alone is not yet favorable for oxymorphone over oxycodone or morphine, further studies of comparative efficacy targeting potential advantages of oxymorphone over other opioids are necessary before considering it for addition to a formulary.

Pharmacodynamic effects of oral oxymorphone: abuse liability, analgesic profile and direct physiologic effects in humans

Oxymorphone is a semisynthetic μ-opioid agonist, marketed as a prescription analgesic purported to be twice as potent as oxycodone for pain relief. Oral formulations of oxymorphone were reintroduced in the United States in 2006 and reports of abuse ensued; however, there are limited data available on its pharmacodynamic effects. The current study aimed to examine the direct physiologic effects, relative abuse liability, analgesic profile and overall pharmacodynamic potency of oxymorphone in comparison with identical doses of oxycodone. Healthy, non-dependent opioid abusers (n = 9) were enrolled in this within-subject, double-blind, placebo-controlled, 3-week inpatient study. Seven experimental sessions (6.5 hours) were conducted, during which an oral dose of immediate-release formulations of oxymorphone (10, 20 and 40 mg), oxycodone (10, 20 and 40 mg) or placebo was administered. An array of physiologic, abuse liability and experimental pain measures was collected. At identical doses, oxymorphone produced approximately twofold less potent effects on miosis, compared with oxycodone. Oxymorphone also produced lesser magnitude effects on measures of respiratory depression, two experimental pain models and observer-rated agonist effects. However, 40 mg of oxymorphone was similar to 40 mg of oxycodone on several abuse-related subjective ratings. Formal relative potency analyses were largely invalid because of the substantially greater effects of oxycodone. Overall, oxymorphone is less potent on most pharmacodynamic measures, although at higher doses, its abuse liability is similar to oxycodone. These data suggest that the published clinical equianalgesic estimates may not be consistent with the observed direct physiologic effects of opioids, results of experimental pain models or abuse liability measures, as assessed in the human laboratory.

The safety and effectiveness of a long-acting transdermal fentanyl solution compared with oxymorphone for the control of postoperative pain in dogs: a randomized, multicentered clinical study

A prospective, double-blinded, positive-controlled, multicenter, noninferiority study was conducted to evaluate the safety and effectiveness of transdermal fentanyl solution (TFS) compared with oxymorphone for the control of postoperative pain in dogs. Five hundred and two (502) client-owned dogs were assigned to a single dose of TFS (2.7 mg/kg) applied 2–4 h prior to surgery or oxymorphone hydrochloride (0.22 mg/kg) administered subcutaneously 2–4 h prior to surgery and q6h through 90 h. Pain was evaluated over 4 days by blinded observers using a modified Glasgow composite pain scale, and the a priori criteria for treatment failure was a pain score ≥8 or adverse event necessitating withdrawal. Four TFS- and eight oxymorphone-treated dogs were withdrawn due to lack of pain control. Eighteen oxymorphone-treated, but no TFS-treated dogs were withdrawn due to severe adverse events. The one-sided upper 95% confidence interval of the difference between TFS and oxymorphone treatment failure rates was −5.3%. Adverse events associated with oxymorphone were greater in number and severity compared with TFS. It was concluded that a single administration of TFS was safe and noninferior to repeated injections of oxymorphone for the control of postoperative pain over 4 days at the dose rates of both formulations used in this study.

Review of oral oxymorphone in the management of pain

Chronic cancer and nonmalignant pain (CNMP) is a common and major health problem afflicting approximately 40 million persons in the US. Most cancer patients, and many patients with CNMP, require opioid analgesics to obtain adequate pain relief. Oral oxymorphone is a new formulation of an existing parenteral opioid that has become available for the treatment of significant pain: acute postoperative, chronic arthritis, chronic low back, and chronic cancer pain. Oxymorphone is a typical mu-opioid agonist that is effective in both immediate- and extended-release (IR and ER) formulations. Oxymorphone is more lipid soluble than morphine, resulting in a rapid onset of action when given in tablet formulation, with a duration of action of approximately 4-6 hours in IR and 12 hours in ER preparations. Oxymorphone provides excellent pain relief for significant pain, with typical opioid side effects that are usually mild or moderate in intensity. Multiple double-blind, prospective, placebo-controlled clinical trials have demonstrated the clinical efficacy and safety of this new oral opioid preparation. Oral oxymorphone is an effective opioid that provides a new therapeutic option for the physician.

Use of oral oxymorphone in the elderly

OBJECTIVE

To review the pharmacodynamics, pharmacokinetics, efficacy, tolerability, dosing, and role of oral oxymorphone immediate-release (IR) and extended-release (ER).

DATA SOURCE

A MEDLINE/PUBMED search (1970 to September 2006) of English language studies. Additional references were obtained from their bibliographies.

STUDY SELECTION

All human studies of oxymorphone were reviewed.

DATA SYNTHESIS

Oral oxymorphone IR/ER tablet formulations were approved in June 2006. Oxymorphone, a semi-synthetic -opioid receptor agonist structurally similar to hydromorphone, has an oral bioavailability of approximately 10%. Oxymorphone is extensively metabolized to oxymorphone-3-glucuronide and the active 6-hydroxyoxymorphone. Rapid clearance mandates every four- to six-hour dosing (IR) and every 12-hour dosing (ER). Hepatic impairment, renal impairment, and aging enhance systemic exposure. Oxymorphone IR was superior to placebo and oxycodone IR (acute pain studies). Oxymorphone ER was superior to placebo and equivalent to oxycodone CR and morphine CR (one acute and five chronic pain studies). Oxymorphone exhibits the expected opioid side effects, being comparable to oxycodone and morphine in clinical trials. Coadministration with ethanol causes "dose-dumping" (ER) and increases intersubject variability in drug absorption. Oxymorphone IR is indicated for the relief of moderate-to-severe pain, while oxymorphone ER is indicated for persistent pain. Initial doses (opioid-naïve) are 10 mg to 20 mg every 4 to 6 hours (IR) and 5 mg every 12 hours (ER). Dosage adjustment is recommended in mild hepatic impairment (Child-Pugh class A), renal impairment (creatinine clearance below 50 mL/min), and in the elderly.

CONCLUSION

Oxymorphone is the newest oral opioid to enter a crowded marketplace now totaling 12 Schedule 2 opioids. It does not appear to have any unique assets or liabilities and should be considered as one of many oral opioids for the management of acute and persistent pain of moderate-to-severe intensity.

Ultrasound-guided infrapatellar nerve block in human volunteers: description of a novel technique

BACKGROUND

Despite the use of various treatment strategies arthroscopic knee surgery is still associated with clinically important postoperative pain. As the infrapatellar nerve (IPN) innervates vital anterior knee structures we decided to investigate the feasibility of a novel ultrasound-guided IPN block technique as a potential therapeutic option for out-patient arthroscopic knee surgery.

METHODS

The IPN was blocked under ultrasonographic guidance in 10 adult volunteers using 5 ml of levobupivacaine 5 mg ml(-1). Success rate, time to maximum cutaneous distribution of the block, distribution of cutaneous analgesia and time until full recovery of cutaneous sensation was noted as was the incidence of concomitant blockade of the saphenous nerve (SN).

RESULTS

The IPN was successfully blocked in 9/10 subjects. However, a varying degree of concomitant SN block was observed as part of all blocks. The time to maximum cutaneous distribution of the block was 8.4 (sd 3.6) min and the duration until complete recovery of cutaneous sensation was 27.5 (19.1) h.

CONCLUSION

Reliable blockade of the IPN can be achieved with ultrasonographic guidance. Because of the very close anatomical relationship between the IPN and the SN it appears inevitable to also get a variable degree of concomitant SN block. The duration of the IPN block was in the majority of subjects greater than 16 h, a finding that may make this block useful for postoperative analgesia in out-patient arthroscopic surgery.