Is oxycodone efficacy reflected in serum concentrations? A multicenter, cross-sectional study in 456 adult cancer patients

Use of CYP2D6 Inhibitors with CYP2D6 Opioids: Association with Emergency Department Visits for Pain

Hydrocodone, tramadol, codeine, and oxycodone are commonly prescribed opioids that rely on activation by cytochrome P450 2D6 (CYP2D6). CYP2D6 inhibitors can significantly decrease CYP2D6 activity, leading to reduced generation of active metabolites, and impairing pain control. To understand this impact, we assessed emergency department (ED) visits in patients initiating these CYP2D6-dependent opioids while on CYP2D6-inhibitor antidepressants vs. antidepressants that do not inhibit CYP2D6. This retrospective cohort study included adult patients prescribed CYP2D6-dependent opioids utilizing electronic health records data from the University of Florida Health (2015-2021). The association between ED visits and inhibitor exposure was tested using multivariable logistic regression. The primary analysis had 12,118 patients (72% female; mean (SD) age, 55 (13.4)) in the hydrocodone/tramadol/codeine cohort and 5,547 patients (64% female; mean (SD) age, 53.6 (14.2)) in the oxycodone cohort. Hydrocodone/tramadol/codeine-treated patients exposed to CYP2D6-inhibitor antidepressants (n = 7,043) had a higher crude rate of pain-related ED visits than those taking other antidepressants (n = 5,075) (3.28% vs. 1.87%), with an adjusted odds ratio (aOR) of 1.75 (95% CI: 1.36 to 2.24). Similarly, in the oxycodone cohort, CYP2D6-inhibitor antidepressant-exposed individuals (n = 3,206) had a higher crude rate of ED visits than individuals exposed to other antidepressants (n = 2,341) (5.02% vs. 3.37%), with aOR of 1.70 (95% CI: 1.27-2.27). Similar findings were observed in secondary and sensitivity analyses. Our findings suggest patients with concomitant use of hydrocodone/tramadol/codeine or oxycodone and CYP2D6 inhibitors have more frequent ED visits for pain, which may be due to inadequate pain control.

Oxycodone, Morphine, and Fentanyl in Patients With Chronic Pain: Proposal of Dose-Specific Concentration Ranges

BACKGROUND

Interpreting opioid concentrations is challenging because of the lack of reference ranges. Therefore, the authors aimed to propose dose-specific concentration ranges in serum for oxycodone, morphine, and fentanyl in patients with chronic pain, based on concentration measurements from a large number of patients and supported by theoretical pharmacokinetic calculations and previously published concentrations.

METHODS

The opioid concentrations in patients undergoing therapeutic drug monitoring (TDM) for various indications (TDM group) and patients with cancer (cancer group) were investigated. Patients were divided based on the daily opioid doses, and the 10th and 90th percentiles of the concentrations in each dose interval were evaluated. In addition, the expected average serum concentrations were calculated for each dose interval based on published pharmacokinetic data, and a targeted literature search for previously reported dose-specific concentrations was performed.

RESULTS

The opioid concentrations in 1054 patient samples were included: 1004 in the TDM group and 50 in the cancer group. In total, 607 oxycodone, 246 morphine, and 248 fentanyl samples were evaluated. The authors proposed dose-specific concentration ranges based mainly on 10th-90th percentiles of the concentrations measured in patient samples, whereas the calculated average concentrations and previously published concentrations were used to adjust the ranges. In general, results from calculations and concentrations retrieved from previous literature were within the 10th-90th percentiles of concentrations from patient samples. However, the lowest calculated average concentrations of fentanyl and morphine were below the 10th percentiles of patient samples in all dose groups.

CONCLUSIONS

The proposed dose-specific ranges may be useful for interpreting steady-state opioid serum concentrations in clinical and forensic settings.

Post-mortem oxycodone blood concentrations of hospitalized cancer and surgery patients compared with fatal poisonings

Oxycodone is a strong opioid drug commonly used to treat acute, cancer, and chronic non-malignant pain. In this study, all oxycodone-related medico-legal cases where death had occurred in a hospital or nursing home in Finland were investigated to determine the range of post-mortem (PM) oxycodone blood concentrations in a therapeutic setting. All toxicology cases in which oxycodone was detected in PM femoral blood during the 4-year period of 2016–2019 in Finland were retrieved from the national PM toxicology database. In this material, the 365 deceased hospital patient cases that met the study inclusion criteria were divided into four groups according to the cause and manner of death. The reference group of 121 fatal oxycodone poisoning cases comprised two groups: those with verified associated drug abuse and those without drug abuse. The median oxycodone concentration in PM blood was significantly higher in cancer patients (0.10 mg/L) than in patients with recent surgery (0.07 mg/L) or other disease (0.06 mg/L) (p < 0.05). In addition, the median oxycodone concentration was significantly lower in all hospital patient groups than in the poisoning groups, the latter displaying 0.38 mg/L (abuse) and 0.64 mg/L (no abuse) (p < 0.001). This study shows that half of the subjects in the cancer patient group had PM blood oxycodone concentrations above the typical clinical therapeutic plasma concentration range (0.005–0.10 mg/L). Appropriate medication of hospitalized surgery and cancer patients can result in concentrations of up to 0.2 and 0.6 mg/L, respectively, while higher concentrations are exceptional.

Use of opioids in patients with cancer with hepatic impairment-a systematic review

PURPOSE

Opioids are recommended for moderate-to-severe cancer pain; however, in patients with cancer, impaired hepatic function can affect opioid metabolism. The aim of this systematic review was to evaluate the evidence for the use of opioids in patients with cancer with hepatic impairment.

METHODS

A systematic review was conducted and the following databases searched: AMED (-2021), MEDLINE (-2021), EMBASECLASSIC + EMBASE (-2021) and Cochrane Central Register of Controlled Trials (-2021). Eligible studies met the following criteria: patients with cancer-related pain, taking an opioid (as defined by the WHO Guidelines for the pharmacological and radiotherapeutic management of cancer pain in adults and adolescents); >18 years of age; patients with hepatic impairment defined using recognised or study-defined definitions; clinical outcome hepatic impairment related; and primary studies. All eligible studies were appraised using the Grading of Recommendations Assessment, Development and Evaluation system.

RESULTS

Three studies (n=95) were eligible but heterogeneity meant meta-analysis was not possible. Each individual study focused on only one each of oxycodone±hydrocotarnine, oxycodone/naloxone and morphine. No recommendations could be formulated on the preferred opioid in patients with hepatic impairment.

CONCLUSIONS

Morphine is the preferred opioid in hepatic impairment owing to clinical experience and pharmacokinetics. This review, however, found little clinical evidence to support this. Dose adjustments of morphine and the oxycodone formulations reviewed remain necessary in the absence of quality evidence. Overall, the quality of existing evidence on opioid treatments in cancer pain and hepatic impairment is low and there remains a need for high-quality clinical studies examining this.

Exploring the use of extended release opioids at shortened dosing intervals in people with chronic pain and high risk medication or substance use

Background Critical attention to rational opioid prescribing has emerged from the opioid epidemic in North America. Individuals with chronic pain are prescribed extended release opioids in an effort to maintain stable drug levels and for more convenient dosing, though evidence to support improvements in pain or function is lacking. It has been observed that extended release opioid products are used at intervals shorter than recommended by product monographs. The need for shortened intervals has been linked with potential inter-patient variability in pharmacokinetics, among other rationale. Implications of shortened dosing intervals for extended release opioids have not been systematically studied. Objective The aim of this study was to characterize the use of extended release opioid formulations at shortened dosing intervals in a population of patients with chronic pain and high risk for opioid-related harms. Setting This study took place in the Interprofessional Pain and Addiction Recovery Clinic, a specialty ambulatory clinic at the Centre for Addiction and Mental Health in Toronto, Canada for adults with chronic pain and a diagnosis or suspicion of substance use disorder. Method This was a retrospective cross-sectional study. Data were collected from records of patients with assessments completed in the years 2012-2017 (n = 210). Main outcome measure Proportion of patients using extended release opioids at shortened intervals. Results Sixty-one percent of individuals using extended release opioids (n = 78) were using them at shortened intervals. This use was associated with a higher daily morphine equivalent dose (533 mg vs 236 mg, p < 0.01), use of oxycodone extended release products (50% vs. 27%, p < 0.01), a longer duration of opioid therapy (8.9 vs. 6.8 years, p = 0.03) and a diagnosis of chronic neuropathic pain (63% vs. 39%, p < 0.01), with no differences in reported pain intensities, compared with use at standard intervals. Conclusion The use of extended release opioids at shortened intervals was associated with increased daily morphine equivalent doses, thus an increased risk of opioid-related mortality. It is unlikely that of those using extended release opioids, the high proportion of use at shortened intervals is the result of inter-patient differences in metabolism alone. Further study is warranted to explore the underlying drivers and implications for people with chronic pain.

Revisiting Oxycodone Analgesia: A Review and Hypothesis

Oxycodone, a semisynthetic opioid analgesic, is widely used in clinical practice. Oxycodone and morphine seem to be equally effective and equipotent; however, morphine is 10 times more potent than oxycodone when given epidurally. This article provides an updated review of the basic pharmacology of oxycodone with a special focus on pharmacokinetic/pharmacodynamics properties. The controversy regarding oxycodone-mediated effects for visceral pain via agonism and the possible role of peripheral opioid analgesia are discussed in the present investigation in an attempt to propose a plausible explanation to the perplexing question of oxycodone analgesia.

Renal function and symptoms/adverse effects in opioid-treated patients with cancer

BACKGROUND

Renal impairment and the risk of toxicity caused by accumulation of opioids and/or active metabolites is an under-investigated issue. This study aimed at analysing if symptoms/adverse effects in opioid-treated patients with cancer were associated with renal function.

METHODS

Cross-sectional multicentre study (European Pharmacogenetic Opioid Study, 2005-2008), in which 1147 adult patients treated exclusively with only one of the most frequently reported opioids (morphine/oxycodone/fentanyl) for at least 3 days were analysed. Fatigue, nausea/vomiting, pain, loss of appetite, constipation and cognitive dysfunction were assessed (EORTC QLQ-C30). Glomerular filtration rate (GFR) was estimated using Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI Creatinine) equations.

RESULTS

Mild to severe low GFR was observed among 40-54% of patients. CG equation showed that patients with mild and moderate/severe low GFR on morphine treatment had higher odds of having severe constipation (P < 0.01) than patients with normal GFR. In addition, patients with moderate/severe low GFR on morphine treatment were more likely to have loss of appetite (P = 0.04). No other significant associations were found.

CONCLUSION

Only severe constipation and loss of appetite were associated with low GFR in patients treated with morphine. Oxycodone and fentanyl, in relation to the symptoms studied, seem to be safe as used and titrated in routine cancer pain care.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Cytochrome P450-mediated changes in oxycodone pharmacokinetics/pharmacodynamics and their clinical implications

In recent years the use of the opioid oxycodone has increased markedly and replacing morphine as the first-line choice of opioid in several countries. There are formulations for oral immediate, oral extended release and intravenous use. The bioavailability is higher than for morphine and less variable. Oxycodone is primarily metabolized in the liver by the cytochrome P450 (CYP) enzymes with CYP3A as the major metabolic pathway and CYP2D6 as the minor metabolic pathway to noroxycodone, oxymorphone and noroxymorphone. Oxycodone exerts its analgesic effect via the µ-opioid receptor. The metabolism of CYP2D6 substrates varies to a large degree between individuals as a result of allele functionality. Poor metabolizers (PM) have two non-functional alleles, extensive metabolizers (EM) are homozygous with two functional alleles or heterozygous with one functional allele and ultrarapid metabolizers (UM) have more than two functional alleles. There are pronounced interethnic differences in the allele distribution. On the basis of studies performed thus far, oxycodone concentrations in comparison with EM are similar in PM and reduced in UM. The pharmacokinetics in UM are insufficiently investigated. Simultaneous inhibition of both CYP3A and CYP2D6 results in increased oxycodone concentrations and such a combination should be avoided. A similar effect is to be expected with use of a CYP3A inhibitor in CYP2D6 PM. Concomitant use of enzyme inducers such as rifampicin, St John's wort and carbamazepine should be avoided because of the risk of subtherapeutic concentrations of oxycodone. When the dosage of morphine may result in unpredictable bioavailability, like in patients with severe hepatic cirrhosis, oxycodone might be beneficial because it has higher and less variability in bioavailability between patients than morphine.

Noninterventional observational study using high-dose controlled-release oxycodone (CR oxycodone) for cancer pain management in outpatient clinics

PURPOSE

Efficacy, safety, and quality of life (QoL) for patients receiving larger doses of controlled-release oxycodone (CR oxycodone) in outpatient clinics are evaluated.

METHODS

The use of high-dose CR oxycodone and adjuvant drugs for pain management, pain intensity, parameters associated with quality of life, and adverse effects in cancer patients treated with high-dose CR oxycodone (≥80 mg/day) was prospectively observed for 8 weeks. Data from 486 cancer patients receiving high-dose CR oxycodone were collected from 44 hospitals during the period from February 2009 to March 2010.

RESULTS

Three hundred eighteen of the total 486 patients treated with high-dose CR oxycodone were followed up for 8 weeks. Pain intensity significantly improved from a mean numeric rating scale (NRS) 5.49 to NRS 4.33 (P < 0.0001). Dosage of CR oxycodone increased from a mean of 130.0 to a mean of 174.9 (P < 0.0001). QoL including activity, walking, and sleeping significantly improved after 8 weeks. At baseline, 138 complained of adverse effects, of which constipation (30.2%) was the most common followed by dry mouth (8.8%) and dizziness (8.2%). After 8 weeks, 128 patients complained of adverse effects such as constipation (27.0%), nausea (5.7%), dry mouth (5.7%), and dizziness (5.0%). After 8 weeks of high-dose CR oxycodone, adverse effects did not increase.

CONCLUSION

This study suggests that over an 8-week period, the use of high-dose CR oxycodone for cancer pain management is efficient, safe, and tolerable in outpatient clinics.

Validation of the Polish version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care in patients with advanced cancer

BACKGROUND

Limited data exist on the validation of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care in advanced cancer patients.

AIM

To adapt the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care to the Polish clinical setting and to evaluate its psychometric properties in advanced cancer patients.

DESIGN

Two quality-of-life measurements were performed at baseline and after 7 days. The concurrent validity of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care was established by the Pearson correlation coefficients with the modified Edmonton Symptom Assessment System, the Karnofsky Performance Status and the Brief Pain Inventory - Short Form. Reliability was assessed using Cronbach's alpha coefficients and the Spearman correlation coefficients of the baseline and of the second measurement of European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care items.

SETTING/PARTICIPANTS

A total of 160 consecutive patients in one academic palliative medicine centre were included.

RESULTS

A total of 129 patients completed the study. The concurrent validity revealed significant correlations of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care pain scale with the Brief Pain Inventory - Short Form, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care symptom items with the modified Edmonton Symptom Assessment System and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care functional scales with the Karnofsky Performance Status scores. High Cronbach's alpha and standardised Cronbach's alpha values were found in the case of both functional (range: 0.830-0.925; 0.830-0.932) and symptom scales (range: 0.784-0.940; 0.794-0.941) of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care, respectively. The Spearman correlation coefficients between the first and the second measurements were significant (p < 0.0001) for all European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care items.

CONCLUSIONS

Polish version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 15 - Palliative Care is a valid and reliable tool recommended for quality-of-life assessment and monitoring in advanced cancer patients.