Should the dosage of controlled-release oxycodone in advanced cancer be modified on the basis of patient characteristics?

Identifying risk factors for opioid-induced neurotoxicity in cancer patients receiving oxycodone

PURPOSE

The aim of this study was to determine the frequency of opioid-induced neurotoxicity (OIN) in cancer patients receiving oral controlled-release oxycodone and to define risk factors for OIN.

METHODS

This was a single-center, retrospective study of hospitalized adult cancer patients receiving oral controlled-release oxycodone between April 1, 2013, and April, 30, 2020. The onset of OIN within 30 days after oxycodone initiation in the study patients was investigated. OIN was defined as any of the following: delirium, hallucinations (visual or auditory), seizure, myoclonus, hyperesthesia, and excessive somnolence. Multivariate logistic regression analysis was performed to identify risk factors for OIN in patients receiving oxycodone.

RESULTS

In total, 520 patients were included in this study. The number of patients with OIN was 65 (12.5%). The median time until onset of OIN after oxycodone initiation was 7.5 days. Multivariate logistic regression analysis revealed that age ≥ 65 years (OR = 2.74, 95% CI [1.30-5.78], p = 0.008), total bilirubin ≥ 1.3 mg/dL (OR = 4.85, 95% CI [2.13-11.0], p < 0.001), and concomitant use of pregabalin or mirogabalin (OR = 3.11, 95% CI [1.47-6.61], p = 0.003) were significant independent risk factors for OIN.

CONCLUSION

Age ≥ 65 years, liver dysfunction, and concomitant use of pregabalin or mirogabalin were independent risk factors for OIN in patients receiving oxycodone. Patients with these risk factors who are receiving oxycodone should be monitored for OIN, especially early in the administration of oxycodone.

Oxycodone Effect on Pupil Constriction in Recreational Opioid Users: A Pharmacokinetic/Pharmacodynamic Meta-Analysis Approach

INTRODUCTION

Understanding the effect of oxycodone pharmacokinetics (PK) on µ-opioid receptor binding benefits from an integrated approach to compiling the results of multiple studies. The current pharmacokinetic/pharmacodynamic (PK/PD) model analysis brings together various studies to support the interpretation of newly collected PK/PD data, putting the new results into the perspective of the full concentration-effect curve.

METHODS

A two-step modeling approach was applied to characterize the PK of oxycodone and its PK/PD relationship for the pupil diameter as a biomarker for µ-opioid receptor binding in recreational opioid users. First, a model-based meta-analysis (MBMA) was used to quantify the state-of-the-art knowledge from seven published studies, each of which contained part of the data needed for full characterization. Subsequently, the estimated parameters with uncertainty from the MBMA were used as prior information for a model developed on newly collected clinical data after intranasal administration in a clinical abuse potential trial.

RESULTS

The inclusion of intravenous data in the MBMA showed that the PK of oxycodone can be described by a two-compartmental model, and allowed for the estimation of absolute bioavailability after intranasal and oral administration. A hysteresis loop was observed when plotting plasma concentrations and pupil constriction, which was approximated using an effect compartment. The totality of literature data enabled the identification of a Hill equation for the drug effect. The model with prior information fitted successfully to the newly collected data, where most parameter estimates had their confidence intervals overlapping with the prior distribution. The new data led to a slightly lower intranasal absorption rate constant, explaining the longer apparent half-life of oxycodone in the newly collected data. The PK/PD model parameters were confirmed by the new data, leading to the following estimates: half maximal inhibitory concentration (IC₅₀) of 26.5 ng/mL, maximum pupil restriction of 66.0% from baseline, and a Hill factor of 1.05.

CONCLUSIONS

The new data confirmed the PK profile and the PK/PD relationship identified using the MBMA, resulting in similar parameter estimates except for the intranasal absorption rate constant. The latter was lower than in the MBMA and explained the slightly longer apparent half-life of oxycodone in the newly collected data.

Gender difference in prescription opioid abuse: A focus on oxycodone and hydrocodone

Several data gathered in the last decade indicate an increase of abuse of prescription opioid drugs oxycodone (OXY) and hydrocodone (HYDRO) in women. However, to date there are no conclusive evidences investigating the gender-dependent abuse liability of prescription opioids. This study aims to supply a specific focus on women's data through a selective summary of the literature analyzing gender differences in the pharmacokinetic and pharmacodynamic dimension of OXY and HYDRO. Findings from this study suggest that the majority of OXY and HYDRO pharmacokinetic and pharmacodynamic effects do not differ according to gender, though confirming a significant difference in the incidence of adverse effects as demonstrated by the increased gastrointestinal adverse reactions in female subjects. Although the majority of recent clinical studies include an equal number of female and male subjects, the main outcome parameters do not relate specifically to gender differences. Due to the gender influence in activity of CYP3A4 and its crucial role in metabolism of both OXY than HYDRO, we suggest that assessing pharmacokinetic and pharmacodynamic interactions in clinical studies may be useful to clarify the effect of the higher CYP3A4 activity in female in relation to CYP2D6 genotype. Overall, considering the paucity of data regarding gender differences in European Union, this work highlights that impact of new abuse deterrent formulations should be assessed with a special focus on data concerning female subjects.

Pharmacokinetics of oxycodone after intravenous and subcutaneous administration in Japanese patients with cancer pain

ABSTRACT In Japan, Oxycodone hydrochloride injection formulation has been approved in 2012. However, its pharmacokinetics has been poorly studied. The aim of this study is to evaluate the pharmacokinetics of oxycodone after intravenous and subcutaneous administration of oxycodone hydrochloride injection in Japanese patients with cancer pain. Noncompartmental analysis and population pharmacokinetic analysis were performed. We conducted a multicenter open-label study of oxycodone hydrochloride administered as constant infusion with the dose titrated individually according to the pain intensity in patients with cancer pain. Pharmacokinetic parameters for plasma oxycodone and its metabolites were estimated using pharmacokinetics of oxycodone was evaluated using a total of 344 plasma concentrations obtained from 89 patients. The estimated geometric mean clearance (CL) of oxycodone was 24.3 L per hour after constant intravenous infusion and 29.5 L per hour after constant subcutaneous infusion, respectively. Population pharmacokinetic analysis indicated that body surface area was the influencing factor on CL and there were no pharmacokinetic differences for CL between intravenous and subcutaneous infusion. These results provide important information for the clinical use of oxycodone injection.