Conversion ratios for opioid switching: a pragmatic study

Initial dose of tapentadol and concomitant use of duloxetine are associated with delirium occurring after initiation of tapentadol therapy in cancer patients

OBJECTIVE

Tapentadol causes fewer gastrointestinal adverse events than other potent opioid analgesics because of its low affinity for opioid receptors; however, development of symptoms related to central nervous system disorders, including delirium, has not been well-studied. This study aimed to identify the factors that influence the development of delirium after initiation of tapentadol therapy in hospitalized patients with cancer.

DESIGN

Retrospective study.

SETTING/PATIENTS

Among 93 patients, for whom treatment using tapentadol was initiated between December 1, 2017, and November 30, 2019, at a single center in Japan, 86 met the inclusion criteria and were enrolled in this study.

MAIN OUTCOME MEASURES

Delirium occurring within 2 weeks of initiation of the tapentadol treatment was diagnosed by a physician or nurse. Patient background information was obtained, including data on age, sex, medical history, adverse events, starting dose of tapentadol, and concomitant medications.

RESULTS

Age ≥ 67 years, male sex, somnolence after initiation of tapentadol therapy, dose of ≥300 mg/day at the beginning of tapentadol therapy, switching from potent opioids, and concomitant use of duloxetine were associated with delirium occurring after tapentadol therapy initiation.

CONCLUSIONS

Among the factors associated with the incidence of delirium after the initiation of tapentadol therapy, patients whose starting dose of tapentadol was 300 mg/day or higher and those receiving concomitant duloxetine, a serotonin-noradrenaline reuptake inhibitor, were at high risk of developing delirium. These findings will help healthcare providers, including pharmacists, in development of treatment plans for preventing delirium when initiating tapentadol therapy in patients with cancer.

Is personal physiology-based rapid prediction digital twin for minimal effective fentanyl dose better than standard practice: a pilot study protocol

INTRODUCTION

Patients with advanced cancer frequently suffer from chronic, severe disabling pain. Opioids such as morphine and fentanyl are commonly used to manage this pain. Transdermal drug delivery systems are important technologies for administering drugs in a non-invasive, continuous and controlled manner. Due to the narrow therapeutic range of fentanyl, individualised dosing is essential to avoid underdosing or overdosing. Standard clinical calculation tools for opioid rotation however do not include important patient characteristics that account for interindividual variability of opioid pharmacology.

METHODS AND ANALYSIS

We developed a clinical protocol to optimise individual fentanyl dosing in patients with advanced cancer switching from oral or intravenous opioids to transdermal fentanyl by using a physics-based digital twin (DT) that is fed by important clinical and physiological parameters. Individual tailoring of transdermal fentanyl therapy is an approach with the potential for personalised and effective care with an improved benefit-risk ratio. However, clinical validation of physics-based digital twins (PBDT) dosing is crucial to proving clinical benefit.Therapeutic drug monitoring will allow to validate the accuracy of PBDT predictions. Additional monitoring for breathing dynamics, sequential pain levels and fentanyl-related adverse events will contribute to evaluating the performance of PBDT-based dosing of transdermal fentanyl. The primary objective of the study is to develop an experimental protocol to validate DT-guided fentanyl dosing in patients with advanced cancer. This clinical study will bring individualised opioid dosing closer to clinical practice.

ETHICS AND DISSEMINATION

Study documents have been approved by the responsible Ethics Committee and study initiation is planned for late summer 2024. Data will be shared with the scientific community no more than 1 year following completion of the study and data assembly.

Implementing physics-based digital patient twins to tailor the switch of oral morphine to transdermal fentanyl patches based on patient physiology

Fentanyl transdermal patches are widely implemented for cancer-induced pain treatment due to the high potency of fentanyl and gradual drug release. However, transdermal fentanyl up-titration for opioid-naïve patients is difficult, which is why opioid treatment is often started with oral/iv morphine. Based on the daily dose of morphine, the initial dose of the fentanyl patch is decided upon. After reaching a stable level of pain, the switch is made from oral/iv morphine to transdermal fentanyl. There are standard calculation tools for transferring from oral/iv morphine to transdermal fentanyl, which is the same for all patients. By considering the variations in the physiology of the patients, a unique switching strategy cannot meet the needs of different patients. This study explores the outcome in terms of pain relief and minute ventilation during opioid therapy. For this, we used physics-based simulations on a virtually-generated population of patients, and we applied the same therapy to all patients. We could show that patients' physiology, such as gender, age, and weight, greatly impact the outcome of the therapy; as such, the correlation coefficient between pain intensity and age is 0.89, and the correlation coefficient between patient's weight and maximum plasma concentration of morphine and fentanyl is -0.98 and -0.97. Additionally, a different combination of the duration of overlap between morphine and fentanyl therapy with different doses of fentanyl was considered for the virtual patients to find the best opioid-switching strategy for each patient. We explored the impact of combining physiological features to determine the best-suited strategy for virtual patients. Our findings suggest that tailoring morphine and fentanyl therapy only based on a limited number of features is insufficient, and increasing the number of impactful physiological features positively influences the outcome of the therapy.