Regular dosing compared with as-needed dosing of opioids for management of chronic cancer pain: systematic review and meta-analysis

Effect of apatinib on the pharmacokinetics of tramadol and O-desmethyltramadol in rats

Since the combination of anticancer drugs and opioids is very common, apatinib and tramadol are likely to be used in combination clinically. This study evaluated the effects of apatinib on the pharmacokinetics of tramadol and its main metabolite O-desmethyltramadol in Sprague-Dawley (SD) rats and the inhibitory effects of apatinib on tramadol in rat liver microsomes (RLMs), human liver microsomes (HLMs) and recombinant human CYP2D6.1. The samples were determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The in vivo results showed that compared with the control group, apatinib increased the AUC(0-t), AUC(0-∞) and Cmax values of tramadol and O-desmethyltramadol, and decreased the values of VZ/F and CLz/F. In addition, the MRT(0-t), MRT(0-∞) values of O-desmethyltramadol were increased. In vitro, apatinib inhibited the metabolism of tramadol by a mixed way with IC50 of 1.927 µM in RLMs, 2.039 µM in HLMs and 15.32 µM in CYP2D6.1. In summary, according to our findings, apatinib has a strong in vitro inhibitory effect on tramadol, and apatinib can increase the analgesic effect of tramadol and O-desmethyltramadol in rats.

Continuous subcutaneous infusion for pain control in dying patients: experiences from a tertiary palliative care center

BACKGROUND

Continuous subcutaneous infusion (CSCI) via ambulatory infusion pump (AIP) is a valuable method of pain control in palliative care. When using CSCI, low-dose methadone as add-on to other opioids might be an option in complex pain situations. This study aimed to investigate the effects, and adverse effects, of CSCI for pain control in dying patients, with particular interest in methadone use.

METHODS

This was an observational cohort study. Imminently dying patients with pain, admitted to specialized palliative inpatient wards and introduced on CSCI, were monitored daily by staff for symptoms (Integrated Palliative Care Outcome Scale - IPOS), sedation (Richmond Agitation and Sedation Scale - RASS), performance status (Eastern Cooperative Oncology Group - ECOG) and delirium (Confusion Assessment Method - CAM).

RESULTS

Ninety-three patients with a median survival of 4 days were included. Of the 47 patients who survived ≥3 days, the proportion of patients with severe/overwhelming pain decreased from 45 to 19% (p < 0.001) after starting CSCI, with only a moderate increase in morphine equivalent daily dose of opioids (MEDD). Alertness was marginally decreased (1 point on the 10-point RASS scale, p = 0.001), whereas performance status and prevalence of delirium, regardless of age, remained unchanged. Both patients with methadone as add-on (MET, n = 13) and patients with only other opioids (NMET, n = 34), improved in pain control (p < 0.05 and 0.001, respectively), despite that MET patients had higher pain scores at baseline (p < 0.05) and were on a higher MEDD (240 mg vs.133 mg). No serious adverse effects demanding treatment stop were reported.

CONCLUSIONS

CSCI via AIP is an effective way to reduce pain in dying patients without increased adverse effects. Add-on methadone may be beneficial in patients with severe complex pain.