Opioid Taper Practices Among Clinicians

Opioid withdrawal symptoms after neurolytic splanchnic nerve block in cancer patients

PURPOSE

Few reports on opioid withdrawal (OW) due to opioid tapering in cancer patients have been published. The incidence of and risk factors for OW after neurolytic splanchnic nerve block (NSNB) are unknown. This study aimed to elucidate the incidence of and risk factors for OW among cancer patients who could have reduced opioid doses after NSNB.

METHODS

This was a multicenter, retrospective, observational study. We reviewed the medical charts of patients who underwent NSNB for intractable cancer pain at four tertiary hospitals in Yokohama City from April 2005 to October 2020. We included patients whose opioid dose was reduced by > 5 mg/day (equivalent oral morphine dose) within 14 days after NSNB. We classified the patients into two groups according to the presence or absence of OW symptoms and compared them.

RESULTS

Of the 50 patients who underwent NSNB, 24 were included in the study. OW was observed in five (20.8%) patients. Pain and opioid use duration were significantly longer in OW patients than in non-OW patients (median pain duration 689 vs. 195 days; P < 0.043 and median opioid use duration 486 vs. 136 days; P < 0.030). The opioid tapering dose was significantly larger in patients with OW than in those without OW (median opioid tapering dose 75 vs. 40 mg; P < 0.046).

CONCLUSIONS

OW was observed in 20.8% of the patients in the study. A longer pain and opioid use duration and a larger opioid tapering dose may predispose patients to OW.

Weight-gain propensity and morphine withdrawal alters locomotor behavior and regional norepinephrine-related gene expression in male and female mice

Interactions between obesity and opioid use are poorly understood. The objective of this study was to determine whether phenotypic differences in diet-induced weight gain altered morphine withdrawal responses. Male and female C57BL/6J mice were characterized as obese prone (OP) or obese resistant (OR) based on median split in body weights following exposure to high-fat diet (45% fat). After classification into OP or OR, all mice were fed a low-fat diet (10% fat) for the remainder of the study (≥5 weeks) to remain weight matched. Mice were treated with a 7-day escalating dosing scheme of morphine (20-100 mg/kg; IP) or saline and underwent a spontaneous withdrawal. Morphine-induced weight loss was restored by withdrawal day 7. On withdrawal day 8, male OP demonstrated less total time mobile in the open field test (OFT). In females, OR-morphine traveled less distance than OR-saline, and OR-morphine spent less time mobile compared with all other groups in the OFT. Female OP also increased time spent in the center of the apparatus, regardless of treatment. On withdrawal day 8, relative gene expression was measured by qPCR. For males, expression of dopamine beta-hydroxylase (dbh), alpha-adrenergic receptor 2 a (adra2a), and orexin receptor 1 (orx1) were increased in the locus coeruleus (LC) region of OP mice, regardless of treatment. In comparison, in females, dbh and adra2a were decreased in the LC region of OP mice, regardless of treatment. Also, in the LC region of females, OP-morphine had lower expression of alpha-adrenergic receptor 1 a (adra1a) than OR-morphine and OP-saline. In the hypothalamic paraventricular nucleus (PVN) of females, adra2a was increased in OP-morphine compared with OP-saline and OR-morphine. Our findings suggest morphine withdrawal responses and regional expression of noradrenergic-related genes are differentially influenced by weight gain propensity.