Switching Ratio from Parenteral to Oral Methadone 1:1.2 Is Safer Compared with Ratio 1:2 in Patients with Controlled Cancer Pain: A Multicenter Randomized-Controlled Trial (RATIOMTD-010810)

Switching to Intravenous Methadone in Advanced Cancer Patients: A Retrospective Analysis

CONTEXT

Information about opioid switching to intravenous methadone is lacking.

OBJECTIVES

The aim of this study was to assess the outcome of opioid switching to intravenous methadone (IV-ME) in patients admitted to an acute supportive/palliative care unit (ASPCU). The secondary outcome was to assess the conversion ratio from IV-ME to oral methadone at time of hospital discharge.

METHODS

We retrieved from the pharmacy registry the list of patients who were prescribed IV-ME during their ASPCU admission for a period of 47 months. Poor analgesia with previous opioids and/or adverse effects were the main indications for opioid switching. IV-ME was titrated until acceptable analgesia was achieved. The effective dose was multiplied by three to establish the intravenous daily dose, given as a continuous infusion. Doses were then changed according to the clinical needs. Once the patient was stabilized, IV-ME dose was converted to oral methadone, by using an initial ratio of 1:1.2. Further dose changes were made according to clinical needs until stabilization, before patients' discharge. Information about patients' characteristics, pain scores on the Edmonton Symptom Assessment Scale (ESAS), Memorial Delirium Assessment Scale (MDAS), Cut-down, Annoyed, Guilty, Eye-opener (CAGE) questionnaire, previous opioids and their doses, expressed as oral morphine equivalents (OME), were recorded. The effective bolus of IV-ME, initial daily infusion rate, and oral methadone doses were assessed, and conversion ratios calculated.

RESULTS

Forty-one patients were taken into consideration for the study. The mean effective bolus of IV-ME titrated for achieving acceptable analgesia was 9 mg (range 5-15 mg). The mean daily continuous infusion rate of IV-ME was 27.6 mg/day (SD 21). The mean daily dose of oral methadone at time of discharge was 46.8 mg/day (SD 43). Discharge occurred within a median of seven days (range 6-9) after admission. Previous opioid (OME)/IV-ME, oral-IV-ME, and previous opioid (OME)/oral methadone were 6.25, 1.7, and 3.7, respectively.

CONCLUSION

IV-ME dose titration followed by intravenous infusion allowed a rapid pain control in few minutes in patients with severe pain intensity, not responsive to previous opioids. Conversion to oral route was successful and facilitated home discharge. Further studies should be performed to confirm these preliminary results.

Caring for Our Patients With Opioid Use Disorder in the Perioperative Period: A Guide for the Anesthesiologist

Opioid use disorder (OUD) is a rising public health crisis, impacting millions of individuals and families worldwide. Anesthesiologists can play a key role in improving morbidity and mortality around the time of surgery by informing perioperative teams and guiding evidence-based care and access to life-saving treatment for patients with active OUD or in recovery. This article serves as an educational resource for the anesthesiologist caring for patients with OUD and is the second in a series of articles published in Anesthesia & Analgesia on the anesthetic and analgesic management of patients with substance use disorders. The article is divided into 4 sections: (1) background to OUD, treatment principles, and the anesthesiologist; (2) perioperative considerations for patients prescribed medications for OUD (MOUD); (3) perioperative considerations for patients with active, untreated OUD; and (4) nonopioid and nonpharmacologic principles of multimodal perioperative pain management for patients with untreated, active OUD, or in recovery. The article concludes with a stepwise approach for the anesthesiologist to support OUD treatment and recovery. The anesthesiologist is an important leader of the perioperative team to promote these suggested best practices and help save lives.

Intravenous Methadone for Perioperative and Chronic Cancer Pain: A Review of the Literature

Intravenous methadone may be useful in acute and chronic pain management compared with other opioids because of its pharmacokinetic and pharmacodynamic characteristics, including the long duration of effect and ability to modulate both pain stimuli propagation and analgesic descending pathways. However, methadone is underused in pain medicine because of several misperceptions. A review of studies was performed to assess data regarding the use of methadone in perioperative pain and chronic cancer pain. The majority of studies have shown that intravenous methadone produces an effective postoperative analgesia and lowers opioid consumption in the postoperative period, without more adverse effects in comparison with other opioid analgesics, and has an interesting potential to prevent persistent postoperative pain. A minority of studies investigated the use of intravenous methadone for cancer pain management. These studies were mostly case series that showed promising activities of intravenous methadone for difficult pain conditions. There is sufficient evidence suggesting that intravenous methadone is effective in perioperative pain, while more studies are needed in patients with cancer pain.

Reply to "A better interpretation of data regarding the opioid switching to methadone"

In our article ?Methadone switching for refractory cancer pain' (BMC palliative care, 2022) we explore the efficacy, safety and economics of methadone in treatment of patients with refractory cancer pain in China. Professor Mercadante provided a better interpretation of data regarding the opioid switching to methadone in the Matters Arising. In this article, we answered the questions in Mercadante et al.'s comments one by one.

What we know and what we don't know about the perioperative use of methadone in children and adolescents

Postoperative pain control is essential to optimizing patient outcomes, improving satisfaction, and allowing patients to resume their baseline functional activities. Methadone, a synthetic mu-opioid agonist, has multiple pharmacologic properties that may be optimal for perioperative use. Compared to other opioids, methadone has a longer duration of action, rapid onset, extended dosing intervals, high oral bioavailability, low cost, lack of active metabolites, and action on multiple receptors. The current literature examining the use of methadone in the perioperative care of children and adolescents is limited and most often reported within the context of spine or cardiothoracic surgery. Overall, these studies support the hypothesis that perioperative methadone in pediatric patients may decrease postoperative pain, opioid consumption, length-of-stay, and the incidence of some opioid-related side effects, like constipation and urinary retention. A variety of protocols for the perioperative use of methadone have been described, including a single intraoperative dose as well as multiple small doses within multimodal pain protocols. The superiority of these protocols has not been established. Like all opioids, methadone has a side effect profile which includes nausea, vomiting, reduced GI motility, sedation, and respiratory depression at high doses. There is also a concern that it can cause QTc prolongation in patients. The primary aim of this educational review is to examine the pharmacologic data, published perioperative protocols, dosing considerations, and risks and benefits associated with inclusion of methadone in analgesic regimens for surgical patients. A secondary aim is to introduce opportunities for research around the perioperative use of methadone in children and adolescents. Based on our review, we would prioritize establishing optimal procedure-specific methadone protocols, determining generalizability for use in routine pediatric surgeries, and investigating methadone safety and efficacy prospectively as the primary opioid for pain management in the postanesthesia care unit or postsurgical floors.

Changes of Intestinal Flora and Its Relationship with Nutritional Status for Patients with Cancer Pain

Objective. To study the changes in the intestinal flora and its relationship with nutritional status for patients with cancer pain. Methods. A prospective research method was adopted. One hundred twenty cancer patients with cancer pain were selected as the research objects, who were treated in our hospital from June 2019 to June 2020, and 120 cancer patients without cancer pain were selected as the control group, who were treated in the same period. The differences of the intestinal flora and nutritional status of patients with different severity between the observation group and the control group were compared to analyze the changes of intestinal flora in patients with cancer pain and its correlation with nutritional status. Results. Hemoglobin (HB) ( $t=17.141$ , $p\le 0.001$ ), albumin (ALB) ( $t=27.654$ , $p\le 0.001$ ), prealbumin (PAB) ( $t=96.192$ , $p\le 0.001$ ), and total protein (TP) ( $t=18.781$ , $p\le 0.001$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in HB ( $f=13.569$ , $p\le 0.001$ ), ALB ( $f=22.229$ , $p\le 0.001$ ), PAB ( $f=19.521$ , $p\le 0.001$ ), and TP ( $f=21.451$ , $p\le 0.001$ ) among patients with cancer pain of different severity. Through these two comparisons, their nutritional indicators showed a significant downward trend with the increase in the severity for cancer pain patients; the levels of Lactobacillus ( $t=2.124$ , $p=0.035$ ), Bifidobacterium ( $t=4.823$ , $p\le 0.001$ ), Enterococcus ( $t=3.578$ , $p\le 0.001$ ), and Eubacterium ( $t=2.394$ , $p=0.017$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in the levels of Lactobacillus ( $f=20.643$ , $p\le 0.001$ ), Bifidobacterium ( $f=19.129$ , $p\le 0.001$ ), Enterococcus ( $f=17.408$ , $p\le 0.001$ ), and Eubacterium ( $f=22.343$ , $p\le 0.001$ ) among patients with cancer pain of different severity. After pairwise comparison, their beneficial intestinal bacteria were significantly lower than those in the control group with the increase in pain in cancer pain patients. Nitric oxide (NO) ( $t=8.418$ , $p\le 0.001$ ), galectin-3 ( $t=14.043$ , $p\le 0.001$ ), occludin (OCLN) ( $t=47.308$ , $p\le 0.001$ ), galectin-1 ( $t=15.298$ , $p\le 0.001$ ), zonula occludens protein 1 (ZO-1) ( $t=23.093$ , $p\le 0.001$ ), and cingulin ( $t=340.198$ , $p\le 0.001$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in NO, galectin-3, OCLN, galectin-1, ZO-1, and cingulin for patients with cancer pain of different severity. By comparison, the NO, galectin-3, OCLN, galectin-1, ZO-1, and cingulin of the patients showed a significant downward trend with the aggravation of cancer pain symptoms. Through correlation analysis, the nutritional indicators of patients were positively correlated with intestinal microorganisms and intestinal barrier function. Conclusion. There was a significant correlation between the changes in intestinal flora and nutritional status for patients with cancer pain, which could be used as an important basis for improving the treatment of cancer pain.