Opioid: toward an effective strategy for better use

Effect of Intranasal Ketamine on Pain Intensity after Cesarean Section: A Single-Center, Double Blind, Randomized Controlled Trial

Background

Although intravenous or intramuscular opioids are widely used for managing postoperative pain after cesarean section (CS), their side effects are bothering and limit their use. The aim of this study was to determine the effect of intranasal ketamine on pain intensity after CS.

Methods

In a single-center, double-blind, parallel-group, randomized controlled trial, a total of 120 patients who were scheduled for elective CS were randomly assigned into two groups. After birth, 1 mg of midazolam was administered to all patients. In addition, 1 mg/kg intranasal ketamine was administered to patients in the intervention group. For patients in control group, normal saline was administered intranasally as a placebo. The severity of pain and nausea in the two groups was evaluated after 15, 30 and 60 minutes, as well as 2, 6 and 12 hours after the initial administration of the medications.

Results

The trend of changes in pain intensity was decreasing and these changes were statistically significant (time effect; P<0.001). The pain intensity in the placebo group was higher than the intervention and the observed difference was statistically significant, regardless of the time studied (group effect; P<0.001). In addition, it was shown that regardless of the study group, the trend of changes in nausea severity was decreasing and these changes were statistically significant (time effect; P<0.001). Regardless of the time studied, the severity of nausea in the placebo group was higher than the intervention group (group effect; P<0.001).

Conclusions

According to the results of this study, it seems that the using of intranasal ketamine (1 mg/kg), can be considered as an effective, well tolerated and safe method in reducing pain intensity as well as the need for postoperative opioid consumption after CS.

Comparison of Antinociceptive Effect of Octreotide With Morphine in a Rat Model of Acute Inflammatory Pain

Background:

Opioids such as morphine are used for treating moderate to severe pain. However, they also produce adverse effects such as nausea, constipation, addiction, and respiratory depression. Thus, other suitable analgesics need to be identified. Somatostatin is an inhibitory neuropeptide that modulates the transmission of pain. However, the half-life of somatostatin is short. In the present study, the antinociceptive effect of octreotide (a stable long-acting analog of somatostatin) was evaluated in rats with acute inflammatory pain.

Methods:

Sprague Dawley rats (n = 42) were divided into control (n = 6) and carrageenan injected groups (n = 36). The carrageena group was divided into three equal subgroups and treated with saline, morphine (10 mg/kg), and octreotide (3 µg). Rats belonging to each subgroup (n = 12) were again randomly divided into two equal sets. They were subjected to (a) behavioral evaluation of pain (allodynia) and estimation of paw edema, followed by immunohistochemical analysis of the expression of somatostatin type 2 receptor (sst2r) in the spinal cord and (b) estimation of open-field activity. Allodynia and paw edema were measured by von Frey filaments and plethysmometer, respectively, at 3 and 4 h after carrageenan injection. Expression of sst2r was examined after 24 hours, whereas open-field activity was evaluated after 3 hours.

Results:

In comparison to the saline-treated group, allodynia was partially attenuated by octreotide, though this was almost completely reversed by morphine. Paw edema was unaffected by octreotide, though it was marginally increased by morphine. This was not related to increased activity of rats, following relief from pain. Immunohistochemistry revealed a significant increase in the expression of sst2r in saline-treated rats, but a decrease in other groups.

Conclusion:

Octreotide has an antinociceptive effect, which was less than morphine. Increased edema following morphine could result from venodilation. Variations in the sst2r expression suggest its involvement in pain modulation at the spinal level. This information may have clinical relevance.

Patients' perception about opioids and addiction in South Korea

Background

Chronic pain affects approximately 22% of the world’s population. Opioids can be useful in chronic pain management. However, some patients have negative perception of opioids. The purpose of this research was to evaluate patients’ perception about opioids and investigate problems associated with prescribing and taking opioids in South Korea.

Methods

Patients who visited a pain clinic in 14 university hospitals of South Korea from September through October 2018 were asked to complete anonymous questionnaires about taking opioids.

Results

Of the 368 patients that were surveyed (female 53.3%, male 46.7%), 56.8% were prescribed opioids. In the opioid group, 92.8% patients had heard of opioids from their doctor and 72.6% of them had a positive perception about opioids. The side effects associated with opioid use were constipation (35.4%), dizziness (24.6%), nausea and vomiting (17.4%), dysuria (6.2%), and addiction (2.0%). In the no opioid group, the primary sources of information about opioids were doctors (49.2%), mass media (30.8%), and the internet (16.2%). The main reasons why 39.0% patients did not take opioids were fear of addiction (57.7%) and side effects (38.5%). There were 71.5% and 60.9% patients in the opioid and no opioid group, respectively, who wished to take opioids when their numeric rating scale pain score was ≥ 7.

Conclusions

Perception of opioids among patients who take them was either neutral or positive. However, 39.0% patients who have not been prescribed opioids did not want an opioid prescription, citing fear of addiction and side effects as the primary reasons.

Agomelatine potentiates anti-nociceptive effects of morphine in a mice model for diabetic neuropathy: involvement of NMDA receptor subtype NR1 within the raphe nucleus and periaqueductal grey

OBJECTIVES

Opioid analgesics have been used for a long time in the treatment of acute and chronic pain. However, they have many side effects including tolerance development to a significant extent. Agomelatine, an atypical antidepressant, has been demonstrated to be effective in experimental studies on pain. However, the effect of agomelatine on morphine tolerance development and its mechanism of action are unknown. The antinociceptive effects of agomelatine, morphine and their combination were assessed in a mice model for painful diabetic neuropathy. The roles of glutamate ionotropic receptor N-methyl-D-aspartate (NMDA) type subunit-1 (GluN1) in raphe nucleus and periaqueductal gray (PAG) in the effect of agomelatine on neuropathic pain were also investigated in diabetic mice.

METHODS

Agomelatine (10 mg/kg), morphine (10 mg/kg) and agomelatine + morphine were administered intraperitoneally for 15 consecutive days (twice per day), and the analgesic responses were assessed at days 1, 3, 6, 9, 12 and 15 in healthy and diabetic mice. Real time polymerase chain reaction (RT-PCR) was used to determine the changes in GluN1 expression.

RESULTS

The tolerance development for morphine was evident, started at 6th day and remained thereafter, but not for agomelatine. GluN1 in raphe nucleus and PAG was upregulated in morphine treated but not in agomelatine-treated groups.

DISCUSSION

The combination of agomelatine with morphine alone causes outlasting analgesic effects of repeated treatment, which can be interpreted as attenuated tolerance. Moreover, we also pointed out for the first time the modulatory effects of agomelatine on GluN1 expression in raphe nucleus and PAG after chronic morphine treatment.

ABBREVIATIONS

Ca²⁺: Calcium; D2DR: Dopamine D2 receptor; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; GluN1: Glutamate ionotropic receptor N-methyl-D-aspartate type subunit-1; 5-HT: 5-hydroxytryptamine; i.p.: intraperitoneal injection; MPE: Maximal possible effect; MT: Melatonin; NMDA: N-methyl-D-aspartate; NMDAR1: NMDA receptors-1; PAG: Periaqueductal grey; PKCγ: Protein kinase C gamma; RT-PCR: Real time polymerase chain reaction; STZ: Streptozotocin.

Medicolegal Consideration to Prevent Medical Malpractice Regarding Opioid Administration: An Analysis of Judicial Opinion in South Korea

PURPOSE

Although the use of opioids is increasing in South Korea, there have been no studies on the serious complications caused by the opioids. The aim of this study was to investigate the rare but serious complications through medicolegal analysis.

MATERIALS AND METHODS

From January 1994 to December 2019, we retrospectively reviewed the closed cases of lawsuits involving the complications of opioids using the database of judgments of the Supreme Court of Korea. General characteristics, opioid-induced complications, and judicial characteristics were analyzed.

RESULTS

Of the 46 cases, 31 cases of complications were finally included in the analysis. There were 28 (90.3%) cases of opioid administration for acute pain and 3 (9.7%) cases for chronic pain. The most commonly prescribed opioid was pethidine (n = 13, 41.9%), and the most common complication was respiratory depression (n = 17, 54.8%). All except two cases were associated with permanent injuries, including 18 (58%) deaths. Twelve (38.7%) cases were ruled in favor of the plaintiff in the claims for damages, with a median payment of United States dollar (USD) 126,346 (IQR: USD 77,275-379,219). Of these cases, the most frequently admitted complaint by the court was the neglect of observation (n = 10, 32.3%), followed by the inappropriate drug choice (n = 4, 12.9%). Eleven (36.7%) cases were plaintiffs' claims for violating explanation obligations, of which 2 (6.7%) were recognized in the court.

CONCLUSION

Our results suggest that physicians must be aware of the serious complications related to opioids and health policies to prevent such complications and malpractice should be adopted.