On subclasses of opioid analgesics

Opioids and pituitary function: expert opinion

PURPOSE

Opioids are highly addictive potent analgesics and anti-allodynics whose use has dramatically increased in recent decades. The precipitous rise in opioid dependency and opioid use disorder is an important public health challenge given the risks for severely adverse health outcomes. The long-term opioid impact on hypothalamic-pituitary axes is particularly underappreciated among both endocrinologists and primary care physicians. We review the effects of opioids on hypothalamic-pituitary-target gland function and their implications for clinical practice.

METHODS

Experts in hypothalamic-pituitary disorders and opioid pharmacology reviewed recently published literature and considered strategies for diagnosing and managing these opioid-induced endocrine effects.

RESULTS

Opioid suppression of hypothalamic-pituitary axes can lead to hypogonadotropic hypogonadism, central adrenal insufficiency, and hyperprolactinemia. These important clinical manifestations are often under-estimated, poorly evaluated, and typically either untreated or not optimally managed. Data on biochemical testing for diagnosis and on the effect of hormone replacement in these patients is limited and prospective randomized controlled studies for guiding clinical practice are lacking.

CONCLUSIONS

Patients should be informed about risks for hypogonadism, adrenal insufficiency, and hyperprolactinemia, and encouraged to report associated symptoms. Based on currently available evidence, we recommend clinical and biochemical evaluation for potential central adrenal insufficiency, central hypogonadism, and/or hyperprolactinemia in patients chronically treated with opioids as well as the use of current expert guidelines for the diagnosis and treatment of these conditions.

Quality of life and functional outcomes with tapentadol prolonged release in chronic musculoskeletal pain: post hoc analysis

Aims: To investigate quality of life (QOL) and functionality changes in chronic pain during tapentadol prolonged release (PR) treatment. Patients & methods: Post hoc analysis of data from three Phase III trials in patients with osteoarthritis knee pain or low back pain. QOL and functionality changes were assessed by SF-36 scores. Results: All SF-36 subdomain scores improved progressively to week 3 of tapentadol titration and were sustained during 12-week maintenance treatment. Improvements in SF-36 scores were similar between tapentadol dose groups (e.g., 200 to <300 mg vs ≥500 mg), with no greater effect from higher doses. QOL and functionality improvements were consistently greater with tapentadol PR than oxycodone controlled release. Conclusion: Tapentadol PR provides consistent, clinically relevant improvements in QOL and functionality in chronic pain.

Consumption trends and prescription patterns of opioids from 2011 to 2016: a survey in a Chinese city

OBJECTIVE

Opioid consumption in China has been very less and has varied widely since 1995. The representatively high level of consumption in Mainland China has never been reported. Our aim was to describe the consumption trends and prescription patterns of opioids in Nanjing, a highly developed city of Mainland China, and compare the results with selected worldwide regions.

METHODS

Application data of opioids in 2011-2016 were extracted from the Jiangsu Medicine Information Institute. Six opioids were included. Consumption was expressed in terms of defined daily doses (DDDs), morphine equivalents (MEs) and expenditure. The correlation between consumption of opioids and gross domestic product (GDP), Human Development Index (HDI) and cancer incidence was analysed by Pearson's correlation test.

RESULTS

DDDs, expenditure and MEs of opioids were, respectively, 256.04, $599.24 and 13.07 g in 2011, and increased to 361.27, $1041.79 and 18.09 g in 2016. DDDs in Nanjing were 2.80-fold that in Mainland China, 1.42-fold that in East and South-East Asia, but only equivalent to 8.89% of the worldwide average level. From 2011 to 2016, the consumption had a linear correlation with GDP, HDI and cancer incidence (p<0.05). However, DDDs varied greatly in countries with similar GDP or HDI. Within 45 Asian countries, the GDP only contributed to 10.47% of change in DDDs, while the HDI contributed to 20.32%. Consumption of non-intravenous opioids or strong opioids always comprised majority of the total consumption. The opioids prescribed predominantly were fentanyl, oxycodone and morphine. Fentanyl and oxycodone account for most of the increase in consumption.

CONCLUSION

Opioid consumption has increased >40% from 2011 to 2016, with consumption of fentanyl and oxycodone accounting for most of that increase. The consumption in Nanjing was higher than the average Chinese level, but lower than the global average. An increase in pain control services might be needed, but this need should be highly regulated.

Analgesia, sedation, and delirium in pediatric surgical critical care

The alleviation of discomfort and distress is an essential component of the management of critically ill surgical patients. Pain and anxiety have multifocal etiologies that may be related to an underlying disease or surgical procedure, ongoing medical therapy, invasive monitors, an unfamiliar, complex and chaotic environment, as well as fear. Pharmacologic and non-pharmacologic therapies have complex risk benefit profiles. A fundamental understanding of analgesia, sedation, and delirium is essential for optimizing important outcomes in critically ill pediatric surgical patients. There has been a recent emphasis on goal directed, evidence based, and patient-centered management of the physical and psychological needs of these children. The purpose of this article is to review and summarize recent advances and describe current practice of these important subjects in the pediatric surgical intensive care environment.

Tapentadol: an analgesic that differs from classic opioids due to its noradrenergic mechanism of action

Chronic pain treatment represents one of the most complex clinical challenges and even though opioids exhibit particular efficacy on nociceptive pain, their use must be controlled to avoid the risk of adverse reactions. A useful approach, aimed at maintaining analgesia and mitigating side effects, is represented by the use of a new class of analgesics endowed of µ-opioid (MOR) receptor agonism and noradrenaline reuptake inhibition (NRI) mechanisms. Tapentadol is the progenitor of this new class of drugs called MOP-NRI. A literature review has been conducted to gain information about the efficacy and the tolerability profile of tapentadol shifting from MOR agonism (acute pain) to NRI activity (chronic pain). The tolerability and therapeutic safety of tapentadol in neuropathic pain models, as well as in clinical settings, has been analyzed showing a good gastrointestinal tolerability profile, a moderate effect on hormone levels (in healthy volunteers and in patients) and on cognitive performance, a lack of significant alteration of the electrocardiogram recording and no changes of the QT/QTc interval, a minimal effect on serotonin reuptake in vivo with a low risk of serotonin syndrome, a longer time for the onset of analgesic tolerance and a less occurrence of abuse liability compared to formulations containing other comparator compounds. Tapentadol represents a great innovation in chronic pain therapy with a unique analgesic profile different form classical opioids, therefore, thanks to its synergistic MOR-NRI action, it may be a good option for the treatment of chronic, neuropathic and mixed pain.

Anaesthetics and analgesics used in adult fish for research: A review

The number of fish used in research has increased in the last decades. Anaesthesia is required when fish must be held immobile and it is crucial to promote fish welfare, because these vertebrates can show signs of stress and/or pain during handling, transport, tagging, sampling and invasive procedures. The use of an inadequate anaesthetic protocol can compromise not only the welfare of the fish, but also the reliability of the research results. Thus, the development of suitable anaesthetic regimes for each fish species is important. This article reviews the main anaesthetic and analgesic agents used in adult fish in a research setting.

Does 'Strong Analgesic' Equal 'Strong Opioid'? Tapentadol and the Concept of 'µ-Load'

Introduction

The distinct properties of the centrally-acting analgesic tapentadol derive from the combined contributions of an opioid component and a nonopioid component. However, the opioid component’s relative contribution to analgesic and adverse effects has not previously been elucidated. Tapentadol’s analgesic effect derives from the combined contribution of an opioid mechanism and a nonopioid mechanism, the extent of which can vary for different pains. Likewise, the interaction can vary for various adverse effects. Hence, the contribution of each mechanism to adverse effects can be different from the contribution to analgesia. We here estimate the percent contribution of each component of the mechanism of action to analgesia and to adverse effects.

Areas Covered

Several approaches to in vitro and in vivo data to estimate the contribution of tapentadol’s opioid component to analgesia and to the two important opioid adverse effects, respiratory depression and constipation. The results are then compared with clinical data.

Expert Opinion

Traditional opioids, such as morphine, oxycodone, and others, produce their analgesic effects primarily through a single mechanism—the activation of µ-opioid receptors (MOR). Therefore, the contribution of the opioid component to adverse effects is 100%. In contrast, the newer strong analgesic tapentadol produces its analgesic effect via two separate and complementary analgesic mechanisms, only one of which is µ-opioid. We applied standard drug–receptor theory and novel techniques to in vitro and in vivo data to estimate by several different ways the μ-load of tapentadol (the % contribution of the opioid component to the adverse effect magnitude relative to a pure/classical µ-opioid at equianalgesia) in respiratory depression and constipation, and we compared the results to clinical evidence. The estimate is remarkably consistent over the various approaches and indicates that the μ-load of tapentadol is ≤ 40% (relative to pure MOR agonists, which have, by definition, a µ-load of 100%).

Funding

Grünenthal GmbH.

Toxicity of tapentadol: a systematic review

BACKGROUND

Tapentadol is a novel atypical opioid. Anecdotal evidence suggests that tapentadol has a lower toxicity than conventional opioids.

OBJECTIVES

To evaluate all single-drug mortality due to tapentadol and assess serious adverse events caused by tapentadol.

METHODS

The Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) reporting guidelines, an evidence-based minimum set of items for reporting in systematic reviews, were followed in this systematic review.

RESULTS

 24 peer-reviewed papers were identified. They indicate that tapentadol toxicity can cause mortality and serious adverse effects.

CONCLUSION(S)

At least four confirmed fatalities, and serious adverse effects have been documented for individuals abusing or using tapentadol as prescribed. Serious adverse effects of tapentadol use may include respiratory depression, confusion, coma, hallucination/delusion, seizures, tachycardia, hypertension, agitation, tremor, miosis, hypotension, dyspnea, electrolyte abnormality, atrial fibrillation or severe upper abdominal pain. Tapentadol is unlikely to cause serotonin syndrome. The toxicity of tapentadol is significantly less than pure mu opioids, such as oxycodone.

Nature's first "atypical opioids": Kratom and mitragynines

WHAT IS KNOWN AND OBJECTIVE

Advances in pain research have led to an understanding that many pains are driven by more than one underlying (patho)physiologic cause (ie, they are "multimechanistic") and that better pain relief is obtained with fewer adverse effects when an analgesic is correspondingly multimechanistic. At least two of the more-modern analgesics combine opioid and non-opioid mechanisms, and have become known as "atypical opioids." Less well known is that just as Nature evolved opioids, it also evolved atypical opioids, presaging modern drug discovery efforts.

COMMENT

Traditional (typical) opioids are extracts or analogs of substances derived from the poppy plant. They produce their analgesic and adverse effects primarily through a single, opioid mechanism (albeit with individual differences). Two most recent analgesics were developed to have both an opioid mechanism and, a second, non-opioid mechanism of action (inhibition of monoamine neurotransmitter reuptake). Little known is that Nature had already evolved a plant source of compounds with the same properties.

WHAT IS NEW AND CONCLUSION

As debate about the use and abuse potential of kratom swirls, conflicting, often contradicting, opinions are expressed. A review of the basic pharmacology of kratom reveals the explanation for the bifurcation in viewpoints: kratom has both opioid and non-opioid properties. Fascinatingly, just as the poppy plant (Papaver) evolved the typical opioids, Mitragyna evolved the mitragynines-Nature's "atypical opioids."

Consumption trend and prescription pattern of opioid analgesics in China from 2006 to 2015

Objectives

To investigate the consumption trend and prescription pattern of opioids in China from 2006 to 2015, and compare the results with those of selected countries and regions, and identify the pain relief level of China.

Methods

Nine different opioid drugs were included in our survey, based on the whole population of China. Consumption of each type of opioid was calculated in grams in reports of the Chinese Food and Drug Administration and the International Narcotics Control Board. Then it was converted to the terms of defined daily doses and morphine equivalents. The correlation between consumption of opioids and gross domestic product, human development index and cancer incidence was analysed by Pearson's correlation test.

Results

Defined daily doses increased by 7.89% per year since 2006, and reached 91.05 in 2015. Morphine equivalents increased by 10.57% per year since 2006, and reached 7.24 g in 2015. The average defined daily doses and morphine equivalents were 85.44 and 5.70 g respectively in 2006-2015. Annual defined daily doses of China were lower than the global average. Consumption was related to gross domestic product, but not human development index and cancer incidence. Furthermore, defined daily doses varied greatly in countries with similar gross domestic product or the human development index. Strong opioids or non-intravenous opioids always constituted the majority of opioids, and sustained an increasing tendency in consumption. The predominantly prescribed opioids were fentanyl and morphine. Consumption of oxycodone had a tendency to increase, whereas pethidine tended to decrease.

Conclusion

Consumption of opioids has shown an increasing tendency and in the meantime the prescription pattern has changed, indicating the progress of pain relief in China, though it remained far lower than the average global level.

The Basic Pharmacology of Opioids Informs the Opioid Discourse about Misuse and Abuse: A Review

Morphine and other opioids are widely used to manage moderate to severe acute pain syndromes, such as pain associated with trauma or postoperative pain, and they have been used to manage chronic pain, even chronic nonmalignant pain. However, recent years have seen a renewed recognition of the potential for overuse, misuse, and abuse of opioids. Therefore, prescribing opioids is challenging for healthcare providers in that clinical effectiveness must be balanced against negative outcomes—with the possibility that neither are achieved perfectly. The current discourse about the dual ‘epidemics’ of under-treatment of legitimate pain and the over-prescription of opioids is clouded by inadequate or inaccurate understanding of opioid drugs and the endogenous pain pathways with which they interact. An understanding of the basic pharmacology of opioids helps inform the clinician and other stakeholders about these simultaneously under- and over-used agents.