Discovery and development of tramadol for the treatment of pain

Tiger nut/coconut dietary intervention as antidotal nutritional remediation strategy against neurobehavioural deficits following organophosphate-induced gut-brain axis dysregulation in mice

Organophosphate poisoning remains a global health crisis without efficacious treatments to prevent neurotoxicity. We examined whether antidotal tiger nut and coconut dietary intervention could ameliorate neurobehavioral deficits from organophosphate dichlorvos-induced gut-brain axis dysregulation in a mouse model. Mice were divided into groups given control diet, dichlorvos-contaminated diets, or dichlorvos plus nut-enriched diets. They were exposed to a DDVP-contaminated diet for 4 weeks before exposure to the treatment diets for another 8 weeks. This was followed by behavioural assessments for cognitive, motor, anxiety-, and depressive-like behaviours. Faecal samples (pre- and post-treatment), as well as blood, brain, and gut tissues, were collected for biochemical assessments following euthanasia. Dichlorvos-exposed mice displayed impairments in cognition, motor function, and mood along with disrupted inflammatory and antioxidant responses, neurotrophic factor levels, and acetylcholinesterase activity in brain and intestinal tissues. Weight loss and altered short-chain fatty acid levels additionally indicated gut dysfunction. However, intervention with tiger nut and/or coconut- enriched diet after dichlorvos exposure attenuated these neurobehavioral, and biochemical alterations. Our findings demonstrate organophosphate-induced communication disruptions between the gut and brain pathways that manifest in neuropsychiatric disturbances. Overall, incorporating fibre-rich nuts may represent an antidotal dietary strategy to reduce neurotoxicity and prevent brain disorders associated with organophosphate poisoning.

Shaping the Anesthetic Approach to TricValve Implantation: Insights From a Case Series

OBJECTIVES

Caval valve implantation (CAVI) represents a minimally invasive strategy for managing severe tricuspid regurgitation in high-risk patients unsuitable for surgical or transcatheter tricuspid valve implantation. This case series aimed to assess the anesthesia management challenges and outcomes associated with this procedure, seeking to generate insights that can inform and refine anesthesia protocols.

DESIGN

A case series.

SETTING

At a cardiac catheterization laboratory of a teaching hospital.

PARTICIPANTS

Eight patients undergoing CAVI with the Tricvalve system INTERVENTIONS: The anesthetic protocol included preprocedural planning, fast-track general anesthesia, and postprocedural debriefing. Intraoperative management involved anesthesia depth monitoring, real-time guidance via transesophageal echocardiography, and hemodynamic stability maintenance. Postoperative analgesia involved preemptive intravenous paracetamol and morphine as needed.

MEASUREMENTS AND MAIN RESULTS

No anesthesia-related or implantation-related complications were observed, with a mean procedure duration of 112 ± 44 minutes. The median hospital stay was 4 days, and only 1 patient required brief intensive care unit monitoring. Postoperative right shoulder pain was reported by half of the patients, and was managed with morphine bolus administration (average dose 4.75 ± 3.6 mg). All patients had the device correctly positioned, as confirmed by postoperative transthoracic echocardiograms. None of the patients required outpatient analgesic therapy upon discharge.

CONCLUSIONS

The authors' study demonstrated the potential of TricValve implantation in effectively managing severe tricuspid regurgitation with no procedure-related complications and a 100% survival rate. A collaborative, interdisciplinary approach and targeted anesthesia management proved crucial for this success. Postoperative shoulder pain emerged as a frequent complication, whose pathogenesis is still not clear, and successfully was managed using targeted analgesic therapy.

REKOVER study protocol: a pRospective patient treatment rEgistry of tramadol and dexKetoprofen trometamol oral fixed-dose combination (SKUDEXA) in mOderate to seVere acutE pain in Real-world setting in Asia

INTRODUCTION

Satisfactory management of acute pain remains a major medical challenge despite the availability of multiple therapeutic options including the fixed-dose combination (FDC) drugs. Tramadol and dexketoprofen trometamol (TRAM/DKP) 75/25 mg FDC was launched in 2018 in Asia and is widely used in the management of moderate to severe acute pain. There are limited data on its effectiveness and safety in Asian patients, and therefore, a need to better understand its usage patterns in clinical practice. We aim to understand the usage pattern of TRAM/DKP FDC, its effectiveness and tolerability in patients with moderate to severe acute pain in Asia.

METHODS AND ANALYSIS

REKOVER is a phase-IV, multicountry, multicentre, prospective, real-world observational study. A total of 750 postsurgical and non-surgical patients (male and female, aged 18-80 years) will be recruited from 13 tertiary-care hospitals (15 sites) in Singapore, Thailand, the Philippines and Malaysia. All patients prescribed with TRAM/DKP FDC and willing to participate in the study will be enrolled. The recruitment duration for each site will be 6 months. The severity of pain will be collected using Numeric Pain Rating Scale through the treatment period from day 1 to day 5, while satisfaction with the treatment will be evaluated using Patient Global Evaluation Scale at the end of treatment. Any adverse event reported during the study duration will be recorded for safety analysis (up to day 6). The study data will be entered into the ClaimIt portal and mobile application (app) (ObvioHealth, USA). All the inpatient data will be entered into the portal by the study site and for outpatient it will be done by patients through an app.

ETHICS AND DISSEMINATION

The study has been approved by the local ethics committee from each study sites in Singapore, Thailand, the Philippines and Malaysia. Findings will be disseminated through local and global conference presentations, publications in peer-reviewed scientific journals and continuing medical education.

Is the reliability of wastewater-based epidemiology affected by season? Comparative analysis with pharmaceuticals prescriptions

Wastewater-based epidemiology (WBE) has been already proposed by several authors for estimating the consumption of drugs, mainly the illicit ones. However, not much information is available about the actual reliability of this tool given the absence of comparison with the actual consumption. This work aims to evaluate the reliability of the WBE as a tool for estimating the consumption of pharmaceuticals in urban area. Measured consumption back-calculated with a WBE approach was compared with prescription of pharmaceutical products as "control." Moreover, seasonal influence on (i) pharmaceutical consumption, (ii) load of pharmaceutical products in the sewer system, and (iii) reliability of WBE was evaluated. Ciprofloxacin, sulfamethoxazole, metoprolol, carbamazepine, and citalopram were estimated by WBE with a difference respect to the "control" value lower than 0.2 order of magnitude while only trimethoprim and sotalol exceeded the 0.5 order of magnitude of difference but below the 1 order of magnitude. Sedatives were the best represented by WBE (on average 0.15 order of magnitude of difference compared to prescription data). However, further studies are suggested to fully estimate the influence of the type of APs on the reliability of the WBE. Seasonal patterns were found for the load of ciprofloxacin in the sewer and for the consumption of sulfamethoxazole and trimethoprim by population but seasonal changes did not have a significant impact (p > 0.05) on the reliability of WBE. Despite some gaps remained to optimize the reliability of the tool, WBE can be considered a valid method to estimate the consumption of prescribed drugs from the analysis of the sewer system.

Nitric oxide and potassium channels but not opioid and cannabinoid receptors mediate tramadol-induced peripheral antinociception in rat model of paw pressure withdrawal

Tramadol, an analgesic classified as an "atypical opioid", exhibits both opioid and non-opioid mechanisms of action. This study aimed to explore these mechanisms, specifically the opioid-, cannabinoid-, nitric oxide-, and potassium channel-based mechanisms, which contribute to the peripheral antinociception effect of tramadol, in an experimental rat model. The nociceptive threshold was determined using paw pressure withdrawal. To examine the mechanisms of action, several substances were administered intraplantarly: naloxone, a non-selective opioid antagonist (50 µg/paw); AM251 (80 µg/paw) and AM630 (100 µg/paw) as the selective antagonists for types 1 and 2 cannabinoid receptors, respectively; nitric oxide synthase inhibitors L-NOArg, L-NIO, L-NPA, and L-NIL (24 µg/paw); and the enzyme inhibitors of guanylatocyclase and phosphodiesterase of cGMP, ODQ, and zaprinast. Additionally, potassium channel blockers glibenclamide, tetraethylammonium, dequalinium, and paxillin were used. The results showed that opioid and cannabinoid receptor antagonists did not reverse tramadol's effects. L-NOarg, L-NIO, and L-NPA partially reversed antinociception, while ODQ completely reversed, and zaprinast enhanced tramadol's antinociception effect. Notably, glibenclamide blocked tramadol's antinociception in a dose-dependent manner. These findings suggest that tramadol's peripheral antinociception effect is likely mediated by the nitrergic pathway and sensitive ATP potassium channels, rather than the opioid and cannabinoid pathways.

Slower intravenous tramadol administration can prevent nausea and vomiting and predict postoperative nausea and vomiting: a randomized controlled trial

Objective

Nausea and vomiting are the most common complications in patients who use tramadol for analgesia. This study evaluated the risk of nausea and vomiting related to intravenous tramadol administration.

Methods

In this study, 315 patients who received pre-analgesia before elective surgery were selected, and participants were divided into groups based on the Apfel risk assessment of nausea and vomiting, as follows: high risk (Apfel=4), medium risk (Apfel=2-3), and low-risk (Apfel=1). Tramadol (1.5 mg/kg) was administered intravenously over a duration of 1 min, 2 min, or 3 min before anaesthesia induction to observe preoperative nausea and vomiting reactions within 10 min.

Results

In the low-risk group, the numeric rating scale for postoperative nausea scores and the incidence of nausea and vomiting were significantly lower in the 3-min group than those in the 1-min group, and the incidence of preoperative nausea and vomiting after intravenous administration of tramadol in the 1-min and 3-min groups were significantly related to the incidence of postoperative nausea and vomiting. The incidence of nausea and vomiting during pre-administration in the 1-min and 3-min groups was identified as an independent risk factor for postoperative nausea and vomiting.

Conclusions

In the clinical treatment of pain with tramadol, the slow intravenous application of tramadol within 3 min is worthy of being adopted and promoted by clinicians in their daily work.

Effects of Ketamine and Tramadol As Adjuvants to Bupivacaine in Spinal Anesthesia for Unilateral Open Ovarian Cystectomy: A Randomized Controlled Trial

BACKGROUND

Spinal anesthesia offers numerous advantages and desirable features. However, it is associated with various side effects related to local anesthetic agents used. Reducing the dose of local anesthetic in spinal anesthesia can help minimize side effects but may lead to a diminished analgesic effect or failure of anesthesia. Therefore, adding an adjuvant may enhance the benefits while mitigating side effects.

OBJECTIVE

This study aimed to evaluate the effects of ketamine and tramadol as adjuvants to bupivacaine on the duration of spinal analgesia. The objectives were to compare the three groups and prove their analgesic effects, safety, and superiority. The primary outcomes were the duration of spinal analgesia, as well as the onset and duration of both sensory and motor blocks. Secondary outcomes included the heart rate, mean arterial pressure, and the incidence of undesired effects such as nausea, vomiting, sedation, shivering, and postoperative headache.

METHODS

In this double-blind randomized controlled trial, 120 female patients undergoing elective open unilateral ovarian cystectomy under spinal anesthesia were studied. The inclusion criteria included patients aged 16-45 years with a physical status classified as American Society of Anesthesiologists (ASA) class I and II. Patients were randomly allocated into three groups: group B (n=40) received only bupivacaine, group BK (n=40) received bupivacaine mixed with preservative-free ketamine, and group BT (n=40) received bupivacaine mixed with preservative-free tramadol.

RESULTS

The mean duration of spinal analgesia, measured in minutes, showed significant differences (P < 0.001) between group BK (165 ± 4) and group B (170 ± 5). There was also a significant difference between group BT (313 ± 8) and group B (170 ± 5) (P < 0.001). Additionally, significant differences were observed between group BK (165 ± 4) and group BT (313 ± 8) (P < 0.001).

CONCLUSION

The administration of 25 mg of ketamine and 25 mg of tramadol as adjuvants to bupivacaine in spinal anesthesia significantly affected the postoperative duration of analgesia. Tramadol prolonged the duration of spinal anesthesia, while ketamine shortened it. The use of both adjuvants did not result in undesired effects.

Optogenetic Activation of Peripheral Somatosensory Neurons in Transgenic Mice as a Neuropathic Pain Model for Assessing the Therapeutic Efficacy of Analgesics

Optogenetics is a novel biotechnology widely used to precisely manipulate a specific peripheral sensory neuron or neural circuit. However, the use of optogenetics to assess the therapeutic efficacy of analgesics is elusive. In this study, we generated a transgenic mouse stain in which all primary somatosensory neurons can be optogenetically activated to mimic neuronal hyperactivation in the neuropathic pain state for the assessment of analgesic effects of drugs. A transgenic mouse was generated using the advillin-Cre line mated with the Ai32 strain, in which channelrhodopsin-2 fused to enhanced yellow fluorescence protein (ChR2-EYFP) was conditionally expressed in all types of primary somatosensory neurons (advillincre/ChR2+/+). Immunofluorescence and transdermal photostimulation on the hindpaws were used to verify the transgenic mice. Optical stimulation to evoke pain-like paw withdrawal latency was used to assess the analgesic effects of a series of drugs. Injury- and pain-related molecular biomarkers were investigated with immunohistofluorescence. We found that the expression of ChR2-EYFP was observed in many primary afferents of paw skin and sciatic nerves and in primary sensory neurons and laminae I and II of the spinal dorsal horns in advillincre/ChR2+/+ mice. Transdermal blue light stimulation of the transgenic mouse hindpaw evoked nocifensive paw withdrawal behavior. Treatment with gabapentin, some channel blockers, and local anesthetics, but not opioids or COX-1/2 inhibitors, prolonged the paw withdrawal latency in the transgenic mice. The analgesic effect of gabapentin was also verified by the decreased expression of injury- and pain-related molecular biomarkers. These optogenetic mice provide a promising model for assessing the therapeutic efficacy of analgesics in neuropathic pain.

Reproducible strategy for excisional skin-wound-healing studies in mice

Wound healing is a complex physiological process involving various cell types and signaling pathways. The capability to observe the dynamics of wound repair offers valuable insights into the effects of genetic modifications, pharmaceutical interventions or other experimental manipulations on the skin-repair process. Here, we provide a comprehensive protocol for a full-thickness, excisional skin-wound-healing assay in mice, which can easily be performed by any scientist who has received an animal welfare course certificate and can be completed within ~3 h, depending on the number of animals. Crucially, we highlight the importance of considering key aspects of the assay that can dramatically contribute to the reliability and reproducibility of these experiments. We thoroughly discuss the experimental design, necessary preparations, wounding technique and analysis. In addition, we discuss the use of lineage-tracing techniques to monitor cell migration, differentiation and the contribution of different cell populations to the repair process. Overall, we explore key aspects of the skin-wound-healing assay, supplying a detailed procedure and guidelines essential for decreasing variability and obtaining reliable and reproducible results.

Use of tramadol as analgesic alternative in Harris hawk (Parabuteo unicinctus)

BACKGROUND

The Harris hawk is a bird of prey susceptible to traumatic injuries because it is useful for several purposes such as conservancy, biological control and falconry. Once received in rehabilitation centres or specialized clinics, it is necessary to provide proper analgesia.

OBJECTIVES

The aim of this study is to demonstrate the analgesic efficacy of tramadol in Harris hawks (PISADOL 50 PiSA Agropecuaria, S.A. de C.V. Calle 1 Norte, Manzana 2-25 Parque Industrial Tula Atitalaquia, Hgo, México), by the assessment of nociceptive threshold.

METHODS

A total of 24 adult Harris hawks were selected from a rehabilitation centre. The birds were randomly divided into four groups: control (saline solution), 5.0, 15.0 and 30.0 mg/kg of intramuscular tramadol. Nociception was produced with electrical stimuli of 9 V, applied in propatagial skin at 1, 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300 and 360 min, assessing the nociceptive threshold and sedative effects produced by each treatment.

RESULTS

No difference was observed between control and tramadol group 5 mg/kg. At 15 mg/kg, the pain threshold increased from 20 to 240 min, with minimal sedative effects. At 30 mg/kg, there was a marked increase in pain threshold from 10 to 300 min, and sedative effects like wing and head drooping for a period of 90 min.

CONCLUSIONS

Tramadol can be an analgesic alternative for Harris's hawks, as it decreases the response to painful stimuli in this species when administered by intramuscular route.

A synopsis of multitarget therapeutic effects of anesthetics on depression

Depression is a profound mental disorder that dampens the mood and undermines volition, which exhibited an increased incidence over the years. Although drug-based interventions remain the primary approach for depression treatment, the available medications still can't satisfy the patients. In recent years, the newly discovered therapeutic targets such as N-methyl-D-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor, and tyrosine kinase B (TrkB) have brought new breakthroughs in the development of antidepressant drugs. Moreover, it has come to light that certain anesthetics possess pharmacological mechanisms intricately linked to the aforementioned therapeutic targets for depression. At present, numerous preclinical and clinical studies have explored the therapeutic effects of anesthetic drugs such as ketamine, isoflurane, N2O, and propofol, on depression. These investigations suggested that these drugs can swiftly ameliorate patients' depression symptoms and engender long-term effects. In this paper, we provide a comprehensive review of the research progress and potential molecular mechanisms of various anesthetic drugs for depression treatment. By shedding light on this subject, we aim to facilitate the development and clinical implementation of new antidepressant drugs based on anesthetic medications.

What do we know about astrocytes and the antidepressant effects of DBS?

Treatment-resistant depression (TRD) is a debilitating condition that affects millions of individuals worldwide. Deep brain stimulation (DBS) has been widely used with excellent outcomes in neurological disorders such as Parkinson's disease, tremor, and dystonia. More recently, DBS has been proposed as an adjuvant therapy for TRD. To date, the antidepressant efficacy of DBS is still controversial, and its mechanisms of action remain poorly understood. Astrocytes are the most abundant cells in the nervous system. Once believed to be a "supporting" element for neuronal function, astrocytes are now recognized to play a major role in brain homeostasis, neuroinflammation and neuroplasticity. Because of its many roles in complex multi-factorial disorders, including TRD, understanding the effect of DBS on astrocytes is pivotal to improve our knowledge about the antidepressant effects of this therapy. In depression, the number of astrocytes and the expression of astrocytic markers are decreased. One of the potential consequences of this reduced astrocytic function is the development of aberrant glutamatergic neurotransmission, which has been documented in several models of depression-like behavior. Evidence from preclinical work suggests that DBS may directly influence astrocytic activity, modulating the release of gliotransmitters, reducing neuroinflammation, and altering structural tissue organization. Compelling evidence for an involvement of astrocytes in potential mechanisms of DBS derive from studies suggesting that pharmacological lesions or the inhibition of these cells abolishes the antidepressant-like effect of DBS. In this review, we summarize preclinical data suggesting that the modulation of astrocytes may be an important mechanism for the antidepressant-like effects of DBS.

Use of Tramadol vs Traditional Opioids and Adverse Outcomes in Patients with Inflammatory Bowel Disease: A Danish Nationwide Cohort Study

BACKGROUND

Use of traditional opioids (TOs) for pain management has been associated with adverse outcomes among patients with inflammatory bowel diseases (IBDs). It is unknown if similar associations exist for tramadol, a partial opioid agonist and serotonin and norephinephrine reuptake inhibitor. We sought to compare adverse outcomes associated with tramadol vs TOs in an IBD population.

METHODS

This nationwide cohort study included adults with IBD diagnosed from 1995 to 2021 in Denmark with subsequent prescriptions for tramadol or TOs. For each analgesic, 2 populations were assessed: initial users (first prescription) and persistent users (first 3 consecutive prescriptions within 365 days). Outcomes included infection, bowel obstruction/ileus, IBD surgery, and mortality within 90 days after the initial use index date (date of first prescription) and within 365 days after the persistent use index date (date of third prescription). Odds ratios adjusted for demographics, comorbidities, and IBD severity were calculated using multivariable logistic regression.

RESULTS

We identified 37 377 initial users and 15 237 persistent users of tramadol or TOs. Initial users of tramadol had lower adjusted odds of infection (adjusted odds ratio [OR], 0.80; 95% confidence interval [CI], 0.65-0.99), bowel obstruction/ileus (aOR, 0.74; 95% CI, 0.53-1.03), and mortality (aOR, 0.43; 95% CI, 0.35-0.55), and a higher adjusted odds of IBD-related surgery (aOR, 1.27; 95% CI, 1.02-1.60) vs initial users of TOs. Similar results were found for persistent users.

CONCLUSIONS

Tramadol was associated with lower odds of infection, bowel obstruction/ileus, and mortality vs TOs among patients with IBD. These associations may be impacted by residual confounding.

Comparison of tramadol and lornoxicam for the prevention of postoperative catheter-related bladder discomfort: a randomized controlled trial

BACKGROUND

Catheter-related bladder discomfort (CRBD is a painful complication of intraoperative urinary catheterization after anaesthesia. We conducted this study to compare the effect of tramadol and lornoxicam for the prevention of postoperative CRBD.

METHODS

One-hundred twenty patients (aged 18-60 years, ASA physical status 1-2, undergoing elective uterine surgery requiring intraoperative urinary catheterization were randomly divided into three groups with 40 patients in each group. Group T received 1.5 mg/kg tramadol, group L received 8-mg lornoxicam, and group C received normal saline. The study drugs were administered intravenously at the end of the surgery. The incidence and severity of CRBD were reported at 0, 1, 2, and 6 h after arrival at the postanaesthesia care unit (PACU).

RESULTS

The incidence of CRBD was significantly lower in groups T and L than in group C at 1, 2, and 6 h after surgery. The incidence of moderate to severe CRBD was also significantly lower in groups T and L than in group C at 0, 1, and 2 h after surgery. The severity of CRBD reported as mild, moderate, and severe was reduced in groups T and L compared with group C at most times after surgery. Group T had a higher incidence of nausea than group C, and there were no differences in dizziness, drowsiness, or vomit among the three groups.

CONCLUSIONS

Tramadol and lornoxicam administered intravenously at the end of the surgery were both effective in preventing the incidence and severity of CRBD after uterine surgery. However, tramadol increased the incidence of nausea compared with saline, but there was no difference between tramadol and lornoxicam.

TRIAL REGISTRATION

ChiCTR2100052003. Registered on 12/10/2021.

Formulation of pH-responsive highly swellable hydrogel scaffolds for controlled release of tramadol HCl: characterization and biocompatibility evaluation

Introduction: The objective of current project was to formulate a system for controlled delivery of Tramadol HCl (TRD), an opioid analgesic used in the treatment of moderate to severe pain. Methods: For this purpose, a pH responsive AvT-co-poly hydrogel network was formulated through free radical polymerization by incorporating natural polymers i.e., aloe vera gel and tamarind gum, monomer and crosslinker. Formulated hydrogels were loaded with Tramadol HCl (TRD) and evaluated for percent drug loading, sol-gel fraction, dynamic and equilibrium swelling, morphological characteristics, structural features and in-vitro release of Tramadol HCl. Results and Discussions: Hydrogels were proved to be pH sensitive as remarkable dynamic swelling response ranging within 2.94g/g-10.81g/g was noticed at pH 7.4 as compared to pH 1.2. Percent drug loading was in the range of 70.28%-90.64% for all formulations. Thermal stability and compatibility of hydrogel components were validated by DSC analysis and FTIR spectroscopy. Controlled release pattern of Tramadol HCl from the polymeric network was confirmed as maximum release of 92.22% was observed for over a period of 24 hours at pH 7.4. Moreover, oral toxicity studies were also conducted in rabbits to investigate the safety of hydrogels. No evidence of any toxicity, lesions and degeneration was reported, confirming the biocompatibility and safety of grafted system.

Pharmaceutical treatment of osteoarthritis

OBJECTIVE

To review the current state of pharmaceutical treatment recommendations for the management of osteoarthritis.

METHOD

A narrative review was drafted to describe treatment guidelines, mechanism of action, pharmacokinetics, and toxicity for nine classes of pharmaceuticals: 1) oral nonsteroidal anti-inflammatory drugs (NSAIDs), 2) topical NSAIDs, 3) COX-2 inhibitors, 4) duloxetine, 5) intra-articular corticosteroids, 6) intra-articular hyaluronic acid, 7) acetaminophen (paracetamol), 8) tramadol, and 9) capsaicin.

RESULTS

In general, oral and topical NSAIDs, including COX-2 inhibitors, are strongly recommended first-line treatments for osteoarthritis due to their ability to improve pain and function but are associated with increased risks in patients with certain comorbidities (e.g., heightened cardiovascular risks). Intra-articular corticosteroid injections are generally recommended for osteoarthritis management and have relatively minor adverse effects. Other treatments, such as capsaicin, tramadol, and acetaminophen, are more controversial, and many updated guidelines offer differing recommendations.

CONCLUSION

The pharmaceutical management of osteoarthritis is a constantly evolving field. Promising treatments are emerging, and medicines that were once considered conventional (e.g., acetaminophen) are gradually becoming less acceptable based on concerns with efficacy and safety. Clinicians need to consider the latest evidence and recommendations to make an informed decision with their patients about how to optimize treatment plans for patients with knee, hip, polyarticular, or hand osteoarthritis.

Reinforcing effect of tramadol in the rat

Tramadol is one of the most commonly prescribed analgesic opioids in various pharmacopeias. Tramadol has been linked to abuse in recent clinical investigations. However, the behavioral effects and neural substrates of the drug have not been well characterized in preclinical studies. As a result, the present study investigated the effects of tramadol on behavioral sensitizations in rats. Its impacts on cellular and molecular alterations in the brain were also investigated. In conditioned place preference (CPP) paradigm, tramadol induced behavioral as well as motor sensitizations. These effects were dramatically reduced by intraperitoneal administration of naltrexone, an opioid receptor antagonist. Tramadol caused changes in several molecular markers (pERK1/2, Δ-FosB, PKCγ, PKMζ GAD67) in the anterior cingulate cortex, which could indicate an increase in excitation within this structure. Tramadol is demonstrated in the present study to be a reinforcing drug in rats, as it increased both behavioral and motor sensitizations. Tramadol's effects are most likely due to the high levels of excitation it causes in the brain, which is mostly caused by the activation of opioid receptors.

Efficacy and Safety of Tramadol for Knee or Hip Osteoarthritis: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

To examine efficacy and safety of tramadol for knee or hip osteoarthritis (OA).

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were searched up to May 2020 for randomized controlled trials (RCTs) comparing any of the following interventions: tramadol 100 mg/day, 200 mg/day, and 300 mg/day, and placebo for knee or hip OA. Pain and function were measured at or near 12 weeks for efficacy. Gastrointestinal, cardiovascular, and central nervous system (CNS) adverse events (AEs), and withdrawals were measured for safety. Bayesian network meta-analysis was conducted.

RESULTS

Six RCTs (3,611 participants) were included. Tramadol 100 mg/day (standardized mean difference [SMD] -0.16 [95% confidence interval (95% CI) -0.34, 0.00]), 200 mg/day (SMD -0.21 [95% CI -0.37, -0.06]), and 300 mg/day (SMD -0.30 [95% CI -0.48, -0.14]) were statistically more effective than placebo in pain relief, but only tramadol 300 mg/day was better than placebo in functional improvement (SMD -0.24 [95% CI -0.47, -0.03]). Tramadol 100 mg/day (relative risk [RR] 2.29 [95% credible interval (CrI) 1.22, 4.25]), 200 mg/day (RR 4.35 [95% CrI 2.31, 8.01]), and 300 mg/day (RR 6.02 [95% CrI 3.22, 11.1]) involved a higher risk of gastrointestinal AEs. Similarly, tramadol 100-300 mg/day showed a higher risk of CNS AEs and withdrawals. However, the risk of cardiovascular AEs remained unclear.

CONCLUSION

Only tramadol 300 mg/day showed minimal improvement in pain and function but with increasing AEs compared with placebo. Tramadol may not be sufficiently recommended for knee or hip OA based on the presented evidence, especially in patients with the risk of gastrointestinal and CNS AEs.

Molecular Docking and Dynamic Simulation Revealed the Potential Inhibitory Activity of Opioid Compounds Targeting the Main Protease of SARS-CoV-2

Opioids are a class of chemicals, naturally occurring in the opium poppy plant, and act on the brain to cause a range of impacts, notably analgesic and anti-inflammatory actions. Moreover, an overview was taken in consideration for SARS-CoV-2 incidence and complications, as well as the medicinal uses of opioids were discussed being a safe analgesic and anti-inflammatory drug in a specific dose. Also, our article focused on utilization of opioids in the medication of SARS-CoV-2. Therefore, the major objective of this study was to investigate the antiviral effect of opioids throughout an in silico study by molecular docking study to fifteen opioid compounds against SARS-CoV-2 main protease (PDB ID 6LU7, M^pro). The docking results revealed that opioid complexes potentially inhibit the M^pro active site and exhibiting binding energy (-11.0 kcal/mol), which is comparably higher than the ligand. Furthermore, ADMET prediction indicated that all the tested compounds have good oral absorption and bioavailability and can transport via biological membranes. Finally, M^pro-pholcodine complex was subjected to five MD (RMSD, RMSF, SASA, Rg, and hydrogen bonding) and two MM-PBSA, and conformational change studies, for 100 ns, confirmed the stability of pholcodine, as a representative example, inside the active site of M^pro.

Influence of tramadol on bacterial burden in the standard neutropenic thigh infection model

The neutropenic thigh infection model is one of the standard models in pharmacokinetic/ pharmacodynamic (PK/PD) characterization of novel antibacterials which are urgently needed due to the rise of antimicrobial resistance. The model enables to investigate PK/PD parameters crucial for translation of animal results towards humans. However, the neutropenic thigh infection model can result in moderate to severe discomfort of the animals, especially when high inocula are used. Tramadol has been proven to reduce pain effectively. This study investigates if tramadol influences the bacterial burden in the primary organ, the thighs, and organs affected by secondary seeding. Therefore, several strains of the ESKAPE pathogens, namely S. aureus, P. aeruginosa, K. pneumoniae, E. coli, A. baumannii and E. faecalis were examined. It was shown that tramadol did not influence the bacterial burden neither in thighs nor in organs affected by secondary seeding for the strains of E. faecalis, S. aureus, P. aeruginosa, K. pneumoniae and E.coli tested here, whereas secondary seeding seemed to be affected by tramadol for the tested strain of A. baumannii. Consequently, it was demonstrated that tramadol is an option to reduce discomfort in the untreated group for the strains of five out of the six tested ESKAPE pathogens and, thereby, contributes to the refinement of one of the standard PK/PD models.

Role of daytime variation in pharmaceutical effects of sufentanil, dezocine, and tramadol: A matched observational study

The role of daytime variation in the comprehensive pharmaceutical effects of commonly used opioid analgesics in clinical setting remains unclear. This study aimed to explore the differences in daytime variation among elective surgery patients who were scheduled to receive preemptive analgesia with equivalent doses of sufentanil, dezocine, and tramadol in the morning and afternoon. The analgesic effect was assessed by changes in the pressure pain threshold before and after intravenous administration of sufentanil, dezocine, and tramadol. Respiratory effects were evaluated using pulse oximetry, electrical impedance tomography, and arterial blood gas analysis. Other side effects, including nausea, sedation, and dizziness, were also recorded, and blood concentration was measured. The results showed that the analgesic effects of sufentanil, dezocine, and tramadol were significantly better in the morning than in afternoon. In the afternoon, sufentanil had a stronger sedative effect, whereas dezocine had a stronger inhibitory respiratory effect. The incidence of nausea was higher in the morning with tramadol. Additionally, significant differences in different side effects were observed among three opioids. Our results suggest that the clinical use of these three opioids necessitates the formulation of individualized treatment plans, accounting for different administration times, to achieve maximum analgesic effect with minimal side effects.

Randomised clinical trial comparing the perioperative analgesic efficacy of oral tramadol and intramuscular tramadol in cats

OBJECTIVES

The aim of this study was to evaluate the analgesic efficacy of oral tramadol in cats undergoing ovariohysterectomy.

METHODS

Twenty-four female domestic cats, American Society of Anesthesiologists class I, aged 4-24 months, were included in this positive controlled, randomised, blinded clinical trial. Cats admitted for ovariohysterectomy were allocated to group oral tramadol (GOT, n = 12) or group intramuscular tramadol (GIMT, n = 12). In GOT, tramadol (6 mg/kg) was given orally 60 mins, and saline was given intramuscularly 30 mins, before induction of anaesthesia. In GIMT, granulated sugar in capsules was given orally 60 mins and tramadol (4 mg/kg) intramuscularly 30 mins before induction of anaesthesia. In both groups, dexmedetomidine (0.007 mg/kg) was given intramuscularly 30 mins before induction of anaesthesia with intravenous propofol. Anaesthesia was maintained with isoflurane in oxygen, and atipamezole (0.037 mg/kg) was given intramuscularly 10 mins after extubation. The UNESP-Botucatu multidimensional composite scale was used to conduct pain assessments before premedication and at 20, 60, 120, 240 and 360 mins post-extubation or until rescue analgesia was given. To compare groups, the 60 min postoperative pain scores and the highest postoperative pain scores were analysed via a two-tailed Mann-Whitney test, and the incidences of rescue analgesia were analysed via a Fisher's exact test; P <0.05.

RESULTS

There was no significant difference between groups for the 60 min (P = 0.68) pain scores. The highest postoperative pain score was higher for GIMT compared with GOT (P = 0.04). Only two cats required rescue analgesia, both from GIMT. The incidence of rescue analgesia was not significantly different between groups (P = 0.46).

CONCLUSIONS AND RELEVANCE

In the present study, preoperative administration of oral tramadol at 6 mg/kg to cats provided adequate analgesia for 6 h following ovariohysterectomy surgery.

Comparative Efficacy of Pharmacological Therapies for Low Back Pain: A Bayesian Network Analysis

Low back pain (LBP) is a common problem, but the efficacy of pharmacological therapies remains controversial. Therefore, we aimed to comprehensively evaluate and quantitatively rank various pharmacological therapies for patients with low back pain. Two meta-analyses were performed: an initial pair-wise meta-analysis, followed by network meta-analysis using a random-effects Bayesian model. We included randomized controlled trials comparing placebos, non-steroidal anti-inflammatory drugs, opioids, skeletal muscular relaxants, pregabalin (or gabapentin), and some drug combinations. The primary and secondary outcomes were pain intensity and physical function. Eighty-eight eligible trials with 21,377 patients were included. Here, we show that only skeletal muscle relaxants significantly decreased the pain intensity of acute (including subacute) low back pain. Several kinds of drugs significantly decreased the pain of chronic low back pain, but only opioids and cyclo-oxygenase 2-selective non-steroidal anti-inflammatory drugs effectively reduced pain and improved function. Pregabalin (or gabapentin) seemed to be an effective treatment to relieve pain, but it should be used with caution for low back pain.

Removal of tramadol from water using Typha angustifolia and Hordeum vulgare as biological models: Possible interaction with other pollutants in short-term uptake experiments

Tramadol (TRD) is widely detected in aquatic ecosystems as a result of massive abuse and insufficient removal from wastewater facilities. As a result, TRD can contaminate groundwater sources and/or agricultural soils. While TRD toxicity has been reported from aquatic biota, data about TRD detection in plants are scarce. Moreover, information regarding plant capability for TRD removal is lacking. To understand the fate of this opioid, we have investigated the uptake, translocation and removal capacity of TRD by plants, addressing short-term and long-term uptake. The uptake rates of TRD, in excised barley and cattail roots, were 5.18 and 5.79 μg g^-1 root fresh weight day^-1, respectively. However, TRD uptake was strongly inhibited after co-exposing these roots either with the drug venlafaxine (similar molecular structure as TRD) or with quinidine (an inhibitor of cellular organic cation transporters). When barley seedlings were exposed to TRD in a hydroponic experiment a removal efficiency up to 90% (within 15 days) was obtained, with bioconcentration and translocation factors close to 9 and 1, respectively. The combination of results from both plants and the inhibition observed after treatment with quinidine revealed that organic cation transporters may be involved in the uptake of TRD by plants.

Tramadol Use in Perioperative Care and Current Controversies

PURPOSE OF REVIEW

The aim of this review is to discuss the use of tramadol in the perioperative period. There is no doubt that tramadol has revolutionized pain treatment, making it important to understand the pharmacokinetics and pharmacodynamics in order to provide patients with the safest and most effective analgesia.

RECENT FINDINGS

Tramadol is a centrally acting synthetic analgesic with a multimode of action used to help treat moderate to severe pain. Pharmacologically, the unique opioid acts as a serotonin-norepinephrine reuptake inhibitor, while its metabolite, O-desmethyltramadol, acts on the μ-opioid receptor. The analgesic strength of tramadol is about one-tenth that of morphine, making it a relatively safe analgesic. Potential side effects of tramadol include nausea, vomiting, constipation, pruritus, and respiratory depression; however, the severity of these symptoms is minimal compared to traditional opioids. Although some of the perioperative uses of tramadol may be rare, it is a pain management option to consider when alternatives have proved ineffective.

Implementation of a Standardized Perioperative Pain Management Protocol to Reduce Opioid Prescriptions in Otolaryngologic Surgery

OBJECTIVE

To evaluate the efficacy of implementing a standardized multimodal perioperative pain management protocol in reducing opioid prescriptions following otolaryngologic surgery.

STUDY DESIGN

Retrospective cohort study.

SETTING

County hospital otolaryngology practice.

METHODS

A perioperative pain management protocol was implemented in adults undergoing otolaryngologic surgery. This protocol included preoperative patient education and a postoperative multimodal pain regimen stratified by pain level: mild, intermediate, and high. Opioid prescriptions were compared between patient cohorts before and after protocol implementation. Patients in the pain protocol were surveyed regarding pain levels and opioid use.

RESULTS

We analyzed 210 patients (105 preprotocol and 105 postprotocol). Mean ± SD morphine milligram equivalents (MMEs) prescribed decreased from 132.5 ± 117.8 to 53.6 ± 63.9 (P < .05) following protocol implementation. Mean MMEs prescribed significantly decreased (P < .05) for each procedure pain tier: mild (107.4 to 40.5), intermediate (112.8 to 48.1), and high (240.4 to 105.0). Mean MMEs prescribed significantly decreased (P < .05) for each procedure type: endocrine (105.6 to 44.4), facial plastics (225.0 to 50.0), general (160.9 to 105.7), head and neck oncology (138.6 to 77.1), laryngology (53.8 to 12.5), otology (77.5 to 42.9), rhinology (142.2 to 44.4), and trauma (288.0 to 24.5). Protocol patients reported a mean 1-week postoperative pain score of 3.4, used opioids for a mean 3.1 days, and used only 39% of their prescribed opioids.

CONCLUSION

Preoperative counseling and standardization of a multimodal perioperative pain regimen for otolaryngology procedures can effectively lower amount of opioid prescriptions while maintaining low levels of postoperative pain.

Comparison between Tramadol and Butorphanol for Treating Postoperative Catheter-Related Bladder Discomfort: A Randomized Controlled Trial

Background

Intraoperative catheterization often leads to postoperative catheter-related bladder discomfort (CRBD) during the restoration period. This study aimed to assess the curative effect of butorphanol as a K receptor agonist in the treatment of postoperative CRBD. Patients and Approaches. Sixty patients with CRBD who underwent elective nonurological surgery at the postanesthesia care unit were randomly and evenly assigned to two groups. The control group was slowly injected with tramadol 1.5 mg/kg using a Murphy dropper, whereas the experimental group was intravenously injected with butorphanol 0.02 mg/kg. Severity, pain score, and sedation score of CRBD were evaluated at 0 min, 5 min, 15 min, 30 min, 1 h, and 6 h later.

Results

The severity score of CRBD and visual analog scale pain score were lower in the butorphanol group than in the control group, whereas the sedation score was higher in the butorphanol group than in the control group.

Conclusion

Butorphanol relieves on postoperative urination discomfort and pain compared with tramadol.

Decreasing Post-Operative Opioid Prescriptions Following Orthopedic Trauma Surgery: The "Lopioid" Protocol

OBJECTIVE

To assess the effectiveness of a multimodal analgesic regimen containing "safer" opioid and non-narcotic pain medications in decreasing opioid prescriptions following surgical fixation in orthopedic trauma.

DESIGN

Retrospective cohort study.

SETTING

One urban, academic medical center.

SUBJECTS

Traumatic fracture patients from 2018 (848) and 2019 (931).

METHODS

In 2019 our orthopedic trauma division began a standardized protocol of post-operative pain medications that included: 50 mg of tramadol four times daily, 15 mg of meloxicam once daily, 200 mg gabapentin twice daily, and 1 g of acetaminophen every 6 hours as needed. This multimodal regimen was dubbed the "Lopioid" protocol. We compared this protocol to all patients from the prior year who followed a standard protocol that included Schedule II narcotics.

RESULTS

Greater mean MME were prescribed at discharge from fracture surgery under the standard protocol compared to the Lopioid protocol (252.3 vs 150.0; p < 0.001) and there was a difference in the type of opioid medication prescribed (p < 0.001). There was a difference in the number of refills filled for patients discharged with opioids after surgical treatment between standard and Lopioid cohorts (0.31 vs 0.21; p = 0.002). There was no difference in the types of medication-related complications (p = 0.710) or the need for formal pain management consults (p = 0.199), but patients in the Lopioid cohort had lower pain scores at discharge (2.2 vs 2.7; p = 0.001).

CONCLUSIONS

The Lopioid protocol was effective in decreasing the amount of Schedule II narcotics prescribed at discharge and the number of opioid refills following orthopedic surgery for fractures.

ANALGESIC EFFICACY OF TRAMADOL/DEXKETOPROFEN VS IBUPROFEN AFTER IMPACTED LOWER THIRD MOLAR EXTRACTION: A RANDOMIZED CONTROLLED CLINICAL TRIAL

OBJECTIVE

Impacted third molar extraction is associated with acute moderate-to-severe pain for up to 48 hours post-surgery. This trial was designed to compare the analgesic effectiveness, swelling, and adverse events after impacted third molar surgery following multimodal therapy with 75 mg tramadol hydrochloride plus 25 mg dexketoprofen or monotherapy with 400 mg ibuprofen.

METHODS

Seventy-two patients were randomly assigned to receiving ibuprofen (n = 36) or tramadol-dexketoprofen (n = 36). Postoperative pain intensity and swelling were measured using a visual analog scale (VAS); pain relief experienced was reported using a 4-point verbal rating scale; the rescue medication requirement, adverse effects, and global impression of the medication were recorded.

RESULTS

No statistically significant between-group difference in pain intensity was observed at any time point; however, pain relief was significantly higher in the tramadol-dexketoprofen treated-group at 6 and 36 hours. Self-reported verbal rating scale assessments showed significantly lower swelling in the tramadol-dexketoprofen group at 24 hours post-surgery but not at 48 or 72 hours, and VAS-swelling scores showed no significant between-group difference. The frequency of postoperative nausea and dizziness was significantly higher in the tramadol-dexketoprofen group.

CONCLUSIONS

Multimodal therapy proved more effective to manage moderate-severe pain after impacted third molar surgery in comparison to monotherapy. However, the improvement in relief must be balanced against the increased risk of adverse effects when considering this multimodal approach.

Analgesic Efficacy and Safety of Local Infiltration Following Lumbar Decompression Surgery: A Systematic Review of Randomized Controlled Trials

This systematic review aims to appraise available clinical evidence on the efficacy and safety of wound infiltration with adjuvants to local anesthetics (LAs) for pain control after lumbar spine surgery. A database search was conducted to identify randomized controlled trials (RCTs) pertinent to wound infiltration with analgesics or miscellaneous drugs adjunctive to LAs compared with sole LAs or placebo. The outcomes of interest were postoperative rescue analgesic consumption, pain intensity, time to first analgesic request, and the occurrence of adverse events. Twelve double-blind RCTs enrolling 925 patients were selected for qualitative analysis. Most studies were of moderate-to-good methodological quality. Dexmedetomidine reduced analgesic requirements and pain intensity within 24 h postoperatively, while prolonged pain relief was reported by one RCT involving adjunctive clonidine. Data on local magnesium seem promising yet difficult to interpret. No clear analgesic superiority could be attributed to steroids. Τramadol co-infiltration was equally effective as sole tramadol but superior to LAs. No serious adverse events were reported. Due to methodological inconsistencies and lack of robust data, no definite conclusions could be drawn on the analgesic effect of local infiltrates in patients undergoing lumbar surgery. The probable positive analgesic efficacy of adjunctive dexmedetomidine and magnesium needs further evaluation.

Maternotoxicity and fetotoxicity in Rattus norvegicus albinus exposed to tramadol during the late phase of pregnancy

OBJECTIVES

Tramadol, an atypical opioid, is clinically efficacious in treating moderate to severe pain. The aim of current study was to find out the toxicological effects of tramadol exposure to pregnant rats and fetuses during the late phase of pregnancy.

METHODS

Wistar pregnant rats were exposed to 1.25, 2.5, or 5 mg/kg/day tramadol from 14th to 20th day of pregnancy. The same therapy was given to nonpregnant rats for 7 days. The body weight, oral glucose and lipid tolerance tests, and effect on complete blood parameters in both pregnant and nonpregnant rats were determined. On 20th day, maternal placentas were excised and weighed while fetuses were observed for any deformity and growth retardation. Oxidative stress biomarkers were estimated in the liver and kidney tissue homogenates of the pregnant and nonpregnant rats while the whole fetus homogenate was processed for the same. Moreover, histopathology of the liver and kidney of pregnant and nonpregnant rats were carried out.

RESULTS

Tramadol administration did not significantly alter the area under curve of the blood glucose and triglyceride levels in both the pregnant and nonpregnant rats. It reduced the live fetuses, placental weights, fetal length, and fetal weights. Tramadol treated pregnant rats showed significantly (p < .05) reduced red blood cells, hematocrit, hemoglobin, and platelets with reference to control group. Similarly, structural abnormalities and malfunctioning of the liver and kidney of pregnant rats were instituted; however, it did not affect the structural integrity of nonpregnant rats. A substantial (p < .001-.0001) altered glutathione and malondialdehyde levels in the fetuses, pregnant, and nonpregnant animals (tissue homogenates) at all dosage levels were indicative of tramadol induced oxidative stress. Furthermore, tramadol exposure resulted in more significant (p < .01-.001) alteration of lipid profile in the pregnant than the nonpregnant animals.

CONCLUSION

Acquired results suggested the maternotoxic and fetotoxic effects of tramadol exposure during the late gestation period.

Effects of chronic tramadol administration on cognitive flexibility in mice

RATIONALE

Tramadol is widely used for pain relief especially in seniors. However, long-term use of tramadol has serious adverse effects, including cognitive impairment. Besides its memory effects, already demonstrated in animals, a recent clinical report suggests that tramadol could also affect executive function in seniors. Several studies have hypothesized that the anti-muscarinic properties of tramadol could be responsible for the deleterious effects of tramadol on cognition.

OBJECTIVES

We aimed at investigating the effects of chronic administration of tramadol on cognitive flexibility in adult male mice, as assessed by a visual discrimination reversal task using a touchscreen device. The effects of tramadol were further compared to those of scopolamine, a reference muscarinic antagonist.

RESULTS

We found that, during the early phase of the reversal task, when cognitive flexibility is most in demand, both tramadol-treated mice (20 mg/kg, s.c., twice a day) and scopolamine-treated mice (0.5 mg/kg, s.c., twice a day) needed more correction trials and showed a higher perseveration index than saline-treated mice. Therefore, tramadol affects cognitive flexibility, and its anticholinergic properties could be at least partly involved in these deficits.

CONCLUSIONS

In view of these deleterious cognitive effects of tramadol, physicians should be cautious when prescribing this analgesic, especially in seniors who are more vulnerable to adverse drug events and in which alternative prescription should be preferred whenever possible.

Recent advances in transition metal-catalyzed (1,n) annulation using (de)-hydrogenative coupling with alcohols

(1,n) annulation reactions using (de)-hydrogenative coupling with alcohols or diols represent a straightforward technique for the synthesis of cyclic moieties. Utilization of such renewable resources for chemical transformations in a one-pot manner is the main focus, which avoids generation of stoichiometric waste. Application of such (1,n) annulation approaches drives the catalysis research in a more sustainable way and generates dihydrogen and water as by-products. This feature article highlights the recent (from 2015 to March 2021) progress in the synthesis of stereo-selective cycloalkanes and cycloalkenes, saturated and unsaturated N-heterocycles (cyclic amine, imide, lactam, tetrahydro β-carboline, quinazoline, quinazolinone, 1,3,5-triazines etc.) and other N-heterocycles with the formation of multiple bonds in a one pot operation. Mechanistic studies, new catalytic approaches, and synthetic applications including drug synthesis and post-drug derivatization, scope, and limitations are discussed.

Amplification by tramadol of PGD2-induced osteoprotegerin synthesis in osteoblasts: Involvement of μ-opioid receptor and 5-HT transporter

Tramadol, a weak μ-opioid receptor (MOR) agonist with inhibitory effects on the reuptake of serotonin (5-hydroxytryptamine; 5-HT) and norepinephrine, is an effective analgesic to chronic pains. Osteoprotegerin produced by osteoblasts is essential for bone remodeling to suppress osteoclastic bone resorption. We previously reported that prostaglandin D₂ (PGD₂) induces osteoprotegerin synthesis whereby p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) are involved in osteoblast-like MC3T3-E1 cells. Herein, we investigated the mechanism underlying the effect of tramadol on the PGD₂-induced osteoprotegerin synthesis in these cells. Tramadol enhanced the PGD₂-induced release and mRNA expression of osteoprotegerin. Naloxone, a MOR antagonist, reduced the amplification by tramadol of the PGD₂-stimulated osteoprotegerin release. Not the selective norepinephrine reuptake inhibitor reboxetine but the selective serotonin reuptake inhibitors fluvoxamine and sertraline upregulated the PGD₂-induced osteoprotegerin release, which was further amplified by morphine. Tramadol enhanced PGD₂-stimulated phosphorylation of p38 MAP kinase and SAPK/JNK, but not p44/p42 MAP kinase. Both SB203580 and SP600125 suppressed the tramadol effect to enhance the PGD₂-stimulated osteoprotegerin release. Tramadol enhanced the PGE₂-induced osteoprotegerin release as well as PGD₂. These results suggest that tramadol amplifies the PGD₂-induced osteoprotegerin synthesis at the upstream of p38 MAP kinase and SAPK/JNK in the involvement of both MOR and 5-HT transporter in osteoblasts.

Full Opioid Agonists and Tramadol: Pharmacological and Clinical Considerations

Opioids are mu receptor agonists and have been an important part of pain treatment for thousands of years. In order to use these drugs appropriately and successfully in patients, whether to control pain, to treat opiate-induced side effects, or opiate withdrawal syndromes, a solid understanding of the pharmacology of such drugs is crucial. The most recognized full agonist opioids are heroin, morphine, codeine, oxycodone, meperidine, and fentanyl. Phenanthrenes refer to a naturally occurring plant-based compound that includes three or more fused rings. The opioids derived from the opium plant are phenanthrene derivatives, whereas most synthetic opioids are simpler molecules that do not have multiple rings. Methadone acts as a synthetic opioid analgesic similar to morphine in both quality and quantity; however, methadone lasts longer and in oral form, has higher efficacy, and is considered a diphenylheptane. Fentanyl is a strong synthetic phenylpiperdine derivative that exhibits activity as a mu-selective opioid agonist approximately 50 to 100 times more potent than morphine. Meperidine is another medication which is a phenylpiperdine. Tramadol is considered a mixed-mechanism opioid drug, as it is a centrally acting analgesic that exerts its effects via binding mu receptors and blocking the reuptake of monoamines. Some of the most common adverse effects shared among all opioids are nausea, vomiting, pruritus, addiction, respiratory depression, constipation, sphincter of Oddi spasm, and miosis (except in the case of meperidine). Chronic opioid usage has also established a relationship to opioid-induced hypogonadism and adrenal suppression. Physicians must be stewards of opioid use and use opioids only when necessary.

Persistent Opioid Usage After Urologic Intervention and the Impact of Tramadol

OBJECTIVE

To determine if patients who receive tramadol are as likely to develop persistent usage compared to other opioids after urologic surgery and procedures.

METHODS

We identified adults 18 to 64 years old who underwent a urologic procedure in the years 2014 to 2017 using the Truven MarketScan database and subsequently filled an opioid prescription within two weeks of discharge. Patients were excluded if they had any previous opioid prescriptions in the year before surgery. A multivariate logistic regression model was constructed to estimate influence of type of opioid on discharge and various comorbidities on persistent use to determine if persistent use was related to the choice of discharge opioid. We also compared these rates to a 1:3 comorbidities matched, non-surgical cohort of patients from the general population.

RESULTS

Overall, 115,687 patients were included. After 1 year, 14.8% of the urologic surgery cohort had persistent opioid usage compared to 10.8% in the opioid naïve matched non-surgical cohort (OR = 1.37; 95% CI 1.35-1.39). Discharge with tramadol was associated with a higher odd of persistent usage compared to class II opioids controlling for type of urologic surgery, age, gender, and pain related comorbidities (OR = 1.23 95% CI 1.13-1.35). The odds of persistent usage varied slightly by type of urologic procedure, but all were higher than matched non-surgical cohort.

CONCLUSION

Patients developed persistent opiate usage after urologic surgery compared to a comorbidity matched non-surgical cohort. In this model, tramadol specifically was associated with higher odds of novel persistent opioid usage compared to other opioids. Urologists should not consider tramadol to be a safer choice with regard to developing persistent usage and consider prospective validation of these results.

Short Onset and Enhanced Analgesia Following Nasal Administration of Non-Controlled Drugs in Nanovesicular Systems

Nasal nanovesicular delivery systems (NVS) containing the noncontrolled analgesic drugs Ketoprofen, Butorphanol or Tramadol, incorporated in a phospholipid nanovesicular carrier, were designed and investigated. The systems were first characterized for their physicochemical properties. Due to their composition, comprising propylene glycol as a lipid bilayers fluidizer, these systems contain soft vesicles. Pharmacokinetic profiles of Tramadol in plasma and brain and of Ketoprofen in plasma were also assessed. The analgesic effect of each of the three tested drugs was evaluated in the acetic acid mice model for pain. One important result obtained in this work is that the concentration of Tramadol in rats' plasma and brain increased rapidly after administration, reaching a peak value 10 min after administration with a C_max of 2 to 5 folds greater than that for the oral or nasal non-vesicular treatments, respectively. In the case of Ketoprofen, the peak of the drug level in plasma was measured 10 min post nasal administration in NVS. The C_max was three-fold higher relative to oral administration of this drug. In the experiment testing analgesia, a rapid and improved analgesia was observed for the tested drugs when delivered nasally in the nanocarrier. On the other hand, a weaker analgesic effect was observed for oral and nasal control systems. This new approach suggests that nasal delivery of non-controlled drugs in soft nanovesicles may open the way for better and noninvasive treatment of severe pain.

Tramadol-induced hiccups: a case-noncase study in the European pharmacovigilance database

Background

Hiccups are usually benign and self-limiting, but can sometimes be persistent. If left untreated, they can provoke severe discomfort, and even death. Hiccups can be idiopathic, organic, psychogenic, and caused by drugs. Although some case reports have suggested a possible association between tramadol and hiccups, to our knowledge, no study has analyzed this possible relationship. The aim of this study was to analyze whether a disproportionate number of cases of hiccups are reported for tramadol in the EudraVigilance database.

Methods

A case-noncase study was conducted to assess the association between hiccups and tramadol, calculating reporting odds ratios (RORs) from 1 January 1995 to 11 September 2020. Cases were selected using the preferred term 'Hiccups'. The noncases used as controls were all other adverse drug reaction reports recorded in EudraVigilance during the same period. Exposure was defined as exposure to tramadol among cases and noncases. To reduce the risk of confounding by indication, the RORs for tramadol compared with other opioids were obtained. Additionally, we performed a confirmatory analysis in the World Health Organization pharmacovigilance database, VigiBase^®.

Results

There were 3089 cases of hiccups in the 7,213,623 reports. Tramadol was involved in 50 cases. The ROR for tramadol exposure was 3.35 [95% confidence interval (CI) 2.53-4.43]. This association persisted when comparing tramadol with other opioids; ROR: 2.13 (95% CI 1.52-2.99). Disproportionality was also observed in VigiBase^®: ROR 1.69 (95% CI 1.47-1.93).

Conclusion

Our study confirms, for the first time, a possible signal for a tramadol-hiccups association. Nevertheless, observational analytical studies are needed to confirm these results.

Plain Language Summary

Evaluation of the relationship between the tramadol and the risk of hiccupsIntroduction: Hiccups are sudden involuntary contractions of the diaphragm. This involuntary contraction causes the vocal cords to close very briefly, which produces the characteristic sound of a hiccup. Hiccups are usually benign and self-limiting, but can sometimes be persistent. If left untreated, they can provoke severe discomfort, depression, disability, and in the most extreme cases, even death. Drugs are a rare cause of hiccups.Methods: This study investigated the possible association between tramadol and hiccups (an unmentioned adverse drug reaction in the Summary of Product Characteristics) in the European pharmacovigilance database (EudraVigilance) and a confirming analysis in the World Health Organization pharmacovigilance database (VigiBase).Results: Our analysis shows that hiccups is relatively more frequently reported in association with tramadol than with other medicinal products, with EudraVigilance and VigiBase confirming this association.Conclusion: Tramadol is an opioid analgesic indicated, alone or in combination with dexketoprofen or paracetamol for pain with various causes, so healthcare professionals and patients should be aware of this possible association.

Computational Bioactivity Fingerprint Similarities To Navigate the Discovery of Novel Scaffolds

As one of the central tasks of modern medicinal chemistry, scaffold hopping is expected to lead to the discovery of structural novel biological active compounds and broaden the chemical space of known active compounds. Here, we report the computational bioactivity fingerprint (CBFP) for easier scaffold hopping, where the predicted activities in multiple quantitative structure-activity relationship models are integrated to characterize the biological space of a molecule. In retrospective benchmarks, the CBFP representation shows outstanding scaffold hopping potential relative to other chemical descriptors. In the prospective validation for the discovery of novel inhibitors of poly [ADP-ribose] polymerase 1, 35 predicted compounds with diverse structures are tested, 25 of which show detectable growth-inhibitory activity; beyond this, the most potent (compound 6) has an IC₅₀ of 0.263 nM. These results support the use of CBFP representation as the bioactivity proxy of molecules to explore uncharted chemical space and discover novel compounds.

EEG and Sleep Effects of Tramadol Suggest Potential Antidepressant Effects with Different Mechanisms of Action

Tramadol is a widely used, centrally acting, opioid analgesic compound, with additional inhibitory effects on the synaptic reuptake of serotonin and noradrenaline, as well as on the 5-HT₂ and NMDA receptors. Preclinical and clinical evidence also suggests its therapeutic potential in the treatment of depression and anxiety. The effects of most widely used antidepressants on sleep and quantitative electroencephalogram (qEEG) are well characterized; however, such studies of tramadol are scarce. Our aim was to characterize the effects of tramadol on sleep architecture and qEEG in different sleep–wake stages. EEG-equipped Wistar rats were treated with tramadol (0, 5, 15 and 45 mg/kg) at the beginning of the passive phase, and EEG, electromyogram and motor activity were recorded. Tramadol dose-dependently reduced the time spent in rapid eye movement (REM) sleep and increased the REM onset latency. Lower doses of tramadol had wake-promoting effects in the first hours, while 45 mg/kg of tramadol promoted sleep first, but induced wakefulness thereafter. During non-REM sleep, tramadol (15 and 45 mg/kg) increased delta and decreased alpha power, while all doses increased gamma power. In conclusion, the sleep-related and qEEG effects of tramadol suggest antidepressant-like properties, including specific beneficial effects in selected patient groups, and raise the possibility of a faster acting antidepressant action.

A randomised-controlled, prospective study on the effect of dorsal penile nerve block after TURP on catheter-related bladder discomfort and pain

PURPOSE

In the present study, the impact of penile nerve block (PNB) on postoperative pain and Catheter-Related Bladder Discomfort (CRBD) in the transurethral resection of prostate(TURP) patients were evaluated.

METHODS

Participants of the present study were selected from patients who performed TURP under spinal anaesthesia for benign prostatic hyperplasia (BPH) between January 2018 and July 2020. The present study was planned as a single-centre, randomised-controlled prospective study in which the patients were divided into two groups. Group 1 was administered Control (n:40), and Group 2 ultrasonography(USG) guided PNB (n:40). The patients were included in the Groups, respectively. Visual analogue scale (VAS) scores were questioned and recorded in order to evaluate the postoperative pain complaints of the patients after the operation. In addition, in order to evaluate the CRBD, VAS scores were questioned and recorded as 0th, 0-1th hour, 1st-2nd hour, 2nd-4th hour, 4th-8th hour, 8th-12th hour, and 12th-24th hour. In addition, postoperative pain and need for analgesic drug were recorded. Tramadol was given to patients with moderate to severe CRBD. The findings were compared between the Groups.

RESULTS

There was no statistical difference demographic and per-operative data between Group 1 and Group 2. The CRBD and pain-related VAS scores were significantly higher in Group 1 between the 0 and 8th hours. There was no difference between VAS scores in the postoperative 8-24th hours. In total 24 hours, Group 2's need for tramadol was significantly less than Group 1. On examining the factors affecting CRBD in the multivariate analysis, age, body mass index(BMI), prostate volume, operation time do not affect CRBD statistically, and only PNB reduces CRBD (P: .029). While less drug-related complications were observed in Group 2, no serious complications related to PNB were observed.

CONCLUSION

Penile nerve block is an effective method for the decrease pain and CRBD after urological surgery. It will also reduce the need for analgesics, and provide painless patients in the postoperative period.

The role of adenosine A1 receptor in the peripheral tramadol's effect in the temporomandibular joint of rats

Peripheral tramadol's delivery in the temporomandibular joint (TMJ) leads to significant analgesic outcomes and inflammatory process's resolvent actions. Mechanistically, these properties are apart from the opioid system. Nevertheless, the molecular mechanisms behind these effects are still unclear. Therefore, the present study investigated the hypothesis that adenosine A₁ receptors are involved in the tramadol-induced analgesic and anti-inflammatory effects in the TMJ. Animals were pretreated with an intra-TMJ injection of DPCPX (antagonist of A₁ receptor) or tramadol and subsequent nociceptive challenge with an intra-TMJ injection of 1.5% formalin. For over 45 min, the nociceptive behavior was quantitated, and by the end of this assessment, the animals were euthanized, and the periarticular tissue was collected. Lastly, an in vitro assay of BMDM (Bone Marrow-Derived Macrophages) was performed to investigate tramadol activity in macrophages. The intra-TMJ injection of tramadol ameliorates formalin-induced hypernociception along with inhibiting leukocyte migration. The tramadol's peripheral anti-inflammatory effect was mediated by the adenosine A₁ receptor and was associated with increased protein expression of α2a-adrenoceptor in the periarticular tissues (p < 0.05: ANOVA, Tukey's test). Also, tramadol inhibits formalin-induced leukocyte migration and protein expression of P2X7 receptors in the periarticular tissue (p < 0.05); however, DPCPX did not alter this effect (p > 0.05). Moreover, DPCPX significantly reduced the protein expression of the M2 macrophage marker, MRC1. In BMDM, tramadol significantly reduces inflammatory cytokines release, and DPCPX abrogated this effect (p < 0.05). We identify tramadol's peripheral effect is mediated by adenosine A₁ receptor, possibly expressed in macrophages in the TMJ tissue. We also determined an important discovery related to the activation of A₁R/α2_a receptors in the tramadol action.

Acetaminophen reduces osteoprotegerin synthesis stimulated by PGE2 and PGF2α in osteoblasts: attenuation of SAPK/JNK but not p38 MAPK or p44/p42 MAPK

Acetaminophen is one of the most widely used analgesic and antipyretic medicines, whose long-period use has reportedly been associated with an increased risk of bone fracture. However, the mechanism underlying this undesired effect remains to be investigated. The homeostatic control of bone tissue depends on the interaction between osteoblasts and osteoclasts. Osteoprotegerin produced by osteoblasts is known to play an essential role in suppressing osteoclast induction. We have previously reported that prostaglandin (PG) E₂ and PGF_2α induce osteoprotegerin synthesis through p38 mitogen-activated protein kinase (MAPK), p44/p42 MAPK and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effects of acetaminophen on the osteoprotegerin synthesis induced by PGE₂ and PGF_2α in MC3T3-E1 cells. Acetaminophen significantly suppressed the osteoprotegerin release stimulated by PGE₂ and PGF_2α. The PGE₂-induced expression of osteoprotegerin mRNA was also reduced by acetaminophen. Acetaminophen markedly downregulated the phosphorylation of SAPK/JNK stimulated by PGE₂ and PGF_2α, but not those of p38 MAPK or p44/p42 MAPK. SP600125, an inhibitor of SAPK/JNK, suppressed the levels of PGE₂- and PGF_2α-upregulated osteoprotegerin mRNA expression. Taken together, these results strongly suggest that acetaminophen reduces the PGE₂- and PGF_2α-stimulated synthesis of osteoprotegerin in osteoblasts, and that the suppressive effect is exerted via attenuation of SAPK/JNK. These findings provide a molecular basis for the possible effect of acetaminophen on bone tissue metabolism.

Acetaminophen and tramadol hydrochloride-loaded soft gelatin capsule: preparation, dissolution and pharmacokinetics in beagle dogs

The objective of this study was to develop a novel acetaminophen and tramadol hydrochloride-loaded soft capsule (ATSC) with enhanced bioavailability of tramadol. The ATSC was manufactured in a pilot-scale batch size with the capsule contents composed of tramadol, acetaminophen, PEG 400 and Capmul MCM at a weight ratio of 37.5:325:177.5:30. Moreover, its dissolution, stability and pharmacokinetics in beagle dogs were carried out compared to commercial tablet. The dissolved amounts of acetaminophen from the ATSC and commercial tablet were not significantly different. However, compared to the latter, the former had significantly higher dissolution rate of tramadol at the initial times. In beagle dogs, the ATSC provided no significant difference in plasma concentrations and AUC of acetaminophen than did the commercial tablet; however, it significantly improved those of tramadol compared to the other, indicating the enhanced oral bioavailability of tramadol. Compared to the commercial tablet, the ATSC had a larger AUC value for tramadol (55.27 ± 11.06 vs. 92.62 ± 21.52 h·ng/ml). In the accelerated long-term stability, the ATSC offered higher than 96% drug content of acetaminophen and tramadol, suggesting that it was stable for at least six months. Therefore, this ATSC would be a recommendable candidate with enhanced oral bioavailability and excellent stability.

Repeated Administration of Clinically Relevant Doses of the Prescription Opioids Tramadol and Tapentadol Causes Lung, Cardiac, and Brain Toxicity in Wistar Rats

Tramadol and tapentadol, two structurally related synthetic opioid analgesics, are widely prescribed due to the enhanced therapeutic profiles resulting from the synergistic combination between μ-opioid receptor (MOR) activation and monoamine reuptake inhibition. However, the number of adverse reactions has been growing along with their increasing use and misuse. The potential toxicological mechanisms for these drugs are not completely understood, especially for tapentadol, owing to its shorter market history. Therefore, in the present study, we aimed to comparatively assess the putative lung, cardiac, and brain cortex toxicological damage elicited by the repeated exposure to therapeutic doses of both prescription opioids. To this purpose, male Wistar rats were intraperitoneally injected with single daily doses of 10, 25, and 50 mg/kg tramadol or tapentadol, corresponding to a standard analgesic dose, an intermediate dose, and the maximum recommended daily dose, respectively, for 14 consecutive days. Such treatment was found to lead mainly to lipid peroxidation and inflammation in lung and brain cortex tissues, as shown through augmented thiobarbituric acid reactive substances (TBARS), as well as to increased serum inflammation biomarkers, such as C reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Cardiomyocyte integrity was also shown to be affected, since both opioids incremented serum lactate dehydrogenase (LDH) and α-hydroxybutyrate dehydrogenase (α-HBDH) activities, while tapentadol was associated with increased serum creatine kinase muscle brain (CK-MB) isoform activity. In turn, the analysis of metabolic parameters in brain cortex tissue revealed increased lactate concentration upon exposure to both drugs, as well as augmented LDH and creatine kinase (CK) activities following tapentadol treatment. In addition, pneumo- and cardiotoxicity biomarkers were quantified at the gene level, while neurotoxicity biomarkers were quantified both at the gene and protein levels; changes in their expression correlate with the oxidative stress, inflammatory, metabolic, and histopathological changes that were detected. Hematoxylin and eosin (H & E) staining revealed several histopathological alterations, including alveolar collapse and destruction in lung sections, inflammatory infiltrates, altered cardiomyocytes and loss of striation in heart sections, degenerated neurons, and accumulation of glial and microglial cells in brain cortex sections. In turn, Masson's trichrome staining confirmed fibrous tissue deposition in cardiac tissue. Taken as a whole, these results show that the repeated administration of both prescription opioids extends the dose range for which toxicological injury is observed to lower therapeutic doses. They also reinforce previous assumptions that tramadol and tapentadol are not devoid of toxicological risk even at clinical doses.

Antinociceptive effects of rotigotine-loaded microspheres and its synergistic interactions with analgesics in inflammatory pain in rats

Rotigotine-loaded microspheres (RoMS) are sustained-release formulations with prolonged anti-Parkinson's effects. Given that pain is a non-motor symptom of Parkinson's disease, this study investigated the antinociceptive effects of RoMS and their synergistic effects with analgesics on inflammatory pain. A model of inflammatory pain was prepared by intraplantarly injecting male Sprague-Dawley rats with carrageenan. The antinociceptive effects of RoMS, acetaminophen, and tramadol, both alone and in combination, were evaluated using the hind paw withdrawal latency in the hot plate test and Randall-Selitto test. The rotigotine concentrations in serum and tissues were assayed using ultra-performance liquid chromatography-tandem mass spectrometry. Isobolographic analysis was performed to evaluate the nature of the interactions of RoMS with acetaminophen or tramadol. The results showed that hind paw withdrawal latency to thermal and mechanical stimuli was significantly increased on day 3 and 7 after administered RoMS. Rotigotine could be detected in serum and tissues 3 and 7 days after an intramuscular injection of RoMS. However, the rotigotine concentration fell the detection limit of the assay on day 14 after administration. RoMS produced synergistic antinociceptive effects in the inflammatory pain model when RoMS is combined with acetaminophen or tramadol. These findings suggest that RoMS can relieve inflammatory pain in rats. Furthermore, the combination of RoMS with acetaminophen or tramadol produces synergistic antinociception, which may be clinically worthy because combination therapies may reduce the drug doses required for antinociception.

Preoperative Analgesia, Complications, and Resource Utilization After Total Hip Arthroplasty: Tramadol Is Associated With Less Risk Than Other Preoperative Opioid Medications

BACKGROUND

Preoperative opioid use is known to be detrimental to outcomes after total hip arthroplasty (THA). This is concerning as multiple societies recommend tramadol for the management of arthritis. The purpose of this study was to determine if tramadol is associated with postoperative complications, increased resource utilization, and revision when compared with patients receiving nontramadol opioids (NTOs) and those who are opioid naive (ON).

METHODS

This is a retrospective cohort study using the Truven MarketScan databases (Truven Health, Ann Arbor, MI). Adult patients undergoing primary THA were identified and divided into 4 cohorts based on preoperative opioid medications (ie, ON, tramadol-only [TO], or NTOs; ±tramadol). Demographics, comorbidities, and 90-day complications were collected and compared between cohorts. Revision rates were compared at 3 years. Univariate and multivariate analyses were performed. Finally, preoperative prescription patterns were trended during the study period.

RESULTS

About 198,357 patients, including 18,694 TO and 106,768 ON, were identified. Compared with ON, TO patients had similar rates of complications and revision surgery (P > .05) but had slightly higher emergency department visits (odds ratio [OR], 1.06; 95% confidence interval [95% CI], 1.01-1.12; P = .027), readmissions (OR, 1.16; 95% CI, 1.09-1.22; P < .001), and nonhome discharges (OR, 1.07; 95% CI, 1.02-1.12; P = .010). TO patients had significantly lower odds of incurring most examined complications, including revision surgery, when compared with NTO (P < .05). From 2009 to 2018, the proportion of patients prescribed preoperative opioids decreased.

CONCLUSION

Preoperative TO is associated with less postoperative risk than NTO use and is similar to opioid naivety. Fortunately, the number of patients receiving preoperative NTOs appears to be decreasing. Our results support tramadol as an appropriate pre-THA analgesic.

The impact of preoperative tramadol-only use on outcomes following total knee arthroplasty - Is tramadol different than traditional opioids?

BACKGROUND

Opioid use prior to total knee arthroplasty (TKA) is known to have detrimental influence on postoperative outcomes. Whether or not the same is true for tramadol is currently unclear. The aim of this study was to clarify the relationship between preoperative tramadol and postoperative complications.

METHODS

The Truven Marketscan® Databases were used to conduct this retrospective cohort study. Patients undergoing primary TKA were identified and divided into cohorts based on preoperative medication status (i.e. opioid naïve, tramadol-only, or non-tramadol opioids). Patient demographics, comorbidities, and 90-day outcomes were collected and compared between cohorts. Revision rates were analyzed at 1- and 3-years postoperatively. Univariate and multivariate analysis was performed.

RESULTS

336,316 patients were included and 23,097 (6.9%) were preoperative tramadol-only users. Tramadol-only patients (v. opioid naïve) had increased odds of 90-day readmission (OR-1.07, 95%CI 1.02-1.12, p = 0.004), wound complication (OR-1.13, 95%CI 1.01-1.27, p = 0.34), and 3-year revision rates (OR-1.35, 95%CI 1.19-1.53, p < 0.001). However, when compared to the preoperative opioid cohorts, tramadol-only patients had decreased odds of nearly all outcomes. Over the study period, the number of patients receiving preoperative opioids decreased while the proportion of patients prescribed tramadol-only increased.

CONCLUSIONS

While tramadol-only use has lower risk than traditional opioids, tramadol-only use preceding TKA is associated with increased rates of readmission, wound complication and revision surgery. This is important information for prescribers who may be using tramadol to treat symptomatic knee arthrosis prior to arthroplasty referral and for thought leaders producing clinical practice guidelines.

LEVEL OF EVIDENCE

Level III, Prognostic.