Clinical pharmacology of tramadol

Molecular Network-Based Identification of Tramadol Metabolites in a Fatal Tramadol Poisoning

Identification of xenobiotics and their phase I/II metabolites in poisoned patients remains challenging. Systematic approaches using bioinformatic tools are needed to detect all compounds as exhaustively as possible. Here, we aimed to assess an analytical workflow using liquid chromatography coupled to high-resolution mass spectrometry with data processing based on a molecular network to identify tramadol metabolites in urine and plasma in poisoned patients. The generated molecular network from liquid chromatography coupled to high-resolution tandem mass spectrometry data acquired in both positive and negative ion modes allowed for the identification of 25 tramadol metabolites in urine and plasma, including four methylated metabolites that have not been previously reported in humans or in vitro models. While positive ion mode is reliable for generating a network of tramadol metabolites displaying a dimethylamino radical in their structure, negative ion mode was useful to cluster phase II metabolites. In conclusion, the combined use of molecular networks in positive and negative ion modes is a suitable and robust tool to identify a broad range of metabolites in poisoned patients, as shown in a fatal tramadol-poisoned patient.

Tramadol Versus Codeine in Hand Surgery

Introduction

Tramadol and codeine are both commonly prescribed in the setting of surgery or injury to the upper extremity. Despite their comparable strength in terms of opioid receptor affinity, the drugs differ pharmacologically and thus are not completely interchangeable.

Methods

This study analyzes all prescriptions for codeine and tramadol by a group of hand surgeons over a one-year period and tests the central hypothesis that the prescribing and refill patterns of these two drugs would be similar.

Results

Despite similar prescription amounts in terms of morphine equivalents, patients receiving tramadol required prescription refills at a significantly higher amount than those receiving codeine, and these individuals tended to be older. Additionally, patients treated nonoperatively were prescribed significantly more tramadol than those treated surgically.

Conclusion

Our findings suggest that codeine and tramadol are not equivalent in managing upper extremity pain. Further study is needed to articulate the situations in which physicians and patients are better served by tramadol versus codeine.

Tramadol and Codeine Stacking/Boosting Dose Exposure Induced Neurotoxic Behaviors, Oxidative Stress, Mitochondrial Dysfunction, and Neurotoxic Genes in Adolescent Mice

In spite of the increasing epidemic of pharmaceutical opioids (codeine and tramadol) misuse and abuse among the adolescents, little is known about the neurotoxic consequences of the widespread practice of tramadol and codeine abuse involving increasing multiple doses across days, referred to as stacking and boosting. Hence, in this study, we replicated stacking and boosting doses of tramadol, codeine alone, or in combination on spontaneous motor activity and cognitive function in adolescent mice and adduced a plausible mechanism of possible neurotoxicity. Ninety-six adolescent mice were randomly distributed into 4 groups (n = 24 per group) and treated thrice daily for 9 days with vehicle, tramadol (20, 40, or 80 mg/kg), codeine (40, 80, or 160 mg/kg), or their combinations. Exposure of mice to tramadol induced hyperactivity and stereotypic behavior while codeine exposure caused hypoactivity and nootropic effect but tramadol-codeine cocktail led to marked reduction in spontaneous motor activity and cognitive function. In addition, tramadol, codeine, and their cocktail caused marked induction of nitroso-oxidative stress and inhibition of mitochondrial complex I activity in the prefrontal cortex (PFC) and midbrain (MB). Real-time PCR expression profiling of genes encoding neurotoxicity (RT) showed that tramadol exposure upregulate 57 and downregulate 16 neurotoxic genes, codeine upregulate 45 and downregulate 25 neurotoxic genes while tramadol-codeine cocktail upregulate 52 and downregulate 20 neurotoxic genes in the PFC. Findings from this study demonstrate that the exposure of adolescents mice to multiple and increasing doses of tramadol, codeine, or their cocktail lead to spontaneous motor coordination deficits indicative of neurotoxicity through induction of oxidative stress, inhibition of mitochondrial complex I activity and upregulation of neurotoxicity encoding genes in mice.

Effect of preoperative tramadol, ibuprofen, ibuprofen/acetaminophen on the anaesthetic efficacy of inferior alveolar nerve block in patients with symptomatic irreversible pulpitis

The purpose of this double-blind clinical trial was to compare the effect of preoperative tramadol 50 mg, tramadol 100 mg, ibuprofen 600 mg, ibuprofen 600 mg/acetaminophen 1000 mg or placebo 60 min before the administration of inferior alveolar nerve blocks (IANB) of mandibular teeth in patients experiencing symptomatic irreversible pulpitis (SIP). Two hundred and fifty emergency patients diagnosed with SIP were randomly divided into five groups and received medications. Endodontic access was begun 15 min after completion of the IANB, and all patients had profound lip numbness. The Heft-Parker visual analogue scale was used to evaluate pain. Premedication with tramadol 100 mg significantly increased the success rate to 62% than the other groups (p < 0.05). The success rates of ibuprofen, ibuprofen/acetaminophen and tramadol 50 mg groups were not significantly different (p > 0.05). Premedication with tramadol 100 mg enhanced the anaesthetic success of IANB in mandibular molars with SIP.

Green Assessment of Chromatographic Methods Used for the Analysis of Four Methamphetamine Combinations with Commonly Abused Drugs

Numerous agents with anxiolytic or stimulant effects have the potential to be overused, and their misuse is associated with serious side effects. In Saudi Arabia, the estimated percentage of Saudis who abuse drugs is around 7–8% and the age range is 12–22 years. Methamphetamine, captagon, tramadol, heroin, and cannabis/cannabinoids have been proven to be the most commonly abused drugs in Saudi Arabia, with methamphetamine being at the top of the list. The present study focuses on the chromatographic analytical methods used for the analysis of methamphetamine in combination with commonly abused drugs, aiming to point out the greenest among them. These mixtures have been chosen as they are analyzed periodically and frequently in criminal evidence and forensic medicine. Therefore, the chances of hazards for analysts and the environment are high if the mixtures are not handled appropriately. This study aims to compare 23 chromatographic methods used for the analysis of methamphetamine mixtures in four major combinations, and to assess their greenness by using three greenness assessment tools, namely, NEMI, ESA and AGREE, to recommend the greenest analytical method. The NEMI results were proven to have low discriminating abilities and, accordingly, the comparisons are based on ESA and AGREE scores. The analysis results show that the safest methods with the most eco-friendly results (based on ESA and AGREE) are the GC-MS method proposed by Mohammed et al. to analyze methamphetamine and captagon mixtures (ESA = 79 and AGREE = 0.57), the UHPLC–MS-MS method proposed by Busardò et al. to analyze methamphetamine and cannabis/cannabinoid mixtures (ESA = 78 and AGREE = 0.57), the LC-MS method proposed by Herrin et al. to analyze methamphetamine and tramadol mixtures (ESA = 81 and AGREE = 0.56), and the LC-MS method proposed by Postigo-et al to analyze methamphetamine and heroin mixtures (ESA = 76 and AGREE = 0.58).

Pharmacovigilance Signals of the Opioid Epidemic over 10 Years: Data Mining Methods in the Analysis of Pharmacovigilance Datasets Collecting Adverse Drug Reactions (ADRs) Reported to EudraVigilance (EV) and the FDA Adverse Event Reporting System (FAERS)

In the past twenty years, the consumption of opioid medications has reached significant proportions, leading to a rise in drug misuse and abuse and increased opioid dependence and related fatalities. Thus, the purpose of this study was to determine whether there are pharmacovigilance signals of abuse, misuse, and dependence and their nature for the following prescription opioids: codeine, dihydrocodeine, fentanyl, oxycodone, pentazocine, and tramadol. Both the pharmacovigilance datasets EudraVigilance (EV) and the FDA Adverse Events Reporting System (FAERS) were analyzed to identify and describe possible misuse-/abuse-/dependence-related issues. A descriptive analysis of the selected Adverse Drug Reactions (ADRs) was performed, and pharmacovigilance signal measures (i.e., reporting odds ratio, proportional reporting ratio, information component, and empirical Bayesian geometric mean) were computed for preferred terms (PTs) of abuse, misuse, dependence, and withdrawal, as well as PTs eventually related to them (e.g., aggression). From 2003 to 2018, there was an increase in ADR reports for the selected opioids in both datasets. Overall, 16,506 and 130,293 individual ADRs for the selected opioids were submitted to EV and FAERS, respectively. Compared with other opioids, abuse concerns were mostly recorded in relation to fentanyl and oxycodone, while tramadol and oxycodone were more strongly associated with drug dependence and withdrawal. Benzodiazepines, antidepressants, other opioids, antihistamines, recreational drugs (e.g., cocaine and alcohol), and several new psychoactive substances, including mitragynine and cathinones, were the most commonly reported concomitant drugs. ADRs reports in pharmacovigilance databases confirmed the availability of data on the abuse and dependence of prescription opioids and should be considered a resource for monitoring and preventing such issues. Psychiatrists and clinicians prescribing opioids should be aware of their misuse and dependence liability and effects that may accompany their use, especially together with concomitant drugs.

Comparative risk-benefit profiles of weak opioids in the treatment of osteoarthritis: a network meta-analysis of randomized controlled trials

BACKGROUND

Despite their poor tolerance, weak opioids are still the most commonly-prescribed medicine for osteoarthritis (OA)-related pain. The objective of this network meta-analysis was to comparatively examine the efficacy and safety of weak opioids in OA treatment.

METHODS

Databases including PubMed, Embase, Cochrane Library and Web of Science were searched from inception to August 5, 2020 to retrieve randomized controlled trials (RCTs) comparing weak opioids with placebo or between one another in OA patients. Bayesian network meta-analysis was performed on the following outcomes of interest, namely the change-from-baseline score in pain relief, gastrointestinal (GI) adverse events (AEs), central nervous system (CNS) AEs, and total number of AEs (i.e., the number of subjects experiencing any AE for at least once) during follow-up.

RESULTS

A total of 14 RCTs involving four types of weak opioids were included in this meta-analysis. Compared to placebo, tramadol (standardized mean difference [SMD] = -0.34, 95% credible interval [CrI]: -0.53 to -0.18) and codeine (SMD = -0.39, 95% CrI: -0.79 to -0.04) were effective for pain relief, but involved a higher risk of GI AEs, CNS AEs and total number of AEs. Dextropropoxyphene demonstrated a significantly lower risk of GI AEs (OR = 0.28, 95%CrI: 0.17 to 0.51), CNS AEs (OR = 0.29, 95%CrI: 0.11 to 0.78) and total number of AEs (OR = 0.35, 95%CrI: 0.15 to 0.82) compared to codeine. Dihydrocodeine had a better safety profile in CNS AEs (SUCRA = 64.8%) and total number of AEs (SUCRA = 66.6%).

CONCLUSIONS

The results of the present study confirmed that tramadol and codeine were effective drugs for the treatment of OA, but involved considerable safety issues. Dextropropoxyphene and dihydrocodeine exhibited a relatively good safety profile but their efficacy still warrant further investigation.

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Military Health System Opioid, Tramadol, and Gabapentinoid Prescription Volumes Before and After a Defense Health Agency Policy Release

BACKGROUND

Clinical practice guidelines (CPGs) and health system policies to mitigate inappropriate opioid prescribing practices may have an extended impact on low-dose opioid (e.g., tramadol) and non-opioid (e.g., gabapentinoid) pain medication prescribing practices.

OBJECTIVE

To evaluate changes in opioid, tramadol, and gabapentinoid prescribing rates from January 2016 to February 2020 within the Military Health System, including the degree to which prescribing rates changed after release of a US Defense Health Agency Procedural Instruction.

METHODS

In this observational health services research study, opioid, tramadol, and gabapentin prescription dispense events of US Military Health System beneficiaries enrolled in care at military treatment facilities prior to US Defense Health Agency Procedural Instruction release (January 2016-May 2018) were used to forecast values from the post-intervention period (June 2018-February 2020).

RESULTS

The median opioid and tramadol prescribing rates decreased from January 2016 to February 2020, aside from tramadol prescribing in Surgery Clinics, which increased. Gabapentinoid prescribing rate changes were mixed. In Bayesian time series models, the forecasted proportion of patients receiving each of the three medications, regardless of age group or clinic type, did not significantly vary from the actual prescribing rates in the post-intervention period.

CONCLUSION

Overall, CPGs and policies targeting opioid prescribing practices may have provided the maximal impetus for providers to re-evaluate their prescribing practices, as the policy did not appear to change the slope in prescribing rates. However, it is unclear whether the policies mitigated the likelihood of plateaus in prescribing rates. Further work is needed to assess the degree to which providers simultaneously altered other non-opioid pain medication prescribing practices, self-management recommendations, and non-pharmacological therapy referrals.

Evaluation of Low-Dose Versus High-Dose Opioid Pathway in Opioid-Naïve Patients After Total Knee Arthroplasty

Background

Pain control after total knee arthroplasty (TKA) remains challenging. Tramadol is a weak opioid with potentially lower side effects and risk for dependency than stronger opioids. The purpose of this study was to evaluate efficacy and safety of tramadol after TKA in opioid-naïve patients compared with stronger opioids.

Methods

A retrospective review of patients who underwent primary TKA was performed. In September 2018, opioid-naïve patients were prescribed tramadol instead of oxycodone. Patients receiving tramadol (low-opioid group) were matched to patients discharged with oxycodone before this transition (high-opioid group). We compared morphine milligram equivalent (MME) consumption and outcomes up to 3 months postoperatively.

Results

Two-hundred and five patients underwent TKA, with 126 receiving tramadol. Fourteen patients were converted to stronger opioid (11.2% conversion rate). Seventy patients from the low-opioid group were matched to 70 patients in the high-opioid group. Average daily inpatient MME consumption was higher in the high-opioid group (40.0 ± 27.4 vs 16.3 ± 10.9, P = .000). Outpatient prescribed MME was significantly higher in the high-opioid group (135.5 ± 71.5 vs 75.3 ± 51.3, P = .000) along with a higher number of refills (0.53 ± 1.1 vs 0.886 ± 0.94, P = .041). Knee range of motion was not statistically different at any timepoint postoperatively. There was higher adverse event rate in the low-opioid group (8.6% vs 5.7%) but not statically significant.

Conclusions

Low opioid regimen following TKA showed lower MME consumption than high opioid regimen with no effect on outcomes up to 3 months. Use of low opioid regimen should be considered for TKA surgery.

The Effect of Ondansetron on the Analgesic Efficacy of Tramadol in Patients Undergoing Laparoscopic Cholecystectomy

Purpose

Investigating the effect of ondansetron on the efficacy of tramadol in patients undergoing laparoscopic cholecystectomy.

Methods

Sixty American Society of Anesthesiologists (ASA) I-II patients over the age of 18 who underwent laparoscopic cholecystectomy were included in this study. All patients were given 1 mg/kg tramadol intravenously (iv) during the intraoperative period. Patients were randomly assigned to receive either 4 mg ondansetron (Group O) or 2 mL saline (Group S). Postoperative tramadol consumption, pain score (NRS), intensity of nausea (NRS), presence of vomiting, consumption of rescue analgesics and antiemetics, and patient satisfaction were recorded.

Results

A total of 60 patients were enrolled in the study; five patients were excluded due to deviation from the protocol. Data from 55 patients (Group O: 28 patients, Group S: 27 patients) were evaluated in the study. No differences between the two groups were detected for postoperative consumption of tramadol, pain score (NRS), intensity of nausea (NRS), presence of vomiting, consumption of rescue analgesics and antiemetics, and patient satisfaction.

Conclusions

The results showed that coadministration of tramadol and ondansetron did not change tramadol consumption during the postoperative 24 hours after laparoscopic cholecystectomy. Clinical trial registration number is as follows: https://clinicaltrials.gov/ct2/show/NCT04745273-01/31/2021.

Intra-socket application of Hyaluronic acid reduces pain and swelling following wisdom teeth removal

Background: Hyaluronic acid (HA) has the potential to promote wound healing. Pain and swelling with trismus are common sequalae post wisdom teeth removal. This study aims to investigate the effectiveness of intra-socket HA solution to reduce these uncomfortable post-operative events. Materials and methods: 30 patients underwent bilateral extractions of mandibular wisdom teeth for this study. Intra-socket application of 0.7 ml 20 mg/2 ml HA solution (Hyalgun) with Gel foam as a scaffold in study site versus Gel foam only on control site was conducted via a split mouth study design. Data collection of five facial reference points for swelling and maximum mouth opening was recorded during the pre-operative period and post-operative 2nd and 7th day. The VAS pain score at post-op 1st, 2nd and 3rd day and the number of analgesics for the 7-day post-operative duration were evaluated. Results: The HA group demonstrated statistically significant less swelling, trismus and analgesia consumption on the 2 and 7 days after surgery. VAS scores on day 1, 2 and 3 after surgery (P = 0.05) were significantly less in the HA group compared to the control group. Conclusion: The application of intra-socket HA has a positive effect for reducing postoperative pain and swelling with trismus after the lower third molar intervention (LTMI).

Tramadol Treatment for Chemotherapy-induced Mucositis Pain in Children

Mucositis, a painful and debilitating condition, is a common side effect of chemotherapy. The role of tramadol in the treatment of mucositis in pediatric patients has not yet been determined. In this retrospective study, we evaluate whether tramadol as single agent achieved a reduction of pain intensity among oncologic children admitted for mucositis. In total, 34 of 54 (63%) episodes were treated with tramadol alone and achieved adequate pain relief. Tramadol's side effects were mild and manageable.

Comparative study of Local Anesthetic Efficacy of 5% Tramadol Versus 2%Lignocaine with 1:100,000 adrenaline for Extraction of fully erupted Maxillary 3rd molars using Infiltration Anesthesia

Introduction

The majority of dental procedures need local anesthesia for pain control, and lidocaine/ lignocaine is the most commonly used anesthetic agent in dentistry. Although effective and safest, the anesthetic agent still has some complications. To overcome these many alternatives have been used. Tramadol has been shown to have some local anesthetic (LA) effects when used for infiltration anesthesia in dentistry.

Methods

In the present study, the local anesthetic efficacy of tramadol was compared with 2% lignocaine containing 1: 100,000 adrenaline for the extraction of maxillary fully erupted 3rd molar teeth. The parameters recorded included the onset of action, duration of action, intraoperative pain, post-operative analgesic effect, and incidence of an allergic reaction. A total of 200 patients were randomly divided into two groups. In group A -Each patient received 0.6 ml of 5% tramadol (Tramataj- 50 mg prepared by Taj pharma company) 0.4 ml buccally and 0.2 ml palatally for extraction of maxillary 3rd molar as local infiltration following strict aseptic precaution. In Group B- patients received 0.6 ml of 2% lignocaine containing 1: 100,000 adrenaline buccally and 0.2 ml palatally as infiltrations.

Results

It was found that 5% tramadol has a local anesthetic efficacy similar to 2% lignocaine with adrenaline but was found to be a comparatively weaker agent.

Conclusion

tramadol is a valid alternative for performing extractions in normal patients or patients allergic to lidocaine.

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.

Exposure to immediate-release tramadol in children 6 years and under - a nationwide French poison control center study

INTRODUCTION

Data regarding immediate-release (IR)-tramadol exposures in children remain sparse. We aimed to investigate the incidence of IR-tramadol exposures in ≤6-year-old children, to describe the characteristics and resulting outcome of ingestions involving IR-tramadol alone, and to estimate a clinically relevant toxic dose in this population.

METHODS

Retrospective analysis of IR-tramadol exposures in ≤6-year-old children, collected by the French Poison Control Centers (PCCs) in 2003-2019. The incidence was estimated using IR-tramadol prescription data from the Health Improvement Network database (the French version of THIN). The Poison severity score (PSS) was used to grade severity.

RESULTS

We found 1260 IR-tramadol exposures in ≤6-year-old children. The number of cases per 100,000 IR-tramadol-treated patients increased over time (p < .0001). One hundred forty-five cases involving IR-tramadol alone were analyzed. The median age was 3.0 years (IQR: 1.9, 4.0), the M/F ratio was 1.5 and the median dose was 5.0 mg/kg (IQR 3.3-11.1). Half of the children (49.7%) remained asymptomatic (PSS0) while 29.6% and 14.5% developed minor (PSS1) or moderate-to-severe (PSS2-PSS3) neurological symptoms, respectively. Twelve children developed respiratory depression. No seizures and no fatality were reported. All symptomatic children recovered within 24 h. The ingested IR-tramadol dose was positively correlated with the PSS (p < .0001). Using a receiver operating characteristic (ROC) curve approach (area under the curve, 0.92; p < .001), ingestion of ≥7.4 mg/kg IR-tramadol was appropriate to recommend hospital referral (sensitivity, 100% [95% confidence interval (CI), 85-100]; specificity, 73% [95% CI, 64-80]; predictive positive value, 39% [95% CI, 35-57]; negative predictive value, 100% [95% CI, 96-100]). Children who ingested <7.4 mg/kg IR-tramadol developed no (n = 68) or minor (n = 22) neurological symptoms.

CONCLUSIONS

Despite increasing tramadol prescriptions in adults during the study period in France, oral exposure to IR-tramadol in ≤6-year-old children was rare but possibly responsible for severe toxicity. Children with no underlying disease and concomitant medication ingesting <7.4 mg/kg IR-tramadol alone could be observed at home. However, given the observed variability in the onset of seizures after tramadol ingestion, which can occur at ingested tramadol doses below 7.4 mg and even at therapeutic doses, parents or guardians should be specifically warned about the risk of seizures.

Title: Novel Analgesic Potential of ß2-Agonists for Neuropathic Pain via ß2-Agonist Action

PURPOSE OF REVIEW

Multimodal therapies are often employed to treat chronic pain, and ß2-agonists are a potential drug class that shows promise. The primary aim of this paper is to discuss the role of ß2-agonists as an adjunctive therapy for chronic pain based on the current literature.

RECENT FINDINGS

Recent studies in mouse models have shown that the ß2-adrenergic system plays an essential role in the analgesic properties of antidepressant drugs used to treat neuropathic pain and that the adrenergic relies on an intact endogenous opioid system to be effective. Studies also show that ß2-agonism alone is adequate to exert anti-allodynic effects in a mouse model. This paper summarized the basic physiology and pharmacology of the sympathetic nervous system and specifically the ß2-adrenergic system and summarized current literature in its involvement in the treatment of chronic neuropathic pain.

Tapentadol shows lower intrinsic efficacy at µ receptor than morphine and oxycodone

Tapentadol is a centrally acting analgesic with a dual mechanism of action. It acts as an agonist at the µ receptor and inhibitor of noradrenaline reuptake. Clinical trials suggest similar analgesic efficacy of tapentadol, oxycodone, and morphine in acute and chronic pain. Given the limited information about the molecular actions of tapentadol at the µ receptor, we investigated the intrinsic efficacy of tapentadol and compared it with other opioids. β-chlornaltrexamine (β-CNA, 100 nM, 20 min) was used to deplete spare receptors in AtT20 cells stably transfected with human µ receptor wild-type (WT). Opioid-mediated changes in membrane potential were measured in real-time using a membrane potential-sensitive fluorescent dye. Using Black and Leff's operational model, intrinsic efficacy relative to DAMGO was calculated for each opioid. Tapentadol (0.05 ± 0.01) activated the GIRK channel with lesser intrinsic efficacy than morphine (0.17 ± 0.02) and oxycodone (0.16 ± 0.02). We further assessed the signaling of tapentadol in the common µ receptor variants (N40D and A6V) which are associated with altered receptor signaling. We found no difference in the response of tapentadol between these receptor variants.

Opioids for chronic pain management in patients with dialysis-dependent kidney failure

Chronic pain is highly prevalent among adults treated with maintenance haemodialysis (HD) and has profound negative effects. Over four decades, research has demonstrated that 50-80% of adult patients treated with HD report having pain. Half of patients with HD-dependent kidney failure (HDKF) have chronic moderate-to-severe pain, which is similar to the burden of pain in patients with cancer. However, pain management in patients with HDKF is often ineffective as most patients report that their pain is inadequately treated. Opioid analgesics are prescribed more frequently for patients receiving HD than for individuals in the general population with chronic pain, and are associated with increased morbidity, mortality and health-care resource use. Furthermore, current opioid prescribing patterns are frequently inconsistent with guideline-recommended care. Evidence for the effectiveness of opioids in pain management in general, and in patients with HDKF specifically, is lacking. Nonetheless, long-term opioid therapy has a role in the treatment of some patients when used selectively, carefully and combined with an ongoing assessment of risks and benefits. Here, we provide a comprehensive overview of the use of opioid therapy in patients with HDKF and chronic pain, including a discussion of buprenorphine, which has potential as an analgesic option for patients receiving HD owing to its unique pharmacological properties.

Postoperative Pain Management in Enhanced Recovery Pathways

Postoperative pain is a common but often inadequately treated condition. Enhanced recovery pathways (ERPs) are increasingly being utilized to standardize perioperative care and improve outcomes. ERPs employ multimodal postoperative pain management strategies that minimize opioid use and promote recovery. While traditional opioid medications continue to play an important role in the treatment of postoperative pain, ERPs also rely on a wide range of non-opioid pharmacologic therapies as well as regional anesthesia techniques to manage pain in the postoperative setting. The evidence for the use of these interventions continues to evolve rapidly given the increasing focus on enhanced postoperative recovery. This article reviews the current evidence and knowledge gaps pertaining to commonly utilized modalities for postoperative pain management in ERPs.

Comparison of Online Patient Reviews and National Pharmacovigilance Data for Tramadol-Related Adverse Events: Comparative Observational Study

BACKGROUND

Tramadol is known to cause fewer adverse events (AEs) than other opioids. However, recent research has raised concerns about various safety issues.

OBJECTIVE

We aimed to explore these new AEs related to tramadol using social media and conventional pharmacovigilance data.

METHODS

This study used 2 data sets, 1 from patients' drug reviews on WebMD (January 2007 to January 2021) and 1 from the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS; January 2016 to December 2020). We analyzed 2062 and 29,350 patient reports from WebMD and FAERS, respectively. Patient posts on WebMD were manually assigned the preferred terms of the Medical Dictionary for Regulatory Activities. To analyze AEs from FAERS, a disproportionality analysis was performed with 3 measures: proportional reporting ratio, reporting odds ratio, and information component.

RESULTS

From the 869 AEs reported, we identified 125 new signals related to tramadol use not listed on the drug label that satisfied all 3 signal detection criteria. In addition, 20 serious AEs were selected from new signals. Among new serious AEs, vascular disorders had the largest signal detection criteria value. Based on the disproportionality analysis and patients' symptom descriptions, tramadol-induced pain might also be an unexpected AE.

CONCLUSIONS

This study detected several novel signals related to tramadol use, suggesting newly identified possible AEs. Additionally, this study indicates that unexpected AEs can be detected using social media analysis alongside traditional pharmacovigilance data.

Rhabdomyolysis and acute kidney injury due to suicide attempt with tramadol: A rare case report

Although acute kidney injury (AKI) is a very rare complication of tramadol (TR) poisoning, overdose use in recent years should be considered. We present a 21-year-old man with metabolic acidosis, seizures, elevated serum creatine phosphokinase (CPK), creatinine, and rhabdomyolysis due to tramadol poisoning.

The Treatment of Painful Diabetic Neuropathy

Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.

Comparative pharmacokinetics between two tablets of tramadol 37.5 mg/acetaminophen 325 mg and one tablet of tramadol 75 mg/acetaminophen 650 mg for extended-release fixed-dose combination

An extended-release (ER) fixed-dose combination (FDC) of tramadol 37.5 mg/acetaminophen 325 mg was developed due to the demand for varying dosages. This study aimed to evaluate the pharmacokinetics (PKs) for two tablets of the new developed tramadol 37.5 mg/acetaminophen 325 mg ER FDC (DW-0920, Wontran Semi ER^®) as test formulation compared to one tablet of the tramadol 75 mg/acetaminophen 650 mg ER FDC (DW-0919, Wontran ER^®) as reference formulation. A randomized, open-label, 2-way crossover study was conducted in 30 healthy subjects. Subjects were orally administered one of 2 formulations followed by an alternate formulation with a 7-day washout period. Blood samples were collected up to 36 hours post-dose. Plasma concentrations of tramadol and acetaminophen were determined using a validated high-performance liquid chromatography with tandem mass spectrometric method. The geometric mean ratios (GMRs) and their 90% confidence intervals (90% CIs) of test formulation to reference formulation were calculated for the maximum plasma concentration (C_max) and the area under the plasma concentration-time curve from zero to the last measurable time point (AUC_last). The PK profiles of 2 formulations were comparable. The GMRs (90% CI) of C_max and AUC_last for tramadol were 1.086 (1.047–1.127) and 1.008 (0.975–1.042), respectively. The corresponding values for acetaminophen were 0.956 (0.897–1.019) and 0.986 (0.961–1.011), respectively. All the values were within the bioequivalence range of 0.80–1.25. Two tablets of DW-0920 were comparable to one tablet of DW-0919. The DW-0920 may be used for optimal pharmacotherapy for pain control with a lower dose.

Evaluation of mitochondrial dysfunction due to oxidative stress in therapeutic, toxic and lethal concentrations of tramadol

Tramadol (TR) is a centrally acting analgesic drug that is used to relieve pain. The therapeutic (0.1-0.8 mg/l), toxic (1-2 mg/l) and lethal (>2 mg/l) ranges were reported for TR. The present study was designed to evaluate which doses of TR can induce liver mitochondrial toxicity. Mitochondria were isolated from the five rats' liver and were incubated with therapeutic to lethal concentrations (1.7-600 μM) of TR. Biomarkers of oxidative stress including: reactive oxygen species (ROS), lipid peroxidation (LPO), protein carbonyl content, glutathione (GSH) content, mitochondrial function, mitochondrial membrane potential (MMP) and mitochondrial swelling were assessed. Our results showed that ROS and LPO at 100 μM and protein carbonylation at 600 μM concentrations of TR were significantly increased. GSH was decreased specifically at 600 μM concentration. Mitochondrial function, MMP and mitochondrial swelling decreased in isolated rat liver mitochondria after exposure to 100 and 300 μM, respectively. This study suggested that TR at therapeutic and toxic levels by single exposure could not induce mitochondrial toxicity. But, in lethal concentration (≥100 μM), TR induced oxidative damage and mitochondria dysfunction. This study suggested that ROS overproduction by increasing of TR concentration induced mitochondrial dysfunction and caused mitochondrial damage via Complex II and membrane permeability transition pores disorders, MMP collapse and mitochondria swelling.

Combined molecular, structural and memory data unravel the destructive effect of tramadol on hippocampus

Tramadol is a synthetic analogue of codeine and stimulates neurodegeneration in several parts of the brain that leads to various behavioral impairments. Despite the leading role of hippocampus in learning and memory as well as decreased function of them under influence of tramadol, there are few studies analyzing the effect of tramadol administration on gene expression profiling and structural consequences in hippocampus region. Thus, we sought to determine the effect of tramadol on both PC12 cell line and hippocampal tissue, from gene expression changes to structural alterations. In this respect, we investigated genome-wide mRNA expression using high throughput RNA-seq technology and confirmatory quantitative real-time PCR, accompanied by stereological analysis of hippocampus and behavioral assessment following tramadol exposure. At the cellular level, PC12 cells were exposed to 600μM tramadol for 48 hrs, followed by the assessments of ROS amount and gene expression levels of neurotoxicity associated with neurodegenerative pathways such as apoptosis and autophagy. Moreover, the structural and functional alteration of the hippocampus under chronic exposure to tramadol was also evaluated. In this regard, rats were treated with tramadol at doses of 50 mg/kg for three consecutive weeks. In vitro data revealed that tramadol provoked ROS production and caused the increase in the expression of autophagic and apoptotic genes in PC12 cells. Furthermore, in-vivo results demonstrated that tramadol not only did induce hippocampal atrophy, but it also triggered microgliosis and microglial activation, causing upregulation of apoptotic and inflammatory markers as well as over-activation of neurodegeneration. Tramadol also interrupted spatial learning and memory function along with long-term potentiation (LTP). Taken all together, our data disclosed the neurotoxic effects of tramadol on both in vitro and in-vivo. Moreover, we proposed a potential correlation between disrupted biochemical cascades and memory deficit under tramadol administration.

A Critical Review of the Pharmacokinetics and Pharmacodynamics of Opioid Medications Used in Avian Patients

Opioid drugs are used to manage moderate to severe pain in mammals and avian species. In dosing opioids for a particular species, it is optimal to use dosing regimens based on pharmacokinetics or pharmacodynamics studies conducted in the same species as variability in the physiology among different species may result in differences in drug pharmacokinetics and pharmacodynamics. Unfortunately, dosing regimens are typically extrapolated from closely related avian species or even mammals, which is unideal. Therefore, this critical review aims to collate and evaluate the dosing regimens of selected opioids: tramadol, hydromorphone, buprenorphine, butorphanol, and fentanyl, in avian species and its related safety, efficacy and pharmacokinetic data. Our review found specific dosing regimens not described in the Exotic Animal Formulary for tramadol used in Indian Peafowl (Pavo cristatus), Muscovy Duck (Cairina moschata) and Hispaniolan Parrot (Amazona ventralis); hydromorphone used in Orange-winged Parrot (Amazona amazonica); buprenorphine used in Cockatiel (Nymphicus hollandicus), American Kestrel (Falco sparverius) and Grey Parrot (Psittacus erithacus); and butorphanol used in Hispaniolan Parrot (Amazona ventralis), Broiler Chicken and Indian Peafowl (Pavo cristatus). Cockatiel appeared to not experience analgesic effects for hydromorphone and buprenorphine, and American Kestrel exhibited sex-dependent responses to opioids. The selected opioids were observed to be generally safe, with adverse effects being dose-dependent.

Prescribed aggression of fishes: Pharmaceuticals modify aggression in environmentally relevant concentrations

Traces of psychoactive substances have been found in freshwaters globally. Fish are chronically exposed to pollution at low concentrations. The changes of aggressive behaviour of chub (Squalius cephalus) were determined under the exposure to four psychoactive compounds (sertraline, citalopram, tramadol, methamphetamine) at environmentally relevant concentrations of 1 μg/L for 42 days. We tested whether (A) the behavioural effect of compounds varies within a single species; (B) there is a correlation between the individual brain concentration of the tested pollutants and fish aggression using the novel analysis of pollutants in brain; and (C) there is detectable threshold to effective pollutant concentration in brain. Behaviour and pollutant concentrations in brain were determined repeatedly (1st, 7th, 21st, 42nd and 56th days), including a two-week-long depuration period. The effect of particular compounds varied. Citalopram and methamphetamine generally increased the fish aggression, while no such effect was found after exposure to tramadol or sertraline. The longitudinal analysis showed an aggression increase after depuration, indicating the presence of withdrawal effects in methamphetamine- and tramadol-exposed fish. The analysis of pollutant concentration in brain revealed a positive linear relationship of citalopram concentration and aggression, while no such effect was detected for other compounds and/or their metabolites. Structural break analyses detected concentration thresholds of citalopram (1 and 3 ng/g) and sertraline (1000 ng/g) in brain tissue, from which a significant effect on behaviour was manifested. While the effect of sertraline was not detected using traditional approaches, there was a reduction in aggression after considering its threshold concentration in the brain. Our results suggest that pursuing the concentration threshold of psychoactive compounds can help to reduce false negative results and provide more realistic predictions on behavioural outcomes in freshwater environments, especially in the case of compounds with bioaccumulation potential such as sertraline.

HPLC-UV assay of tramadol and O-desmethyltramadol in human plasma containing other drugs potentially co-administered to participants in a paediatric population pharmacokinetic study

Multimodal analgesia is employed in paediatric pain management to maximise analgesia and minimise side effects. Tramadol is dosed at 1-1.5 mg/kg to treat severe pain in children but the assay for tramadol in plasma samples for pharmacokinetic and toxicology studies does not often consider concurrently administered medications. In this study we developed and validated an HPLC-UV method to quantify tramadol and its main metabolite (O-desmethyltramadol) in human plasma in the presence of seven potentially interfering drugs. Sample preparation method was developed by combining liquid-liquid extraction and protein precipitation. Chromatographic separation was achieved on a BDS-Hypersil-C18 column (5 µm, 250 × 4.6 mm) using a double gradient method. The limit of quantification was 6.7 ng/ml for both tramadol and ODT. The precision and accuracy were in compliance with ICH guidelines. This method was successfully employed to analyse the blood samples of 137 paediatric participants in a tramadol pharmacokinetic trial.

Analgesic Efficacy of Tramadol and Morphine in White's Tree Frogs (Litoria caerulea)

Published data are sparse regarding the recognition of clinically relevant pain and appropriate analgesia in amphibians. The amphibian analgesia literature has primarily focused on nociceptive pathways in a single species, the northern leopard frog (Rana pipiens). The objective of the current study was to assess the analgesic efficacy and safety of oral tramadol and subcutaneous morphine in a commonly maintained zoo and pet species, White's tree frog (Litoria caerulea). We hypothesized that tramadol and morphine would provide dose-dependent antinociception, as measured by significant increases in hindlimb withdrawal latency after exposure to a noxious thermal stimulus. Two randomized, placebo-controlled, complete crossover studies were performed, with tramadol (n = 12) administered at 15, 25, and 40 mg/kg PO and morphine (n = 12) administered at 5 and 10 mg/kg SC. Hindlimb withdrawal latency was measured for a maximum of 72 h. No adverse side effects or signs of sedation were observed with any dose or drug evaluated. No significant difference in withdrawal latency was detected between the control and either tramadol or morphine. These negative results were surprising, suggesting that the thermal nociceptive model may not be biologically relevant in amphibian species.

Toxicokinetics of U-47700, tramadol, and their main metabolites in pigs following intravenous administration: is a multiple species allometric scaling approach useful for the extrapolation of toxicokinetic parameters to humans?

New synthetic opioids (NSOs) pose a public health concern since their emergence on the illicit drug market and are gaining increasing importance in forensic toxicology. Like many other new psychoactive substances, NSOs are consumed without any preclinical safety data or any knowledge on toxicokinetic (TK) data. Due to ethical reasons, controlled human TK studies cannot be performed for the assessment of these relevant data. As an alternative animal experimental approach, six pigs per drug received a single intravenous dose of 100 µg/kg body weight (BW) of U-47700 or 1000 µg/kg BW of tramadol to evaluate whether this species is suitable to assess the TK of NSOs. The drugs were determined in serum and whole blood using a fully validated method based on solid-phase extraction and LC–MS/MS. The concentration–time profiles and a population (pop) TK analysis revealed that a three-compartment model best described the TK data of both opioids. Central volumes of distribution were 0.94 L/kg for U-47700 and 1.25 L/kg for tramadol and central (metabolic) clearances were estimated at 1.57 L/h/kg and 1.85 L/h/kg for U-47700 and tramadol, respectively. The final popTK model parameters for pigs were upscaled via allometric scaling techniques. In comparison to published human data, concentration–time profiles for tramadol could successfully be predicted with single species allometric scaling. Furthermore, possible profiles for U-47700 in humans were simulated. The findings of this study indicate that unlike a multiple species scaling approach, pigs in conjunction with TK modeling are a suitable tool for the assessment of TK data of NSOs and the prediction of human TK data.

Tramadol versus codeine and the short-term risk of cardiovascular events in patients with non-cancer pain: A population-based cohort study

AIMS

The effect of tramadol on the cardiovascular system is largely unknown. There is concern that, with its multimodal mechanism of action to increase serotonin and norepinephrine levels in the body, it could increase the risk of arterial ischaemia and cardiovascular events. We aimed to compare the short-term risk of cardiovascular events with the use of tramadol to that of codeine among patients with non-cancer pain.

METHODS

We conducted a retrospective population-based cohort study using data from the Clinical Practice Research Datalink (CPRD) with new users of tramadol or codeine from April 1998 to March 2017. Exposure was defined using an approach analogous to an intention-to-treat, with a maximum follow-up of 30 days. The primary endpoint was myocardial infarction, and secondary endpoints were unstable angina, ischaemic stroke, coronary revascularization, cardiovascular death and all-cause mortality. Hazard ratios (HRs) were estimated using Cox proportional hazards models, adjusted for high-dimensional propensity score.

RESULTS

The final cohort included 123 394 tramadol users and 914 333 codeine users. When tramadol was compared to codeine, the adjusted hazard ratio (HR) of myocardial infarction was 1.00 (95% CI 0.81-1.24). There was also no evidence of elevated risks of unstable angina (0.92; 95% CI 0.67-1.27), ischaemic stroke (0.98; 95% CI 0.82-1.17), coronary revascularization (0.97; 95% CI 0.69-1.38), cardiovascular death (1.07; 95% CI 0.93-1.23) or all-cause mortality (1.03; 95% CI 0.94-1.14) when tramadol was compared to codeine.

CONCLUSIONS

Short-term use of tramadol, compared with codeine, was not associated with an increased risk of cardiac events among patients with non-cancer pain.

Morphometric, hematological and oxidative stress changes in Clarias gariepinus following sub-chronic exposure to tramadol

Tramadol is among the most famous analgesic drugs used for the management, treatment and relief of moderate to severe pain conditions. The present study investigated the effects of tramadol on the behavior, mortality, morphometric, hematology and oxidative stress parameters of C. gariepinus juveniles. The 96 h LC₅₀ value of tramadol determined by probit analysis was 88.76 mg/L. Based on this value, fish were exposed to sublethal concentrations of 4.44, 8.88, 17.75 mg/L tramadol and 0.0 mg/L (control) for the period of 15 days and allowed to recover for 5 days. Fish exposed to tramadol showed some abnormal behavioral responses and mortality increased with increase in the exposure duration and concentrations except for the control. There were variations in hepatosomatic index (HSI) and condition factor (CF) in fish exposed to tramadol. Exposure of C. gariepinus to tramadol elicited reduction in the values of white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), packed cell volume (PCV) and mean corpuscular volume (MCV) while the values of mean corpuscular hemoglobin (MCH) and the mean corpuscular hemoglobin concentration (MCHC) increased. The values of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), reduced glutathione (GSH) and lipid peroxidation (LPO) increased significantly in the exposed fish compared with the control. The values of glutathione peroxidase (GPx) however decreased. The results of the present study demonstrate that tramadol is toxic to fish and its use should be monitored in the aquatic environment.

Chronic exposure to tramadol induces cardiac inflammation and endothelial dysfunction in mice

Tramadol is an opioid extensively used to treat moderate to severe pain; however, prolonged therapy is associated with several tissues damage. Chronic use of tramadol was linked to increased hospitalizations due to cardiovascular complications. Limited literature has described the effects of tramadol on the cardiovascular system, so we sought to investigate these actions and elucidate the underlying mechanisms. Mice received tramadol hydrochloride (40 mg/kg body weight) orally for 4 successive weeks. Oxidative stress, inflammation, and cardiac toxicity were assessed. In addition, eNOS expression was evaluated. Our results demonstrated marked histopathological alteration in heart and aortic tissues after exposure to tramadol. Tramadol upregulated the expression of oxidative stress and inflammatory markers in mice heart and aorta, whereas downregulated eNOS expression. Tramadol caused cardiac damage shown by the increase in LDH, Troponin I, and CK-MB activities in serum samples. Overall, these results highlight the risks of tramadol on the cardiovascular system.

Drug repurposing for opioid use disorders: integration of computational prediction, clinical corroboration, and mechanism of action analyses

Morbidity and mortality from opioid use disorders (OUD) and other substance use disorders (SUD) is a major public health crisis, yet there are few medications to treat them. There is an urgency to accelerate SUD medication development. We present an integrated drug repurposing strategy that combines computational prediction, clinical corroboration using electronic health records (EHRs) of over 72.9 million patients and mechanisms of action analysis. Among top-ranked repurposed candidate drugs, tramadol, olanzapine, mirtazapine, bupropion, and atomoxetine were associated with increased odds of OUD remission (adjusted odds ratio: 1.51 [1.38-1.66], 1.90 [1.66-2.18], 1.38 [1.31-1.46], 1.37 [1.29-1.46], 1.48 [1.25-1.76], p value < 0.001, respectively). Genetic and functional analyses showed these five candidate drugs directly target multiple OUD-associated genes including BDNF, CYP2D6, OPRD1, OPRK1, OPRM1, HTR1B, POMC, SLC6A4 and OUD-associated pathways, including opioid signaling, G-protein activation, serotonin receptors, and GPCR signaling. In summary, we developed an integrated drug repurposing approach and identified five repurposed candidate drugs that might be of value for treating OUD patients, including those suffering from comorbid conditions.

Narcotic Use for Acute Postoperative Pain Management in Mohs Micrographic Surgery Patients With End Stage Renal Disease: A Review of the Literature

BACKGROUND

Uncontrolled acute postoperative pain presents a significant management challenge when opioids are used in patients with end-stage renal disease (ESRD). Currently, there is a lack of quality pharmacokinetic and pharmacodynamic data regarding opioid medication use in ESRD patients to optimize safe and effective management.

OBJECTIVE

To review the published literature on pharmacologic evidence for and against the use of opioid medications for acute postoperative pain following Mohs micrographic surgery in ESRD patients.

METHODS

A search of PubMed was conducted to identify articles on the pharmacokinetic and pharmacodynamic properties of opioid pain medications in ESRD patients through March 1, 2020.

RESULTS

Seventy-five articles were reviewed. Limited data exist on opioids safe for use in ESRD and are mostly confined to small case series. Studies suggest tramadol and hydromorphone could be considered when indicated. Methadone may be a safe option, but should be reserved for treatment coordinated by a trained pain subspecialist.

CONCLUSION

Randomized clinical trials are lacking. Studies that are available are not sufficient to perform a quantitative methodologic approach. Evidence supports the judicious use of postoperative opioid medications in ESRD patients at the lowest possible dose to achieve clinically meaningful improvement in pain and function.

Physiologically-based Pharmacokinetic Modeling to Assess the Impact of CYP2D6-Mediated Drug-Drug Interactions on Tramadol and O-Desmethyltramadol Exposures via Allosteric and Competitive Inhibition

Tramadol is an opioid medication used to treat moderately severe pain. Cytochrome P450 (CYP) 2D6 inhibition could be important for tramadol, as it decreases the formation of its pharmacologically active metabolite, O‐desmethyltramadol, potentially resulting in increased opioid use and misuse. The objective of this study was to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O‐desmethyltramadol pharmacokinetics using quinidine and metoprolol as prototypical perpetrator drugs. A physiologically based pharmacokinetic model for tramadol and O‐desmethyltramadol was developed and verified in PK‐Sim version 8 and linked to respective models of quinidine and metoprolol to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O‐desmethyltramadol exposure. Our results show that there is a differentiated impact of CYP2D6 inhibitors on tramadol and O‐desmethyltramadol based on their mechanisms of inhibition. Following allosteric inhibition by a single dose of quinidine, the exposure of both tramadol (51% increase) and O‐desmethyltramadol (52% decrease) was predicted to be significantly altered after concomitant administration of a single dose of tramadol. Following multiple‐dose administration of tramadol and a single‐dose or multiple‐dose administration of quinidine, the inhibitory effect of quinidine was predicted to be long (≈42 hours) and to alter exposure of tramadol and O‐desmethyltramadol by up to 60%, suggesting that coadministration of quinidine and tramadol should be avoided clinically. In comparison, there is no predicted significant impact of metoprolol on tramadol and O‐desmethyltramadol exposure. In fact, tramadol is predicted to act as a CYP2D6 perpetrator and increase metoprolol exposure, which may necessitate the need for dose separation.

The effect of pre-operative submucosal administration of dexamethasone, tramadol, articaine on the success rate of inferior alveolar nerve block on mandibular molars with symptomatic irreversible pulpitis: A randomized, double-blind placebo-controlled clinical trial

AIM

To establish the effects of submucosal tramadol, dexamethasone and articaine on the success of inferior alveolar nerve blocks (IANB) during root canal treatment of mandibular molars with symptomatic irreversible pulpitis (SIP).

METHODOLOGY

In this randomized double-blind, controlled clinical trial, 120 patients with the diagnosis of SIP in their mandibular first or second molars were included and randomly divided into four groups (n = 30). The control group received normal saline and three experimental groups received a single dose of dexamethasone (8 mg/2 mL), or tramadol (100 mg/2 mL) or articaine (4% / 2 mL). The pre-operative pain levels of the patients were measured with the Heft-Parker visual analogue scale (HP VAS). All patients received standard IANB of 4% articaine with 1:200000 epinephrine. Following the observation of lip numbness, submucosal injections were administered into the mucobuccal fold adjacent to the mandibular molars. After 15 min, standard root canal treatment was initiated, and the pain intensity levels recorded from the access cavity preparation to pulp extirpation were measured with HP VAS. The duration of the anaesthesia was also evaluated. The experimental groups were compared using one-way ANOVA or Kruskal-Wallis H-test. The groups that were significantly different were compared pairwise using the Tukey Multiple Comparison test. The Chi-square test was used to compare the categorical variables.

RESULTS

The submucosal administration of articaine significantly increased the success rate to 63% in comparison with the control group that received submucosal saline (p < .05). The success rate of pulpal anaesthesia was 37% in the control group, 57% in the tramadol group and 47% in the dexamethasone group, with no significant difference in the success rate among these groups. In the dexamethasone group, the duration of the anaesthetic effect of IANB was significantly longer than those in the other groups (p < .001).

CONCLUSIONS

In patients with SIP, pre-operative submucosal administration of articaine increased the success rate of IANB, while administration of dexamethasone increased the duration of anaesthesia. These agents can be used in cases where effective anaesthesia cannot be obtained during root canal treatments.

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.

Toxicities of opioid analgesics: respiratory depression, histamine release, hemodynamic changes, hypersensitivity, serotonin toxicity

Opioid-induced respiratory depression is potentially life-threatening and often regarded as the main hazard of opioid use. Main cause of death is cardiorespiratory arrest with hypoxia and hypercapnia. Respiratory depression is mediated by opioid μ receptors expressed on respiratory neurons in the CNS. Studies on the major sites in the brainstem mediating respiratory rate suppression, the pre-Bӧtzinger complex and parabrachial complex (including the Kӧlliker Fuse nucleus), have yielded conflicting findings and interpretations but recent investigations involving deletion of μ receptors from neurons have led to greater consensus. Some opioid analgesic drugs are histamine releasers. The range of clinical effects of released histamine include increased cardiac output due to an increase in heart rate, increased force of myocardial contraction, and a dilatatory effect on small blood vessels leading to flushing, decreased vascular resistance and hypotension. Resultant hemodynamic changes do not necessarily relate directly to the concentration of histamine in plasma due to a range of variables including functional differences between mast cells and histamine-induced anaphylactoid reactions may occur less often than commonly believed. Opioid-induced histamine release rarely if ever provokes bronchospasm and histamine released by opioids in normal doses does not lead to anaphylactoid reactions or result in IgE-mediated reactions in normal patients. Hypersensitivities to opioids, mainly some skin reactions and occasional type I hypersensitivities, chiefly anaphylaxis and urticaria, are uncommon. Hypersensitivities to morphine, codeine, heroin, methadone, meperidine, fentanyl, remifentanil, buprenorphine, tramadol, and dextromethorphan are summarized. In 2016, the FDA issued a Drug Safety Communication concerning the association of opioids with serotonin syndrome, a toxicity associated with raised intra-synaptic concentrations of serotonin in the CNS, inhibition of serotonin reuptake, and activation of 5-HT receptors. Opioids may provoke serotonin toxicity especially if administered in conjunction with other serotonergic medications. The increasing use of opioid analgesics and widespread prescribing of antidepressants and psychiatric medicines, indicates the likelihood of an increased incidence of serotonin toxicity in opioid-treated patients.

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.

Tapentadol Versus Tramadol: A Narrative and Comparative Review of Their Pharmacological, Efficacy and Safety Profiles in Adult Patients

We conducted a narrative review of the literature to compare the pharmacological, efficacy and safety profiles of tapentadol and tramadol, and to assess the clinical interest of tapentadol in adult patients. Tapentadol and tramadol share a mixed mechanism of action, including both mu-agonist and monoaminergic properties. Tapentadol is approximately two to three times more potent than tramadol and two to three times less potent than morphine. It has no identified analgesically active metabolite and is not significantly metabolised by cytochrome P450 enzymes, thus overcoming some limitations of tramadol, including the potential for pharmacokinetic drug-drug interactions and interindividual variability due to genetic polymorphisms of cytochrome P450 enzymes. The toxicity profiles of tramadol and tapentadol are similar; however tapentadol is likely to result in less exposure to serotoninergic adverse effects (nausea, vomiting, hypoglycaemia) but cause more opioid adverse effects (constipation, respiratory depression, abuse) than tramadol. The safety of tapentadol in real-world conditions remains poorly documented, particularly in at-risk patient subgroups and also in the ability to assess the risk associated with its residual serotonergic activity (serotonin syndrome, seizures). Because of an earlier market introduction, more real-world safety data are available for tramadol, including data from at-risk patient subgroups. The level of evidence on the efficacy of both tramadol and tapentadol for the treatment of chronic pain is globally low. The trials published to date show overall that tapentadol does not provide a clinically significant analgesic improvement compared to existing treatments, for which the safety profile is much better known. In conclusion, tapentadol is not a first-line opioid but represents an additional analgesic in the therapeutic choices, which some patients may benefit from after careful examination of their clinical situation, co-morbidities and co-medications.

Analysis of 39 drugs and metabolites, including 8 glucuronide conjugates, in an upstream wastewater network via HPLC-MS/MS

Pharmaceutical compounds ingested by humans are metabolized and excreted in urine and feces. These metabolites can be quantified in wastewater networks using wastewater-based epidemiology (WBE) methods. Standard WBE methods focus on samples collected at wastewater treatment plants (WWTPs). However, these methods do not capture more labile classes of metabolites such as glucuronide conjugates, products of the major phase II metabolic pathway for drug elimination. By shifting sample collection more upstream, these unambiguous markers of human exposure are captured before hydrolysis in the wastewater network. In this paper, we present an HPLC-MS/MS method that quantifies 8 glucuronide conjugates in addition to 31 parent and other metabolites of prescription and synthetic opioids, overdose treatment drugs, illicit drugs, and population markers. Calibration curves for all analytes are linear (r2 > 0.98), except THC (r2 = 0.97), and in the targeted range (0.1-1,000 ng mL-1) with lower limits of quantification (S/N = 9) ranging from 0.098 to 48.75 ng mL-1. This method is fast with an injection-to-injection time of 7.5 min. We demonstrate the application of the method to five wastewater samples collected from a manhole in a city in eastern Massachusetts. Collected wastewater samples were filtered and extracted via solid-phase extraction (SPE). The SPE cartridges are eluted and concentrated in the laboratory via nitrogen-drying. The method and case study presented here demonstrate the potential and application of expanding WBE to monitoring labile metabolites in upstream wastewater networks.

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.

Exploration of Analgesia with Tramadol in the Coxsackievirus B3 Myocarditis Mouse Model

Infection of mice with Coxsackievirus B3 (CVB3) triggers inflammation of the heart and this mouse model is commonly used to investigate underlying mechanisms and therapeutic aspects for viral myocarditis. Virus-triggered cytotoxicity and the activity of infiltrating immune cells contribute to cardiac tissue injury. In addition to cardiac manifestation, CVB3 causes cell death and inflammation in the pancreas. The resulting pancreatitis represents a severe burden and under such experimental conditions, analgesics may be supportive to improve the animals’ well-being. Notably, several known mechanisms exist by which analgesics can interfere with the immune system and thereby compromise the feasibility of the model. We set up a study aiming to improve animal welfare while ensuring model integrity and investigated how tramadol, an opioid, affects virus-induced pathogenicity and immune response in the heart. Tramadol was administered seven days prior to a CVB3 infection in C57BL/6 mice and treatment was continued until the day of analysis. Tramadol had no effect on the virus titer or viral pathogenicity in the heart tissue and the inflammatory response, a hallmark of myocardial injury, was maintained. Our results show that tramadol exerts no disruptive effects on the CVB3 myocarditis mouse model and, therefore, the demonstrated protocol should be considered as a general analgesic strategy for CVB3 infection.