Tramadol: a review of its use in perioperative pain

Analgesic and sedative effects of caudal epidural tramadol in dromedary camels

This study aimed to investigate the analgesic efficacy of caudal epidural administration of tramadol in dromedary camels (Camelus dromedarius). A total of 10 dromedary camels of both sexes were selected and randomly assigned to one of two groups to receive epidurally either 1 mg/kg or 2 mg/kg of tramadol hydrochloride. The injections were made into the epidural space at first intercoccygeal junction. Using a pinprick method, analgesia was tested. Duration and onset of complete perineal analgesia were determined. Ataxia and sedation were also assessed and recorded. Clinical parameters including heart rate, respiratory rate and rectal temperature were measured. The lower dose (1 mg/kg) of tramadol induced analgesia only in the tail but the higher dose produced complete antinociception in the tail, anus and perineum. Analgesia of the hind limbs was not achieved after either doses of tramadol. The mean times to onset and duration of complete analgesia in camels receiving epidural tramadol at a dose of 2 mg/kg were 22±2.55 min and 65±8.66 min, respectively. Various degrees of ataxia occurred in all camels. Mild to deep sedation was observed following both doses. Mean heart rate, respiratory rate, and rectal temperature tended to increase for the first 15 or 30 min after injection. Based on the results of this study, analgesic effects of caudal epidural tramadol were dose dependent. Epidural tramadol at a dose of 2 mg/kg would provide suitable postoperative analgesia for various manipulations in the tail, anus and perineum in standing dromedary camels.

Oral Coadministration of Fluconazole with Tramadol Markedly Increases Plasma and Urine Concentrations of Tramadol and the O-Desmethyltramadol Metabolite in Healthy Dogs

Tramadol is used frequently in the management of mild to moderate pain conditions in dogs. This use is controversial because multiple reports in treated dogs demonstrate very low plasma concentrations of O-desmethyltramadol (M1), the active metabolite. The objective of this study was to identify a drug that could be coadministered with tramadol to increase plasma M1 concentrations, thereby enhancing analgesic efficacy. In vitro studies were initially conducted to identify a compound that inhibited tramadol metabolism to N-desmethyltramadol (M2) and M1 metabolism to N,O-didesmethyltramadol (M5) without reducing tramadol metabolism to M1. A randomized crossover drug-drug interaction study was then conducted by administering this inhibitor or placebo with tramadol to 12 dogs. Blood and urine samples were collected to measure tramadol, tramadol metabolites, and inhibitor concentrations. After screening 86 compounds, fluconazole was the only drug found to inhibit M2 and M5 formation potently without reducing M1 formation. Four hours after tramadol administration to fluconazole-treated dogs, there were marked statistically significant (P < 0.001; Wilcoxon signed-rank test) increases in plasma tramadol (31-fold higher) and M1 (39-fold higher) concentrations when compared with placebo-treated dogs. Conversely, plasma M2 and M5 concentrations were significantly lower (11-fold and 3-fold, respectively; P < 0.01) in fluconazole-treated dogs. Metabolite concentrations in urine followed a similar pattern. This is the first study to demonstrate a potentially beneficial drug-drug interaction in dogs through enhancing plasma tramadol and M1 concentrations. Future studies are needed to determine whether adding fluconazole can enhance the analgesic efficacy of tramadol in healthy dogs and clinical patients experiencing pain.

An overview of tramadol and its usage in pain management and future perspective

Patients with chronic non-malignant pain report impairment of physical and social life along with psychological state affecting their overall quality of life. The purpose of managing pain is to reduce the trauma and improve the patient comfort with better quality of life. Tramadol is a centrally acting weak μ-opioid receptor analgesic and is a racemic mixture of (+)-tramadol and (-)-tramadol enantiomers. Tramadol is used worldwide and is listed in many medical guidelines for pain management. The (+)-tramadol has greater affinity for μ-opioid receptor and provides additional prevention of 5- hydroxy tryptamine reuptake, while the (-)-tramadol is a successful noradrenaline reuptake inhibitor and intensifies its release by activating the auto receptor. Tramadol is prescribed to relieve moderate to severe pain management in patients. Tramadol does not show much serious adverse effects without any dependency potential in therapeutic doses as seen in other opioids, like morphine. Tramadol metabolite M1 also has μ-opioid receptor agonist activity, but it faces poor blood brain barrier permeability. In this review, we report the complete updated status of Tramadol along with its chemistry, synthesis, pharmacology, medicinal uses, adverse effects and its combinations available in the market. We have also covered Tramadol patents so that a complete overview provides a broader perspective for future designing of its derivatives and increase their potential use for pain management in terminal cancer patients.

Patient-controlled intravenous tramadol versus patient-controlled intravenous hydromorphone for analgesia after secondary cesarean delivery: a randomized controlled trial to compare analgesic, anti-anxiety and anti-depression effects

Introduction

This study aimed to compare the postoperative analgesic effects of tramadol and hydromorphone for secondary cesarean delivery (CD) as well as their anti-anxiety and anti-depression properties.

Methods

A total of 106 patients receiving secondary CD under spinal anesthesia were randomly allocated to the tramadol group (n=53) and the hydromorphone group (n=53). Each group received patient-controlled intravenous analgesia using flurbiprofen 4 mg/kg combined with tramadol (4 mg/kg) or hydromorphone (0.04 mg/kg) immediately after the surgery. Postoperative pain numerical rating scale (NRS) for incision and visceral pain, hospital anxiety and depression scale (HADS), early walking time and length of hospital stay were assessed.

Results

Patients in the tramadol and hydromorphone groups exhibited equivalent incision pain NRS at different time points (P>0.05). Visceral pain in the tramadol group was higher than that in the hydromorphone group at postoperative 4 hours (2.9 [1.2] vs 2.3 [1.4], P=0.011) and 8 hours (2.4 [1.1] vs 1.8 [1.1], P=0.028). One week after the surgery, the patients in the tramadol group, as compared to the hydromorphone group, had lower anxiety scores (1.9 [3.5] vs 3.6 [4.1], P=0.033) and depression scores (0.8 [1.3] vs 2.7 [4.1], P=0.023). In addition, early walking time (25.3 [7.0] hours vs 29.3 [9.6] hours, P=0.016) and length of hospital stay (2.9 [0.8] days vs 3.3 [0.8] days, P= 0.008) after the surgery in the tramadol group were less than those in the hydromorphone group.

Conclusion

Postoperative intravenous analgesia with tramadol or hydromorphone for secondary CD provides comparable analgesic effects on incision pain. Tramadol is less effective in controlling visceral pain compared to hydromorphone. However, tramadol can help to alleviate anxiety and depression in the early postpartum period, improve patients’ early mobilization and shorten their hospital stay.

Clinical trial number and registry URL

No: ChiCTR-IIR-17011043; URL: www.chictr.org.cn.

Tramadol hydrochloride: An alternative to conventional local anaesthetics for intraoral procedures- a preliminary study

Purpose

To evaluate and compare the soft tissue anaesthesia produced by tramadol hydrochloride on gingival tissues in maxilla.

Methods

A total of 50 ASA physical status I subjects between 18 and 35 years of age, both male and female were included in the study. Each individual received 0.5 ml of 50 mg tramadol in the soft tissues over maxillary canine tooth as local infiltration on one and 0.5 ml of 20 mg lignocaine on the contralateral side in a double-blinded fashion. After completing the injection, the author recorded pain on injection, the onset of action, duration of anaesthesia, side effects, and feedback from patient.

Results

The mean onset of anaesthesia for tramadol was 172.00 s (standard deviation 39.898) while for lignocaine it was 162.60 s (standard deviation 35.098) and there was no statistically significant difference between the two groups (p = 0.214). The mean duration of anaesthesia for tramadol group was 45.70 min with a standard deviation of 8.512 min whereas for lignocaine group it was 44.70 min with a standard deviation of 8.107 min. There was no statistical relevant difference between the two groups in duration of anaesthesia (p = 0.549). None of the subjects reported any side effect in both the groups. There was no significant difference in pain on injection between the two groups.

Conclusions

Tramadol has a local anaesthetic effect similar to lignocaine when injected as infiltration in oral soft tissues.

Analgesic effect of morphine and tramadol in standard toxicity assays in mice injected with venom of the snake Bothrops asper

Routine laboratory animal tests necessary to assess the toxicity of snake venoms and the preclinical neutralizing ability of antivenoms and other inhibitory substances induce significant pain and distress. This has prompted initiatives to introduce the routine use of analgesia. In this study, the analgesic effect of morphine and tramadol was assessed in tests assessing the lethal, hemorrhagic, myotoxic and edema-forming activities of the venom of the viperid snake Bothrops asper. The Mouse Grimace Scale (MGS) and mouse-exploration activity were used to assess pain and its inhibition by the analgesics. Results demonstrate that tests assessing lethality and myotoxicity induce higher levels of pain than assays quantifying hemorrhagic and edema-forming activities. Our observations also indicate that pretreatment of mice with both analgesics, at the doses used, were similarly effective in reducing the MGS magnitude and increase mouse-exploration activity after the administration of B. asper venom. Moreover, the analgesic effect of both drugs was more evident in the myotoxic and lethality assays. Combined with previous observations showing that these analgesics do not alter the extent of toxic effects induced by B. asper venom, our results strongly indicate that the use of analgesia (using either morphine or tramadol) should be considered in the routine assessment of venom toxicity and antivenom efficacy.

Protocol for a randomised, double-blind, placebo-controlled trial to explore the effect of tramadol in the prevention of postpartum depression (ETPPD)

INTRODUCTION

Postpartum depression is one of the most commonly experienced psychological disorders for women patients undergoing caesarean section, which accounts for about one-third of puerpera worldwide. Tramadol, a commonly used analgesic with an inhibitory effect on the reuptake of norepinephrine and serotonin, is an effective and well-tolerated agent for analgesia after caesarean section. Based on the role of changes in the postpartum levels of serotonin and norepinephrine in postpartum depression, we speculated that postoperative intravenous analgesia using tramadol may decrease the incidence of postpartum depression for caesarean patients. Therefore, this trial aimed to explore the effect of tramadol in the prevention of postpartum depression.

METHODS AND ANALYSIS

A randomised double-blind placebo-controlled trial will be performed and 1230 singleton parturients will be randomised to receive patient-controlled intravenous analgesia with tramadol or hydromorphone, or patient-controlled epidural analgesia with ropivacaine. The primary outcome of this trial will be the incidence of postpartum depression at 4 weeks after the caesarean section, together with the collection of the relevant data during hospitalisation and at 3 months after the caesarean section. Subgroup data according to the preoperative depression score will be analysed. Demographic characteristics, postoperative analgesic effects and postoperative recovery score will also be summarised and presented.

ETHICS AND DISSEMINATION

The current trial protocol was approved by the Institutional Ethics Committee of Xinqiao Hospital (ID: 2017-026), Third Military Medical University, Chongqing, China. The results of this trial will be disseminated at scientific meetings and in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03309163; Pre-results.

Identification of canine cytochrome P-450s (CYPs) metabolizing the tramadol (+)-M1 and (+)-M2 metabolites to the tramadol (+)-M5 metabolite in dog liver microsomes

We previously showed that (+)-tramadol is metabolized in dog liver to (+)-M1 exclusively by CYP2D15 and to (+)-M2 by multiple CYPs, but primarily CYP2B11. However, (+)-M1 and (+)-M2 are further metabolized in dogs to (+)-M5, which is the major metabolite found in dog plasma and urine. In this study, we identified canine CYPs involved in metabolizing (+)-M1 and (+)-M2 using recombinant enzymes, untreated dog liver microsomes (DLMs), inhibitor-treated DLMs, and DLMs from CYP inducer-treated dogs. A canine P-glycoprotein expressing cell line was also used to evaluate whether (+)-tramadol, (+)-M1, (+)-M2, or (+)-M5 are substrates of canine P-glycoprotein, thereby limiting their distribution into the central nervous system. (+)-M5 was largely formed from (+)-M1 by recombinant CYP2C21 with minor contributions from CYP2C41 and CYP2B11. (+)-M5 formation in DLMs from (+)-M1 was potently inhibited by sulfaphenazole (CYP2C inhibitor) and chloramphenicol (CYP2B11 inhibitor) and was greatly increased in DLMs from phenobarbital-treated dogs. (+)-M5 was formed from (+)-M2 predominantly by CYP2D15. (+)-M5 formation from (+)-M1 in DLMs was potently inhibited by quinidine (CYP2D inhibitor) but had only a minor impact from all CYP inducers tested. Intrinsic clearance estimates showed over 50 times higher values for (+)-M5 formation from (+)-M2 compared with (+)-M1 in DLMs. This was largely attributed to the higher enzyme affinity (lower Km) for (+)-M2 compared with (+)-M1 as substrate. (+)-tramadol, (+)-M1, (+)-M2, or (+)-M5 were not p-glycoprotein substrates. This study provides a clearer picture of the role of individual CYPs in the complex metabolism of tramadol in dogs.

Provider preferences for postoperative analgesia in obese and non-obese patients undergoing ambulatory surgery

Background

Few guidelines exist on safe prescription of postoperative analgesia to obese patients undergoing ambulatory surgery. This study examines the preferences of providers in the standard treatment of postoperative pain in the ambulatory setting.

Methods

Providers from five academic medical centers within a single US city were surveyed from May–September 2015. They were asked to provide their preferred postoperative analgesic routine based upon the predicted severity of pain for obese and non-obese patients. McNemar’s tests for paired observations were performed to compare prescribing preferences for obese vs. non-obese patients. Fisher’s exact tests were performed to compare preferences based on experience: > 15 years vs. ≤15 years in practice, and attending vs. resident physicians.

Results

A total of 452 providers responded out of a possible 695. For mild pain, 119 (26.4%) respondents prefer an opioid for obese patients vs. 140 (31.1%) for non-obese (p = 0.002); for moderate pain, 329 (72.7%) for obese patients vs. 348 (77.0%) for non-obese (p = 0.011); for severe pain, 398 (88.1%) for obese patients vs. 423 (93.6%) for non-obese (p < 0.001). Less experienced physicians are more likely to prefer an opioid for obese patients with moderate pain: 70 (62.0%) attending physicians with > 15 years in practice vs. 86 (74.5%) with ≤15 years (p = 0.047), and 177 (68.0%) attending physicians vs. 129 (83.0%) residents (p = 0.002).

Conclusions

While there is a trend to prescribe less opioid analgesics to obese patients undergoing ambulatory surgery, these medications may still be over-prescribed. Less experienced physicians reported prescribing opioids to obese patients more frequently than more experienced physicians.

Comparison of Local Anaesthetic Efficacy of Tramadol Versus Lignocaine for Extraction of Tooth Under Supraperiosteal Infiltration

Background

Tramadol has been shown to have a local anaesthetic effect when used as infiltration anaesthesia.

Methods

The local anaesthetic efficacy of tramadol was compared with that of lignocaine for the extraction of teeth in terms of their onset of action, duration of action, intraoperative pain, post-operative analgesic effect and adverse reactions. Apart from this, incidence of allergic reaction was also recorded for both the drugs. A total of 100 patients were divided into two groups randomly. Each patient was assigned to receive either a maximum of 2 ml of 5% tramadol (Supridol 50 mg, Neon laboratories), Group T (n = 50), as a local anaesthetic solution for extraction of maxillary premolar for orthodontic reason under supraperiosteal infiltration following strict aseptic precaution or a maximum of 2 ml of 2% lignocaine (Lox 2%, Neon laboratories), Group L (n = 50), in a double-blinded fashion.

Results

In group T, the mean subjective onset of action was 33.66 s, while in group L it was 33.06 s (p = 0.881). In group T, the mean objective onset of action was 3.04 min, while in group L it was 3.18 min (p > 0.05). The mean duration of action in group T was 55.60 min, while in group L it was 57.50 min (p = 0.432). Only 2 patients in group T and 1 patient in group L had nausea (p = 0.245).

Conclusion

We conclude that 5% tramadol has a local anaesthetic efficacy similar to 2% lignocaine but is comparatively a weaker agent.

Evidence for the Involvement of the Dopaminergic System in Seizure and Oxidative Damage Induced by Tramadol

Tramadol (TR) is a synthetic analgesic drug with central function that can induce seizures even at therapeutic doses. The exact mechanism of TR effect on seizure generation is not clear, but inhibition of the serotonin and nitric oxide pathways and inhibitory effects on GABA receptors are the most common hypotheses about the seizure-inducing mechanism of the TR. This study aimed to evaluate the role of dopaminergic system on the seizure and oxidative damage induced by TR using agonist and antagonist drugs of this system in the Albino mice. Clonic seizure induced by TR was evaluated as seizure threshold. Haloperidol (0.2 mg/kg, IP), a predominantly D₂ receptor antagonist, and cabergolin (0.5 mg/kg, IP), a dopamine agonist specific for the D₂ receptors, were injected 60 minutes before the seizure induction. The seizure threshold was significantly increased by dopaminergic antagonist, but it was decreased significantly by pretreatment with the selective agonist. Oxidative stress biomarkers (reactive oxygen species, lipid peroxidation, and protein carbonyl content) significantly increased and glutathione content significantly decreased in brain mitochondria by TR compared with the control group, whereas oxidative markers were decreased significantly after pretreatment with haloperidol compared with the TR group. This study revealed that the dopaminergic system is involved in TR-induced seizure, and meanwhile, inhibition of dopamine D₂ receptors can increase the TR threshold seizure and decrease the oxidative damage in the brain mitochondria. Conversely, stimulation of dopamine D₂ receptors by cabergolin can decrease the TR threshold seizure and glutathione content in the brain mitochondria.

Pain Management Strategies in Shoulder Arthroplasty

Pain control in total shoulder arthroplasty demands a multidisciplinary approach with collaboration between patients, surgeon, and anesthetist. A multimodal approach with preemptive medication, regional blockade, local anesthetics, and a combination of acetaminophen, nonsteroidal antiinflammatory drugs, tramadol, and gabapentinoids postoperatively leads to pain control and patient satisfaction. Assessment of patients' expectations constitutes a vital aspect of the preoperative patient evaluation. Educating and psychologically preparing patients reduces postoperative pain. Patients with anxiety and depression, preoperative narcotic use, and medical comorbidities are at an increased risk for suboptimal pain control. Minimizing narcotic use decreases opioid-related adverse effects and facilitates productive rehabilitation efforts.

Tramadol ameliorates behavioural, biochemical, mitochondrial and histological alterations in ICV-STZ-induced sporadic dementia of Alzheimer's type in rats

Alzheimer disease represents a major public health issue with limited therapeutic interventions. We explored the possibility of therapeutic approach by repurposing of tramadol in a sporadic animal model of Alzheimer's type. Streptozocin (STZ 3 mg/kg; bilaterally) was injected to male SD rats through intracerebroventricular (ICV) route. Drug treatment was started just after streptozocin administration and continued for 3 weeks. The rats were killed on the 21st day following the last behavioral test, and cytoplasmic fractions of the hippocampus and pre-frontal cortex were prepared for the quantification of acetylcholinesterase, oxidative stress parameter, mitochondrial enzymes activity and histological examination. Tramadol (5, 10 and 20 mg/kg, i.p.) was used as a treatment drug, and memantine (10 mg/kg, i.p.) was used as a standard. Tramadol significantly attenuated behavioral, biochemical, mitochondrial and histological alterations at low (5 mg/kg) and intermediate (10 mg/kg) dose, suggesting its neuroprotective potential in ICV-STZ-treated rats. Further, the neuroprotective effect of tramadol (10 mg/kg) was comparable to memantine (10 mg/kg). In conclusion, our results indicate the effectiveness of tramadol in preventing ICV-STZ-induced cognitive impairment as well as mito-oxidative stress. Further, these findings reveal the possibility of MOR agonist as a therapeutic approach for sporadic Alzheimer disease.

New Findings on Local Tramadol Use in Oral Surgery

In modern times, all procedures in oral surgery need to be painless and management of postoperative pain needs to be adequate. The surgical extraction of the third molar or alveolectomy of the wisdom tooth is one of the most common surgical procedures carried out in oral surgery and it includes rising a flap, bone removal and suturing. These surgical procedures usually cause swelling, trismus and moderate to severe pain. Third molar surgery is often used as a model in clinical trials that are directed toward reducing postoperative pain and improving its management. Tramadol is a well-known central acting opioid analgesic that produces analgesia against multiple pain conditions such as postsurgical pain, obstetric pain, terminal cancer pain, pain of coronary origin and neuropathic pain. Tramadol is an atypical opioid. When administered locally, it has both analgesic and anesthetic properties. The aim of this paper was to present new findings on local effects of tramadol in oral surgery.

A Pilot Study on the use of Tramadol Hydrochloride for Pain Control in an Emergency Department

Introduction

Tramadol hydrochloride is a synthetic μ,-opioid agonist. It has been used in the control of moderate to severe pain. Most of the studies on tramadol were related to post-operative pain control. Data on acute pain control in the emergency setting were limited. This study reported on the initial evaluation of tramadol for pain control in an emergency department.

Materials and methods

It was a prospective observational study. Patients aged 16 years or above attending our emergency department with moderate to severe pain were recruited. Patients with known allergy, current psychiatric medication, intake of alcohol, major systemic illness and opioid dependence were excluded. All patients received 100 mg intramuscular tramadol injection. A 10 cm Visual Analogue Scale (VAS) was used to assess the pain severity before injection, 30 minutes and 60 minutes after injection. Vital signs and side effects were also recorded.

Results

Forty patients (M: 24, F: 16) were recruited from October to December 2002. Their mean age was 53.5 years. The majority of them suffered from acute musculoskeletal pain or arthritis. Tramadol was shown to be effective in pain control. The VAS decreased by 1.90 (p<0.001) and 3.38 (p<0.001) at 30 minutes and 60 minutes respectively. Four patients reported nausea and three patients vomited.

Conclusion

Tramadol appeared to be a safe drug to be used in the emergency setting. Only a few insignificant side effects were reported. The comparison of efficacy with other analgesics requires further studies.

SLC22A1/OCT1 Genotype Affects O-desmethyltramadol Exposure in Newborn Infants

BACKGROUND

This study determined whether the SLC22A1 [encoding the organic cation transporter 1 (OCT1)] genotype could explain, in addition to the postmenstrual age (referring to gestational plus postnatal age) and CYP2D6 genotype, the tramadol (M) pharmacokinetic variability in early infancy.

METHODS

Fifty infants, median postmenstrual age 39.5 (interquartile range: 36.8-41.3) weeks, received an i.v. M loading dose (2 mg/kg) followed by a continuous infusion (5-8 mg·kg·24 h). Blood was sampled from 4 to 24 hours after start of the M treatment, which generated 230 observations. M and O-desmethyltramadol (M1) concentrations were measured by high-performance liquid chromatography.

RESULTS

Linear mixed-model analysis illustrated that the SLC22A1/OCT1 genotype was independently associated with a log-transformed M1/M ratio (P = 0.013), with carriers of <2 SLC22A1/OCT1 functional gene copies having a higher M1/M ratio (2.25; 95% CI, 2.01-2.48) than infants with 2 functional gene copies (1.86; 95% CI, 1.66-2.06). The CYP2D6/SLC22A1 combined genotype was associated with 57.8% higher M1/M ratio in carriers of ≥2 CYP2D6 functional gene copies and <2 SLC22A1/OCT1 functional gene copies compared with infants with <2 active CYP2D6 functional gene copies and SLC22A1/OCT1 normal activity (P < 0.001).

CONCLUSIONS

These findings highlight the additional role of SLC22A1/OCT1 genetics in M1 exposure in neonates. They also suggest that OCT1 is already active early after birth, which may have impact on the disposition of other OCT1 substrates in this population.

Tramadol prescription patterns in patients followed by general practitioners and orthopedists in Germany in the year 2015

OBJECTIVES

The aim of this study was to analyze tramadol prescription patterns in acute pain patients followed by general practitioners and orthopedists in Germany.

METHODS

This study included patients ≥18 years diagnosed with acute pain who received at least one tramadol prescription each in one of 1,129 general or 179 orthopedic practices in Germany between January and December 2015 (index date). Patients were excluded if they had received a prescription for another analgesic in the year prior to the index date, had a follow-up of less than 15 months after the index date, or were prescribed tramadol for a period of more than three months. The main outcome of this retrospective study was the share of patients receiving tramadol in combination therapy. Combination therapy was defined as the prescription of tramadol in conjunction with at least one other analgesic during the same medical visit.

RESULTS

The present study included a total of 8,766 individuals. Overall, 1,492 (22.0%) of tramadol patients seen by general practitioners and 370 (18.7%) of those seen by orthopedists received tramadol in combination with other analgesics. Although this proportion was similar throughout the different subgroups in orthopedic practices, it was considerably higher in patients >80 years and in those with private health insurance coverage in general practices.

CONCLUSIONS

Approximately one of five tramadol patients was prescribed tramadol in combination therapy. Further research is needed to gain a better understanding of the demographic and clinical factors that have an effect on tramadol prescription patterns in Germany.

Loss-of-function polymorphisms in the organic cation transporter OCT1 are associated with reduced postoperative tramadol consumption

The organic cation transporter OCT1 (SLC22A1) mediates uptake and metabolism of the active tramadol metabolite (+)O-desmethyltramadol in the liver. In this study, the influence of OCT1 genetic polymorphisms on pharmacokinetics and analgesic efficacy of tramadol in patients recovering from surgery was analyzed in addition to the CYP2D6 genotype. Postoperative patients who received tramadol through patient-controlled analgesia were enrolled. Genotypes resulting in 0, 1, or 2 active OCT1 alleles were determined as well as CYP2D6 genotypes. The primary endpoint was the 24-hour postoperative tramadol consumption in patients with 0 vs at least 1 active OCT1 allele. Secondary endpoint was the OCT1-dependent plasma concentration (areas under the concentration-time curves) of the active tramadol metabolite (+)O-desmethyltramadol. Of 205 patients, 19, 82, and 104 carried 0, 1, and 2 active OCT1 alleles, respectively. Cumulative tramadol consumption through patient-controlled analgesia was lowest in patients with 0 active OCT1 allele compared with the group of patients with 1 or 2 active alleles (343 ± 235 vs 484 ± 276 mg; P = 0.03). Multiple regression revealed that the number of active OCT1 alleles (P = 0.014), CYP2D6 (P = 0.001), pain scores (P < 0.001), and the extent of surgery (0.034) had a significant influence on tramadol consumption. Plasma areas under the concentration-time curves of (+)O-desmethyltramadol were 111.8 (95% confidence interval: 63.4-160.1), 80.2 (65.1-95.3), and 64.5 (51.9-77.2) h·ng·mL in carriers of 0, 1, or 2 active OCT1 alleles (P = 0.03). Loss of OCT1 function resulted in reduced tramadol consumption and increased plasma concentrations of (+)O-desmethyltramadol in patients recovering from surgery. Therefore, analyzing OCT1 next to CYP2D6 genotype might further improve future genotype-dependent dose recommendations for tramadol.

Avaliação da dexmedetomidina e do tramadol, associados ao midazolam, em gatas anestesiadas com isoflurano e submetidas à ovário-histerectomia

RESUMO Objetivou-se comparar as alterações cardiorrespiratórias e a analgesia pós-operatória promovidas pela dexmedetomidina e pelo tramadol, quando associados ao midazolam, em felinas. Para tal, foram selecionadas 18 gatas hígidas, divididas em dois grupos randomizados: GDM, tratadas com dexmedetomidina (10µg/kg) e GTM, tratadas com tramadol (2mg/kg), ambos associados a midazolam (0,2mg/kg,) IM. Após 15 minutos, procedeu-se à indução anestésica com propofol (1,46±0,79mL), mantendo-se a anestesia com isoflurano. As felinas foram submetidas à ovário-histerectomia, registrando-se as variáveis cardiorrespiratórias 15 minutos após a MPA (M0), 15 minutos após a indução (M15) e sequencialmente a cada cinco minutos, até o término do procedimento cirúrgico (M20, M25, M30, M35 e M40). A avaliação da dor iniciou-se 30 minutos após o término do procedimento cirúrgico (MP30) e sequencialmente em intervalos de 30 minutos (MP60, MP90, MP120). A partir do MP120, as avaliações foram registradas a cada hora (MP180, MP240 e MP360). A associação dexmedetomidina-midazolam infere diminuição inicial de frequência cardíaca (FC) sem significado clínico e está relacionada à sedação mais pronunciada, à analgesia menor e menos duradoura e a episódios de êmese, quando comparada à associação tramadol-midazolam. Ambos os protocolos denotaram estabilidade cardiorrespiratória e podem ser considerados seguros em felinas submetidas à ovário-histectomia.

Current practice and usual care of major cervical disorders in Korea: A cross-sectional study of Korean health insurance review and assessment service national patient sample data

Neck pain is a highly common condition and is the 4th major cause of years lived with disability. Previous literature has focused on the effect of specific treatments, and observations of actual practice are lacking to date. This study examined Korean health insurance review and assessment service (HIRA) claims data to the aim of assessing prevalence and comparing current medical practice and costs of cervical disorders in Korea.Current practice trends were determined through assessment of prevalence, total expenses, per-patient expense, average days in care, average days of visits, sociodemographic characteristics, distribution of medical costs, and frequency of treatment types of high frequency cervical disorders (cervical sprain/strain, cervical intervertebral disc displacement [IDD], and cervicalgia).Although the number of cervical IDD patients was few, total expenses, per-patient expense, average days in care, and average days of visits were highest. The proportion of women was higher than men in all 3 groups with highest prevalence in the ≥50s middle-aged population for IDD compared to sprain/strain. Primary care settings were commonly used for ambulatory care, of which approximately 70% chose orthopedic specialist treatment. In analysis of medical expenditure distribution, costs of visit (consultation) (22%-34%) and physical therapy (14%-16%) were in the top 3 for all 3 disorders. Although heat and electrical therapies were the most frequently used physical therapies, traction use was high in the cervical IDD group. In nonnarcotics, aceclofenac and diclofenac were the most commonly used NSAIDs, and pethidine was their counterpart in narcotics.This study investigated practice trends and cost distribution of treatment regimens for major cervical disorders, providing current usage patterns to healthcare policy decision makers, and the detailed treatment reports are expected to be of use to clinicians and researchers in understanding current usual care.

Simultaneous quantitation of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene in human plasma using solid-phase extraction and gas chromatography/mass spectrometry: Method validation and application to cardiovascular safety of therapeutic doses

RATIONALE

Several opioid analgesics have been related to the prolongation of cardiac repolarization, a condition which can be fatal. In order to establish a correct estimation of the risk/benefit balance of therapeutic doses of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene, it was necessary to develop an analytical method to determinate plasma concentrations of these opioids.

METHODS

Here we describe a method which incorporates strong alkaline treatment to obtain norpropoxyphene amide followed by a one-elution step solid-phase extraction, and without further derivatization. Separation and quantification were achieved by gas chromatography/electron ionization mass spectrometry (GC/EI-MS) in selected-ion monitoring mode. Quantification was performed with 500 μL of plasma by the addition of deuterated analogues as internal standards.

RESULTS

The proposed method has been validated in the linearity range of 25-1000 ng/mL for all the analytes, with correlation coefficients higher than 0.990. The lower limit of quantification was 25 ng/mL. The intra- and inter-day precision, calculated in terms of relative standard deviation, were 2.0-12.0% and 6.0-15.0%, respectively. The accuracy, in terms of relative error, was within a ± 10% interval. The absolute recovery and extraction efficiency ranged from 81.0 to 111.0% and 81.0 to 105.0%, respectively.

CONCLUSIONS

A GC/MS method for the rapid and simultaneous determination of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene in human plasma was developed, optimized and validated. This procedure was shown to be sensitive and specific using small specimen amounts, suitable for application in routine analysis for forensic purposes and therapeutic monitoring. To our knowledge, this is the first full validation of the simultaneous determination of these opioids and their metabolites in plasma samples.

Effect of tramadol as an adjuvant to local anesthetics for brachial plexus block: A systematic review and meta-analysis

BACKGROUND

Tramadol, a 4-phenyl-piperidine analog of codeine, has a unique action in that it has a central opioidergic, noradrenergic, serotonergic analgesic, and peripheral local anesthetic (LA) effect. Many studies have reported contradictory findings regarding the peripheral analgesic effect of tramadol as an adjuvant to LA in brachial plexus block (BPB). This meta-analysis aimed to evaluate the effects of tramadol as an adjunct to LA in BPB during shoulder or upper extremity surgery.

METHODS

We searched the PubMed, EMBASE, Cochrane, KoreaMed databases, and Google Scholar for eligible randomized controlled trials (RCTs) that compared BPB with LA alone and BPB with LA and tramadol. Primary outcomes were the effects of tramadol as an adjuvant on duration of sensory block, motor block, and analgesia. Secondary outcomes were the effects of tramadol as an adjuvant on time to onset of sensory block and motor block and on adverse effects. We performed the meta-analysis using Review Manager 5.3 software.

RESULTS

We identified 16 RCTs with 751 patients. BPB with tramadol prolonged the duration of sensory block (mean difference [MD], -61.5 min; 95% CI, -95.5 to -27.6; P = 0.0004), motor block (MD, -65.6 min; 95% CI, -101.5 to -29.7; P = 0.0003), and analgesia (MD, -125.5 min; 95% CI, -175.8 to -75.3; P < 0.0001) compared with BPB without tramadol. Tramadol also shortened the time to onset of sensory block (MD, 2.1 min; 95% CI, 1.1 to 3.1; P < 0.0001) and motor block (MD, 1.2 min; 95% CI, 0.2 to 2.1; P = 0.010). In subgroup analysis, the duration of sensory block, motor block, and analgesia was prolonged for BPB with tramadol 100 mg (P < 0.05) but not for BPB with tramadol 50 mg. The quality of evidence was high for duration of analgesia according to the GRADE system. Adverse effects were comparable between the studies.

CONCLUSIONS

In upper extremity surgery performed under BPB, use of tramadol 100 mg as an adjuvant to LA appears to prolong the duration of sensory block, motor block, and analgesia, and shorten the time to onset of sensory and motor blocks without altering adverse effects.

Safety, Tolerability, and Pharmacokinetics of Therapeutic and Supratherapeutic Doses of Tramadol Hydrochloride in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Multiple-Ascending-Dose Study

This randomized, double-blind, parallel-group multiple-ascending-dose study evaluated the safety, tolerability, and pharmacokinetics of tramadol hydrochloride in healthy adults to inform dosage and design for a subsequent QT/QTc study. Healthy men and women, 18 to 45 years old (inclusive), were sequentially assigned to the tramadol 200, 400, or 600 mg/day treatment cohort and within each cohort, randomized (4:1) to either tramadol or placebo every 6 hours for 9 oral doses. Of the 24 participants randomized to tramadol (n = 8/cohort), 22 (91.7%) completed the study. The AUC_tau,ss of tramadol increased approximately 2.2- and 3.6-fold for the (+) enantiomer and 2.0- and 3.5-fold for the (-) enantiomer with increasing dose from 200 to 400  and 600 mg/day, whereas the C_max,ss increased 2.1- and 3.3-fold for the (+) enantiomer and 2.0- and 3.2-fold for the (-) enantiomer. Overall, 21 participants (87.5%) participants reported ≥1 treatment-emergent adverse event; most frequent were nausea (17 of 24, 70.8%) and vomiting (7 of 24, 29.2%). Vomiting (affected participants and events) increased with increasing dose from 200 to 600 mg/day but was mild (5 of 24) or moderate (2 of 24) in severity. All tested dosage regimens of tramadol showed acceptable safety and tolerability profile for further investigation in a thorough QT/QTc study.

The role of tramadol in pain management in Latin America: a report by the Change Pain Latin America Advisory Panel

OBJECTIVE

Change Pain Latin America (CPLA) was created to enhance chronic pain understanding and develop pain management improving strategies in this region. During its seventh meeting (August 2016), the main objective was to discuss tramadol's role in treating pain in Latin America. Furthermore, potential pain management consequences were considered, if tramadol was to become more stringently controlled.

METHODS

Key topics discussed were: main indications for prescribing tramadol, its pharmacological characteristics, safety and tolerability, effects of restrictions on its availability and use, and consequent impact on pain care quality.

RESULTS

The experts agreed that tramadol is used to treat a wide spectrum of non-oncological pain conditions (e.g. post-surgical, musculoskeletal, post-traumatic, neuropathic, fibromyalgia), as well as cancer pain. Its relevance when treating special patient groups (e.g. the elderly) is recognized. The main reasons for tramadol's high significance as a treatment option are: its broad efficacy, an inconspicuous safety profile and its availability, considering that access to strong analgesics - mainly controlled drugs (classical opioids) - is highly restricted in some countries. The CPLA also agreed that tramadol is well tolerated, without the safety issues associated with long-term nonsteroidal anti-inflammatory drug (NSAID) use, with fewer opioid-like side effects than classical opioids and lower abuse risk.

CONCLUSIONS

In Latin America, tramadol is a valuable and frequently used medication for treating moderate to severe pain. More stringent regulations would have significant impact on its availability, especially for outpatients. This could cause regression to older and frequently inadequate pain management methods, resulting in unnecessary suffering for many Latin American patients.

A physiologically based model for tramadol pharmacokinetics in horses

This work proposes an application of a minimal complexity physiologically based pharmacokinetic model to predict tramadol concentration vs time profiles in horses. Tramadol is an opioid analgesic also used for veterinary treatments. Researchers and medical doctors can profit from the application of mathematical models as supporting tools to optimize the pharmacological treatment of animal species. The proposed model is based on physiology but adopts the minimal compartmental architecture necessary to describe the experimental data. The model features a system of ordinary differential equations, where most of the model parameters are either assigned or individualized for a given horse, using literature data and correlations. Conversely, residual parameters, whose value is unknown, are regressed exploiting experimental data. The model proved capable of simulating pharmacokinetic profiles with accuracy. In addition, it provides further insights on un-observable tramadol data, as for instance tramadol concentration in the liver or hepatic metabolism and renal excretion extent.

Tramadol for neuropathic pain in adults

BACKGROUND

This review is an update of a review of tramadol for neuropathic pain, published in 2006; updating was to bring the review in line with current standards. Neuropathic pain, which is caused by a lesion or disease affecting the somatosensory system, may be central or peripheral in origin. Peripheral neuropathic pain often includes symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the peripheral nervous system.

OBJECTIVES

To assess the analgesic efficacy of tramadol compared with placebo or other active interventions for chronic neuropathic pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase for randomised controlled trials from inception to January 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing tramadol (any route of administration) with placebo or another active treatment for neuropathic pain, with subjective pain assessment by the participant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH), using standard methods. We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We identified six randomised, double-blind studies involving 438 participants with suitably characterised neuropathic pain. In each, tramadol was started at a dose of about 100 mg daily and increased over one to two weeks to a maximum of 400 mg daily or the maximum tolerated dose, and then maintained for the remainder of the study. Participants had experienced moderate or severe neuropathic pain for at least three months due to cancer, cancer treatment, postherpetic neuralgia, peripheral diabetic neuropathy, spinal cord injury, or polyneuropathy. The mean age was 50 to 67 years with approximately equal numbers of men and women. Exclusions were typically people with other significant comorbidity or pain from other causes. Study duration for treatments was four to six weeks, and two studies had a cross-over design.Not all studies reported all the outcomes of interest, and there were limited data for pain outcomes. At least 50% pain intensity reduction was reported in three studies (265 participants, 110 events). Using a random-effects analysis, 70/132 (53%) had at least 50% pain relief with tramadol, and 40/133 (30%) with placebo; the risk ratio (RR) was 2.2 (95% confidence interval (CI) 1.02 to 4.6). The NNT calculated from these data was 4.4 (95% CI 2.9 to 8.8). We downgraded the evidence for this outcome by two levels to low quality because of the small size of studies and of the pooled data set, because there were only 110 actual events, the analysis included different types of neuropathic pain, the studies all had at least one high risk of potential bias, and because of the limited duration of the studies.Participants experienced more adverse events with tramadol than placebo. Report of any adverse event was higher with tramadol (58%) than placebo (34%) (4 studies, 266 participants, 123 events; RR 1.6 (95% CI 1.2 to 2.1); NNH 4.2 (95% CI 2.8 to 8.3)). Adverse event withdrawal was higher with tramadol (16%) than placebo (3%) (6 studies, 485 participants, 45 events; RR 4.1 (95% CI 2.0 to 8.4); NNH 8.2 (95% CI 5.8 to 14)). Only four serious adverse events were reported, without obvious attribution to treatment, and no deaths were reported. We downgraded the evidence for this outcome by two or three levels to low or very low quality because of small study size, because there were few actual events, and because of the limited duration of the studies.

AUTHORS' CONCLUSIONS

There is only modest information about the use of tramadol in neuropathic pain, coming from small, largely inadequate studies with potential risk of bias. That bias would normally increase the apparent benefits of tramadol. The evidence of benefit from tramadol was of low or very low quality, meaning that it does not provide a reliable indication of the likely effect, and the likelihood is very high that the effect will be substantially different from the estimate in this systematic review.

Multimodal analgesia in moderate-to-severe pain: a role for a new fixed combination of dexketoprofen and tramadol

BACKGROUND

Untreated and under-treated pain represent one of the most pervasive health problems, which is worsening as the population ages and accrues risk for pain. Multiple treatment options are available, most of which have one mechanism of action, and cannot be prescribed at unlimited doses due to the ceiling of efficacy and/or safety concerns. Another limitation of single-agent analgesia is that, in general, pain is due to multiple causes. Combining drugs from different classes, with different and complementary mechanism(s) of action, provides a better opportunity for effective analgesia at reduced doses of individual agents. Therefore, there is a potential reduction of adverse events, often dose-related. Analgesic combinations are recommended by several organizations and are used in clinical practice. Provided the two agents are combined in a fixed-dose ratio, the resulting medication may offer advantages over extemporaneous combinations.

CONCLUSIONS

Dexketoprofen/tramadol (25 mg/75 mg) is a new oral fixed-dose combination offering a comprehensive multimodal approach to moderate-to-severe acute pain that encompasses central analgesic action, peripheral analgesic effect and anti-inflammatory activity, together with a good tolerability profile. The analgesic efficacy of dexketoprofen/tramadol combination is complemented by a favorable pharmacokinetic and pharmacodynamic profile, characterized by rapid onset and long duration of action. This has been well documented in both somatic- and visceral-pain human models. This review discusses the available clinical evidence and the future possible applications of dexketoprofen/tramadol fixed-dose combination that may play an important role in the management of moderate-to-severe acute pain.

Structural influences on the activity of bismuth(III) indole-carboxylato complexes towards Helicobacter pylori and Leishmania

Seven new bismuth(III) complexes derived from indole-carboxylic acids have been synthesised: five are homoleptic; [Bi(IAA)₃] B1, [Bi(IPA)₃] B2, [Bi(IBA)₃] B3, [Bi(MICA)₃] B4, [Bi(IGA)₃] B6, and two are heteroleptic [BiPh(MICA)₂] B5 (where IAA-H=2-(1H-indol-3-yl)acetic acid, IPA-H=3-(1H-indol-3-yl)propanoic acid, IBA-H=4-(1H-indol-3-yl)butanoic acid, IGA-H=2-(1H-indol-3-yl)-2-oxoacetic acid, and MICA-H=1-methyl-1H-indole-3-carboxylic acid). All complexes were fully characterised by elemental analysis, infrared and mass-spectroscopy, and nuclear magnetic resonance (¹H, ¹³C) spectroscopy. Complex [BiPh(IGA)₂] B7 is structurally authenticated by X-ray crystallography as a dimer in the solid-state. The in-vitro anti-bacterial activity of the indole-carboxylic acids and their bismuth(III) complexes was assessed against Helicobacter pylori. While the acids were non-toxic at <100μgmL^-1, all the bismuth compounds showed an MIC of 6.25μgmL^-1, indicating that the anti-bacterial activity is insensitive to the degree of substitution at the Bi(III) centre or the composition of the indole-carboxylate ligands. All compounds were further tested for their anti-parasitic activity against Leishmania major and for their toxicity towards mammalian cells. From the anti-parasitic studies, it was found that the heteroleptic bismuth(III) complexes are the most active, with B5 and B7 showing comparable activity to Amphotericin B, without any toxicity towards the mammalian cells at their effective concentration.

Tramadol with or without paracetamol (acetaminophen) for cancer pain

BACKGROUND

Tramadol is an opioid analgesic licensed for use in moderate to severe pain. It is considered as a low risk for abuse, so control regulations are not as stringent as for 'strong' opioids such as morphine. It has a potential role as a step 2 option of the World Health Organization (WHO) analgesic ladder.

OBJECTIVES

To assess the benefits and adverse effects of tramadol with or without paracetamol (acetaminophen) for cancer-related pain.

SEARCH METHODS

We searched the following databases using a wide range of search terms: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and LILACS. We also searched three clinical trials registry databases. The date of the last search was 2 November 2016.

SELECTION CRITERIA

We selected studies that were randomised, with placebo or active controls, or both, and included a minimum of 10 participants per treatment arm. We were interested particularly in blinded studies, but also included open studies.We excluded non-randomised studies, studies of experimental pain, case reports, and clinical observations.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data using a standard form and checked for agreement before entry into Review Manager 5. We included information about the number of participants treated and demographic details, type of cancer, drug and dosing regimen, study design (placebo or active control) and methods, study duration and follow-up, analgesic outcome measures and results, withdrawals, and adverse events. We collated multiple reports of the same study, so that each study, rather than each report, was the unit of interest in the review. We assessed the evidence using GRADE and created a 'Summary of findings' table.The main outcomes of interest for benefit were pain reduction of 30% or greater and 50% or greater from baseline, participants with pain no worse than mild, and participants feeling much improved or very much improved.

MAIN RESULTS

We included 10 studies (12 reports) with 958 adult participants. All the studies enrolled participants with chronic malignant tumour-related pain who were experiencing pain intensities described as moderate to severe, with most experiencing at least 4/10 with current treatment. The mean ages were 59 to 70 years, with participants aged between 24 and 87 years. Study length ranged from one day to six months. Five studies used a cross-over design. Tramadol doses ranged from 50 mg as single dose to 600 mg per day; doses of 300 mg per day to 400 mg per day were most common.Nine studies were at high risk of bias for one to four criteria (only one high risk of bias for size). We judged all the results to be very low quality evidence because of widespread lack of blinding of outcome assessment, inadequately described sequence generation, allocation concealment, and small numbers of participants and events. Important outcomes were poorly reported. There were eight different active comparators and one comparison with placebo. There was little information available for any comparison and no firm conclusions could be drawn for any outcome.Single comparisons of oral tramadol with codeine plus paracetamol, of dihydrocodeine, and of rectal versus oral tramadol provided no data for key outcomes. One study used tramadol combined with paracetamol; four participants received this intervention. One study compared tramadol with flupirtine - a drug that is no longer available. One study compared tramadol with placebo and a combination of cobrotoxin, tramadol, and ibuprofen, but the dosing schedule poorly explained.Two studies (191 participants) compared tramadol with buprenorphine. One study (131 participants) reported a similar proportion of no or mild pain at 14 days.Three studies (300 participants) compared tramadol with morphine. Only one study, combining tramadol, tramadol plus paracetamol, and paracetamol plus codeine as a single weak-opioid group reported results. Weak opioid produced reduction in pain of at least 30% from baseline in 55/117 (47%) participants, compared with 91/110 (82%) participants with morphine. Weak opioid produced reduction in pain of at least 50% in 49/117 (42%) participants, compared with 83/110 (75%) participants with morphine.There was no useful information for any other outcome of benefit or harm.

AUTHORS' CONCLUSIONS

There is limited, very low quality, evidence from randomised controlled trials that tramadol produced pain relief in some adults with pain due to cancer and no evidence at all for children. There is very low quality evidence that it is not as effective as morphine. This review does not provide a reliable indication of the likely effect. The likelihood that the effect will be substantially different is very high. The place of tramadol in managing cancer pain and its role as step 2 of the WHO analgesic ladder is unclear.

The anti-inflammatory effect of tramadol in the temporomandibular joint of rats

Tramadol is a centrally acting analgesic drug able to prevent nociceptor sensitization when administered into the temporomandibular joint (TMJ) of rats. The mechanism underlying the peripheral anti-inflammatory effect of tramadol remains unknown. This study demonstrated that intra-TMJ injection of tramadol (500µg/TMJ) was able to inhibit the nociceptive response induced by 1.5% formalin or 1.5% capsaicin, suggesting that tramadol has an antinociceptive effect, acting directly on the primary nociceptive neurons activating the nitric oxide/cyclic guanosine monophosphate signaling pathway. Tramadol also inhibited the nociceptive response induced by carrageenan (100µg/TMJ) or 5-hydroxytryptamine (225µg/TMJ) along with inhibition of inflammatory cytokines levels, leukocytes migration and plasma extravasation. In conclusion, the results demonstrate that peripheral administration of tramadol has a potential antinociceptive and anti-inflammatory effect. The antinociceptive effect is mediated by activation of the intracellular nitric oxide/cyclic guanosine monophosphate pathway, at least in part, independently from the opioid system.

Tramadol vs dexmedetomidine for emergence agitation control in pediatric patients undergoing adenotonsillectomy with sevoflurane anesthesia: prospective randomized controlled clinical study

Background

This study was designed to compare the efficacy of an intraoperative single dose administration of tramadol and dexmedetomidine on hemodynamics and postoperative recovery profile including pain, sedation, emerge reactions in pediatric patients undergoing adenotonsillectomy with sevoflurane anesthesia.

Methods

Seventy-seven patient, aged 2–12, undergoing adenotonsillectomy with sevoflurane anesthesia was enrolled in this study. Patients were randomly assigned to receive either intravenous 2 mg/kg tramadol (Group T; n = 39) or 1 μg/kg dexmedetomidine (Group D; n = 38) after intubation. Heart rates (HR), mean arterial pressure (MAP) were recorded before induction, at induction and every 5 min after induction. Observational pain scores (OPS), pediatric anesthesia emergence delirium (PAED) scores, percentage of patients with OPS ≥ 4 or PAED scale items 4 or 5 with an intensity of 3 or 4, and Ramsay sedation scores (RSS) were recorded on arrival to the postoperative care unit (PACU) and at 5, 10, 15, 30, 45, 60 min. Extubation time and time to reach Alderete score > 9 were recorded.

Results

Dexmedetomidine significantly decreased the HR and MAP 10 and 15 min after induction; increased the RSS 15, 30 and 45 min after arrival to PACU. OPS and PAED scores and percentage of patients with OPS ≥ 4 or PAED scale items 4 or 5 with an intensity of 3 or 4 in both groups did not show any significant difference. Extubation time and time to have Alderete score > 9 was significantly longer in Group D.

Conclusion

Both tramadol and dexmedetomidine were effective for controlling pain and emergence agitation. When compared with tramadol intraoperative hypotension, bradycardia and prolonged sedation were problems related with dexmedetomidine administration.

Trial registration

Retrospectively registered, registration number: ISRCTN89326952 registration date: 14.07.2016

Interaction of a Cannabinoid-2 Agonist With Tramadol on Nociceptive Thresholds and Immune Responses in a Rat Model of Incisional Pain

The aim of this study was to elucidate the antinociceptive interaction between cannabinoids and tramadol and their impact on proinflammatory response, in terms of serum intereleukin-6 (IL-6) and interleukin-2 (IL-2) release, in a rat model of incisional pain. Prospective randomized trial assessing the individual or combined application of intraperitoneal tramadol (10 mg/kg) and the selective cannabinoid-2 (CB-2) agonist (R,S)-AM1241 (1 mg/kg) applied postsurgical stress stimulus. Pharmacological specificity was established by antagonizing tramadol with naloxone (0.3 mg/kg) and (R,S)-AM1241 with SR144528 (1 mg/kg). Thermal allodynia was assessed by hot plate test 30 (T30), 60 (T60), and 120 (T120) minutes after incision. Blood samples for plasma IL-6 and IL-2 level determination were obtained 2 hours after incision. Data from 42 rats were included in the final analyses. Significant augmentation of thermal threshold was observed at all time points, after administration of either tramadol or (R,S)-AM1241 compared with the control group (P = 0.004 and P = 0.015, respectively). The combination of (R,S)-AM1241 plus tramadol promoted the induced antinociception in an important manner compared with control (P = 0.002) and (R,S)-AM1241 (P = 0.022) groups. Although the antiallodynic effect produced by tramadol was partially reversed by naloxone 30 and 60 minutes after incision (P = 0.028 and P = 0.016, respectively), SR144528 blocked the effects of (R,S)-AM1241 administration in a significant manner (P = 0.001) at all time points. Similarly, naloxone plus SR144528 also blocked the effects of the combination of (R,S)-AM1241 with tramadol at all time points (P = 0.000). IL-6 level in (R,S)-AM1241 plus tramadol group was significantly attenuated compared with control group (P = 0.000). Nevertheless, IL-2 levels remained unchanged in all experimental groups. It seems that the concomitant administration of a selective CB-2 agonist with tramadol in incisional pain model may improve antinociceptive effects and immune responses of cannabinoids, but this effect does not seem to be superior to that of tramadol alone.

Adverse Drug Reactions in the Orofacial Region

A wide spectrum of drugs can sometimes give rise to numerous adverse orofacial manifestations, particularly dry mouth, taste disturbances, oral mucosal ulceration, and/or gingival swelling. There are few relevant randomized double-blind controlled studies in this field, and therefore this paper reviews the data from case reports, small series, and non-peer-reviewed reports of adverse drug reactions affecting the orofacial region (available from a MEDLINE search to April, 2003). The more common and significant adverse orofacial consequences of drug therapy are discussed.

Comparative metabolism of tramadol and tapentadol: a toxicological perspective

Tramadol and tapentadol are centrally acting, synthetic opioid analgesics used in the treatment of moderate to severe pain. Main metabolic patterns for these drugs in humans are well characterized. Tramadol is mainly metabolized by cytochrome P450 CYP2D6 to O-desmethyltramadol (M1), its main active metabolite. M1 and tapentadol undergo mainly glucuronidation reactions. On the other hand, the pharmacokinetics of tramadol and tapentadol are dependent on multiple factors, such as the route of administration, genetic variability in pharmacokinetic components and concurrent consumption of other drugs. This review aims to comparatively discuss the metabolomics of tramadol and tapentadol, namely by presenting all their known metabolites. An exhaustive literature search was performed using textual and structural queries for tramadol and tapentadol, and associated known metabolizing enzymes and metabolites. A thorough knowledge about tramadol and tapentadol metabolomics is expected to provide additional insights to better understand the interindividual variability in their pharmacokinetics and dose-responsiveness, and contribute to the establishment of personalized therapeutic approaches, minimizing side effects and optimizing analgesic efficacy.

Validated determination method of tramadol and its desmethylates in human plasma using an isocratic LC-MS/MS and its clinical application to patients with cancer pain or non-cancer pain

Background

This study aimed to develop a simultaneous determination method for tramadol and its desmethylates in human plasma using isocratic liquid chromatography coupled to tandem mass spectrometry and to validate it for pharmacokinetic evaluation in patients with cancer pain or non-cancer pain.

Methods

The pretreatments for human plasma involved protein precipitation using acetonitrile and methanol under basic conditions. Tramadol, O-desmethylate, N-desmethylate, and N,O-didesmethylate were separated on an octadecylsilyl column filled with 3-μm particles using isocratic mixture of methanol and 0.15 % formic acid in water (35:65, v/v). The mass spectrometer was run in positive ion multiple reaction monitoring mode. This method was applied to the determination of plasma samples in patients treated with oral tramadol.

Results

The chromatographic total run time was 10 min. The calibration curves in human plasma of tramadol, O-desmethylate, N-desmethylate, and N,O-didesmethylate were linear over the concentration ranges of 12.5–1600, 2.5–320, 2.5–320, and 2.5–320 ng/mL, respectively. The lower limits of quantitation of tramadol and its desmethylates in human plasma were 12.5 and 2.5 ng/mL. Their extraction recoveries were 85.5–106.3 %. The intra-day and inter-day precisions and accuracies were 1.6–10.2 % and 89.2–106.2 % for all analytes. The plasma concentration ranges of tramadol, O-desmethylate, N-desmethylate, and N,O-didesmethylate were 18.2–564, 11.8–137, 4.9–250, and 6.1–147 ng/mL in cancer patients, and 32.8–670, 7.0–84.8, 5.1–317, and 6.7–85.2 ng/mL, respectively, in non-cancer patients.

Conclusions

The present method with acceptable analytical performance can be helpful for evaluating the pharmacokinetics of oral tramadol, including the determination of its desmethylates, for patients with cancer pain or non-cancer pain in clinical settings.