Tramadol--present and future

Opioids-induced inhibition of HERG ion channels and sudden cardiac death, a systematic review of current literature

BACKGROUND

It is estimated that over 60 million individuals regularly use opioids globally, with opioid use disorder increasing substantially in the past decade. Several reports have linked sudden cardiac death, QTc prolongation, and other adverse cardiovascular outcomes with opioid use through their inhibitory effect on the human ether-a-go-go-related gene (HERG) ion channel. Therefore, understanding this underlying mechanism may be critical for risk prevention and management in prescribing opioids and treating patients with opioid dependency.

AIM

The present systematic review summarizes the current literature on the impact of opioids-induced inhibition of HERG channel function and its relationship with sudden cardiac death, QTc prolongation, and other cardiovascular adverse effects.

METHODS

A systematic review was conducted of the databases PubMed, EMBASE, Cochrane, and ClinicalTrials.gov of primary studies that reported the effects of opioids on HERG channel function and associated cardiovascular outcomes.

RESULTS

The search identified 1,546 studies, of which 12 were finally included for data extraction. Based on the current literature, methadone, oliceridine, l-α-acetylmethadol (LAAM), and fentanyl were found to inhibit the HERG channel function and were associated with QTc prolongation. However, other opioids such as morphine, codeine, tramadol, and buprenorphine were not associated with inhibition of HERG channels or QTc prolongation. Additional cardiac outcomes associated with opioid related HERG channels dysfunction included sudden cardiac death and Torsade de Pointes.

CONCLUSION

Our findings suggest that certain opioid consumption may result in the inhibition of HERG channels, subsequently prolonging the QTc interval and increasing patient susceptibility to sudden cardiac death.

Subcutaneous versus intravenous tramadol for extremity injury with moderate pain in the emergency department: a randomised controlled noninferiority trial

BACKGROUND AND IMPORTANCE

Musculoskeletal trauma is a common presentation in the emergency department (ED). Tramadol as an analgesic has been recommended by pain management guidelines for musculoskeletal pain. Parenteral tramadol in the ED is commonly administered intravenously. Subcutaneously administered tramadol may have other advantages such as easier and faster preparation, avoids the need for intravenous (i.v.) access, and reduces the incidence of respiratory and gastrointestinal effects. However, studies comparing subcutaneous (s.c.) and i.v. tramadol for the management of acute moderate pain in patients with extremity injury are lacking.

OBJECTIVE

The objective of this study was to compare the clinical efficacy of s.c. tramadol vs. i.v. tramadol in patients with moderate pain due to extremity injury in the ED.

DESIGN, SETTINGS, AND PARTICIPANTS

This non-inferiority randomized controlled trial included adult patients presented to an academic, tertiary hospital ED with moderate pain (pain score of 4-6 on the visual analog scale) due to extremity injury. Intervention patients stratified to pain score were randomized to receive 50 mg of i.v. or s.c. tramadol.

OUTCOMES MEASURE AND ANALYSIS

Primary outcome measure was the difference in the pain score reduction at 30 min after tramadol administration between the two groups. The noninferiority null hypothesis was that the therapeutic difference in terms of pain score reduction of more than 0.8 exists between the two treatment groups at the endpoint.

MAIN RESULTS

In total 232 patients were randomized to i.v. ( n  = 115) or s.c. ( n  = 117). Although 225 were analyzed in the per-protocol population (i.v. = 113; s.c. = 112). The baseline median pain score was 6 (IQR, 5-6). Median pain score reduction at 30 min after administration was 2 (IQR, 1-3) in the IV group vs. 2 (IQR, 1-2) in the s.c. group with a median difference of 0 (IQR, 0-0), which was below the prespecified noninferiority margin of 0.8. Adverse events in the i.v. group were higher compared to the s.c. group (33.6% vs. 8.9%, P  ≤ 0.001).

CONCLUSIONS

The s.c. tramadol is noninferior to i.v. tramadol in the treatment of moderate pain from extremity injuries.

CYP24A1 and CYP3A4 Levels, Renal, Hepatic Changes, and Incidence of Oxidative Stress in Tramadol-Alcohol Concomitant Misuse

Introduction Long-term population-based research has demonstrated a link between heavy drinking and the prevalence of kidney disorders; similarly, alcohol abuse has long been recognized as one of the main causes of liver diseases. A recent trend of concomitant use of the opioid analgesic Tramadol and alcohol among young males in sub-Saharan Africa has emerged. Aim and objectives This study's primary aim was to evaluate the incidence of concomitant use of alcohol and Tramadol among adult males, and observe the role of cytochrome p450 3A4 and CYP24A1 proteins and some oxidative stress indicators such as Malondialdehyde, lactate dehydrogenase, among study participants. The secondary aim was to evaluate the effect of alcohol and Tramadol concomitant use on Liver and kidney indices. Methods Our study population was male subjects with a history of Alcohol and Tramadol concomitant use. Liver enzymes, renal indices, oxidative stress markers, and CYP3A4 and CYP24A1 were determined from the serum of test and control participants. IBM Statistical Package for Social Sciences (SPSS) Statistics (version 21.0) was used to analyze the data obtained. Result One hundred and forty-two male subjects were included in this study. Eighty two (82) were males who admitted to abuse of Alcohol and Tramadol concomitantly for at least a year. The dose of Tramadol commonly used by Test subjects was 200 mg (43.9% of the test population), Tramadol users in the study population were largely Undergraduates (75.6% of Test participants). Gamma-glutamyl transferase and lactate dehydrogenase were significantly higher in Test subjects consuming Tramadol and alcohol combination (43.13±1.02 and 117.29±2.45, respectively) versus control (24.87±0.82; p=0.00 and 101.93±1.25; p=0.00). There was a significant decrease in serum bicarbonate levels of Test subjects (16.19±0.53) versus control (22.60±0.68; p=0.000). Cytochrome P450 24A1, was significantly lower in Test subjects (subjects consuming Tramadol and alcohol combination) (0.90±0.06; p=0.01), and significantly threefold higher in subjects with acute myeloid leukemia (AML) (5.16±0.5; p=0.00), when compared with values of non-drug/alcohol users that served as normal control (1.27±0.07). Conclusion The menace of Tramadol and alcohol concomitant abuse has taken a worrisome dimension in sub-Saharan Africa. In this study 77.4% of participants reported euphoria as reason for combining Alcohol and Tramadol, 6.5% claimed it was for faster pain relief and enhanced sexual performance or prolong penile erection was the response of 58.1% of the test participants. Findings of reduced CYP3A4 with Alcohol and Tramadol concomitant use could be associated with delayed drug inactivation and increased drug euphoric action.

A comparative study of postmortem distribution and postmortem diffusion of tramadol in rabbits

In recent years, the cases of tramadol intoxication have become more frequent in many countries. However, most of the previous studies have been based on cases of tramadol intoxication, and the detailed information on the differences between postmortem distribution and diffusion of tramadol remains unclear. To investigate this issue systematically, we established a postmortem distribution model and two postmortem diffusion models. Then, gas chromatography-mass spectrometry (GC/MS) was used to measure the concentrations of tramadol in various biological specimens of fluids and tissues. In postmortem distribution, the results showed an uneven distribution of tramadol in various biological specimens, and the concentrations of tramadol in urine were significantly higher than those in other fluids. In postmortem diffusion, the results showed a dosage-dependent increase of tramadol concentration in most specimens; at all time points from 0.25 to 6 h after postmortem administration, the concentrations of tramadol in fluids were not significantly different from those in tissues, and the concentrations of tramadol in urine were lower than those in both tissues and other fluids in most time points. We recommend a quantitative examination of the specimens of both fluids and tissues to provide more evidence for the forensic identification, and the realization that there is a correlation between the concentrations of fluids and tissues is important for determining antemortem and postmortem administration of tramadol. This information can serve as ancillary data in inferring the contribution of a drug to death in cases of suspected tramadol poisoning.

Tramadol regulates the activation of human platelets via Rac but not Rho/Rho-kinase

Tramadol is a useful analgesic which acts as a serotonin and noradrenaline reuptake inhibitor in addition to μ-opioid receptor agonist. Cytoplasmic serotonin modulates the small GTPase activity through serotonylation, which is closely related to the human platelet activation. We recently reported that the combination of subthreshold collagen and CXCL12 synergistically activates human platelets. We herein investigated the effect and the mechanism of tramadol on the synergistic effect. Tramadol attenuated the synergistically stimulated platelet aggregation (300 μM of tramadol, 64.3% decrease, p<0.05). Not morphine or reboxetine, but duloxetine, fluvoxamine and sertraline attenuated the synergistic effect of the combination on the platelet aggregation (30 μM of fluvoxamine, 67.3% decrease, p<0.05; 30 μM of sertraline, 67.8% decrease, p<0.05). The geranylgeranyltransferase inhibitor GGTI-286 attenuated the aggregation of synergistically stimulated platelet (50 μM of GGTI-286, 80.8% decrease, p<0.05), in which GTP-binding Rac was increased. The Rac1-GEF interaction inhibitor NSC23766 suppressed the platelet activation and the phosphorylation of p38 MAPK and HSP27 induced by the combination of collagen and CXCL12. Tramadol and fluvoxamine almost completely attenuated the levels of GTP-binding Rac and the phosphorylation of both p38 MAPK and HSP27 stimulated by the combination. Suppression of the platelet aggregation after the duloxetine administration was observed in 2 of 5 patients in pain clinic. These results suggest that tramadol negatively regulates the combination of subthreshold collagen and CXCL12-induced platelet activation via Rac upstream of p38 MAPK.

The Effect of Different Opioids on Acid-Base Balance and Blood Gas Analysis in Hospitalized Dogs

Pain management is central to veterinary practice, contributing to successful case outcomes and enhancement of the veterinarian-client-patient relationship. Analgesic drugs represent one of the pillars of the multimodal approach to acute and chronic pain management. In dogs, the most used opioids are methadone, buprenorphine and tramadol. Several episodes of hypoglycemia in people treated with tramadol and methadone have recently been described. The aim of this work is to evaluate the changes in the glycemic and acid-base balance induced by tramadol, methadone and buprenorphine in hospitalized dogs. A retrospective review of the medical records of dogs hospitalized for both medical and surgical reasons was performed. During 2018-2020, a total of 876 canine patients were treated with opioids, including 228 with tramadol, 273 with methadone and 375 with buprenorphine. Of all these dogs, only a small percentage met the inclusion criteria presented in the initial design. All the hospitalized animals were monitored daily through clinical examination and blood sampling. Blood samples were obtained before opioid administration (T0), and 24 h (T1) and 48 h (T2) after °pioid administration. The following parameters were evaluated: blood gas value (pH, pCO₂), acid-base state (cHCO₃), oxymetric values (ctHb, haematocrit), electrolyte values (K+, Na+, iCa, Cl-) and metabolic values (glucose, lactate, anion GAP K+c). The glycemic value in enrolled dogs showed a decrease over time, regardless of the type of opioid used, but remained within the physiological range. The highest average glycemic drop was recorded for methadone, between T0 and T1, followed by tramadol between T1 and T2, while buprenorphine recorded the highest overall glycemic drop between T0-T2 when compared to the other two opioids. Female dogs showed the greatest drop in glycemic value. Lactate concentration always presented values beyond the physiological range at an early stage, which then normalized quickly. Measurement of electrolyte concentrations showed a consistent increase in the values of iCa, Na and Cl. In hospitalized dogs treated with opioids monitoring of gas analytic parameters is important and more attention should be paid to patients hospitalized with certain metabolic and endocrine diseases.

The Effects of Bariatric Surgery and Gastrectomy on the Absorption of Drugs, Vitamins, and Mineral Elements

Bariatric surgery, which is an effective treatment for obesity, and gastrectomy, which is the primary treatment method for gastric cancer, alter the anatomy and physiology of the digestive system. Weight loss and changes in the gastrointestinal tract may affect the pharmacokinetic parameters of oral medications. Both bariatric and cancer patients use drugs chronically or temporarily. It is important to know how surgery affects their pharmacokinetics to ensure an effective and safe therapy. The Cochrane, PubMed, and Scopus databases were searched independently by two authors. The search strategy included controlled vocabulary and keywords. Studies show that bariatric surgery and gastrectomy most often reduce the time to maximum plasma concentration (t_max) and decrease the maximum plasma concentration (C_max) in comparison with the values of these parameters measured in healthy volunteers. Vitamin and mineral deficiencies are also observed. The effect depends on the type of surgery and the properties of the drug. It is recommended to use the drugs that have been tested on these groups of patients as it is possible to monitor them.

Gonadotoxic effect of tramadol administration: A prospective controlled study

Objective

To detect the possible gonadotoxic effects of tramadol dependence on seminal fluid parameters, and prolactin and testosterone hormone levels.

Patients, Subjects, and Methods

There were 94 participants who were divided into a tramadol-dependent group (T-group; 56 patients) and a control group (C-group; 38 healthy volunteers). The following variables were evaluated: testosterone level, prolactin level, erectile function, libido, semen parameters, and effect of tramadol dose and dependence duration.

Results

There was a significant increase in erectile dysfunction (ED) and decreased libido in the T-group vs C-group. Also, the serum testosterone level was lower in the T-group vs the C-group, while the serum prolactin level was significantly higher in the T-group vs the C-group. All semen parameters were low in the T-group except for abnormal forms, which were high. As the dose of tramadol increased there was a more negative effect on the previous parameter, while ED, libido, semen volume and concentration showed no significant changes. When comparing tramadol doses of 400–1000 mg/day to >1000 mg/day, the tramadol blood level increased with high doses, while serum testosterone level decreased when the dose increased and the prolactin level increased when the dose increased. Progressive motility of the sperm decreased and abnormal forms increased. Also increased duration of tramadol administration was also accompanied by a more negative effect on these parameters

Conclusion

Tramadol administration has a negative effect on hormone levels, libido, erectile function, and semen characters.Abbreviations: ED: erectile dysfunction; EF: erectile function

New Insights on Tramadol and Immunomodulation

PURPOSE OF REVIEW

Opioids are administered to cancer patients although concerns have been raised that they may promote tumour growth or metastasis owing to their ability to suppress anti-cancer immunity. Tramadol has been reported to preserve or promote the immune response and may therefore be preferred to other opioids in cancer patients. We reviewed the literature documenting the immunomodulatory effects of tramadol.

RECENT FINDINGS

Recent clinical evidence appears to confirm that tramadol possesses anti-inflammatory properties, and preserves some signalling cascades of the immune system relevant to anti-cancer defence. Tramadol is reported to promote or preserve immunity including natural killer cell activity which is important in anti-cancer defences.

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

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

Dynamic Distribution and Postmortem Redistribution of Tramadol in Poisoned Rats

In the past dozen years, the cases of tramadol intoxication have become frequent in many countries. Most previous studies focused on tramadol's pharmacology, such as pharmacokinetics, pharmacodynamics and pharmacogenetics. However, the dynamic distribution and postmortem redistribution (PMR) of tramadol remain unclear. Our study aimed to investigate these two issues systematically in various specimens of 216 poisoned male rats. A validated gas chromatography-mass spectrometry method was used in this study to measure the concentrations of tramadol. In the first part, 66 tramadol poisoned rats were sacrificed at 11 different time points and their organs were collected separately for the study of tramadol's dynamic distribution, which made it feasible to investigate its PMR later on. The results of this part showed that tramadol's concentrations varied according to the organ and time, and peaked 2 h after intragastric administration in the specimens of liver, kidney, spleen, lung, brain and heart-blood (except stomach and heart). Based on the results of the first part, the concentration of tramadol peaked 2 h in most tissues. Therefore, this time point was used for the study of tramadol's PMR. In the second part, the remaining 150 rats were sacrificed 2 h after intragastric administration of tramadol, and the carcasses were stored under three different conditions (-20, 4 and 20°C). The autopsy was carried out at eight different time points and their organs were collected separately. The results of this part showed that under storage temperatures of -20 and 4°C, the concentrations of tramadol in individual organs showed no significant changes at different time points whereas under a storage temperature of 20°C, the concentrations in certain organs (liver, kidney, spleen, lung, brain and heart-blood) increased significantly at the last few time points. PMR of tramadol was therefore confirmed. The process of PMR of tramadol could be slowed or stopped at lower storage temperatures (-20 or 4°C), which is significant in cases of suspected tramadol poisoning.

No Difference in Pain After Spine Surgery with Local Wound Filtration of Morphine and Ketorolac: A Randomized Controlled Trial

BACKGROUND

Controlling postoperative pain after spinal surgery is important for rehabilitation and patient satisfaction. Wound infiltration with local anesthetics may improve postoperative pain, but true multimodal approaches for achieving analgesia after spinal surgery remain unknown.

QUESTIONS/PURPOSES

In this randomized, controlled, double-blind trial after lumbar interbody fusion, we asked: (1) Does multimodal analgesia reduce VAS pain scores by a clinically important amount? (2) Does this analgesic approach reduce the amount of morphine patients consume after surgery? (3) Is this approach associated with fewer opioid-related side effects after surgery?

METHODS

This study included 80 adult patients undergoing lumbar interbody fusion who were randomized into two groups: A control group (n = 40) who received infiltration of the surgical incision at the end of the procedure with an injection of 0.5% bupivacaine 100 mg (20 mL) and epinephrine 0.5 mg (0.5 mL), and the multimodal group (n = 40), who received wound infiltration with the same approach but with different medications: 0.5% bupivacaine 92.5 mg (18.5 mL), ketorolac 30 mg (1 mL), morphine 5 mg (0.5 mL), and epinephrine 0.5 mg (0.5 mL). There were no between-group differences in the proportion of patients who were male, nor in the mean age, height, weight, preoperative pain score, or surgical time. All treatments were administered by one surgeon. All patients, the surgeon, and the researchers were blinded to the allocation of patients to each group. Pain at rest was recorded using the VAS. Postoperative morphine consumption (administered using a patient-controlled analgesia pump) and opiod-associated side effects including nausea/vomiting, pruritus, urinary retention, and respiratory depression were assessed; this study was analyzed according to intention-to-treat principles. No loss to follow-up or protocol deviations were noted. We considered a 2-cm change on a 10-cm scale on the VAS as the minimum clinically important difference (MCID). Differences smaller than this were considered unlikely to be important.

RESULTS

At no point were there between-group differences in the VAS scores that exceeded the MCID, indicating no clinically important reductions in pain associated with administering multimodal injections. The highest treatment effect was observed at 3 hours that showed only a -1.3 cm mean difference between the multimodal and the control groups (3.2 ± 1.8 versus 4.5 ± 1.9 [95% CI -1.3 to -0.3]; p < 0.001), which was below the MCID. Morphine consumption was very slightly higher in the control group than in the multimodal group (2.8 ± 2.8 versus 0.3 ± 1.0, mean difference 2.47; p < 0.001). The percentage of patients reporting opioid-related side effects was lower in the multimodal group than in the control group. The proportions of nausea and vomiting were higher in the control group (30% [12 of 40] than in the multimodal group (3% [1 of 40]; p = 0.001). All of these side effects were transient and none was severe.

CONCLUSIONS

Multimodal wound infiltration with an NSAID and morphine did not yield any clinically important reduction in pain or opioid consumption. Since no substantial benefit of adding these drugs to a patient's aftercare regimen was achieved, and considering the potential risks of administering opioids and NSAIDs (such as, polypharmacy in older patients, serious adverse effects of NSAIDs), we recommend against routine use of this approach in clinical practice.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Efficacy and Safety of Two Fixed-Dose Combinations of Tramadol Hydrochloride and Diclofenac Sodium in Postoperative Dental Pain

OBJECTIVE

To evaluate the analgesic efficacy and safety of tramadol hydrochloride/diclofenac sodium fixed-dose combination 25 mg/25 mg (FDC 25/25) and 50 mg/50 mg (FDC 50/50) vs tramadol 50 mg (T50) and diclofenac 50 mg (D50) monotherapies in acute postoperative dental pain.

SETTING

Eight sites across Mexico.

SUBJECTS

Adults (N = 829) with moderate to severe pain after third molar extraction.

DESIGN

Prospective, randomized, double-blind, diclofenac- and tramadol-controlled, parallel-group, noninferiority, phase 3 trial.

METHODS

Subjects were randomized to receive three doses (one every eight hours) of oral FDC 25/25, FDC 50/50, T50, or D50 over a 24-hour period. Pain intensity and pain relief were evaluated frequently over the 24 hours postdose. Secondary measures included peak pain relief, onset, and duration of effect. The primary objective was to compare the analgesic efficacy and safety of FDC 50/50 or analgesic noninferiority of FDC 25/25 vs D50 or T50. The primary efficacy end point was total pain relief over four hours after dose 1 (TOTPAR4).

RESULTS

TOTPAR4 scores showed that FDC 25/25 was noninferior (P < 0.0001, delta = 1.5) and FDC 50/50 was superior (P < 0.0001) to the individual components. All secondary efficacy measures supported these results. The safety profile of FDC 25/25 and FDC 50/50 was consistent with the known safety profile of D50 and T50 monotherapies, with no unexpected safety findings observed.

CONCLUSIONS

Tramadol/diclofenac FDC 25/25 and FDC 50/50 provide superior analgesia for acute pain after third molar extraction than either of the individual components. Minor adverse effects appeared to be related to the higher doses of tramadol.

Effect of tramadol dependence on male sexual dysfunction

Tramadol dependence became an increasing and alarming problem in the Egyptian community. Wide availability of tramadol as a pain killer and its role in the treatment of premature ejaculation may be the most apparent causes of increased magnitude of the problem among youth who believe that tramadol has a positive impact on their sexual functions. This study aimed to explore the real impact of chronic tramadol administration on sexual functions in males dependent on tramadol. The study was carried on 80 subjects (50 subjects were tramadol dependent group and 30 subjects represented the control group). Personal, family and past histories were obtained from all the participants in addition to the toxicological history from tramadol dependent group. Urine screening for tramadol was done for all cases of history of tramadol dependence then confirmation by HPLC technique to measure tramadol blood level was done. Both groups were investigated for serum testosterone and prolactin level. Curiosity (22%) and treatment of premature ejaculation (20%) were the main motives for dependence. Erectile dysfunction and decreased libido occurred in 44% and 48% of tramadol dependent group respectively. Significant increase in erectile dysfunction and decreased libido was noted as the duration of dependence increased. Additionally, significant decrease in serum testosterone level and increase in serum prolactin level as tramadol daily dose and duration increased was found. In conclusion, men who take tramadol for premature ejaculation or any other purpose must know that they are very susceptible to many sexual dysfunctions.

Evaluation of the Effect of CYP2D6 Genotypes on Tramadol and O-Desmethyltramadol Pharmacokinetic Profiles in a Korean Population Using Physiologically-Based Pharmacokinetic Modeling

Tramadol is a μ-opioid receptor agonist and a monoamine reuptake inhibitor. O-desmethyltramadol (M1), the major active metabolite of tramadol, is produced by CYP2D6. A physiologically-based pharmacokinetic model was developed to predict changes in time-concentration profiles for tramadol and M1 according to dosage and CYP2D6 genotypes in the Korean population. Parallel artificial membrane permeation assay was performed to determine tramadol permeability, and the metabolic clearance of M1 was determined using human liver microsomes. Clinical study data were used to develop the model. Other physicochemical and pharmacokinetic parameters were obtained from the literature. Simulations for plasma concentrations of tramadol and M1 (after 100 mg tramadol was administered five times at 12-h intervals) were based on a total of 1000 virtual healthy Koreans using SimCYP^® simulator. Geometric mean ratios (90% confidence intervals) (predicted/observed) for maximum plasma concentration at steady-state (C_max,ss) and area under the curve at steady-state (AUC_last,ss) were 0.79 (0.69-0.91) and 1.04 (0.85-1.28) for tramadol, and 0.63 (0.51-0.79) and 0.67 (0.54-0.84) for M1, respectively. The predicted time-concentration profiles of tramadol fitted well to observed profiles and those of M1 showed under-prediction. The developed model could be applied to predict concentration-dependent toxicities according to CYP2D6 genotypes and also, CYP2D6-related drug interactions.

Ramosetron Does Not Reduce the Analgesic Efficacy of Tramadol after Gynecological Laparoscopic Surgery

Background

The effect of ramosetron on the analgesic action of tramadol is not well known when ramosetron is added to intravenous-tramadol patient-controlled analgesia (PCA) and infused continuously. The aim of this randomized noninferiority study was to evaluate the effects of ramosetron on the analgesic action of tramadol when it is administered simultaneously in women undergoing laparoscopic gynecology who are receiving tramadol via IV PCA.

Method

This study used a prospective, randomized, controlled, noninferiority clinical trial design and compared the analgesic effect of tramadol plus ramosetron with that of tramadol only. A total of 110 postoperative patients, who were using IV PCA tramadol, were randomly assigned either to a group receiving ramosetron (group R, n=49) or to a group that received the same volume of normal saline continuously (group N, n=51). Observation time points for cumulative tramadol consumption were the first hour, and every 4 h up to 12 h and then 24 h after surgery. Pain intensity at rest and during movement, coughing, and nausea scores, the analgesic and antiemetic doses used, side effects, and patient satisfaction were evaluated 1 and 24 h after surgery.

Results

Groups R and N received, respectively, 88 ± 55 vs. 79 ± 42 mg tramadol (P=0.511) after 1 h, 211 ± 122 vs. 198 ± 109 mg cumulative tramadol (P=0.610) after 4 h, 244 ± 150 vs. 231 ± 134 mg cumulative tramadol (P= 0.793) after 8 h, 250 ± 156 vs. 247 ± 153 mg cumulative tramadol (P=0.972) after 12 h, and 294 ± 190 vs. 284 ± 178 mg cumulative tramadol (P=0.791) after 24 h, postsurgery. Tramadol plus ramosetron was shown to be not significantly inferior to tramadol alone in alleviating the postoperative pain.

Conclusions

The analgesic effect of tramadol combined with ramosetron was found to be noninferior to tramadol alone for postoperative PCA after laparoscopic gynecologic surgery.

Randomised trial of perioperative tramadol for canine sterilisation pain management

Surgical sterilisation to manage free-roaming dog populations is widely used in many countries. However, few studies have examined optimal postoperative pain management regimens at low-resource, high-throughput veterinary clinics. The aim of this study was to examine the efficacy of two intravenous analgesic regimens, preoperative administration of meloxicam and tramadol, or meloxicam alone, in free-roaming dogs undergoing sterilisation. A total of 125 dogs were included, with 64 dogs in the meloxicam-tramadol arm and 61 dogs in the meloxicam-only arm in a non-inferiority study design. Pain levels in sterilisation surgery patients were assessed at four time points after surgery using the Colorado State University Canine Acute Pain Scale, a Visual Analogue Scale and a modified version of the Glasgow Composite Measure Pain Scale - Short Form. Non-inferiority was supported for each of the main scoring outcomes using non-inferiority margins of 0.5, 5 and 0.8, respectively. One dog from the meloxicam-tramadol group and four dogs in the meloxicam-only arm required rescue analgesia, with no difference between groups (P=0.21).The study demonstrated that meloxicam was effective in controlling postoperative pain in a high proportion of dogs. The addition of tramadol alongside meloxicam treatment was not found to be of clinical benefit.

Effects of tramadol on emergence agitation after general anesthesia for nasal surgery: A retrospective cohort study

Emergence agitation (EA) is common after nasal surgery. Strong opioids and N-methyl-D-aspartate (NMDA) receptor antagonists prevent EA. Tramadol also acts as an opioid receptor agonist and an NMDA receptor antagonist, but few studies have evaluated the effects of tramadol on EA. This retrospective study investigated whether tramadol is effective for reducing EA in adult patients undergoing nasal surgery.Of 210 adult patients undergoing a nasal surgical procedure under general anesthesia, the medical records of 113 were analyzed retrospectively. The patients were divided into 2 groups: patients who received tramadol during the operation (tramadol group, n = 52) and patients who did not (control group, n = 61). The incidence of EA, recovery time, changes in hemodynamic parameters, postoperative pain scores, and adverse events were compared between the 2 groups.The incidence of EA was higher in the control group than in the tramadol group (50.8% [31/61] vs 26.9% [14/52]; odds ratio 2.805; 95% confidence interval, 1.3 to 6.2; P = .010). Changes in systolic blood pressure in the 2 groups were similar, whereas changes in heart rate during emergence differed depending on the group (P = .020), although pairwise comparisons did not reveal any differences between the groups. Recovery time, postoperative pain scores, and adverse events were similar in the 2 groups.In adult patients undergoing nasal surgery, tramadol infusion decreases the incidence of EA after sevoflurane anesthesia without delaying recovery or increasing the number of adverse events.

Severe Uncontrolled Pain in Buttock in a Patient on Naltrexone: A Diagnostic Challenge

A 26-year-old woman with a history of intravenous drug use was admitted to hospital with worsening pain in the right buttock radiating to the lateral part of the thigh and to the calf with no suspicion of cauda equina compression. Eventually, a diagnosis of sacroiliitis was made and appropriate antibiotics were administered. Provision of analgesia for this patient was difficult. On admission her medications included naltrexone, venlafaxine and tramadol. Initially naltrexone was continued and analgesia provided by epidural local anaesthetic and clonidine, intravenous ketamine and oral agents. After several days, naltrexone was ceased and opioids were used in addition to the other analgesics. The epidural analgesia was only partially effective, perhaps because of inadequate blockade of the L4-S1 nerve roots, which carry sensation from the sacroiliac joint.

Naltrexone is a long-acting opioid antagonist. If opioid analgesia is planned, it is necessary to cease naltrexone for 24 to 72 hours. In an emergency, if non-opioid techniques prove ineffective, short-acting opioids can be titrated to effect in a monitored environment.

Multimodal Analgesia in Foot and Ankle Surgery

Progress in surgical acute pain management has allowed most foot and ankle surgery to be performed in ambulatory outpatient surgical centers. Multimodal analgesia focuses on improving postoperative pain by combining pharmacologic and other modalities, addressing multiple pain mechanisms and receptor pathways while reducing adverse effects through lower doses of oral medications. Local anesthesia techniques provide excellent pain relief with few adverse events. Multimodal analgesia in foot and ankle surgery provides superior pain relief, and reduced opioid dependence and opioid-related side effects, improving patient satisfaction, safety, and timely return to function.

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.

Successful treatment of mixed (mainly cancer) pain by tramadol preparations

The patient, a 70-year-old Japanese woman diagnosed with parotid gland cancer, underwent wide excision and reconstruction (facial nerve ablation, nerve transposition). At 1 month after the surgery, she was brought to our hospital's pain medicine department because her postoperative pain and cancer-related pain were poorly controlled. She had already been prescribed a tramadol (37.5 mg)/acetaminophen (325 mg) combination tablet (5 tablets/day). However, in addition to the continuous pain in her face and lower limbs, she was troubled by a trigeminal neuralgia-like prominence ache. Because this pain could not be controlled by an increase to eight combination tablets per day, we switched her medication to a tramadol capsule. At 11 months post-surgery, we then switched her medication to an orally disintegrating tramadol tablet to improve medication adherence of the drug. From 14 months post-surgery, the patient also used a sustained-release tramadol preparation, and she was then able to sleep well. Her current regimen is an orally disintegrating sustained-release tablet combination (total 300 mg tramadol) per day, and she achieved sufficient pain relief. Because tramadol is not classified as a medical narcotic drug, it widely available and was shown here to be extremely useful for the treatment of our patient's mixed (mainly cancer) pain. J. Med. Invest. 64: 311-312, August, 2017.

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.

Tramadol Exposures Reported to Statewide Poison Control System

BACKGROUND:

Tramadol is a unique analgesic that has been associated with seizures on overdose.

OBJECTIVE:

To determine the toxic effects associated with tramadol exposure.

METHODS:

A retrospective chart review of tramadol exposures reported to a multisite, state-wide poison control system over a 2.5-year period was performed.

RESULTS:

A total of 602 cases were retrieved; 190 had sufficient data for study evaluation. Cases with coingestants or unknown outcomes were eliminated. Of the 190 remaining cases, 55% were females. Acute ingestions represented 90.0%, chronic ingestions 7.9%, and acute on chronic 2.1% of the overdoses. Ages of the patients ranged from 9 months to 80 years. Suicide attempts represented the largest group of exposures. Main symptoms included central nervous system (CNS) depression (27.4%), nausea and vomiting (21.1%), tachycardia (17.4%), and seizures (13.7%). Dosage ranged from a taste amount to 5000 mg. The smallest amount of tramadol associated with seizure was 200 mg, and 84.6% of seizures occurred within 6 hours of time of ingestion. Logistic regression analysis showed an association between seizures and tramadol use in males, chronic use, suicide attempts, intentional abuse or misuse, and tachycardia (HR >100 beats/min). No effect was seen in 36.3% of patients, minor effects in 43.7%, moderate effects in 19.5%, and major effects in 0.5%. Symptoms resolved within 24 hours in 96.7% of the 121 patients who had symptoms. Naloxone improved CNS depression in 7 of 8 patients in whom a response was documented.

CONCLUSIONS:

Tramadol overdoses frequently cause CNS depression, nausea/vomiting, tachycardia, and seizures. Symptoms generally resolve within 24 hours. Accidental ingestions in children were well tolerated, primarily causing sedation.

Latarjet Procedure for Anterior Shoulder Instability Due to Tramadol-Induced Seizures: A Multicenter Study

BACKGROUND

Seizures, commonly due to epilepsy, are known to cause shoulder instability. Tramadol addiction has recently been found to induce seizures in patients who exceed the recommended dose. Because of the easy accessibility and low cost of tramadol, an increasingly alarming phenomenon of tramadol abuse has been demonstrated in recent years.

PURPOSE/HYPOTHESIS

The purpose of this multicenter study was to investigate shoulder instability resulting from tramadol-induced seizure (TIS) as well as to recommended management for such shoulder instability. The hypothesis was that TIS leads to anterior shoulder dislocations with major bony defects, which favors bony reconstructive procedures as a suitable method of treatment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This prospective case series study was conducted on 73 patients (78 shoulders) who presented with anterior shoulder dislocations and a clear history of tramadol abuse. The mean age of the patients was 26.8 years, and the mean number of dislocations was 14. The mean duration of addiction was 17 months, with a mean dose of 752 mg of tramadol hydrochloride per day. Glenoid and humeral bone loss ranged from 15% to 35% and from 15% to 40%, respectively. The mean follow-up period was 28 months. All patients underwent an open Latarjet procedure.

RESULTS

Postoperative mean Rowe score and American Shoulder and Elbow Surgeons score at final follow-up (24 months) improved significantly from 20 to 84 and from 44 to 91, respectively (P < .05). The patient satisfaction rate reached 95%, and the mean period of return to work was 12.8 weeks. Five patients (9%) had postoperative seizures due to relapse of the tramadol abuse, but only 3 patients (5%) had redislocations with nonunion or breakage of the graft or hardware.

CONCLUSION

Tramadol addiction has evolved as an important cause of seizures that can result in shoulder dislocation. Anterior shoulder instability with TIS occurs mainly with higher levels of addiction and results in significant humeral and/or glenoid bone defects. The Latarjet procedure is recommended for these patients, after control of addiction, and provides 95% satisfaction at midterm follow-up.

Intrathecal ropivacaine with or without tramadol for lower limb orthopedic surgeries

BACKGROUND AND AIM

Preservative free tramadol has been used as an adjuvant to intrathecal bupivacaine. However, the effect of the addition of tramadol on intrathecal isobaric ropivacaine has never been studied.

MATERIAL AND METHODS

This prospective, randomized, double-blind study was conducted in 50 adult male American Society of Anesthesiologists grade I or II patients, aged 18-60 years, being operated for unilateral femur fractures. An epidural catheter was inserted in L2-L3 interspace and subarachnoid block was given in L3-L4 space. The patients were randomized to receive 0.5 mL normal saline (group R) or 0.5 mL (25 mg) preservative free tramadol (group RT) with 2.5 mL of 0.75% intrathecal ropivacaine. Hemodynamic parameters, sensory level, motor block, sedation and side-effects were recorded. Statistical analysis was done using Student's t-test, Chi-square test, Fischer's exact test and repeated measures ANOVA.

RESULTS

The time of sensory block onset was 9.2 ± 4.9 min and 8.6 ± 5.3 min (P = 0.714) in group R and group RT, respectively. The motor block onset was also comparable in both the groups (P = 0.112). The duration of sensory block was 147.2 ± 37.4 min in group R and 160.4 ± 40.9 min in group RT (P = 0.252). The median maximum block height achieved in both the groups was T6 and the time to achieve the maximum block was also comparable statistically (P = 0.301).

CONCLUSION

The addition of intrathecal tramadol 25 mg to the isobaric ropivacaine does not alter the block characteristics produced by intrathecal ropivacaine alone.

PRESSÃO INTRAOCULAR, PRESSÃO ARTERIAL MÉDIA E DIÂMETRO PUPILAR EM COELHOS ( (Oryctolagus cuniculus) ) SUBMETIDOS AO BLOQUEIO RETROBULBAR COM DIFERENTES PROTOCOLOS ANESTÉSICOS

Resumo O objetivo deste estudo foi buscar novos protocolos de anestesia loco regional para procedimentos oftálmicos que proporcionem segurança e manutenção das funções vitais, além de manter a pressão intraocular estável, com centralização do bulbo do olho e acinesia palpebral. Foram utilizados 20 coelhos da raça Nova Zelândia para a realização de quatro protocolos de anestesia local através do bloqueio retrobulbar com lidocaína 2% com vasoconstritor, lidocaína 2% sem vasoconstritor associada ao tramadol, ropivacaína 1% e bupivacaína 0,5%, cada animal recebeu o volume anestésico de 1,0 mL. Todos os protocolos anestésicos utilizados promoveram acinesia palpebral e centralização do bulbo do olho durante todo o período de avaliação. A realização do bloqueio retrobulbar com os protocolos anestésicos demonstrou ser factível e segura quanto à manutenção da pressão intraocular, pressão arterial invasiva e diâmetro pupilar e pode ser utilizada para realização de cirurgias intraoculares. Os anestésicos proporcionaram bom bloqueio retrobulbar, entretanto a bupivacaína foi o anestésico que ocasionou o maior diâmetro pupilar comparativamente aos demais fármacos testados.

Effect of the CYP2D6 gene polymorphism on postoperative analgesia of tramadol in Han nationality nephrectomy patients

OBJECTIVE

Tramadol is a synthetic opioid which has analgesic efficacy in the postoperative pain. It is metabolized by polymorphic enzyme cytochrome P450 (CYP2D6). Patients with different CYP2D6 genotypes would have different responses to tramadol in pain relief. The CYP2D6*10 allele is the most common allele in a Chinese population. The aim of this study was to evaluate whether the different CYP2D6*10 genotypes have an effect on the postoperative tramadol analgesia in the Chinese population after elective nephrectomy.

METHODS

One hundred and twenty patients after performed elective nephrectomy were enrolled in this study after being approved by the local Ethics Committee. The patients were given patient-controlled analgesia (PCA) which included 10 mg/ml tramadol after receiving a loading dose of 100 mg tramadol and 1 mg granisetron intravenously. Blood samples were collected after induction of anesthesia. The CYP2D6*10 polymorphism was analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). According to the results, the patients were divided into three groups (CYP2D6*1/*1, n = 33; CYP2D6*1/*10, n = 28; CYP2D6*10/*10, n = 50). The total consumption of tramadol, visual analogue scale (VAS) score, and PCA control times among the three genotype groups for 2, 4, 24, 48, and 72 h after operation were compared.

RESULTS

Nine out of 120 patients were dropped out of the study; 111 patients completed the study. The frequency of CYP2D6*10 allele was 57.7%. The demographic data among the three groups were comparable. The consumption of tramadol, patient self-control times of pump, and VAS score in CYP2D6*10/*10 group were significantly higher than that in CYP2D6*1/*1 or CYP2D6*1/*10 group at 2 and 4 h (P < 0.05), while it did not differ between CYP2D6*1/*1 and CYP2D6*1/*10 group (P > 0.05). There was no difference in the incidence of nausea and vomiting among the three groups (P > 0.05). No sever apnea was recorded in these groups.

CONCLUSIONS

Different CYP2D6*10 genotypes have an influence on the analgesic effect of tramadol in Han nationality patients after elective nephrectomy.

Tramadol can selectively manage moderate pain in children following European advice limiting codeine use

The European Medicine Agency recommendations limiting codeine use in children have created a void in managing moderate pain. We review the evidence on the pharmacokinetic, pharmacodynamic and safety profile of tramadol, a possible substitute for codeine.

CONCLUSION

Tramadol appears to be safe in both paediatric inpatients and outpatients. It may be appropriate to limit the current use of tramadol to monitored settings in children with risk factors for respiratory depression, subject to further safety evidence.

Efficacy of tramadol as a preincisional infiltration anesthetic in children undergoing inguinal hernia repair: a prospective randomized study

Background

Preincisional local anesthetic infiltration at the surgical site is a therapeutic option for postoperative pain relief for pediatric inguinal hernia. Additionally, tramadol has been used as an analgesic for postoperative pain in children. Recently, the local anesthetic effects of tramadol have been reported. The aim of this study was to determine both the systemic analgesic and the local anesthetic effects of tramadol and to determine how it differs from bupivacaine when administered preincisionally.

Methods

Fifty-two healthy children, aged 2–7 years, who were scheduled for elective herniorrhaphy were randomly allocated to receive either preincisional infiltration at the surgical site with 2 mg/kg tramadol (Group T, n=26) or 0.25 mL/kg 0.5% bupivacaine (Group B, n=26). At the time of anesthetic administration, perioperative hemodynamic parameters were recorded. The pain assessments were performed 10 minutes after the end of anesthesia and during the first 6-hour period, using pain scores. The time of first dose of analgesia and need for additional analgesia were recorded.

Results

Between T and B groups, the anesthesia time, perioperative hemodynamic changes, and pain scores were not statistically different. However, in group B, the postoperative analgesic requirement was higher than in group T.

Conclusion

Tramadol shows equal analgesic effect to bupivacaine and decreases additional analgesic requirement, when used for preincisional infiltration anesthesia in children undergoing inguinal herniorrhaphy.

The antinociceptive effect of systemic administration of a combination of low-dose tramadol and dexmedetomidine in a rat model of bone cancer pain

BACKGROUND

Multiple factors are involved in the mechanism of bone cancer pain. Treatment with a single drug is not adequate to target all of the different mechanisms.

OBJECTIVE

To study the analgesic effect of a combination of low-dose dexmedetomidine (DEX) and tramadol (TRA) on bone cancer pain in rats.

DESIGN

A randomised, controlled study.

SETTING

Central Laboratory of Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai China, from July 2011 to June 2012.

ANIMALS

Adult female Wistar rats weighing 180 to 200g.

INTERVENTIONS

Rats with bone cancer were divided into five groups based on drug treatment (n=12 for each group): T5 group (TRA 5 mg kg), T10 group (TRA 10 mg kg), D1 group (DEX 1 μg kg), T5+D1 group (TRA 5 mg kg+DEX 1μg kg) and IS (isotonic saline 0.5 ml) group.

MAIN OUTCOME MEASURES

The mechanical threshold and spontaneous paw withdrawal were measured in all groups.

RESULTS

Both the T5+D1 group and T10 group showed a significantly increased mechanical threshold and a lower incidence of spontaneous paw withdrawal compared with the IS group. Interestingly, there was no significant difference between the T5+D1 and T10 groups.

CONCLUSION

We found that a combination of DEX and TRA at low doses provided equal or superior analgesic effects on bone cancer pain compared to high-dose TRA alone. Our animal data might indicate the clinical administration of these two drugs in bone cancer pain therapy.

Tramadol toxicity in a cat: case report and literature review of serotonin syndrome

OVERVIEW

Tramadol toxicity has not previously been reported in a cat.

CASE SUMMARY

This report describes the clinical signs, diagnosis and treatment of tramadol toxicity, manifesting as serotonin syndrome, in a cat in Australia.

PRACTICAL RELEVANCE

For any cat with suspicion of serotonin syndrome, in particular secondary to tramadol overdose, it is recommended that decontamination, monitoring and supportive care are instituted as soon as clinical signs develop. Prolonged hospitalisation may be required in the event of a severe overdose.

LITERATURE REVIEW

The literature relating to the pharmacology of tramadol and tramadol overdose, clinical manifestations of tramadol overdose, and serotonin syndrome in cats, humans and dogs is reviewed. Recommended treatment for tramadol overdose and serotonin syndrome is also discussed.

Pharmacokinetics and postoperative analgesia of epidural tramadol: A prospective, pilot study

BACKGROUND

Tramadol, a centrally acting analgesic drug, can be administered via multiple routes and is generally well tolerated.

OBJECTIVE

This study was designed to assess the pharmacokinetics of epidural tramadol administered preoperatively in Japanese patients undergoing upper abdominal surgery.

METHOD

Japanese patients who were scheduled to undergo upper abdominal surgery in The Kitasato Institute Hospital, Tokyo, Japan, were included. Patients received tramadol 2 mg/kg with 5 mL of 1% mepivacaine epidurally 10 minutes before incision. The serum concentration of tramadol was determined by high-performance liquid chromatography for 21 hours after administration. Serum concentration was determined before tramadol administration and 10, 20, 30, and 60 minutes after tramadol administration, first postoperative night, and first postoperative day. Pain score and adverse events (AEs) were assessed at 1, 3, 6, 12, 18, 24, 36, and 48 hours after surgery by patient interview.

RESULTS

Eleven patients were assessed for enrollment. Seven patients (6 men, 1 woman; mean [SD] age, 61.3 [12.6] years; mean [SD] weight, 59.9 [8.9] kg) provided consent and completed the study. The mean (SD) serum Cmax of tramadol was 1385.5 (390.8) ng/mL, Tmax was 0.33 (0.22) hour, and terminal elimination half-life (t1/2β) was 10.5 (2.3) hours. Four patients complained of nausea; however, only 1 patient was administered an antiemetic. No other AEs were reported.

CONCLUSION

This pilot study found that epidural tramadol administered before incision induced a Cmax within 30 minutes of administration. The drug was detected in serum at ∼21 hours after surgery.

Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of O-desmethyltramadol hydrochloride an active metabolite in tramadol--an analgesic drug

O-desmethyltramadol is one of the main metabolites of tramadol widely used clinically and has analgesic activity. The FTIR and FT-Raman spectra of O-desmethyl tramadol hydrochloride are recorded in the solid phase in the regions 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The observed fundamentals are assigned to different normal modes of vibration. Theoretical studies have been performed as its hydrochloride salt. The structure of the compound has been optimised with B3LYP method using 6-31G(**) and cc-pVDZ basis sets. The optimised bond length and bond angles are correlated with the X-ray data. The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT methods. The IR and Raman intensities are determined with B3LYP method using cc-pVDZ and 6-31G(d,p) basic sets. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/cc-pVDZ method to display electrostatic potential (electron+nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of O-desmethyltramadol hydrochloride has been performed to indicate the presence of intramolecular charge transfer. The (1)H and (13)C NMR chemical shifts of the molecule have been anlysed.

Comparison of patient-controlled analgesia versus continuous infusion of tramadol in post-cesarean section pain management

AIM

To evaluate and compare analgesic efficacy, drug consumption and patient satisfaction with the i.v. patient-controlled and continuous infusion modes of administration of tramadol.

METHODS

A total of 40 pregnant women in American Society of Anesthesiologists physical status classification system risk classes I-II scheduled for cesarean section were randomized into two groups to receive treatment in single-blind fashion. Patients in both groups received tramadol as an i.v. infusion 15 min before the end of surgery under general anesthesia for cesarean section. In the post-anesthesia care unit, the 20 patients allocated to group I were given i.v. tramadol in patient-controlled anesthesia (PCA), while the 20 other patients assigned to group II received it as a continuous infusion. Pain visual analog scores (VAS), mean arterial pressure (MAP), heart rate, total tramadol consumption, sedation scores, side-effects (nausea/vomiting) and patient satisfaction were evaluated seven times in the course of the first postoperative 24 h. The Mann-Whitney U-test and Friedman's anova were used for the statistical treatment of data.

RESULTS

VAS, sedation scores and nausea/vomiting scores were similar in both groups (P > 0.05). The 24-h tramadol consumption was significantly lower in group I (420.15 ± 66.58 mg) than in group II (494.00 ± 29.45 mg), while patient satisfaction was significantly higher in group I (P < 0.05).

CONCLUSION

While tramadol administration by either of the methods used may ensure efficient early postoperative anesthesia in cesarean section patients, i.v. PCA may be preferred because of the lower drug consumption and higher patient satisfaction associated with it.