Comparison of tramadol and tramadol/droperidol mixture for patient-controlled analgesia

Drugs for preventing postoperative nausea and vomiting in adults after general anaesthesia: a network meta-analysis

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common adverse effect of anaesthesia and surgery. Up to 80% of patients may be affected. These outcomes are a major cause of patient dissatisfaction and may lead to prolonged hospital stay and higher costs of care along with more severe complications. Many antiemetic drugs are available for prophylaxis. They have various mechanisms of action and side effects, but there is still uncertainty about which drugs are most effective with the fewest side effects.

OBJECTIVES

• To compare the efficacy and safety of different prophylactic pharmacologic interventions (antiemetic drugs) against no treatment, against placebo, or against each other (as monotherapy or combination prophylaxis) for prevention of postoperative nausea and vomiting in adults undergoing any type of surgery under general anaesthesia • To generate a clinically useful ranking of antiemetic drugs (monotherapy and combination prophylaxis) based on efficacy and safety • To identify the best dose or dose range of antiemetic drugs in terms of efficacy and safety SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, and reference lists of relevant systematic reviews. The first search was performed in November 2017 and was updated in April 2020. In the update of the search, 39 eligible studies were found that were not included in the analysis (listed as awaiting classification).

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing effectiveness or side effects of single antiemetic drugs in any dose or combination against each other or against an inactive control in adults undergoing any type of surgery under general anaesthesia. All antiemetic drugs belonged to one of the following substance classes: 5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, corticosteroids, antihistamines, and anticholinergics. No language restrictions were applied. Abstract publications were excluded.

DATA COLLECTION AND ANALYSIS

A review team of 11 authors independently assessed trials for inclusion and risk of bias and subsequently extracted data. We performed pair-wise meta-analyses for drugs of direct interest (amisulpride, aprepitant, casopitant, dexamethasone, dimenhydrinate, dolasetron, droperidol, fosaprepitant, granisetron, haloperidol, meclizine, methylprednisolone, metoclopramide, ondansetron, palonosetron, perphenazine, promethazine, ramosetron, rolapitant, scopolamine, and tropisetron) compared to placebo (inactive control). We performed network meta-analyses (NMAs) to estimate the relative effects and ranking (with placebo as reference) of all available single drugs and combinations. Primary outcomes were vomiting within 24 hours postoperatively, serious adverse events (SAEs), and any adverse event (AE). Secondary outcomes were drug class-specific side effects (e.g. headache), mortality, early and late vomiting, nausea, and complete response. We performed subgroup network meta-analysis with dose of drugs as a moderator variable using dose ranges based on previous consensus recommendations. We assessed certainty of evidence of NMA treatment effects for all primary outcomes and drug class-specific side effects according to GRADE (CINeMA, Confidence in Network Meta-Analysis). We restricted GRADE assessment to single drugs of direct interest compared to placebo.

MAIN RESULTS

We included 585 studies (97,516 randomized participants). Most of these studies were small (median sample size of 100); they were published between 1965 and 2017 and were primarily conducted in Asia (51%), Europe (25%), and North America (16%). Mean age of the overall population was 42 years. Most participants were women (83%), had American Society of Anesthesiologists (ASA) physical status I and II (70%), received perioperative opioids (88%), and underwent gynaecologic (32%) or gastrointestinal surgery (19%) under general anaesthesia using volatile anaesthetics (88%). In this review, 44 single drugs and 51 drug combinations were compared. Most studies investigated only single drugs (72%) and included an inactive control arm (66%). The three most investigated single drugs in this review were ondansetron (246 studies), dexamethasone (120 studies), and droperidol (97 studies). Almost all studies (89%) reported at least one efficacy outcome relevant for this review. However, only 56% reported at least one relevant safety outcome. Altogether, 157 studies (27%) were assessed as having overall low risk of bias, 101 studies (17%) overall high risk of bias, and 327 studies (56%) overall unclear risk of bias. Vomiting within 24 hours postoperatively Relative effects from NMA for vomiting within 24 hours (282 RCTs, 50,812 participants, 28 single drugs, and 36 drug combinations) suggest that 29 out of 36 drug combinations and 10 out of 28 single drugs showed a clinically important benefit (defined as the upper end of the 95% confidence interval (CI) below a risk ratio (RR) of 0.8) compared to placebo. Combinations of drugs were generally more effective than single drugs in preventing vomiting. However, single NK₁ receptor antagonists showed treatment effects similar to most of the drug combinations. High-certainty evidence suggests that the following single drugs reduce vomiting (ordered by decreasing efficacy): aprepitant (RR 0.26, 95% CI 0.18 to 0.38, high certainty, rank 3/28 of single drugs); ramosetron (RR 0.44, 95% CI 0.32 to 0.59, high certainty, rank 5/28); granisetron (RR 0.45, 95% CI 0.38 to 0.54, high certainty, rank 6/28); dexamethasone (RR 0.51, 95% CI 0.44 to 0.57, high certainty, rank 8/28); and ondansetron (RR 0.55, 95% CI 0.51 to 0.60, high certainty, rank 13/28). Moderate-certainty evidence suggests that the following single drugs probably reduce vomiting: fosaprepitant (RR 0.06, 95% CI 0.02 to 0.21, moderate certainty, rank 1/28) and droperidol (RR 0.61, 95% CI 0.54 to 0.69, moderate certainty, rank 20/28). Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol showed clinically important benefit, but low doses showed no clinically important benefit. Aprepitant was used mainly at high doses, ramosetron at recommended doses, and fosaprepitant at doses of 150 mg (with no dose recommendation available). Frequency of SAEs Twenty-eight RCTs were included in the NMA for SAEs (10,766 participants, 13 single drugs, and eight drug combinations). The certainty of evidence for SAEs when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to low. Droperidol (RR 0.88, 95% CI 0.08 to 9.71, low certainty, rank 6/13) may reduce SAEs. We are uncertain about the effects of aprepitant (RR 1.39, 95% CI 0.26 to 7.36, very low certainty, rank 11/13), ramosetron (RR 0.89, 95% CI 0.05 to 15.74, very low certainty, rank 7/13), granisetron (RR 1.21, 95% CI 0.11 to 13.15, very low certainty, rank 10/13), dexamethasone (RR 1.16, 95% CI 0.28 to 4.85, very low certainty, rank 9/13), and ondansetron (RR 1.62, 95% CI 0.32 to 8.10, very low certainty, rank 12/13). No studies reporting SAEs were available for fosaprepitant. Frequency of any AE Sixty-one RCTs were included in the NMA for any AE (19,423 participants, 15 single drugs, and 11 drug combinations). The certainty of evidence for any AE when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to moderate. Granisetron (RR 0.92, 95% CI 0.80 to 1.05, moderate certainty, rank 7/15) probably has no or little effect on any AE. Dexamethasone (RR 0.77, 95% CI 0.55 to 1.08, low certainty, rank 2/15) and droperidol (RR 0.89, 95% CI 0.81 to 0.98, low certainty, rank 6/15) may reduce any AE. Ondansetron (RR 0.95, 95% CI 0.88 to 1.01, low certainty, rank 9/15) may have little or no effect on any AE. We are uncertain about the effects of aprepitant (RR 0.87, 95% CI 0.78 to 0.97, very low certainty, rank 3/15) and ramosetron (RR 1.00, 95% CI 0.65 to 1.54, very low certainty, rank 11/15) on any AE. No studies reporting any AE were available for fosaprepitant. Class-specific side effects For class-specific side effects (headache, constipation, wound infection, extrapyramidal symptoms, sedation, arrhythmia, and QT prolongation) of relevant substances, the certainty of evidence for the best and most reliable anti-vomiting drugs mostly ranged from very low to low. Exceptions were that ondansetron probably increases headache (RR 1.16, 95% CI 1.06 to 1.28, moderate certainty, rank 18/23) and probably reduces sedation (RR 0.87, 95% CI 0.79 to 0.96, moderate certainty, rank 5/24) compared to placebo. The latter effect is limited to recommended and high doses of ondansetron. Droperidol probably reduces headache (RR 0.76, 95% CI 0.67 to 0.86, moderate certainty, rank 5/23) compared to placebo. We have high-certainty evidence that dexamethasone (RR 1.00, 95% CI 0.91 to 1.09, high certainty, rank 16/24) has no effect on sedation compared to placebo. No studies assessed substance class-specific side effects for fosaprepitant. Direction and magnitude of network effect estimates together with level of evidence certainty are graphically summarized for all pre-defined GRADE-relevant outcomes and all drugs of direct interest compared to placebo in http://doi.org/10.5281/zenodo.4066353.

AUTHORS' CONCLUSIONS

We found high-certainty evidence that five single drugs (aprepitant, ramosetron, granisetron, dexamethasone, and ondansetron) reduce vomiting, and moderate-certainty evidence that two other single drugs (fosaprepitant and droperidol) probably reduce vomiting, compared to placebo. Four of the six substance classes (5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, and corticosteroids) were thus represented by at least one drug with important benefit for prevention of vomiting. Combinations of drugs were generally more effective than the corresponding single drugs in preventing vomiting. NK₁ receptor antagonists were the most effective drug class and had comparable efficacy to most of the drug combinations. 5-HT₃ receptor antagonists were the best studied substance class. For most of the single drugs of direct interest, we found only very low to low certainty evidence for safety outcomes such as occurrence of SAEs, any AE, and substance class-specific side effects. Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol were more effective than low doses for prevention of vomiting. Dose dependency of side effects was rarely found due to the limited number of studies, except for the less sedating effect of recommended and high doses of ondansetron. The results of the review are transferable mainly to patients at higher risk of nausea and vomiting (i.e. healthy women undergoing inhalational anaesthesia and receiving perioperative opioids). Overall study quality was limited, but certainty assessments of effect estimates consider this limitation. No further efficacy studies are needed as there is evidence of moderate to high certainty for seven single drugs with relevant benefit for prevention of vomiting. However, additional studies are needed to investigate potential side effects of these drugs and to examine higher-risk patient populations (e.g. individuals with diabetes and heart disease).

Reintegrating droperidol into emergency medicine practice

Purpose

After a long period of low utilization, droperidol has become easier to obtain in the US market. This comprehensive review discusses the safety, indications, clinical efficacy, and dosing of droperidol for use in the emergency department (ED) setting.

Summary

In 2001 the US Food and Drug Administration (FDA) mandated a boxed warning in the labeling of droperidol after reports of QT interval prolongation associated with droperidol use. Since that time, it has been difficult to access droperidol in the United States; as a result, many practicing clinicians lack experience in its clinical use. Multiple studies have been conducted to assess the clinical efficacy and safety of droperidol use in ED patients. Results consistently show the safety of droperidol and its clinical efficacy when used as an analgesic, antiemetic, and sedative. Now that droperidol is more widely available for use in the US market, pharmacists and prescribers need to reliably translate safety and efficacy data compiled since 2001 to help ensure appropriate and effective use of the medication.

Conclusion

Droperidol is an effective and safe option for the treatment of acute agitation, migraine, nausea, and pain for patients in the ED setting. Healthcare professionals can adopt droperidol for use in clinical practice, and they should become familiar with how to dose and monitor droperidol for safe and effective use.

WITHDRAWN: Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

Who are Prone to Develop Adverse Effects with Oral Tramadol? a Retrospective Cohort Study

Objective

Oral tramadol is a commonly prescribed analgesic in Hong Kong. Significant adverse effects are frequently observed in our locality. Our study aims to describe the rate of significant adverse effect that warrant discontinuation of oral tramadol and identify the risk factors for development of adverse effect.

Design

Retrospective cohort study.

Methods

Adult patients aged greater than 18 years old admitted to the emergency medicine ward of a large-scale local hospital in Hong Kong being prescribed with oral tramadol during in-hospital stay were recruited. Significant adverse effects during the hospital stay were observed as the outcome of interest.

Results

A total of 575 subjects were recruited. 29.9% experienced significant adverse effects likely related to tramadol. Age (p=0.006; odds ratio [OR] = 1.017, 95% confidence interval [CI] = 1.005-1.029) and sex (p=0.006; OR=1.696, 95% CI= 1.166-2.465) were statistically significant predictors of adverse effects after oral tramadol.

Conclusion

Our study suggests that female and increasing age patients are significant predictors for the development of adverse effect after taking oral tramadol. Possible adverse effects should be explained to the patients careful especially the higher risk groups. (Hong Kong j. emerg.med. 2014;21:3-9)

[Postoperative nausea and vomiting and opioid-induced nausea and vomiting: guidelines for prevention and treatment]

Postoperative nausea and vomiting (PONV) causes patient discomfort, lowers patient satisfaction, and increases care requirements. Opioid-induced nausea and vomiting (OINV) may also occur if opioids are used to treat postoperative pain. These guidelines aim to provide recommendations for the prevention and treatment of both problems. A working group was established in accordance with the charter of the Sociedad Española de Anestesiología y Reanimación. The group undertook the critical appraisal of articles relevant to the management of PONV and OINV in adults and children early and late in the perioperative period. Discussions led to recommendations, summarized as follows: 1) Risk for PONV should be assessed in all patients undergoing surgery; 2 easy-to-use scales are useful for risk assessment: the Apfel scale for adults and the Eberhart scale for children. 2) Measures to reduce baseline risk should be used for adults at moderate or high risk and all children. 3) Pharmacologic prophylaxis with 1 drug is useful for patients at low risk (Apfel or Eberhart 1) who are to receive general anesthesia; patients with higher levels of risk should receive prophylaxis with 2 or more drugs and baseline risk should be reduced (multimodal approach). 4) Dexamethasone, droperidol, and ondansetron (or other setrons) have similar levels of efficacy; drug choice should be made based on individual patient factors. 5) The drug prescribed for treating PONV should preferably be different from the one used for prophylaxis; ondansetron is the most effective drug for treating PONV. 6) Risk for PONV should be assessed before discharge after outpatient surgery or on the ward for hospitalized patients; there is no evidence that late preventive strategies are effective. 7) The drug of choice for preventing OINV is droperidol.

Droperidol analgesia for opioid-tolerant patients

BACKGROUND

Patients with acute and chronic pain syndromes such as migraine headache, fibromyalgia, and sickle cell disease represent a significant portion of emergency department (ED) visits. Certain patients may have tolerance to opioid analgesics and often require large doses and prolonged time in the ED to achieve satisfactory pain mitigation. Droperidol is a unique drug that has been successfully used not only as an analgesic adjuvant for the past 30 years, but also for treatment of nausea/vomiting, psychosis, agitation, sedation, and vertigo.

OBJECTIVES

In this review, we examine the evidence supporting the use of droperidol for analgesia, adverse side effects, and controversial United States (US) Food and Drug Administration (FDA) black box warning.

DISCUSSION

Droperidol has myriad pharmacologic properties that may explain its efficacy as an analgesic, including: dopamine D2 antagonist, dose-dependent GABA agonist/antagonist, α2 adrenoreceptor agonist, serotonin antagonist, histamine antagonist, muscarinic and nicotinic cholinergic antagonist, anticholinesterase activity, sodium channel blockade similar to lidocaine, and μ opiate receptor potentiation.

CONCLUSION

Droperidol is an important adjuvant for patients who are tolerant to opioid analgesics. The FDA black box warning does not apply to doses below 2.5 mg.

Weak opioids--an educational substitute for morphine?

The World Health Organization guidelines suggest the use of weak opioids on the second step of the analgesic ladder for cancer pain relief. Weak opioids are important substitutes for low doses of morphine, although their analgesic efficacy is lower than that of non-opioid or strong opioid analgesics. The use of weak opioids has great educational impact and has helped spread the use of the guidelines. Furthermore, weak opioids are more freely available and are expected to have a better side-effect profile. Controlled long-term studies are required for confirmation.

Intravenous magnesium sulphate decreases postoperative tramadol requirement after radical prostatectomy*

BACKGROUND

The purpose of this study was to assess whether the addition of intravenous magnesium sulphate (Mg) at the induction of anaesthesia to a balanced anaesthetic protocol including wound infiltration, paracetamol and tramadol resulted in improved analgesic efficiency after radical prostatectomy.

METHODS

We conducted a randomized, double-blind, controlled study. Thirty ASA I or II males scheduled to undergo radical retropubic prostatectomy with general anaesthesia were prospectively assigned to one of the two groups (n = 15 each). The Mg group (Gr Mg) received 50 mg kg-1 of MgSO4 in 100 mL of isotonic saline over 20 min immediately after induction of anaesthesia and before skin incision. The patients in the control group (Gr C) received the same volume of saline over the same period. At the time of abdominal closure, wound infiltration with 190 mg (40 mL) of ropivacaine was performed in both groups. Pain was assessed by a 10-point visual analogue scale in the recovery room starting from the time of tracheal extubation. Standardized postoperative analgesia included paracetamol and tramadol administered via a patient-controlled analgesia device.

RESULTS

In the postoperative period, both groups experienced an identical pain course evolution. Cumulative mean tramadol dose after 24 h was 226 mg in the magnesium group and 446 mg in the control group (P < 0.001). Postoperative nausea occurred in two patients in each group. Two vs. eight patients required analgesic rescue in magnesium and control groups, respectively (P = 0.053).

CONCLUSIONS

This study shows that intravenous magnesium sulphate reduces tramadol consumption when used as a postoperative analgesic protocol in radical prostatectomy.

Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

A comparison of postoperative cognitive function and pain relief with fentanyl or tramadol patient-controlled analgesia

STUDY OBJECTIVE

The use of different opioids for patient-controlled analgesia (PCA) may affect postoperative cognitive function differently. Patient-controlled analgesia fentanyl has been shown to preserve cognitive function better than morphine. The effect of PCA tramadol on cognitive function is unknown. This study aims to compare postoperative cognitive function and analgesia of PCA fentanyl or tramadol.

DESIGN

Prospective randomized double-blinded study.

SETTING

Metropolitan teaching hospital.

PATIENTS

30 ASA physical status I, II, and III patients undergoing lower abdominal operations.

INTERVENTIONS

Patients received standard general anesthesia for their operations. Postoperatively, patients received either fentanyl (group F, 10 mug bolus, n = 17) or tramadol (group T, 20 mg bolus, n = 13) for PCA. Group F patients also received fentanyl boluses and group T patients received tramadol boluses intraoperatively.

MEASUREMENTS

Cognitive function was measured using Mini-Mental State Examination and Benton Visual Retention Test (BVRT) preoperatively and on days 1 and 2. Pain was measured by numerical rating scale.

RESULTS

No differences were found in postoperative Mini-Mental State Examination or BVRT scores, but significantly fewer (29.4%; 95% confidence interval [CI], 13.3%-53.1%) group F patients were able to complete BVRT compared with group T patients (84.6%; 95% CI, 57.8%-95.7%; 95% CI of difference, 19.4%-74.8%) (P = 0.010) on day 1. In the first 24 hours, group F and group T patients had similar analgesia at rest, but group T patients had better analgesia during cough (mean Numeric Rating Scale, 7.6; 95% CI, 7.0-8.2 vs 6.0; 95% CI, 4.8-7.2, group F vs group T) (P = 0.018; 95% CI of difference, 0.4-2.8). No differences were found in frequency of side effects or patient satisfaction.

CONCLUSIONS

Tramadol or fentanyl PCA has similar cognitive effects on days 1 and 2; however, patients receiving tramadol PCA are more motivated to undergo cognitively demanding tasks and have slightly better analgesia on postoperative day 1.

Clinical pharmacology of tramadol

Tramadol, a centrally acting analgesic structurally related to codeine and morphine, consists of two enantiomers, both of which contribute to analgesic activity via different mechanisms. (+)-Tramadol and the metabolite (+)-O-desmethyl-tramadol (M1) are agonists of the mu opioid receptor. (+)-Tramadol inhibits serotonin reuptake and (-)-tramadol inhibits norepinephrine reuptake, enhancing inhibitory effects on pain transmission in the spinal cord. The complementary and synergistic actions of the two enantiomers improve the analgesic efficacy and tolerability profile of the racemate. Tramadol is available as drops, capsules and sustained-release formulations for oral use, suppositories for rectal use and solution for intramuscular, intravenous and subcutaneous injection. After oral administration, tramadol is rapidly and almost completely absorbed. Sustained-release tablets release the active ingredient over a period of 12 hours, reach peak concentrations after 4.9 hours and have a bioavailability of 87-95% compared with capsules. Tramadol is rapidly distributed in the body; plasma protein binding is about 20%. Tramadol is mainly metabolised by O- and N-demethylation and by conjugation reactions forming glucuronides and sulfates. Tramadol and its metabolites are mainly excreted via the kidneys. The mean elimination half-life is about 6 hours. The O-demethylation of tramadol to M1, the main analgesic effective metabolite, is catalysed by cytochrome P450 (CYP) 2D6, whereas N-demethylation to M2 is catalysed by CYP2B6 and CYP3A4. The wide variability in the pharmacokinetic properties of tramadol can partly be ascribed to CYP polymorphism. O- and N-demethylation of tramadol as well as renal elimination are stereoselective. Pharmacokinetic-pharmacodynamic characterisation of tramadol is difficult because of differences between tramadol concentrations in plasma and at the site of action, and because of pharmacodynamic interactions between the two enantiomers of tramadol and its active metabolites. The analgesic potency of tramadol is about 10% of that of morphine following parenteral administration. Tramadol provides postoperative pain relief comparable with that of pethidine, and the analgesic efficacy of tramadol can further be improved by combination with a non-opioid analgesic. Tramadol may prove particularly useful in patients with a risk of poor cardiopulmonary function, after surgery of the thorax or upper abdomen and when non-opioid analgesics are contraindicated. Tramadol is an effective and well tolerated agent to reduce pain resulting from trauma, renal or biliary colic and labour, and also for the management of chronic pain of malignant or nonmalignant origin, particularly neuropathic pain. Tramadol appears to produce less constipation and dependence than equianalgesic doses of strong opioids.

Comparison of the antiemetic efficacy of tropisetron and droperidol with patient-given tramadol

We compared the antiemetic efficacy of tropisetron versus droperidol in women given tramadol after total hysterectomy. Forty patients were randomly allocated to group 1 (n = 20, tropisetron 0.05 mg/kg intravenously) or group 2 (n = 20, droperidol 15 micrograms/kg intravenously). Tramadol infusion (intravenously), for post-operative analgesia, was started at fascia closure. Incidences of post-operative nausea and vomiting, pain intensity, tramadol use, and the need for a rescue antiemetic (metoclopramide 10 mg) were recorded 0 h, 2 h, 6 h, 12 h, 24 h and 48 h post-operatively. Vomiting and nausea incidences were reported fewer in group 1 than in group 2, but statistical significance was only reached for vomiting incidence 6 h post-operation. Tropisetron seems to have better antiemetic properties than droperidol in patients receiving tramadol because of the length of its duration of action. Further studies, investigating alternative ways of managing post-operative nausea and vomiting, and the use of tramadol for post-operative analgesia, are needed.

The addition of droperidol or clonidine to epidural tramadol shortens onset time and increases duration of postoperative analgesia

PURPOSE

To compare tramadol alone and the combinations of either tramadol-clonidine or tramadol-droperidol with regard to analgesic and adverse effects.

METHODS

After Ethic's Committee approval and patient informed consent were obtained, epidural catheters were inserted preoperatively at the L(3-4) interspace in 90 ASA physical status I-II adult patients undergoing lower abdominal surgery. Anesthesia was standardized. Patients were randomly assigned to one of three groups. Group I (T) patients received tramadol 75 mg, Group II (TD) patients received tramadol 75 mg plus droperidol 2.5 mg, and Group III (TC) patients received tramadol 75 mg plus clonidine 150 microg in a total volume of 10 mL administered as a single epidural injection in the postanesthesia care unit. The onset time of analgesia and duration of analgesia, visual analogue pain scores, sedation, nausea scores, vital signs and side effects were recorded.

RESULTS

Duration of analgesia was similar in both the TD and TC groups, and significantly longer than in the T group (P < 0.001). Group TC patients displayed a significant increase in sedation scores and decrease in blood pressure and heart rate when compared with other groups (P < 0.001). No adverse effects were observed in Group TD, while nausea scores were high in both the T and TC groups (P < 0.001). Pain score, respiration rate, and SpO(2) values were similar in all study groups.

CONCLUSION

We conclude that epidural tramadol in combination with droperidol or clonidine prolongs the duration of analgesia; however, droperidol appears to be a better alternative when adverse effects and antiemetic properties are taken into consideration.

Drug interactions with patient-controlled analgesia

Patient-controlled analgesia (PCA) has become standard procedure in the clinical treatment of pain. Its widespread use in patients with all kinds of diseases opens a variety of possible interactions between analgesics used for PCA and other drugs that might be administered concomitantly to the patient. Many of these drug interactions are of little clinical importance. However, some drug interactions have been reported to result in serious clinical problems. Drug interactions can either predominantly affect the pharmacokinetics or pharmacodynamics of the drug. Most important pharmacokinetic drug interactions occur at the level of drug metabolism or protein binding. Acceleration of methadone metabolism caused by cytochrome P450 (CYP) 3A4 induction by antiretroviral drugs or rifampicin (rifampin) has caused methadone withdrawal symptoms. Lack of morphine formation from codeine as a result of CYP2D6 inhibition by quinidine results in an almost complete loss of the analgesic effects of codeine. Alterations of methadone protein binding caused by an inhibition of alpha1-acid glycoprotein synthesis by alkylating substances are another possibility for predominantly pharmacokinetically based drug interactions during PCA. Furthermore, inhibition of P-glycoprotein by anticancer drugs could result in altered transmembrane transport of morphine, methadone or fentanyl, although this has not been shown to be of clinical relevance. Synergistic effects of systemically administered opioids with spinally or topically delivered opioids or anaesthetics have been reported frequently. The same is true for the opioid-sparing effects of coadministered non-opioid analgesics. Antidepressants, anticonvulsants or alpha2-adrenoreceptor agonists have also been shown to exert additive analgesic effects when administered together with an opioid. Inconsistent findings, however, are reported regarding the treatment of patients with opioid-induced nausea and sedation, since coadministration of antiemetics either increased or decreased the respective adverse effects or revealed additional unwanted drug effects.

The analgesic efficacy of tramadol is impaired by concurrent administration of ondansetron

Tramadol has weak opioid properties, and an analgesic effect that is mediated mainly by inhibition of the reuptake of norepinephrine and serotonin (5-hydroxytryptamine [5-HT]) and facilitation of 5-HT release (1,2) at the spinal cord. Because 5-HT3 receptors play a key role in pain transmission at the spinal level (3), the 5-HT3 antagonist ondansetron may decrease the efficacy of tramadol, as suggested in an abstract by Maroof et al. In that study, a small dose of 1 mg/kg tramadol was administered along with ondansetron 0.1 mg/kg or placebo, 15 min before the induction of anesthesia. Early postoperative pain scored differed significantly between the test groups. We therefore tested the hypothesis that the tramadol requirement by patient-controlled analgesia (PCA) may be increased when ondansetron is administered for antiemetic prophylaxis.

Intraoperative loading attenuates nausea and vomiting of tramadol patient-controlled analgesia

PURPOSE

To evaluate the adverse effect profile of tramadol by patient-controlled analgesia (PCA) with administration of the loading dose either intraoperatively or postoperatively.

METHODS

Sixty adult patients scheduled for elective abdominal surgery were enrolled into this prospective, randomized, double blind study. The patients were anesthetized in a similar manner. At the beginning of wound closure, the patients were randomly allocated to receive 5 mg x kg(-1) tramadol (Group 1) or normal saline (Group 2). In the post-anesthesia care unit (PACU), when patients in either group complained of pain, 30 mg x ml(-1) tramadol i.v. were given every three minutes until visual analogue scale (VAS) 3, followed by tramadol PCA with bolus dose of 30 mg and five minute lockout interval. Pain control and adverse effect assessments were done in the PACU and every six hours for 48 hr post drug by an independent observer.

RESULTS

The loading dose was 290 +/- 45 mg in Group 1 and 315 +/- 148 mg in Group 2. In PACU, more nausea/vomiting both in terms of incidence (13/30, 43% vs 2/30, 6.6%, P < 0.05) and severity (nausea/vomiting score 2.5 +/- 2.0 vs 0.2 +/- 0.6, P < 0.05) was observed in patients with postoperative loading than in those with intraoperative loading of tramadol.

CONCLUSION

Administering the loading dose of tramadol during surgery decreases the nausea/vomiting associated with high dose of tramadol and improves the quality of tramadol PCA in the relief of postoperative pain.

Comparison of patient-controlled analgesia (PCA) with tramadol or morphine

PURPOSE

To compared the clinical efficacy of tramadol and morphine using a patient-controlled analgesia (PCA) delivery system.

METHODS

In a prospective, randomized, double blind study, we evaluated 80 adult patients scheduled for elective hip or knee arthroplasty with general inhalational anesthesia. When patients complained of pain in the recovery room, patients were randomized to receive either tramadol or morphine by titration in 30 min to achieve analgesia (VAS < or =4). Equivalent volumes containing either 30 mg x ml(-1) tramadol or 1 mg x ml(-1) morphine were used for PCA with a lockout interval of 10 min. The patients were followed six-hourly for 48 hr for VAS, satisfaction rate, analgesic dose, and side effects.

RESULTS

Patients obtained adequate analgesia with either drug. More patients had very good satisfaction scores in the morphine group in the recovery room (43% vs. 23%, P<0.05) and at 24 hr (40% vs. 20%, P<0.05) than those in the tramadol group. More nausea was evident in the tramadol group (48% vs. 11% in recovery room and 28% vs. 12% in 24 hr, P<0.05) than in the morphine group. Vomiting was also more (28% vs. 5% in recovery room, 15% vs. 3% in 24 hr, P<0.05). Morphine produced more sleepiness (45% vs. 23% in recovery room, P<0.05 and 35% vs. 15% in 24 hr, P<0.05).

CONCLUSION

Tramadol PCA can provide effective analgesia following major orthopedic surgery provided sufficiently high doses are given for loading and by patient demand. However, the incidence of nausea/vomiting is also higher causing decreased satisfaction.

Prevention of postoperative nausea and vomiting in gynaecological laparotomies: a comparison of tropisetron and ondansetron

In a randomized, double-blind study, the antiemetic efficacy of a single bolus of tropisetron 5 mg (group T, 37 patients), ondansetron 4 mg (group O, 39 patients) or saline (group C, 45 patients) given at induction was compared in a homogeneous group of 121 patients undergoing gynaecological laparotomy and receiving postoperative patient-controlled intravenous morphine for 24 to 48 hours. Fewer group T and group O patients developed severe nausea compared to group C (P < 0.01, log rank test in Kaplan-Meier analysis). Group T patients also had lower nausea scores than group O at 8 to 16h (P < 0.05). The overall incidences of severe nausea in groups T, O, and C were 5.4%, 17.9%, and 44.4% respectively (P < 0.001, group T vs group C; P < 0.05 group O vs group C). In conclusion, the 5-hydroxytryptamine 3 receptor antagonists tropisetron and ondansetron were superior to placebo in preventing PONV.

Efficacy and adverse effects of prophylactic antiemetics during patient-controlled analgesia therapy: a quantitative systematic review

Nausea and vomiting are frequent adverse effects of patient-controlled analgesia (PCA) with opioids. To identify the optimal prophylactic antiemetic intervention in this setting, we performed a systematic search for randomized trials (MEDLINE, EMBASE, Cochrane library, reference lists, hand-searching, no language restriction) published up to May 1998 that compared prophylactic antiemetic interventions with placebo or no treatment in the postoperative PCA-setting with opioids. Fourteen placebo-controlled trials (1117 patients) with different regimens of droperidol, ondansetron, hyoscine TTS, tropisetron, metoclopramide, propofol, and promethazine were analyzed. One PCA was with tramadol, all others were with morphine. At 24 h, the cumulative incidence of nausea and vomiting without antiemetics was approximately 50%. Droperidol 0.017-0.17 mg/mg of morphine (0.5-11 mg/d droperidol) was statistically significantly more effective than placebo without evidence of dose-responsiveness; the number needed to treat to prevent nausea compared with placebo was 2.7 (95% confidence interval 1.8-5.2), and that to prevent vomiting was 3.1 (2.3-4.8). Compared with placebo, the incidence of minor adverse effects with droperidol was increased with doses >4 mg/d.

IMPLICATIONS

Of 100 patients treated with droperidol added in a patient-controlled analgesia pump with morphine, 30 who would have vomited or been nauseated had they not received droperidol will not suffer these effects. There is no evidence of dose-responsiveness for efficacy with droperidol, but the risk of adverse effects is dose-dependent. There is a lack of evidence for other antiemetics.

Perioperative antinociceptive effects of tramadol. A prospective, randomized, double-blind comparison with morphine

PURPOSE

To compare the efficacy of tramadol and morphine for intra- and postoperative analgesia in patients undergoing laparoscopic cholecystectomy.

METHODS

In a prospective, randomized, double-blind study 100 patients were allocated randomly into two groups. Ten minutes before induction of anaesthesia, patients in group 1 received 100 mg tramadol and those in group 2 received 10 mg morphine i.v. Anaesthesia was induced with 5 mg.kg-1 thiopental and was maintained with O2, N2O plus isoflurane with additional doses of tramadol or morphine as decided by the attending anaesthetist. Postoperatively, patients in group 1 and group 2 received tramadol and morphine, respectively, from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr.

RESULTS

Intraoperative consumption of tramadol and morphine were 137 +/- 37 and 12.2 +/- 3 mg, respectively. Compared with morphine, patients receiving tramadol had higher blood pressures and required greater mean ETisQ to control haemodynamic variables (P < 0.05). Postoperatively, there were no differences in observer pain score or visual analogue pain score during the first 24 hr between groups except at 30, 45, and 90 min where patients in the tramadol group reported higher pain scores (P < 0.05). The cumulative, 24 hr PCA consumption was 111 +/- 93 and 7.5 +/- 6.6 mg of tramadol and morphine, respectively.

CONCLUSIONS

There was no difference between the use of tramadol and morphine to treat pain after laparoscopic cholecystectomy from 90 min after the end of surgery. Morphine was more effective than tramadol as an intraoperative analgesic.