Role of anti-oxidant (vitamin-C) in post-operative pain relief in foot and ankle trauma surgery: A prospective randomized trial

The Use of High-Dose Intravenous L-Ascorbate in Pain Therapy: Current Evidence from the Literature

INTRODUCTION

Pain is the most common reason for seeking medical treatment. Despite extensive research efforts and effective analgesics modulating pain, there is still a major therapeutic gap in addressing the root causes of pain. Pain is associated with tissue damage induced by oxidative stress and induction of inflammatory mediators following high consumption of antioxidants. The role of antioxidants in general, and the administration of L-ascorbate in particular, is still controversially discussed and underestimated in the daily clinical practice.

METHODS

The current literature on the therapeutic effect of L-ascorbate, ascorbic acid, and vitamin C on various pain conditions was evaluated against the background of evidence-based medicine. Those articles, obtained from systematic search in PubMed, were critically assessed and rated in terms of evidence level and methodological quality by two independent experts. The primary purpose of this work was to establish specific pain therapy guidance for intravenous L-ascorbate.

RESULTS

A PubMed search revealed 14 suitable articles comprising controlled clinical trials and meta-analyses. An additional ten publications could be identified via secondary literature. There is supporting evidence for the efficacy of ascorbate treatment in inflammatory pain conditions, in the complex regional pain syndrome, in post zoster neuralgia, in neuropathic pain, in post-operative pain conditions, and in tumor-related pain. However, the considered studies differ in the type of administration, in dosage, in duration of treatment, as well as in quality of research. Despite all study heterogeneity, it became evident that research of high scientific quality is in support of the efficacy of L-ascorbate in pain treatment.

DISCUSSION

Oxidative stress is present in almost all pain conditions. Because oral administration of most magistral formulas of vitamin C does not provide biological availability, parenteral administration should be preferred and can be supported by an oral dose with high bioavailability on days without intravenous treatment. L-ascorbate should be preferred for parenteral high dosage, rather than ascorbic acid, as it does not release acid valences under physiological conditions.

CONCLUSIONS

L-ascorbate is an effective, safe, and economically favorable integrative treatment option for various pain conditions, addressing the root cause of tissue damage and inflammatory mediator burst.

Unveiling the potential impact of vitamin C in postoperative spinal pain

BACKGROUND

Spinal surgery is a common procedure associated with significant postoperative pain, and identifying effective interventions to manage this pain is crucial for optimizing patient outcomes. This review assesses the existing literature to determine the overall impact of vitamin C supplementation on spinal postoperative pain. Vitamin C, also known as ascorbic acid, is an essential nutrient that plays a vital role in numerous physiological processes. It functions as a potent antioxidant, neutralizing free radicals and reducing oxidative stress within the body. Furthermore, vitamin C is a cofactor in collagen synthesis, a crucial component of connective tissues, including those found in the spinal structures. Given its antioxidant and collagen-promoting properties, vitamin C has piqued interest as a potential therapeutic option for postoperative spinal pain. Based on the available evidence, vitamin C may have a beneficial effect on postoperative spinal pain, including reducing pain scores, analgesic consumption, and the incidence of complications such as complex regional pain syndrome. However, more research is needed to fully understand the optimal dosage and duration of vitamin C supplementation for postoperative pain management.

CONCLUSION

Vitamin C could be considered a potentially beneficial adjunctive therapy for managing spinal postoperative pain, but its routine use requires further investigation.

The Role of Perioperative Nutritional Status and Supplementation in Orthopaedic Surgery: A Review of Postoperative Outcomes

» Identification of malnourished and at-risk patients should be a standardized part of the preoperative evaluation process for every patient.» Malnourishment is defined as a disorder of energy, protein, and nutrients based on the presence of insufficient energy intake, weight loss, muscle atrophy, loss of subcutaneous fat, localized or generalized fluid accumulation, or diminished functional status.» Malnutrition has been associated with worse outcomes postoperatively across a variety of orthopaedic procedures because malnourished patients do not have a robust metabolic reserve available for recovery after surgery.» Screening assessment and basic laboratory studies may indicate patients' nutritional risk; however, laboratory values are often not specific for malnutrition, necessitating the use of prognostic screening tools.» Nutrition consultation and perioperative supplementation with amino acids and micronutrients are 2 readily available interventions that orthopaedic surgeons can select for malnourished patients.

Does the vitamin C level affect postoperative analgesia in patients who undergo orthognathic surgery?

Vitamin C has a critical role in pain management because of its antioxidative, neuroprotective, and anti-nociceptive properties. Oxidative stress caused by surgery increases the requirement for vitamin C. The aim of this study was to evaluate the change in vitamin C level and its effect on postoperative pain in patients undergoing orthognathic surgery. Thirty patients were included in the study. The relationships between the postoperative plasma vitamin C level, duration of surgery, postoperative analgesic consumption, and pain scores (visual analogue scale) were analysed. The difference between the mean pre- and postoperative vitamin C levels was found to be statistically significant (7.5 ± 2.9 mg/l vs 4.9 ± 2.3 mg/l, respectively; P = 0.001). There was no significant relationship between the duration of surgery and the vitamin C level decrease (P > 0.05). There was an inverse correlation between the postoperative vitamin C level and the amount of analgesic requested via patient-controlled analgesia (r = -0.699, P < 0.001). The findings suggest that, in patients who undergo orthognathic surgery, plasma vitamin C levels decrease significantly (34.6%), and an increase in the duration of surgery is not associated with any decrease in the vitamin C levels. A low postoperative plasma vitamin C level was found to be associated with greater postoperative analgesic consumption. In patients with preoperative plasma vitamin C levels ≤ 42 µmol/l, perioperative vitamin C administration may be considered for postoperative pain management.

Effect of Immature Rubus occidentalis on Postoperative Pain in a Rat Model

Background and Objectives: This study aimed to identify the analgesic properties of immature Rubus occidentalis extract (iROE) using a postoperative-pain rat model. We also aimed to compare the analgesic effects of iROE to those of mature R. occidentalis extract (mROE) and examine the proinflammatory cytokine response and associated underlying mechanisms. Materials and Methods: In adult male Sprague Dawley rats, acute postoperative pain was induced through plantar hind-paw incisions. After the plantar incisions were made, the rats were intraperitoneally administered with normal saline or various doses of iROE and mROE to investigate and compare the analgesic effects of iROE and mROE. The mechanisms underlying iROE-induced analgesia were investigated via post-incisional administration of yohimbine, dexmedetomidine, prazosin, naloxone, atropine, or mecamylamine, followed by iROE. Mechanical withdrawal threshold (MWT) evaluations with von Frey filaments were carried out at different time points. Serum levels of tumor necrosis factor α, interleukin (IL)-1β, and IL-6 were measured to assess inflammatory responses. Multivariate analysis of variance (MANOVA) and linear mixed-effects model (LMEM) analysis were used to analyze the analgesic effect data. Results: The MWTs demonstrated significant increases in iROE in a dose-dependent manner up to 2 h after the plantar incisions were made. An LMEM analysis demonstrated that iROE yielded a significantly greater analgesic effect than mROE, but there was no significant difference between the two according to MANOVA. Dexmedetomidine enhanced the MWT-confirmed iROE response, while yohimbine and naloxone diminished it. Administration of iROE significantly attenuated the post-incisional increases in serum IL-1β and IL-6 levels. Conclusions: The iROE demonstrated analgesic and anti-inflammatory effects in a rat model of incisional pain, which were more pronounced than those associated with mROE. The analgesic activity of iROE may be associated with α₂-adrenergic and opioid receptors.

Effect of Perioperative Vitamin C on the Incidence of Complex Regional Pain Syndrome: A Systematic Review and Meta-Analysis

Complex regional pain syndrome type 1 (CRPS-I) is a complex complication that occurs after limb extremity surgeries. Controversy exists regarding the effectiveness of vitamin C in reducing that condition. Therefore, we conducted this systematic review and meta-analysis to assess the role of vitamin C on CRPS-I and functional outcomes after distal radius, wrist, foot, and ankle surgeries. We searched Medline (via PubMed), Embase, the Cochrane Library, Clinicaltrial.gov, and Google Scholar for relevant studies comparing perioperative vitamin C versus placebo after distal radius, wrist, foot, and ankle surgeries from infinity to May 2021. Continuous data such as functional outcomes and pain scores were pooled as mean differences, while dichotomous variables such as the incidence of complex regional pain syndrome and complications were pooled as odds ratios, with 95% confidence interval, using R software (meta package, version 4.9-0) for Windows. Eight studies were included. The timeframe for vitamin C administration in each study ranged from 42 to 50 days postinjury and/or surgical fixation. The effect size showed that vitamin C was associated with a decreased rate of CRPS-1 than placebo (odds ratio 0.33, 95% confidence interval [0.17, 0.63]). No significant difference was found between vitamin C and placebo in terms of complications (odds ratio 1.90, 95% confidence interval [0.99, 3.65]), functional outcomes (mean difference 6.37, 95% confidence interval [-1.40, 14.15]), and pain scores (mean difference -0.14, 95% confidence interval [-1.07, 0.79]). Overall, vitamin C was associated with a decreased rate of CRPS-I than placebo, while no significant difference was found regarding complications, functional outcomes, and pain scores. These results hold true when stratifying fracture type (distal radius, ankle, and foot surgeries) and vitamin C dose (500 mg or 1 g).

Multivitamin Use in Enhanced Recovery After Surgery Protocols: A Cost Analysis

INTRODUCTION

Enhanced Recovery After Surgery (ERAS) protocols have shown significant benefits in multiple areas including early mobilization, improved pain control, and early oral intake. Deficient nutritional states may compromise the operative outcomes. Several essential vitamins, e.g., B12, C, D, and E, have demonstrated anti-inflammatory properties and may promote wound healing. Given the low risk of oral multivitamin supplementation and the potential benefits, we hypothesized that adding a multivitamin to our institution's ERAS protocols would be a low-cost perioperative intervention accounting for a very small fraction of the annual pharmacy budget.

METHODS

A cost analysis for vitamin supplementation for all adult orthopedic surgical cases for the fiscal year 2018 was conducted. To assess the potential cost for multivitamin supplementation in the perioperative period, the fiscal year 2018 pharmacy budget and current costs of multivitamins were obtained from the hospital pharmacy. Medication costs were obtained from the medical logistics ordering system at per unit (i.e., bottle) and per tablet levels for all formulary oral multivitamins. We also determined the number of adult orthopedic surgical cases for our facility in the fiscal year 2018 from our surgery scheduling system. The cost for supplementation for a single day (day of surgery), 1 week (first postoperative week), 6 weeks plus 1 week preop, and 6 months plus 1 week preop for all cases was then calculated.

RESULTS

Our institution's pharmacy budget for the fiscal year 2018 was $123 million dollars with two oral multivitamins on formulary. Prenatal tablets, containing vitamins A-E, calcium, iron, and zinc, cost $1.52 per bottle of 100 tablets and $0.0152 per tablet, while renal formulation tablets, containing water-soluble vitamins B and C, cost $2.79 per bottle of 100 tablets and $0.0279 per tablet. For one fiscal year, the medication cost to supplement every adult orthopedic surgery patient with an oral multivitamin for 1 day, 1 week, 6 weeks plus 1 week preop, and 6 months plus 1 week preop would range from $60.47 to $110.99, from $423.29 to $776.93, from $2,963.03 to $5,438.51, and from $10,582.25 to $19,423.25, respectively, depending on which multivitamin was prescribed. These costs would represent between 0.00005% and 0.00009% of the annual pharmacy budget for 1 day, between 0.0003% and 0.0006% for 1 week, between 0.00245% and 0.441% for 6 weeks plus 1 week preop, and between 0.00875% and 1.575% for 6 months plus 1 week preop, respectively.

DISCUSSION/CONCLUSIONS

The relative nutrient-deficient state in the perioperative patient from decreased oral intake contributes to the metabolic derangements resulting from the surgery. The current ERAS protocols help to mitigate this with early feeding, and the addition of multivitamin supplementation may enhance this process. Multivitamins are safe, widely accessible, and inexpensive, and early investigations of pain control and healing have shown encouraging results. Further prospective studies are needed for incorporating multivitamins into ERAS protocols in order to elucidate the effective dosages, duration of treatment, and effect on outcomes.

Non-drug pain relievers active on non-opioid pain mechanisms

This review is aimed to summarize the pain-relieving effect of non-drug substances, mostly prescribed as integrators in treatment of pain, including especially in chronic postoperative pain (CPSP) and in chronic back pain after acute episodes. Their use reflects the fact that the current treatments for these syndromes continue to pose problems of unsatisfactory responses in a significant portion of patients and/or of an excess of side effects like those noted in the present opioid crisis. As integrators are frequently introduced into the market without adequate clinical testing, this review is aimed to collect the present scientific evidence either preclinical or clinical for their effectiveness. In particular, we reviewed the data on the use of: B vitamins; vitamin C; vitamin D; alpha lipoic acid (ALA); N-acetylcysteine; acetyl L-carnitine; curcumin; boswellia serrata; magnesium; coenzyme Q10, and palmitoylethanolamide. The combination of preclinical findings and clinical observations strongly indicate that these compounds deserve more careful attention, some of them having interesting clinical potentials also in preventing chronic pain after an acute episode. In particular, examining their putative mechanisms of action it emerges that combinations of few of them may exert an extraordinary spectrum of activities on a large variety of pain-associated pathways and may be eventually used in combination with more traditional pain killers in order to extend the duration of the effect and to lower the doses. Convincing examples of effective combinations against pain are vitamin B complex plus gabapentin for CPSP, including neuropathic pain; vitamin B complex plus diclofenac against low back pain and also in association with gabapentin, and ALA for burning mouth syndrome. These as well as other examples need, however, careful controlled independent clinical studies confirming their role in therapy.

Dimethyl Fumarate Reduces Oxidative Stress and Pronociceptive Immune Responses in a Murine Model of Complex Regional Pain Syndrome

BACKGROUND

Complex regional pain syndrome (CRPS) is a highly disabling cause of pain often precipitated by surgery or trauma to a limb. Both innate and adaptive immunological changes contribute to this syndrome. Dimethyl fumarate (DMF) works through the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor and other targets to activate antioxidant systems and to suppress immune system activation. We hypothesized that DMF would reduce nociceptive, functional, and immunological changes measured in a model of CRPS.

METHODS

Male C57BL/6 mice were used in the well-characterized tibial fracture model of CRPS. Some groups of mice received DMF 25 mg/kg/d orally, per os for 3 weeks after fracture versus vehicle alone. Homozygous Nrf2 null mutant mice were used as test subjects to address the need for this transcription factor for DMF activity. Allodynia was assessed using von Frey filaments and hindlimb weight-bearing data were collected. The markers of oxidative stress malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were quantified in the skin of the fractured mice using immunoassays along with the innate immune system cytokines IL-1β and IL-6. The accumulation of IgM in the fractured limbs and lymph node hypertrophy were used as indexes of adaptive immune system activation, and the passive transfer of serum from wildtype fractured mice to B cell-deficient fractured muMT mice (mice lacking B cells and immunoglobulin) helped to assess the pronociceptive activity of humoral factors.

RESULTS

We observed that oral DMF administration strongly prevented nociceptive sensitization and reduced uneven hindlimb weight bearing after fracture. DMF was also very effective in reducing the accumulation of markers of oxidative stress, activation of innate immune mediator production, lymph node hypertrophy, and the accumulation of IgM in fractured limbs. The sera of fractured vehicle-treated but not DMF-treated mice conferred pronociceptive activity to recipient mice. Unexpectedly, the effects of DMF were largely unchanged in the Nrf2 null mutant mice.

CONCLUSIONS

Oxidative stress and immune system activation are robust after hindlimb fracture in mice. DMF strongly reduces activation of those systems, and the Nrf2 transcription factor is not required. DMF or drugs working through similar mechanisms might provide effective therapy for CRPS or other conditions where oxidative stress causes immune system activation.

A meta-analysis of randomized clinical trials on the impact of oral vitamin C supplementation on first-year outcomes in orthopedic patients

This meta-analysis aimed at investigating the impact of oral vitamin C supplementation on the post-procedural recovery of orthopedic patients, including functional outcomes and complex regional pain syndrome type I (CRPS I). Literature search using the Medline, Cochrane Library, and Embase databases from inception till March 2021 identified seven eligible randomized controlled trials with 1,361 participants. Forest plot revealed no significant difference in the functional outcomes at 6–12 months [standardized mean difference (SMD) = −0.00, 95% CI − 0.19 to 0.18, 467 patients], risk of overall complications (RR = 0.98, 95% CI 0.68 to 1.39, 426 patients), and pain severity at 3–6 months (SMD = − 0.18, 95% CI − 0.49 to 0.12, 486 patients) between patients with and without oral vitamin C supplementation. Pooled analysis showed that vitamin C treatment reduced the risk of CRPS I regardless of dosage (RR = 0.46, 95% CI 0.25 to 0.85, 1143 patients). In conclusion, the current meta-analysis demonstrated that oral vitamin C supplementation may reduce the risk of complex regional pain syndrome type I but did not improve the functional outcomes in orthopedic patients. Nevertheless, because of the small number of trials included in the present study, further large-scale clinical studies are warranted to support our findings.

Vitamin C in orthopedic practices: Current concepts, novel ideas, and future perspectives

Vitamin C (ascorbic acid), is an important antioxidant that has been applied broadly in the field of orthopaedics. Current research on vitamin C examines the molecule's role in bone and tendon physiology, as well as joint replacement and Postoperative pain. Most laboratory and human studies associate the use of vitamin C with improved bone health and tendon healing. Recent literature moderately supports the use of vitamin C to improve functional outcomes, decreased postoperative pain, and prevent complex regional pain syndrome following orthopaedic procedures. The perioperative use of vitamin C in patients undergoing joint replacement surgery and anterior cruciate ligament reconstruction is still under investigation. Overall, there is need for high-quality human trials to confirm whether vitamin C can potentiate the outcomes of orthopaedic procedures and to determine optimal dosage and means of administration to maximize its proposed benefits. The purpose of this review was to summarize the application of vitamin C in orthopaedic practices and to identify potential areas for future study.

Chronic Post-Surgical Pain in the Frail Older Adult

Older adults are the fastest growing segment of the population and surgical procedures in this group increase each year. Chronic post-surgical pain is an important consideration in the older adult as it affects recovery, physical functioning, and overall quality of life. It is increasingly recognized as a public health issue but there is a need to improve our understanding of the disease process as well as the appropriate treatment and prevention. Frailty, delirium, and cognition influence post-operative outcomes in older adults and have been implicated in the development of chronic post-surgical pain. Further research must be conducted to fully understand the role they play in the occurrence of chronic post-surgical pain in the older adult. Additionally, careful attention must be given to the physiologic, cognitive, and comorbidity differences between the older adult and the general population. This is critical for elucidating the proper chronic post-surgical pain treatment and prevention strategies to ensure that the older adult undergoing surgical intervention will have an appropriate and desirable post-operative outcome.

The Effect of Perioperative Vitamin C on Postoperative Analgesic Consumption: A Meta-Analysis of Randomized Controlled Trials

Because the analgesic effect of vitamin C against acute pain remains poorly addressed, this meta-analysis aimed at investigating its effectiveness against acute postoperative pain. A total of seven randomized controlled trials with placebo/normal controls were identified from PubMed, Cochrane Library, Medline, Google Scholar, and Embase databases. Pooled analysis showed a lower pain score (standardized mean difference (SMD) = -0.68, 95% CI: -1.01 to -0.36, p < 0.0001; I2 = 57%) and a lower morphine consumption (weighted mean difference (WMD) = -2.44 mg, 95% CI: -4.03 to -0.86, p = 0.003; I2 = 52%) in the vitamin group than that in the placebo group within postoperative 1-2 h. At postoperative 24 h, a lower pain score (SMD = -0.65, 95% CI: -1.11 to -0.19, p = 0.005; I2 = 81%) and lower morphine consumption (WMD = -6.74 mg, 95% CI: -9.63 to -3.84, p < 0.00001; I2 = 85%) were also noted in the vitamin group. Subgroup analyses demonstrated significant reductions in pain severity and morphine requirement immediately (1-2 h) and 24 h after surgery for patients receiving intravenous vitamin C but not in the oral subgroup. These findings showed significant reductions in pain score and opioid requirement up to postoperative 24 h, respectively, suggesting the effectiveness of perioperative vitamin C use. Further large-scale trials are warranted to elucidate its optimal intravenous dosage and effectiveness against chronic pain in the postoperative pain control setting.

Neuroprotective Effect of Antioxidants in the Brain

The brain is vulnerable to excessive oxidative insults because of its abundant lipid content, high energy requirements, and weak antioxidant capacity. Reactive oxygen species (ROS) increase susceptibility to neuronal damage and functional deficits, via oxidative changes in the brain in neurodegenerative diseases. Overabundance and abnormal levels of ROS and/or overload of metals are regulated by cellular defense mechanisms, intracellular signaling, and physiological functions of antioxidants in the brain. Single and/or complex antioxidant compounds targeting oxidative stress, redox metals, and neuronal cell death have been evaluated in multiple preclinical and clinical trials as a complementary therapeutic strategy for combating oxidative stress associated with neurodegenerative diseases. Herein, we present a general analysis and overview of various antioxidants and suggest potential courses of antioxidant treatments for the neuroprotection of the brain from oxidative injury. This review focuses on enzymatic and non-enzymatic antioxidant mechanisms in the brain and examines the relative advantages and methodological concerns when assessing antioxidant compounds for the treatment of neurodegenerative disorders.

Citral-induced analgesia is associated with increased spinal serotonin, reduced spinal nociceptive signaling, and reduced systemic oxidative stress in arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Citral (3,7-dimethyl-2,6-octadienal) is the main component of Cymbopogon citratus (DC) Stapf, an herb with analgesic properties. Arthritic pain is the main unpleasant component of rheumatoid arthritis. The pharmacological approaches used to treat arthritic pain are often accompanied by adjuvant drugs or non-pharmacological treatments, showing a constant need in identifying new efficient analgesic drugs.

AIM OF THE STUDY

To test the hypothesis that citral, which is a monoterpenoid compound with therapeutic properties, reduces nociception, spinal pro-nociceptive and pro-inflammatory signaling, and systemic oxidative stress in arthritic rats.

MATERIALS AND METHODS

Complete Freund's adjuvant (CFA) was administrated in the left knee joint of rats. Oral treatment with citral was performed during eight days and mechanical allodynia was monitored during the period of treatment to evaluate the analgesic effect of citral. We assessed the levels of serotonin (5-hydroxytryptamine, 5-HT) in the lumbar dorsal horn of the spinal cord (DHSC) and the profiles of expression of the glycogen synthase kinase-3β (GSK3β), which is a 5-HT-regulated intracellular protein, and of the stress-activated protein kinase (SAPK)/jun N-terminal kinase (JNK) in the DHSC. Plasma levels of superoxide dismutase (SOD) were assessed as an indicator of oxidative stress.

RESULTS

Administration of CFA induced mechanical allodynia associated with reduced spinal GSK3β phosphorylation, increased spinal SAPK/JNK phosphorylation, and increased plasma SOD levels. Oral administration of citral reversed mechanical allodynia, increased endogenous spinal 5-HT levels, reduced spinal SAPK/JNK phosphorylation, and reduced plasma SOD levels.

CONCLUSION

Citral shows anti-nociceptive effects in an animal model of arthritic pain by modulating spinal nociceptive signaling.

Comparison of the effects of preoperative melatonin or vitamin C administration on postoperative analgesia

The analgesic benefit of melatonin and vitamin C as primary or adjuvant agents has been reported in various studies; however, their analgesic effects in the treatment of postoperative pain remain unclear. Thus, we aimed to evaluate the effect of single preoperative dose of oral melatonin or vitamin C administration on postoperative analgesia. In this study, we recruited 165 adult patients undergoing elective major abdominal surgery under general anesthesia. Patients were randomly divided into three equal (n = 55) groups. One hour before surgery, patients received orally melatonin (6 mg) in group M, vitamin C (2 g) in group C, or a placebo tablet in group P. Pain, sedation, patient satisfaction, total morphine consumption from a patient-controlled analgesia device, supplemental analgesic requirement, and the incidence of nausea and vomiting were recorded throughout 24 h after surgery. The mean pain score and total morphine consumption were found significantly lower in both M and C groups compared with group P (p < 0.001). There were no significant differences between group M and C with respect to pain scores (p = 0.117) and total morphine consumption (p = 0.090). Patients requested less supplemental analgesic and experienced less nausea and vomiting in groups M and C compared with group P. In conclusion, preoperative oral administration of 6 mg melatonin or 2 g vitamin C led to a reduction in pain scores, total morphine consumption, supplemental analgesic requirement, and the incidence of nausea and vomiting compared with placebo.