A systematic review and trial sequential analysis of intravenous vs. oral peri-operative paracetamol

Environmental and financial impacts of perioperative paracetamol use: a multicentre international life-cycle assessment

BACKGROUND

Pharmaceuticals account for 19-32% of healthcare greenhouse gas (GHG) emissions. Paracetamol is a common perioperative analgesic agent. We estimated GHG emissions associated with i.v. and oral formulations of paracetamol used in the perioperative period.

METHODS

Life-cycle assessment of GHG emissions (expressed as carbon dioxide equivalents CO2e) of i.v. and oral paracetamol preparations was performed. Perioperative paracetamol prescribing practices and costs for 26 hospitals in USA, UK, and Australia were retrospectively audited. For those surgical patients for whom oral formulations were indicated, CO2e and costs of actual prescribing practices for i.v. or oral doses were compared with optimal oral prescribing.

RESULTS

The carbon footprint for a 1 g dose was 38 g CO2e (oral tablet), 151 g CO2e (oral liquid), and 310-628 g CO2e (i.v. dependent on type of packaging and administration supplies). Of the eligible USA patients, 37% received paracetamol (67% was i.v.). Of the eligible UK patients, 85% received paracetamol (80% was i.v.). Of the eligible Australian patients, 66% received paracetamol (70% was i.v.). If the emissions mitigation opportunity from substituting oral tablets for i.v. paracetamol is extrapolated to USA, UK, and Australia elective surgical encounters in 2019, ∼5.7 kt CO2e could have been avoided and would save 98.3% of financial costs.

CONCLUSIONS

Intravenous paracetamol has 12-fold greater life-cycle carbon emissions than the oral tablet form. Glass vials have higher greenhouse gas emissions than plastic vials. Intravenous administration should be reserved for cases in which oral formulations are not feasible.

Environmental impact of intravenous versus oral administration materials for acetaminophen and ketoprofen in a French university hospital: an eco-audit study using a life cycle analysis

PURPOSE

The combination of acetaminophen with a nonsteroidal anti-inflammatory drug is the cornerstone of perioperative multimodal analgesia. These drugs can be administered intravenously or orally as premedication, consistent with the concept of pre-emptive and preventive analgesia. We aimed to assess the environmental impact of their intravenous and oral administration in a French university hospital.

METHODS

We carried out a life cycle assessment to determine the amount of greenhouse gas emissions and depletion of water resources resulting from the oral vs intravenous administration of 1 g acetaminophen and 50 mg ketoprofen. We assessed two schemes of intravenous administration, depending on the use of the same or a different infusion set for each drug.

RESULTS

At our centre, the intravenous administration of both drugs was associated with the emission of 444-556 g CO2 equivalent (CO2e), and with 9.8-12.2 L of water waste. The oral administration of both drugs generated 8.36 g of CO2e emissions and consumed 1.16 L of water. At a national level, the switch from intravenous to oral premedication of the drugs could avoid the emission of 2,900-3,700 tons of CO2e and the waste of 58,000-74,000 m3 of water each year.

CONCLUSION

This eco-audit indicates that oral administration of acetaminophen and ketoprofen results in significantly lower carbon emissions and water consumption than intravenous administration. These findings highlight the importance of using the oral route for most patients, limiting intravenous administration for those with specific needs because of higher environmental impact and cost.

Efficacy of different routes of acetaminophen administration for postoperative pain in children: a systematic review and network meta-analysis

PURPOSE

Acetaminophen is the most common drug used to treat acute pain in the pediatric population, given its wide safety margin, low cost, and multiple routes for administration. We sought to determine the most efficacious route of acetaminophen administration for postoperative acute pain relief in the pediatric surgical population.

METHODS

We conducted a systematic review of randomized controlled trials (RCTs) that included children aged between 30 days and 17 yr who underwent any type of surgical procedure and that evaluated the analgesic efficacy of different routes of administration of acetaminophen for the treatment of postoperative pain. We searched MEDLINE, CENTRAL, Embase, CINAHL, LILACs, and Google Scholar databases for trials published from inception to 16 April 2023. We assessed the risk of bias in the included studies using the Cochrane Risk of Bias 1.0 tool. We performed a frequentist network meta-analysis using a random-effects model. Our primary outcome was postoperative pain using validated pain scales.

RESULTS

We screened 2,344 studies and included 14 trials with 829 participants in the analysis. We conducted a network meta-analysis for the period from zero to two hours, including six trials with 496 participants. There was no evidence of differences between intravenous vs rectal routes of administration of acetaminophen (difference in means, -0.28; 95% confidence interval [CI], -0.62 to 0.06; very low certainty of the evidence) and intravenous vs oral acetaminophen (difference in means, -0.60; 95% CI, -1.20 to 0.01; low certainty of the evidence). For the comparison of oral vs rectal routes, we found evidence favouring the oral route (difference in means, -0.88; 95% CI, -1.44 to -0.31; low certainty of the evidence). Few trials reported secondary outcomes of interest; when comparing the oral and rectal routes in the incidence of nausea and vomiting, there was no evidence of differences (relative risk, 1.20; 95% CI, 0.81 to 1.78).

CONCLUSION

The available evidence on the effect of the administration route of acetaminophen on postoperative pain in children is very uncertain. The outcomes of postoperative pain control and postoperative vomiting may differ very little between the oral and rectal route. Better designed and executed RCTs are required to address this important clinical question.

STUDY REGISTRATION

PROSPERO (CRD42021286495); first submitted 19 November 2021.

Adjuvants for balanced anesthesia in ambulatory surgery

Balanced anesthesia relies on the simultaneous administration of different drugs to attain an anesthetic state. The classic triad of anesthesia is a combination of a hypnotic, an analgesic, and a neuromuscular blocker. It is predominantly the analgesic pillar of this triad that became more and more supported by adjuvant therapy. The aim of this approach is to evolve into an opioid-sparing technique to cope with undesirable side effects of the opioids and is fueled by the opioid epidemic. The optimal strategy for balanced general anesthesia in ambulatory surgery must aim for a transition to a multimodal analgesic regimen dealing with acute postoperative pain and ideally reduce the most common adverse effects patients are faced with at home; sore throat, delayed awakening, memory disturbances, headache, nausea and vomiting, and negative behavioral changes. Over the years, this continuum of "multimodal general anesthesia" adopted many drugs with different modes of action. This review focuses on the most recent evidence on the different adjuvants that entered clinical practice and gives an overview of the different mechanisms of action, the potential as opioid-sparing or hypnotic-sparing drugs, and the applicability specifically in ambulatory surgery.

Parenteral Ready-to-Use Fixed-Dose Combinations Including NSAIDs with Paracetamol or Metamizole for Multimodal Analgesia-Approved Products and Challenges

The combination of non-steroidal anti-inflammatory drugs (NSAIDs) with non-opioid analgesics is common in clinical practice for the treatment of acute painful conditions like post-operative and post-traumatic pain. Despite the satisfactory results achieved by oral analgesics, parenteral analgesia remains a key tool in the treatment of painful conditions when the enteral routes of administration are inconvenient. Parenteral ready-to-use fixed-dose combinations of non-opioid analgesics combinations, including NSAIDs and paracetamol or metamizole, could play a central role in the treatment of painful conditions by combining the advantages of multimodal and parenteral analgesia in a single formulation. Surprisingly, only in 2020, a parenteral ready-to-use fixed-dose combination of ibuprofen/paracetamol was launched to the market. This review aims to investigate the current availability of combinations of NSAIDs with paracetamol or metamizole in both European and American markets, and how the combination of such drugs could play a central role in a multimodal analgesia strategy. Also, we explored how the parenteral formulations of NSAIDs, paracetamol, and metamizole could serve as starting elements for the development of new parenteral ready-to-use fixed-dose combinations. We concluded that, despite the well-recognized utility of combining NSAIDs with paracetamol or metamizole, several randomized clinical trial studies demonstrate no clear advantages concerning their efficacy and safety. Future clinical trials specifically designed to assess the efficacy and safety of pre-formulated fixed-dose combinations are required to generate solid evidence about their clinical advantages.

Unlocking the Optimal Analgesic Potential: A Systematic Review and Meta-Analysis Comparing Intravenous, Oral, and Rectal Paracetamol in Equivalent Doses

Paracetamol (acetaminophen) is an extensively used analgesic for acute and chronic pain management. Currently, paracetamol is manufactured for oral, rectal, and intravenous (IV) use. Research has shown varied results on the analgesic properties of IV paracetamol compared to oral and rectal paracetamol; however, research on the same doses of paracetamol is limited. Therefore, this review was constructed to explore the analgesic properties of IV paracetamol compared with oral and rectal paracetamol administered in equivalent doses. A broad and thorough literature search was performed on five electronic databases, including PubMed, ScienceDirect, Medline, Scopus, and Google Scholar. Statistical analysis of all outcomes in our review was then performed using the Review Manager software. Outcomes were categorized as primary (pain relief and time to request rescue analgesia) and secondary (adverse events after analgesia). An extensive quality appraisal was also done using the Review Manager software's Cochrane risk of bias tool. The literature survey yielded 2,945 articles, of which 12 were used for review and analysis. The pooled analysis for patients undergoing surgical procedures showed that IV paracetamol had statistically similar postoperative pain scores at two (mean difference (MD) = -0.14; 95% confidence interval (CI) -0.58-0.29; p = 0.51), 24 (MD = 0.09; 95% CI = -0.02-0.21; p = 0.12), and 48 (MD = 0.04; 95% CI = -0.08-0.16; p = 0.52) hours as oral paracetamol. Similarly, the data on time to rescue analgesia showed no considerable difference between the IV and oral paracetamol groups (MD = -1.58; 95% CI = -5.51-2.35; p = 0.43). On the other hand, the pooled analysis for patients presenting non-surgical acute pain showed no significant difference in the mean pain scores between patients treated with IV and oral paracetamol (MD = -0.35; 95% CI = -2.19-1.48; p = 0.71). Furthermore, a subgroup analysis of analgesia-related adverse events showed that the incidences of vomiting/nausea and pruritus did not differ between patients receiving IV and oral paracetamol (odds ratio (OR) = 0.71; 95% CI = 0.45-1.11; p = 0.13 and OR = 0.48; 95% CI = 0.18-1.29; p = 0.05, respectively). A review of information from two trials comparing equal doses of IV and rectal paracetamol suggested that the postoperative pain scores were statistically similar between the groups. IV paracetamol is not superior to oral or rectal paracetamol administered in equal doses. Therefore, we cannot recommend or refute IV paracetamol as the first-line analgesia for acute and postoperative pain.

Metabolism of Acetaminophen by Enteric Epithelial Cells Mitigates Hepatocellular Toxicity In Vitro

The gut-liver axis is defined by dietary and environmental communication between the gut, microbiome and the liver with its redox and immune systems, the overactivation of which can lead to hepatic injury. We used media preconditioning to mimic some aspects of the enterohepatic circulation by treating the human Caco-2 intestinal epithelial cell line with 5, 10 and 20 mM paracetamol (N-acetyl-para-aminophenol; APAP) for 24 h, after which cell culture supernatants were transferred to differentiated human hepatic HepaRG cells for a further 24 h. Cell viability was assessed by mitochondrial function and ATP production, while membrane integrity was monitored by cellular-based impedance. Metabolism by Caco-2 cells was determined by liquid chromatography with tandem mass spectrometry. Caco-2 cell viability was not affected by APAP, while cell membrane integrity and tight junctions were maintained and became tighter with increasing APAP concentrations, suggesting a reduction in the permeability of the intestinal epithelium. During 24 h incubation, Caco-2 cells metabolised 64-68% of APAP, leaving 32-36% of intact starting compound to be transferred to HepaRG cells. When cultured with Caco-2-preconditioned medium, HepaRG cells also showed no loss of cell viability or membrane integrity, completely in contrast to direct treatment with APAP, which resulted in a rapid loss of cell viability and membrane integrity and, ultimately, cell death. Thus, the pre-metabolism of APAP could mitigate previously observed hepatotoxicity to hepatic tight junctions caused by direct exposure to APAP. These observations could have important implications for the direct exposure of hepatic parenchyma to APAP, administered via the intravenous route.

Management of routine postoperative pain for children undergoing cardiac surgery: a Paediatric Acute Care Cardiology Collaborative Clinical Practice Guideline

BACKGROUND

Pain following surgery for cardiac disease is ubiquitous, and optimal management is important. Despite this, there is large practice variation. To address this, the Paediatric Acute Care Cardiology Collaborative undertook the effort to create this clinical practice guideline.

METHODS

A panel of experts consisting of paediatric cardiologists, advanced practice practitioners, pharmacists, a paediatric cardiothoracic surgeon, and a paediatric cardiac anaesthesiologist was convened. The literature was searched for relevant articles and Collaborative sites submitted centre-specific protocols for postoperative pain management. Using the modified Delphi technique, recommendations were generated and put through iterative Delphi rounds to achieve consensus.

RESULTS

60 recommendations achieved consensus and are included in this guideline. They address guideline use, pain assessment, general considerations, preoperative considerations, intraoperative considerations, regional anaesthesia, opioids, opioid-sparing, non-opioid medications, non-pharmaceutical pain management, and discharge considerations.

CONCLUSIONS

Postoperative pain among children following cardiac surgery is currently an area of significant practice variability despite a large body of literature and the presence of centre-specific protocols. Central to the recommendations included in this guideline is the concept that ideal pain management begins with preoperative counselling and continues through to patient discharge. Overall, the quality of evidence supporting recommendations is low. There is ongoing need for research in this area, particularly in paediatric populations.

Regional anesthesia and acute perioperative pain management in thoracic surgery: a narrative review

Background and Objective

Thoracic surgery causes significant pain which can negatively affect pulmonary function and increase risk of postoperative complications. Effective analgesia is important to reduce splinting and atelectasis. Systemic opioids and thoracic epidural analgesia (TEA) have been used for decades and are effective at treating acute post-thoracotomy pain, although both have risks and adverse effects. The advancement of thoracoscopic surgery, a focus on multimodal and opioid-sparing analgesics, and the development of ultrasound-guided regional anesthesia techniques have greatly expanded the options for acute pain management after thoracic surgery. Despite the expansion of surgical techniques and analgesic approaches, there is no clear optimal approach to pain management. This review aims to summarize the body of literature regarding systemic and regional anesthetic techniques for thoracic surgery in both thoracotomy and minimally invasive approaches, with a goal of providing a foundation for providers to make individualized decisions for patients depending on surgical approach and patient factors, and to discuss avenues for future research.

Methods

We searched PubMed and Google Scholar databases from inception to May 2021 using the terms “thoracic surgery”, “thoracic surgery AND pain management”, “thoracic surgery AND analgesia”, “thoracic surgery AND regional anesthesia”, “thoracic surgery AND epidural”. We considered articles written in English and available to the reader.

Key Content and Findings

There is a wide variety of strategies for treating acute pain after thoracic surgery, including multimodal opioid and non-opioid systemic analgesics, regional anesthesia including TEA and paravertebral blocks (PVB), and a recent expansion in the use of novel fascial plane blocks especially for thoracoscopy. The body of literature on the effectiveness of different approaches for thoracotomy and thoracoscopy is a rapidly expanding field and area of active debate.

Conclusions

The optimal analgesic approach for thoracic surgery may depend on patient factors, surgical factors, and institutional factors. Although TEA may provide optimal analgesia after thoracotomy, PVB and emerging fascial plane blocks may offer effective alternatives. A tailored approach using multimodal systemic therapies and regional anesthesia is important, and future studies comparing techniques are necessary to further investigate the optimal approach to improve patient outcomes.

Effect of Intravenous Paracetamol on Opioid Consumption in Multimodal Analgesia After Lumbar Disc Surgery: A Meta-Analysis of Randomized Controlled Trials

Background: Intravenous paracetamol, as an adjunct to multimodal analgesia, has been shown to successfully reduce opioid consumption after joint arthroplasty, abdominal surgery, and caesarean delivery. However, there are limited data on the opioid-sparing effect of intravenous paracetamol on lumbar disc surgery. Objectives: The aim of this study was to investigate the effectiveness and safety of intravenous paracetamol for reducing opioid consumption in lumbar disc surgery. The primary outcome was cumulative opioid consumption within 24 h postoperatively. Method: We followed the PRISMA-P guidelines and used GRADE to assess the quality of evidence. The review was registered in PROSPERO under the registration number CRD42021288168. Two reviewers conducted electronic searches in PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, and Web of Science (Clarivate Analytics). Randomized controlled trials (RCTs) that compared the postoperative opioid consumption of intravenous paracetamol with placebo in lumbar discectomy were included. Results: Five trials comprising a total of 271 patients were included. The overall opioid consumption within 24 h postoperatively was reduced [mean difference (MD), -10.61 (95% CI, -16.00 to -5.22) mg, p = 0.0001, I2 = 90%] in patients with intravenous paracetamol. Intravenous paracetamol significantly reduced the postoperative pain scores at 1 h [MD, -2.37 (95%CI, -3.81 to -0.94), p = 0.001, I2 = 82%], 2 h [MD, -3.17 (95%CI, -3.85 to -2.48), p < 0.00001, I2 = 38%], 6 h [MD, -1.75 (95%CI, -3.10 to -0.40), p = 0.01], 12 h [MD, -0.96 (95%CI, -1.77 to -0.15), p = 0.02], and 24 h [MD, -0.97 (95%CI, -1.67 to -0.27), p = 0.006] compared with the placebo. There were no differences in postoperative adverse effects. Conclusion: Intravenous paracetamol reduced postoperative opioid consumption and decreased postoperative pain scores without increasing adverse effects. The overall GRADE quality of the evidence was rated as low to moderate. Intravenous paracetamol appears to be an applicable option as an important part of multimodal analgesia for postoperative analgesia after lumbar disc surgery. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, CRD42021288168.

Paracetamol for multimodal analgesia

Pain and related disability remain a major social and therapeutic problem. Comorbidities and therapies increase drug interactions and side effects making pain management more compounded especially in the elderly who are the fastest-growing pain population. Multimodal analgesia consists of using two or more drugs and/or techniques that target different sites of pain, increasing the level of analgesia and decreasing adverse events from treatment. Paracetamol enhances multimodal analgesia in experimental and clinical pain states. Strong preclinical evidence supports that paracetamol has additive and synergistic interactions with anti-inflammatory, opioid and anti-neuropathic drugs in rodent models of nociceptive and neuropathic pain. Clinical studies in young and adult elderly patients confirm the utility of paracetamol in multimodal, non-opioid or opioid-sparing, therapies for the treatment of acute and chronic pain.

Comparison of intravenous and oral administration of acetaminophen in adults undergoing general anesthesia

BACKGROUND

Acetaminophen is a widely clinically used analgesic. However, the clinical effect of the route of administration on postoperative analgesia as well as on postoperative nausea and vomiting in patients undergoing general anesthesia remains unclear. This study aimed to explore whether the route of administration of acetaminophen affects postoperative analgesia, nausea, and vomiting in patients undergoing general anesthesia.

METHODS

We included all randomized controlled trials investigating the effects of the route of administration of acetaminophen on postoperative pain, nausea, and vomiting in patients undergoing general anesthesia. Independent examiners reviewed the literature and extracted data, with disagreements resolved through negotiation or the involvement of a third party. The Cochrane risk assessment tool was used to evaluate the quality of the included randomized controlled trials. A narrative synthesis was conducted to summarize the qualitative information from the included studies. A meta-integration of quantitative data was performed using RevMan 5.4.

RESULTS

Ten studies met the inclusion criteria. Eight studies assessed postoperative pain, whereas two assessed postoperative nausea and vomiting. Data from the eight studies assessing postoperative pain confirmed that there was no difference between intravenously and orally administered acetaminophen in adults (OR = -0.13; 95% CI, -0.36 to 0.11; p = 0.3). Data from the two studies assessing postoperative nausea and vomiting revealed no difference between intravenously and orally administered acetaminophen in adults (OR = 0.89; 95% CI, 0.64-1.25; p = 0.51). The included studies were of poor quality, with a heterogeneity of 68%.

CONCLUSIONS

No differences in postoperative analgesia or postoperative nausea and vomiting were observed between the routes of administration (intravenous vs. oral) of acetaminophen in adult patients undergoing general anesthesia. There is a need for future large sample studies to increase the reliability of the results.

Paracetamol: A Review of Guideline Recommendations

Musculoskeletal pain conditions are age-related, leading contributors to chronic pain and pain-related disability, which are expected to rise with the rapid global population aging. Current medical treatments provide only partial relief. Furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are effective in young and otherwise healthy individuals but are often contraindicated in elderly and frail patients. As a result of its favorable safety and tolerability record, paracetamol has long been the most common drug for treating pain. Strikingly, recent reports questioned its therapeutic value and safety. This review aims to present guideline recommendations. Paracetamol has been assessed in different conditions and demonstrated therapeutic efficacy on both acute and chronic pain. It is active as a single agent and is additive or synergistic with NSAIDs and opioids, improving their efficacy and safety. However, a lack of significant efficacy and hepatic toxicity have also been reported. Fast dissolving formulations of paracetamol provide superior and more extended pain relief that is similar to intravenous paracetamol. A dose reduction is recommended in patients with liver disease or malnourished. Genotyping may improve efficacy and safety. Within the current trend toward the minimization of opioid analgesia, it is consistently included in multimodal, non-opioid, or opioid-sparing therapies. Paracetamol is being recommended by guidelines as a first or second-line drug for acute pain and chronic pain, especially for patients with limited therapeutic options and for the elderly.

Opioid-Sparing Anesthetic Technique for Pediatric Patients Undergoing Adenoidectomy: A Pilot Study

INTRODUCTION

An opioid-sparing anesthetic involves a multi-modal technique with non-opioid medications targeting different analgesic pathways. Such techniques may decrease adverse effects related to opioids. These techniques may be considered in patients at higher risk for opioid-related adverse effects including obstructive sleep apnea or sleep disordered breathing.

METHODS

A prospective, pilot study was performed in 10 patients (3-8 years of age), presenting for adenoidectomy. The perioperative regimen included oral dextromethorphan (1 mg/kg) and acetaminophen (15 mg/kg) plus single boluses of intraoperative dexmedetomidine (0.5 μg/kg) and ketamine (0.5 mg/kg). Pain scores were assessed in the post anesthesia care unit (PACU) using the FLACC (Face, Legs, Activity, Cry, Consolability) scale. Patients with a pain score >4 received fentanyl as needed. PACU time, pain scores, and parent satisfaction were recorded. Postoperatively, patients were instructed to use oral acetaminophen or ibuprofen every 6 hours as needed for pain.

RESULTS

The study cohort included 10 patients, 3-8 years of age. All patients had opioid-free anesthetic care. PACU time ranged from 24 to 102 minutes (median: 56 minutes). FLACC pain scores were 0 for all PACU assessments. Nine patients were discharged home and 1 patient had a planned overnight admission. Following hospital discharge, the pain scores were satisfactory during the 72-hour study period and 90% of the patients' guardians were satisfied or highly satisfied with their child's pain control.

CONCLUSION

This opioid-sparing approach provided safe and effective pain control as well as parental satisfaction following adenoidectomy in children. Additional prospective studies are needed to determine whether this regimen is effective in a larger cohort of patients with and for other otolaryngology procedures.