Intravenous paracetamol (acetaminophen)

Molecular Precision Medicine: Application of Physiologically Based Pharmacokinetic Modeling to Predict Drug-Drug Interactions Between Lidocaine and Rocuronium/Propofol/Paracetamol

The perioperative period, encompassing preoperative, intraoperative, and postoperative phases, is crucial for comprehensive patient care. During this time, the use of opioids and other drugs can lead to drug-drug interactions (DDIs), potentially resulting in adverse drug reactions (ADRs) that increase morbidity, mortality, and healthcare costs. This study investigates the drug-drug interactions (DDIs) between rocuronium, propofol, paracetamol, and lidocaine, focusing on the CYP-mediated metabolism of these drugs in the perioperative context, where these drugs are frequently co-administered. Using physiologically based pharmacokinetic (PBPK) modeling through the GastroPlus™ software and in vitro experiments with Hep G2 cells, we aimed to assess potential toxicities and pharmacokinetic interactions. Cellular viability assays revealed significant toxicity when lidocaine was combined with propofol and rocuronium, while paracetamol exhibited no considerable impact on viability. PBPK simulations confirmed moderate interactions with rocuronium and weak interactions with propofol but no relevant interactions with paracetamol. These findings emphasize the need for dose adjustments in perioperative settings to enhance patient safety, particularly with propofol and rocuronium, while supporting the co-administration of lidocaine and paracetamol. These findings show the importance of moving towards a personalized medicine model, adjusting the clinical use of lidocaine according to individual patient needs, thus promoting safer and more effective perioperative care and moving beyond the "one-size-fits-all" approach in anesthetic management.

Comparative Effectiveness of Analgesia for Early Pain Management After Pediatric Tonsillectomy: A Systematic Review and Network Meta-Analysis

BACKGROUND

Timely and effective analgesia after tonsillectomy in children is crucial, but there is currently no consensus on the optimal analgesics. This analysis aimed to identify the most effective for this surgery.

METHODS

We conducted a systematic review and network meta-analysis (random-effects model) of randomized controlled trials comparing analgesics for pediatric tonsillectomy. We searched relevant studies in PubMed, Embase, Cochrane Library, and Web of Science databases from database inception until June 30, 2023. Children (≤18 years old) who underwent tonsillectomy with or without adenoidectomy were eligible for inclusion. Primary outcomes encompassed pain score and postoperative complications; secondary outcomes included postoperative supplementary analgesia, functional evaluation, and sedation score.

RESULTS

In total 82 randomized controlled trials involving 6110 patients were included, forming the primary network that comprised comparative data for 16 different interventions (including placebo) across 6 types of analgesics. The integrated analysis revealed that nonsteroidal anti-inflammatory drugs except ketoprofen had no significant effects in relieving postoperative pain (mean difference [MD], -2.96; 95% confidence interval [CI], -5.59 to -0.32; P = .10). Local anesthetic infiltration (bupivacaine: MD, -2.76; 95% CI, -3.88 to -1.64, P = .01; ropivacaine: MD, -2.49; 95% CI, -4.25 to -0.73, P = .02; lidocaine: MD, -1.86; 95% CI,-3.52 to -0.2, P = .02; levobupivacaine: MD, -1.06; 95% CI, -2.00 to -0.12, P = .01), analgesics (morphine: MD, -2.07; 95% CI, -3.14 to -1.00; P = .02), and glucocorticoids (dexamethasone: MD, -0.45; 95% CI, -0.73 to -0.16; P = .01) were effective in relieving pain after pediatric tonsillectomy. In reducing incidence of postoperative complications, dexamethasone was superior to bupivacaine (relative risk [RR], 0.60; 95% CI, 0.43-0.83; P = .02). Regarding the number of patients needing rescue analgesic, levobupivacaine was superior to lidocaine (RR, 0.51; 95% CI, 0.32-0.81; P = .01). In rescue analgesia requirement, morphine outperformed lidocaine (RR, 0.44; 95% CI, 0.25-0.75; P = .01) and ropivacaine (RR, 0.54; 95% CI, 0.32-0.91; P = .01) in efficacy but not different from bupivacaine (P = .10) and levobupivacaine (P = .12).

CONCLUSIONS

Based on these results, we would recommend local bupivacaine infiltration or local levobupivacaine infiltration for older children and dexamethasone injection for younger children for early analgesia after tonsillectomy. However, clinicians should choose the optimal analgesic based on the individual child's condition and clinical situation.

Intravenous Acetaminophen Versus Ketorolac for Prehospital Analgesia: A Retrospective Data Review

BACKGROUND

Parenteral ketorolac and intravenous (IV) acetaminophen have been used for prehospital analgesia, yet limited data exist on their comparative effectiveness.

STUDY OBJECTIVES

To evaluate the comparative effectiveness of IV acetaminophen and parenteral ketorolac for analgesia in the prehospital setting.

METHODS

We conducted a retrospective cross-sectional evaluation of patients receiving IV acetaminophen or parenteral ketorolac for pain management in a large suburban EMS system between 1/1/2019 and 11/30/2021. The primary outcome was change in first to last pain score. Subgroup analysis was performed on patients with traumatic pain. We used inverse probability of treatment weighting (IPTW) and propensity score matching (PSM) to estimate the treatment effect of acetaminophen versus ketorolac among all patients and the subgroup of those with traumatic pain.

RESULTS

Of 2178 patients included, 856 (39.3%) received IV acetaminophen and 1322 (60.7%) received parenteral ketorolac. The unadjusted mean change in pain score was -1.9 (SD 2.4) for acetaminophen group and -2.4 (SD 2.4) for ketorolac. In the propensity score analyses, there was no statistically significant difference in pain score change for the acetaminophen group versus ketorolac among all patients (mean difference, IPTW: 0.11, 95% confidence interval [CI] -0.16, 0.37; PSM: 0.15, 95% CI -0.13, 0.43) and among those with traumatic pain (unadjusted: 0.18, 95% CI -0.35, 0.72; IPTW: 0.23, 95% CI -0.25, 0.71; PSM: -0.03, 95% CI -0.61, 0.54).

CONCLUSIONS

We found no statistically significant difference in mean pain reduction of IV acetaminophen and parenteral ketorolac for management of acute pain.

Oral versus intravenous acetaminophen for perioperative pain management in adult patients undergoing non-cardiac surgery: A quantile segmented regression analysis

STUDY OBJECTIVE

Determine whether preferential use of perioperative enteral acetaminophen is associated with changes in perioperative pain, narcotic administration, or time to meeting criteria for post anesthesia care unit (PACU) discharge, compared to preferential parenteral administration.

DESIGN

Retrospective Cohort with quantile segmented regression analysis. Groups determined by date of surgery, one year pre-initiative and one year post-initiative.

SETTING

Operating room and PACU of a tertiary academic medical center.

PATIENTS

Adult (age > 18 years), ASA status 1-5, non-pregnant patients undergoing non-cardiac surgery of less than six hours duration admitted to the PACU postoperatively.

INTERVENTIONS

A multidisciplinary initiative to preferentially utilize enteral over parenteral acetaminophen.

MEASUREMENTS

The primary outcome was narcotic consumption in the PACU. Secondary outcomes were intraoperative narcotic administration, pain score on PACU admission and discharge, and time to meeting criteria for PACU discharge.

RESULTS

24,701 patients were included in the analysis; 12,379 had surgery prior to the initiative and 12,322 after. Enteral acetaminophen administration increased preoperatively from 13.49% to 26.84%, and postoperatively from 43.16% to 51.45%, while intraoperative parenteral APAP use dropped from 43.23% to 6.81%. Quantile Segmented regression analysis after adjusting for period (pre versus postintervention), day, age, gender, inpatient status, and ASA class demonstrated a decrease in adjusted median perioperative acetaminophen dose (-175 mg P < 0.001), with no significant difference in level change of intraoperative or PACU narcotic administration. There was no significant difference in median time to meet criteria for PACU discharge, though there was a significant change in the slope, (-0.36, p = 0.007.) Median pain scores measured on a standard 0-10 numeric rating scale at PACU admission did not change, while median pain scores at PACU discharge decreased slightly (-0.24 p < 0.001). There was no change in the probability of PONV.

CONCLUSION

In adult patients undergoing non-cardiac surgery of <6 h duration, preferential use of enteral rather than parenteral acetaminophen is associated with non-inferior outcomes in narcotic requirements, pain scores, time to PACU discharge, and probability of PONV when compared with routine parenteral administration. Further studies are needed to validate these findings.

Opioid sparing effects of intravenous and oral acetaminophen in hip fracture patients: A population-based study

STUDY OBJECTIVE

Acetaminophen (APAP) and intravenous acetaminophen (IVAPAP) has been proposed as a part of many opioid-sparing multimodal analgesic pathways. The aim of this analysis was to compare the effectiveness of IVAPAP with oral APAP on opioid utilization and opioid-related adverse effects.

DESIGN

Retrospective study of population-based database.

PATIENTS

The Premier Healthcare database was queried patients undergoing surgery for a primary diagnosis of hip fracture from 2011 to 2019 yielding 245,976 patients. Primary exposure was use of IVAPAP or oral APAP on the day of surgery.

INTERVENTIONS

None.

MEASUREMENTS

The primary outcome of interest was opioid utilization over the hospital stay, secondary outcomes included opioid-related adverse effects, length, and costs of hospital stay. Mixed effect models measured the association of IVPAP and APAP and outcomes.

MAIN RESULTS

In the study population 30.67% (75,445) received at least 1 dose of IVAPAP on the day of surgery. Upon adjusting for relevant covariates, patients who received IVPAP on the day of surgery had slightly higher opioid use standardized by length of hospital stay (2.8% CI: 2%, 3.6%; p < .001), higher hospital cost (2.7% CI: 2.1%, 3.4%), and higher odds of naloxone use (1.18, CI: 1.1, 1.27; p < .001) when compared with patients who received oral APAP.

CONCLUSIONS

In this population, IVAPAP use on the day of surgery failed to reduce opioid use or associated opioid related adverse effects when compared with oral APAP. IVAPAP was associated with increased overall costs, opioid requirements, and naloxone use. These results do not support the use of IV over oral APAP routinely for hip fracture surgery patients.

Comparison of a Non-Opioid Multimodal Analgesia Protocol with Opioid-Based Patient-Controlled Analgesia for Pain Control Following Robot-Assisted Radical Prostatectomy: A Randomized, Non-Inferiority Trial

Background

Opioid use after surgery is a potential contributor to the opioid epidemic. An adequate pain control method after surgery while minimizing opioid exposure is needed. This study aimed to compare the effect of non-opioid multimodal analgesia (NOMA) protocol with opioid-based patient-controlled analgesia (PCA) for pain relief after robot-assisted radical prostatectomy (RARP).

Methods

This prospective randomized, open, non-inferiority trial included 80 patients scheduled for RARP. The NOMA group received pregabalin, paracetamol, bilateral quadratus lumborum block, and pudendal nerve block. PCA group received PCA. Pain scores, postoperative nausea and vomiting, opioid requirements, and quality of recovery were recorded 48 hours after surgery.

Results

We found no significant differences in pain scores. The mean difference in pain score during rest at 24 h was 0.5 (95% CI -0.5 to 2.0). This result demonstrated the non-inferiority of NOMA protocol to PCA at our non-inferiority margin (-1). In addition, 23 patients in the NOMA group did not receive any opioid agonist for 48 h after surgery. Recovery of bowel function was also faster in the NOMA group than in the PCA group (25.0 hours vs 33.4 hours, p = 0.01).

Limitations

We did not evaluate whether our NOMA protocol could decrease the incidence of new continuous opioid use after surgery.

Conclusion

NOMA protocol successfully controlled postoperative pain and was non-inferior to morphine-based PCA regarding patient-reported pain intensity. It also promoted recovery of bowel function and decreased postoperative nausea and vomiting.

Clinical efficacy of acupuncture for pain relief from renal colic: A meta-analysis and trial sequence analysis

Background

This meta-analysis aimed at investigating the efficacy of acupuncture for relieving renal colic and reducing the risk of analgesic-related complications.

Methods

Randomized controlled trials (RCTs) comparing the efficacy of acupuncture (acupuncture group) with conventional interventions (control group) were screened from MEDLINE, EMBASE, Cochrane library databases, China Knowledge Network (CNKI), and Airiti Library till July 15, 2022. The primary outcome was the rate of effective pain relief (response rate), while secondary outcomes included the time of onset of pain relief, visual analog scale (VAS) at 30-60 min and risk of side effects.

Results

Thirteen eligible studies involving 1,212 participants published between 1992 and 2021 were analyzed. Compared with the control group, patients receiving acupuncture had a higher overall response rate [risk ratio (RR) = 1.12, 95% CI: 1.05-1.19, p = 0.0002, I ² = 41%, 1,136 patients] (primary outcome) and a faster pain relief [MD = -10.74 min, 95% CI: -12.65 to -8.82, p < 0.00001, I ² = 87%, 839 patients]. Patients receiving acupuncture had a lower pain score [MD = -0.65, 95% CI: -1.09 to -0.21, p = 0.21, I ² = 55%, 327 patients] and risk of side effects (RR = 0.11, 95% CI: 0.04-0.26, p < 0.00001, I ² = 0, 314 patients) compared to those receiving conventional interventions. Results from trial sequence analysis revealed sufficient evidence supporting the beneficial effects of acupuncture on response rate, time to pain relief, and pain score at 30-60 min.

Conclusion

Compared with conventional analgesic-based interventions, acupuncture can more efficiently relieve renal colic with fewer adverse effects. The limited number and quality of included studies warrant more clinical RCTs to support our findings.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022346714.

Intravenous paracetamol infusion and tramadol as agents for post operative pain relief in urosurgical patient: A randomized control trial

Analgesia is one of the most important consideration in perioperative setting as it determines the recovery and discharge of a patient. Among the drugs used for analgesia, non steroidal anti-inflammatory drugs and opioids are the most commonly used ones in the current scenario. The aim of this study was to compare the efficacy of intravenous (IV) paracetamol and IV tramadol in alienating pain postoperatively. 100 adult patients of ASA grade I & II in the age group of 25-55 years were randomized into two groups of 50 patients , scheduled for elective urosurgical procedures and  were administered IV paracetamol and IV tramadol 30 minutes before the completion of surgery for postoperative analgesia and assessment was done with visual analog scale (VAS)score. In the present study, both the drugs showed effective pain relief. The onset of analgesia is faster in tramadol group. In paracetamol group, the onset of analgesia was slightly delayed but pain scores significantly decreased after 60 min, and this was observed up to 6 h with a statistically significant decrease in post operative nausea vomiting( PONV )with paracetamol group . 

Evaluation of efficacy and safety of subcutaneous acetaminophen in geriatrics and palliative care (APAPSUBQ)

INTRODUCTION

Subcutaneous infusion (SC) or hypodermoclysis is an old perfusion technique that is often used off-label although it has been shown to be effective. Acetaminophen (paracetamol) subcutaneous injection is performed in some centers despite the lack of conclusive evidence on its effectiveness. This study aims to evaluate the efficacy of subcutaneous infusion of Acetaminophen in the treatment of pain and fever in geriatrics and in palliative care and to determine its safety profile and possible side effects.

MATERIAL AND METHODS

This experimental study was conducted between 2018 and 2019 on adult patients in palliative care or in geriatrics in several hospitals and nursing homes in Lebanon. Primary outcomes were change in temperature; change in pain score on the numerical rating scale (NS) or on the Algoplus scale after 60 min from the start of the infusion; and the appearance of local side effects at the infusion site. Changes in the various parameters at 30 min and 180 min were also evaluated as secondary outcomes.

RESULTS

Thirty-one patients were included in the study, with a total of 120 doses of acetaminophen. At 60 min, the mean decrease in pain on the NS was 5.35 points, while the mean decrease in temperature was 0.79 degrees Celsius. At 60 min, 75%, CI = [47.62-92.73] of the patients who received acetaminophen for pain and 66.67%, CI = [38.38-88.17] of those who received it for fever had clinically significant improvement. The overall effect of subcutaneous acetaminophen, defined as any clinically significant effect on pain or fever, was 70.97%, CI = [51.96-85.78]. The overall effect at 30 min and at 180 min was 23.33%, CI = [9.93-42.28] and 87.10%, CI = [70.17-96.37], respectively. The side effects reported 30 min after the injection and observed after at least one of the doses were: local edema in 16 patients (51.61%), induration in one patient (3.23%), local pain in one patient (3.23%) and local heat in one patient (3.23%). At 180 min, only 2 patients (6.45%) still had edema at the infusion site.

CONCLUSION

Subcutaneous administration of acetaminophen is effective and well tolerated in geriatric and palliative care patients. It is appropriate when no other route is available, especially for home-based care. Comparative studies are needed to allow the expansion of this practice.

Comparison of paracetamol and hyoscine-N-butylbromide in the treatment of abdominal pain and cramps due to acute gastroenteritis

Background and objective: Hyoscine-N-butyl bromide (HBB) and paracetamol (acetaminophen)are widely used in emergency departments for abdominal pain and cramps. However, there is not enough data on the efficacy, safety, and superiority of each other in treating acute gastroenteritis (AGE) related abdominal pain and cramps. In this study HBB and paracetamol were compared for the treatment of abdominal pain and cramps related to acute gastroenteritis. Materials and methods: The study was conducted in a tertiary university hospital emergency department as a prospective, randomized-controlled, and double-blind study. Intravenous (IV) 1000 mg paracetamol and IV 20 mg hyoscine-N-butyl bromide (HBB) were used to treat abdominal pain and cramps related to AGE. Visual analogue scale (VAS) was used to evaluate the degree of abdominal pain before and after treatment. Results: HBB and paracetamol groups consisted of 123 and 158 cases respectively. In both groups, it was observed that the VAS score gradually decreased from the 0th hour to the 1st and 2nd hours (p<0.001).When comparing each time within itself, it was observed that HBB and paracetamol measurements had similar values (p>0.05). No severe side effects were observed in any of the patients. Conclusion: HBB and paracetamol were used for symptomatic treatment in AGE patients presenting with abdominal pain and cramps. A significant reduction in pain and cramps was achieved in both patient groups. There was no difference between the two drugs in terms of treatment efficacy and side effects. IMC J Med Sci 2022; 16(1): 009 *Correspondence: Hasan Gümüşboğa, Department of Emergency, Şehitkamil State Hospital, Gaziantep, Turkey, Posta code: 27500; Email: profhasan@hotmail.com; ORCID:0000-0003-2097-7102.

The Nuts and Bolts of a Successful Non-Narcotic Perioperative Enhanced Recovery After Surgery Protocol

BACKGROUND

Enhanced recovery after surgery (ERAS) protocols are widely utilized approaches to perioperative care that advocate preoperative counseling, multimodal perioperative medication management, and early postoperative mobilization to improve post-surgical patient outcomes and satisfaction.

OBJECTIVES

The authors aimed to elucidate the mechanism by which each medication utilized in the senior author's ERAS protocol acts, determine the efficacy of this protocol in postoperative pain management, and reveal other factors that may play a role in patients' degree of postoperative pain.

METHODS

A literature review was performed on the medications utilized in the senior author's ERAS protocol. Evidence from the author's previous study on the efficacy of this regimen and anecdotal evidence regarding the psychological component of pain was also compiled.

RESULTS

There is evidence that an ERAS protocol is as effective if not more effective than regimens involving opioid medications in management of postoperative pain. These medications act synergistically to block perception of pain by multiple pathways, while minimizing adverse effects that may be associated with high doses of a single medication and are affordable for both the patient and the surgeon.

CONCLUSIONS

ERAS protocols effectively manage postoperative pain while avoiding the adverse effects associated with opioid medications. Although an emphasis has often been placed on the medications involved in various protocols and avoidance of opioid medications, appropriate counseling on patients' expectations concerning postoperative "pain" or discomfort and a systemic shift in the approach to perioperative pain are perhaps the most important components to holistic non-narcotic postoperative care.

Oral acetaminophen as an adjunct to continuous epidural infusion and patient-controlled epidural analgesia in laboring parturients: a randomized controlled trial

BACKGROUND

Intravenous acetaminophen is safe and effective as an adjunct to labor analgesia with combined spinal-epidural (CSE) analgesia and patient-controlled epidural analgesia (PCEA). Oral acetaminophen is a much cheaper and safe option but has not been studied as an adjunct to labor analgesia till date. The aim of the present study is to evaluate the effect of oral acetaminophen as an adjunct in patients receiving local anesthetic-opioid combination using CSE analgesia.

METHOD

In this ethically approved randomized double-blind placebo-controlled trial, 60 consenting parturients were randomly allocated to two groups of 30 each: acetaminophen (who received oral acetaminophen 1 g) or placebo, 45 min before the procedure. CSE was administered as per hospital protocol. All the patients received continuous epidural infusion (CEI) of levobupivacaine 0.1% and fentanyl 2 mcg/mL at 5 ml/h and PCEA boluses of 5 mL of the same drug with a lockout interval of 15 min if needed. The primary outcome was hourly mean consumption of levobupivacaine and fentanyl mixture (mL/h). Secondary outcomes included pain score, sensory and motor block, hemodynamic parameters of mother, duration of the second stage of labor, mode of delivery, maternal satisfaction, Apgar scores, fetal heart rate, and adverse effects.

RESULTS

The mean drug consumption per hour was significantly less in the acetaminophen group than in the placebo group (7.66 mL/h, SD 2.01 vs. 9.01 mL/h, SD 2.83; p = 0.04). The requirement for bolus was also significantly less in the acetaminophen group than in the placebo group (median 2.5, IQR 3 vs. median 3.5, IQR 2; p = 0.04).

CONCLUSION

The use of 1 g of oral acetaminophen could be a cheap, safe, and effective adjunct to CEI plus PCEA in labor analgesia.

A narrative review of paracetamol-induced hypotension: Keeping the patient safe

Aim

To understand the prevalence and epidemiology of paracetamol‐induced hypotension and clinical implications for contemporaneous practice.

Design

Narrative review.

Methods

In May and June 2020, an open‐date literature search of English publications indexed in ProQuest, PubMed, and EBSCO was conducted with the search terms ‘acetaminophen’ and ‘hypotension’ and related search combinations (‘paracetamol’, ‘propacetamol’, ‘low blood pressure’, ‘fever’, ‘sepsis’, and ‘shock’) to identify peer‐reviewed publications of blood pressure changes after paracetamol administration in humans.

Results

A pattern of blood pressure reduction following the administration of paracetamol is demonstrated in the 27 studies included in this review. Haemodynamic intervention often followed persistent blood pressure reduction, and was greatest in febrile critically ill patients who received parenteral paracetamol.

Effectiveness of scheduled intravenous acetaminophen in the postoperative pain management of video-assisted thoracic surgery

PURPOSE

The scheduled administration of intravenous acetaminophen (scheduled-IV-AcA) is one of the more effective multimodal analgesic approaches for postoperative pain in abdominal/orthopedic surgeries. However, there is little evidence concerning scheduled-IV-AcA after general thoracic surgery, especially when limited to video-assisted thoracoscopic surgery (VATS). We investigated the efficacy of scheduled-IV-AcA administration in patients after undergoing VATS.

METHODS

Ninety-nine patients who underwent VATS lobectomy or segmentectomy via an 8-cm access window and 1 camera port were retrospectively reviewed by categorizing them into groups either with scheduled-IV-AcA (Group AcA: n = 29) or without it (Group non-AcA: n = 70). Group AcA received 1 g of IV-AcA every 6 h from the end of the operation until the end of POD2. Postoperative pain was measured using a numeric rating scale (NRS) three times per day until discharge.

RESULTS

NRS scores were significantly lower in Group AcA with motion (on POD1 to the first point of POD2) than in Group non-AcA. Group non-AcA was also more likely to use additional analgesics than Group AcA (39% vs. 17%, p = 0.058).

CONCLUSIONS

Scheduled-IV-AcA administration is a safe and effective multimodal analgesic approach in patients undergoing VATS pulmonary resection via an 8-cm access window.

Intravenous versus oral paracetamol in a UK ambulance service: a case control study

OBJECTIVES

To determine the effectiveness of intravenous versus oral paracetamol (acetaminophen) in the management of acute pain in the out-of-hospital setting.

METHODS

We extracted ambulance electronic patient care records for all patients who received 1 g intravenous paracetamol throughout January 2019, and case matched these by sex and age with consecutive patients who received 1 g oral paracetamol over the same time period. Eligible for inclusion were all patients aged ≥ 18 who received 1 g paracetamol for acute pain and who were transported to the emergency department (ED). The primary outcome was the mean reduction in pain score using the numeric rating scale (NRS), with a reduction of 2 or more accepted as clinically significant.

RESULTS

80 care records were eligible for analysis; 40 patients received intravenous and 40 patients received oral paracetamol. The mean age of both groups was 54 years (± 3 years) and 67.5% (n = 54) were female. Patients receiving intravenous paracetamol had a clinically significant mean (SD) improved pain score compared to those receiving oral paracetamol, 2.02 (1.64) versus 0.75 (1.76), respectively [p = 0.0013]. 13/40 (32.5%) patients who received intravenous paracetamol saw an improved pain score of ≥ 2 compared to 8/40 (20%) who received oral paracetamol. No patients received additional analgesia or reported any adverse symptoms. Abdominal pain, infection and trauma were the most common causes of pain in both groups.

CONCLUSION

Our study suggests that intravenous paracetamol is more effective than oral paracetamol when managing acute pain in the out-of-hospital setting. Our findings support further investigation of the role of paracetamol in paramedic practice using more robust methods.

Paracetamol as a basic component of a modern approach to adequate perioperative analgesia

The problem of adequate perioperative anesthesia is one of the most pressing in the current health care system, given its medical, humanistic and socio-economic aspects. Currently, the standard of postoperative analgesia is multimodal analgesia (MMA). One of the major and required components of MMA is paracetamol, which has antipyretic and analgesic effects with limited peripheral anti-inflammatory activity. Most authors consider intravenous paracetamol as a base drug in a multimodal analgesia strategy for a variety of surgical interventions, which reduces the need for opioids and reduces the side effects of the latter, which in turn significantly affects the results of treatment and the length of hospital stay.Numerous studies in many countries have created a broad evidence base for the clinical use of this drug. Due to its pharmacokinetic and pharmacodynamic properties, it has been shown that intravenous paracetamol has several advantages over oral and rectal forms: early and more effective onset of analgesia and stable maintenance of the therapeutic dose of paracetamol are explained by the formation of a faster and higher peak in the concentration of the drug. The side effects of using paracetamol can be compared with placebo. The mechanism of action of the drug is different from the mechanism of action of NSAIDs, however, is still not fully understood. It may possibly involve inhibition of cyclooxygenase, cannabinoid, or nitric oxide pathways in the central nervous system. Intravenous paracetamol is a safe and effective first-line drug for the treatment of moderate pain in the perioperative period.

Intravenous Acetaminophen (Paracetamol) for Postcraniotomy Pain: Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Acute pain control after supratentorial craniotomy is considered among the most important indicators of postoperative recovery. The aim of this study was to determine the effects of intravenous acetaminophen on postcraniotomy pain.

METHODS

We searched databases including Embase, Scopus, Medline, Cochrane Library, and Web of Science until April 2019. Cochran Q test and I² statistic were used to assess the heterogeneity across included clinical trials. Standardized mean difference (SMD) and 95% confidence interval (CI) were used to estimate pooled effect sizes.

RESULTS

Out of 479 reports, 5 randomized controlled trials met the inclusion criteria and were appropriate for our meta-analysis, which included a total of 2635 patients. The pooled results of included clinical trials indicated that paracetamol intake significantly decreased rescue dose (SMD, -0.67; 95% CI, -1.15 to -0.19; P < 0.01; I² = 90.0%), total dosage of rescue (SMD, -0.78; 95% CI, -1.18 to -0.37; P < 0.01; I² = 86.0%), intensive care unit length of stay (SMD, -0.24; 95% CI, -0.44 to -0.04; P = 0.01; I² = 0.0%), and visual analog scale score (SMD, -0.16; 95% CI, -0.31 to -0.00; P = 0.04; I² = 71.7%) and increased patient satisfaction (SMD, 0.28; 95% CI, 0.14-0.43; P < 0.01; I² = 10.2%) among patients with craniotomy. Time to rescue (SMD, 0.21; 95% CI, -0.42 to 0.85; P = 0.51; I² = 94.3%) and hospital length of stay (SMD, -0.04; 95% CI, -0.24 to 0.16; P = 0.69; I² = 0.0%) did not significantly change after paracetamol intake.

CONCLUSIONS

The results of this systematic review and meta-analysis indicate that preoperative intravenous administration of acetaminophen is associated with decreased postoperative pain, need for rescue analgesics, and dosages of analgesics after craniotomy surgery.

How to manage fever in brain-injured patients

Fever represents a frequent and dangerous secondary insult for the injured brain and is often associated with worsened neurological outcomes. The identification of fever in the Neuro-Intensive Care Unit requires careful monitoring and rapid and effective treatment. The main objective of this article was to provide practical information regarding temperature monitoring, triggers for intervention and fever management in brain injured patients.

Hypotensive Response to IV Acetaminophen in Pediatric Cardiac Patients

OBJECTIVES

Acetaminophen is ubiquitously used as antipyretic/analgesic administered IV to patients undergoing surgery and to critically ill patients when enteral routes are not possible. Widely believed to be safe and free of adverse side effects, concerns have developed in adult literature regarding the association of IV acetaminophen and transient hypotension. We hypothesize that there are hemodynamic effects after IV acetaminophen in the PICU and assess the prevalence of such in a large pediatric cardiovascular ICU population using high-fidelity data.

DESIGN

Observational study analyzing an enormous set of continuous physiologic data including millions of beat to beat blood pressures surrounding medication administration.

SETTING

Quaternary pediatric cardiovascular ICU between January 1, 2013, and November 13, 2017.

PATIENTS

All patients less than or equal to 18 years old who received IV acetaminophen. Mechanical support devices excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Physiologic vital sign data were analyzed in 5-minute intervals starting 60 minutes before through 180 minutes after completion. Hypotension defined as mean arterial pressure -15% from baseline and relative hypotension defined -10%. Only doses where patients received no other medications, including vasopressors, within the previous hour were included. t test and a correlation matrix were used to eliminate correlated factors before a logistic regression analysis was performed. Six-hundred eight patients received 777 IV acetaminophen doses. Median age was 8.8 months (interquartile range, 2-62 mo) with a dose of 12.5 mg/kg (interquartile range, 10-15 mg/kg). Data were normalized for age and reference values. One in 20 doses (5%) were associated with hypotension, and one in five (20%) associated with relative hypotension. Univariate analysis revealed hypotension associated with age, baseline mean arterial pressure, and skin temperature (p = 0.05, 0.01, and 0.09). Logistic regression revealed mean arterial pressure (p = 0.01) and age (p = 0.05) remained predictive for hypotension.

CONCLUSIONS

In isolation of other medication, a hemodynamic response to IV acetaminophen has a higher prevalence in critically ill children with cardiac disease than previously thought and justifies controlled studies in the perioperative and critical care setting. The added impact on individual patient hemodynamics and physiologic instability will require further study.

Population Pharmacokinetic Modeling in the Presence of Missing Time-Dependent Covariates: Impact of Body Weight on Pharmacokinetics of Paracetamol in Neonates

Body weight is the primary covariate in pharmacokinetics of many drugs and dramatically changes during the first weeks of life of neonates. The objective of this study is to determine if missing body weights in preterm and term neonates affect estimates of model parameters and which methods can be used to improve performance of a population pharmacokinetic model of paracetamol. Data for our analysis were obtained from previously published studies on the pharmacokinetics of intravenous paracetamol in neonates. We adopted a population model of body weight change in neonates to implement three previously introduced methods of handling missing covariates based on data imputation, likelihood function modification, and full random effects modeling. All models were implemented in NONMEM 7.4, and population parameters were estimated using the FOCE method. Our major finding was that missing body weights minimally affect population estimates of pharmacokinetic parameters but do affect the covariate relationship parameters, particularly the one describing dependence of clearance on body weight. None of the tested methods changed estimates of between-subject variability nor impacted the predictive performance of the model. Our analysis shows that a modeling approach towards handling missing covariates allows borrowing information gathered in various studies as long as they target the same population. This approach is particularly useful for handling time-dependent missing covariates.

Effectiveness of intravenous acetaminophen for postoperative pain management in hip and knee arthroplasties: a population-based study

BACKGROUND AND OBJECTIVES

The significance of intravenous over oral acetaminophen (APAP) as part of multimodal analgesic protocols is contested, particularly when considering its relatively high price and use in a surgical cohort such as total hip or knee arthroplasty (THA/TKA), which generally tolerates oral medications. This study aims to elucidate APAP's effectiveness in a large, population-based patient sample.

METHODS

1 039 647 THA/TKA procedures were sampled from the Premier Healthcare claims database 2011-2016. APAP use was categorized by intravenous/oral and use on the day of surgery, postoperative day 1 and thereafter. Outcomes were opioid utilization (in oral morphine equivalents), length and cost of hospitalization, and opioid-related adverse effects (respiratory, gastrointestinal, and naloxone use as a proxy). Mixed-effects models measured the associations between intravenous/oral APAP use and outcomes. Percent (%) change and 95% CIs are reported.

RESULTS

Overall, 23.6% (n=245 454) of patients received intravenous APAP; of these, 56.3% (n=138 180) received just one dose on the day of surgery. After adjustment for relevant covariates, particularly use of >1 dose of intravenous APAP (compared with no use) on postoperative day 1 was associated with -6.0% (CI -7.2% to -4.7%) reduced opioid utilization; this was -10.7% (CI -11.4% to -9.9%) for use of > 1 dose oral APAP on postoperative day 1. Further comparisons regarding other outcomes also favored oral (over intravenous) APAP.

CONCLUSIONS

These results do not support the routine use of intravenous APAP in patients undergoing lower joint arthroplasty, especially since oral APAP shows more beneficial outcome patterns.

Transplacental transport of paracetamol and its phase II metabolites using the ex vivo placenta perfusion model

In Europe, 50-60% of pregnant women uses paracetamol (PCM), also known as acetaminophen. While it was considered to be safe, recent studies have shown an association between prenatal exposure to PCM and increased incidences of autism, cryptorchidism, asthma and ADHD. In this study the transplacental transfer of PCM and its metabolites was investigated using an ex vivo human placenta perfusion model (closed circuit; n = 38). Maternal-to-foetal (M-F) and foetal-to-maternal (F-M) transplacental transfer was determined at a concentration correlating with the maximum and steady state concentration in normal clinical use. Antipyrine (AP) was added as reference compound. Samples of the foetal and maternal perfusion medium were taken until 210 (PCM) or 360 min (paracetamol sulphate (PCM-S) and paracetamol glucuronide (PCM-G). PCM and AP concentrations reached an equilibrium between foetal and maternal compartments within the duration of the perfusion experiment and irrespective of the transfer direction. The percentage placental transfer of PCM was 45% (M-F and F-M). For PCM-S, transfer was 39% (M-F) and 28% (F-M), while the PCM-G transfer was 34% (M-F) and 25% (F-M). During placenta perfusions with the metabolites slight conversion (3.5-4.1%) to PCM was observed. In conclusion, PCM crosses the placental barrier rapidly via passive diffusion. Differences in flow rate and villous placental structure explain the significantly faster M-F transfer than F-M transfer of PCM. The larger and more hydrophilic molecules PCM-S and PCM-G cross the placenta at a significantly lower rate. Moreover, their F-M transport is about 40% slower than M-F transport, suggesting involvement of a transporter.

Prospective, double-blind randomized study of comparison of analgesic efficacy of parenteral paracetamol and diclofenac for postoperative pain relief

Background and Aims:

Injectable paracetamol has analgesic and antipyretic activities, especially used in postoperative period. The aim of this study was to assess the analgesic efficacy and safety of IV paracetamol in comparison with IV diclofenac for postoperative pain relief.

Material and Methods:

Randomly selected 120 patients who underwent elective surgery under general anesthesia were divided into two groups: group A (paracetamol group): patients received IV paracetamol (15 mg/kg)/100 mL, 30 min before completion of surgery over the period of 15 min (rounded of to 1 g), the selected cases were in range of 60-70 kg body weight. Group B (diclofenac group): patients received IV diclofenac (1 mg/kg) diluted in 100 mL NS, 30 min before completion of surgery over the period of 15 min (rounded of to 75 mg). Pain relief and side effects were observed in postoperative period. Statistical analysis of continuous data was done by unpaired t-test and Chi-square test was applied for discrete data.

Results:

Both IV paracetamol and IV diclofenac were effective for postoperative pain relief. No significant differences were found between them for any measures of analgesic activity. Only minor and common adverse events were reported, with no overall differences between groups.

Conclusion:

Both paracetamol and diclofenac drugs are safe to provide analgesia through IV route in postoperative period without any major significant side effects.

The antipyretic efficacy and safety of propacetamol compared with dexibuprofen in febrile children: a multicenter, randomized, double-blind, comparative, phase 3 clinical trial

BACKGROUND

We aimed to compare the antipyretic efficacy, safety, and tolerability between oral dexibuprofen and intravenous propacetamol in children with upper respiratory tract infection (URTI) presenting with fever.

METHODS

Patients aging from 6 months to 14 years admitted for URTI with axillary body temperature ≥ 38.0 °C were enrolled and randomized into the study or control group. Patients in the study group were intravenously infused with propacetamol and subsequently oral placebo medication was administered. Patients in the control group were intravenously infused with 100 mL of 0.9% sodium chloride solution without propacetamol and then oral dexibuprofen was administered. We checked the body temperature of all patients at 0.5 h (hr), 1 h, 1.5 h, 2 h, 3 h, 4 h, and 6 h after oral placebo or dexibuprofen had been applied.

RESULTS

A total of 263 patients (125 in the study group) were finally enrolled. The body temperatures of patients in the study group were significantly lower until 2 h after administration (37.73 ± 0.58 vs 38.36 ± 0.69 °C (p < 0.001), 37.37 ± 0.53 vs 37.88 ± 0.69 °C (p < 0.001), 37.27 ± 0.60 vs 37.62 ± 0.66 °C (p < 0.001), 37.25 ± 0.62 vs 37.40 ± 0.60 °C (p = 0.0452), at 0.5 h, 1 h, 1.5 h, and 2 h, respectively). The two groups showed no significant differences in terms of the range of body temperature decrease, the Area Under the Curve of body temperature change for antipyretic administration-and-time relationship, the maximum value of body temperature decrease during the 6 h test period, the number of patients whose body temperature normalized (< 37.0 °C), the mean time when first normalization of body temperature, and the development of adverse events including gastrointestinal problem, elevated liver enzyme, and thrombocytopenia.

CONCLUSIONS

Intravenous propacetamol may be a safe and effective choice for pediatric URTI patients presenting with fever who are not able to take oral medications or need faster fever control.

TRIAL REGISTRATION

CRIS KCT0002888 . Date of registration: July 31st, 2013.

Evidence-based use of acetaminophen for hemodynamically significant ductus arteriosus in preterm infants

While cyclooxygenase inhibitors have been the most common medications used to facilitate earlier closure of patent ductus arteriosus in preterm infants, adverse effects and variable efficacy have highlighted a need for alternative options. Acetaminophen facilitates ductal closure via an alternate pathway of prostaglandin inhibition. Despite treatment with high doses, toxicity is uncommon in preterm infants, possibly due to immature hepatic metabolism. Pooled data from randomized clinical trials of early treatment demonstrate that acetaminophen has similar efficacy as cyclooxygenase inhibitors for PDA closure with a favorable side effect profile and without any apparent increase in adverse neonatal outcomes. Acetaminophen may therefore be an ideal first-line agent among moderately and extremely preterm infants, though there is a paucity of data from controlled trials regarding its use in infants at the border of viability (gestation age ≤25 weeks). Evidence from clinical studies of limited quality supports acetaminophen treatment as rescue therapy for infants with persistent PDA after unsuccessful cyclooxygenase inhibitor treatment, including those being considered for surgical ligation.

Effective Postoperative Analgesia Using Intravenous Flurbiprofen and Acetaminophen

PURPOSE

Management of postoperative pain is one of the most important components in postoperative care, because most patients have pain after dental surgery. The aim of this study was to evaluate whether acetaminophen could be an alternative to fentanyl in combination with a nonsteroidal anti-inflammatory drug (NSAID) as an analgesic after dental surgery in cases in which narcotic drugs were contraindicated.

MATERIALS AND METHODS

Patients were 24- to 54-year-old men who underwent enucleation of a mandibular cyst under general anesthesia. The authors measured time from discontinuation of anesthetic administration until discharge from the operating room and postoperative pain during 4 hours after discharge. They compared these parameters between patients who were intravenously administered an NSAID such as flurbiprofen with fentanyl (NSAID/fentanyl group) and those administered an NSAID with acetaminophen (NSAID/acetaminophen group). Parametric data of time were analyzed using Student t test. Nonparametric data of the analgesic effect were analyzed using Mann-Whitney U test.

RESULTS

Time until discharge from the operating room after discontinuation of anesthetics in the NSAID/fentanyl group was significantly longer than that in the NSAID/acetaminophen group (P < .05). In contrast, there was no significant difference in analgesic effect between the NSAID/acetaminophen and NSAID/fentanyl groups (P > .05).

CONCLUSION

Although recovery time in the operating room of the flurbiprofen and acetaminophen group was markedly shorter than that of the flurbiprofen and fentanyl group, the postoperative analgesic effects of the 2 drugs were equipotent. Therefore, acetaminophen can be an alternative to fentanyl in cases in which narcotic drugs are contraindicated.

Comparison of Antipyretic Efficacy of Intravenous (IV) Acetaminophen versus Oral (PO) Acetaminophen in the Management of Fever in Children

OBJECTIVE

To assess the dynamics of the onset of antipyretic efficacy of intravenous (IV) acetaminophen vs. oral (PO) acetaminophen in the management of fever in children.

METHODS

This observational single-dose study was conducted at Department of Pedriatrics, Army Hospital (Research and Referral), a multispecialty tertiary care center in New Delhi in fever patients to assess the antipyretic efficacy of IV acetaminophen 15 mg/kg/dose vs. PO acetaminophen 15 mg/kg/dose over 6 h. Subjects were randomly assigned to receive either IV acetaminophen (n = 200) or PO acetaminophen (n = 200).

RESULTS

Demographics and baseline characteristics were similar between the two groups and were normally distributed. Allergic reaction was found in 7 (3.5%) patients in IV acetaminophen group and was absent in PO acetaminophen group. Onset of constipation and dry mouth was found in 8 patients (4%) in IV acetaminophen group and was absent in PO acetaminophen group. Additional dose was required in 6 patients (3%) in intravenous acetaminophen group and 10 patients (5%) in oral acetaminophen group respectively. Statistically significant differences in the rate of fall in temperature through 180 min were observed in favor of the IV acetaminophen group when compared to those receiving PO acetaminophen.

CONCLUSIONS

A single dose of intravenous acetaminophen is safe and effective in reducing fever where patients are unable to tolerate oral administration or when rapid reduction of temperature is desirable.

Intravenous versus oral paracetamol for acute pain in adults in the emergency department setting: a prospective, double-blind, double-dummy, randomised controlled trial

OBJECTIVE

To determine if intravenous paracetamol was superior to oral paracetamol as an adjunct to opioids in the management of moderate to severe pain in the ED setting.

METHODS

A prospective, randomised, double-blind, double-dummy, controlled trial was conducted at a single academic tertiary care ED. Adult patients with moderate to severe pain were randomly assigned to receive either the intravenous paracetamol or oral paracetamol. The primary outcome was Visual Analogue Scale (VAS) pain reduction at 30 min. A clinically significant change in pain was defined as 13 mm.

RESULTS

87 participants were included in the final analysis, with a median age of 43.5 years and 59.8% were female. Overall mean baseline VAS pain score was 67.9 mm (±16.0). Both formulations achieved a clinically significant mean pain score reduction at 30 min, with no significant difference between the groups with 16.0 mm (SD 19.1 mm) in the intravenous group and 14.6 mm (SD 26.4) in the oral group; difference -1.4 mm (95% CI -11.6 to 8.8, P=0.79). Secondary outcomes, including postintervention intravenous opioid administration, patient satisfaction, side effects and length of stay, did not differ between groups.

CONCLUSIONS

Overall, there was a small but clinically significant decrease in pain in each group. No superiority was demonstrated in this trial with intravenous paracetamol compared with oral paracetamol in terms of efficacy of analgesia and no difference in length of stay, patient satisfaction, need for rescue analgesia or side effects.

Combined intraoperative paracetamol and preoperative dexamethasone reduces postoperative sore throat: a prospective randomized study

PURPOSE

Postoperative sore throat (POST) after general anesthesia with endotracheal intubation is a common and undesirable complication. In this study, we evaluated the combined effects of paracetamol and dexamethasone on the prevention of POST in patients after general anesthesia.

METHODS

A total of 226 patients scheduled for urologic surgery under general anesthesia were randomly assigned to one of two groups. In the DexaPara group (n = 113), dexamethasone (10 mg) and paracetamol (1000 mg) was infused. In the Dexa group (n = 113), dexamethasone (10 mg) alone was given. POST, hoarseness, and dysphagia were monitored. The postoperative wound pain score and perioperative opioid requirements were compared. In addition, complications related to opioids were compared between the groups.

RESULTS

The overall incidence of POST was lower in the DexaPara group than in the Dexa group [42 (37%) vs. 72 (64%), p < 0.001]. The incidence of POST while resting at postoperative 1 and 6 h was lower in the DexaPara group than in the Dexa group (p = 0.008 and p = 0.004, respectively). The incidence of postoperative nausea, vomiting, drowsiness, shivering, and headache was comparable between the groups.

CONCLUSIONS

Paracetamol and dexamethasone infusion reduced the incidence of POST without serious complications in patients for urologic surgery under general anesthesia.

Patient-controlled Analgesia With Propacetamol-Fentanyl Mixture for Prevention of Postoperative Nausea and Vomiting in High-risk Patients Undergoing Spine Surgery: A Randomized Controlled Trial

BACKGROUND

This randomized trial evaluated the effect of intravenous patient-controlled analgesia (IV-PCA) based on fentanyl mixed with either propacetamol or an equivalent volume of normal saline on postoperative nausea and vomiting (PONV) in highly susceptible patients undergoing spinal surgery.

MATERIALS AND METHODS

One hundred eight nonsmoking female patients were randomly and evenly allocated to receive IV-PCA with either propacetamol (4 g) or normal saline mixed to fentanyl (20 μg/kg). Primary study outcome was PONV incidence at 24 hours postsurgery. Secondary outcomes were nausea severity, pain intensity (100-mm visual analog scale), use of rescue antiemetics and analgesics, patient satisfaction, and adverse events at 6, 12, and 24 hours postsurgery.

RESULTS

Postsurgery, the propacetamol versus normal saline group had lower PONV incidence at 24 hours (41% vs. 66%, P=0.011); pain intensity at rest and rescue analgesic requirements at 6 to 12 hours (30±15 vs. 41±19, P=0.008; and 25% vs. 49%, P=0.036, respectively) and at 12 to 24 hours (25±15 vs. 35±17, P=0.008; and 19% vs. 42%, P=0.044, respectively); and higher patient satisfaction score (6.4±1.4 vs. 5.7±1.8, P=0.028).

CONCLUSIONS

In patients undergoing spinal surgery and at risk of developing PONV, continuous IV-PCA based on propacetamol mixed to fentanyl, relative to fentanyl alone, effectively reduced the incidence of PONV, pain intensity at rest, and additional use of rescue analgesics with higher patient satisfaction.

Neonatal Maturation of Paracetamol (Acetaminophen) Glucuronidation, Sulfation, and Oxidation Based on a Parent-Metabolite Population Pharmacokinetic Model

OBJECTIVES

This study aimed to model the population pharmacokinetics of intravenous paracetamol and its major metabolites in neonates and to identify influential patient characteristics, especially those affecting the formation clearance (CL_formation) of oxidative pathway metabolites.

METHODS

Neonates with a clinical indication for intravenous analgesia received five 15-mg/kg doses of paracetamol at 12-h intervals (<28 weeks' gestation) or seven 15-mg/kg doses at 8-h intervals (≥28 weeks' gestation). Plasma and urine were sampled throughout the 72-h study period. Concentration-time data for paracetamol, paracetamol-glucuronide, paracetamol-sulfate, and the combined oxidative pathway metabolites (paracetamol-cysteine and paracetamol-N-acetylcysteine) were simultaneously modeled in NONMEM 7.2.

RESULTS

The model incorporated 259 plasma and 350 urine samples from 35 neonates with a mean gestational age of 33.6 weeks (standard deviation 6.6). CL_formation for all metabolites increased with weight; CL_formation for glucuronidation and oxidation also increased with postnatal age. At the mean weight (2.3 kg) and postnatal age (7.5 days), CL_formation estimates (bootstrap 95% confidence interval; between-subject variability) were 0.049 L/h (0.038-0.062; 62 %) for glucuronidation, 0.21 L/h (0.17-0.24; 33 %) for sulfation, and 0.058 L/h (0.044-0.078; 72 %) for oxidation. Expression of individual oxidation CL_formation as a fraction of total individual paracetamol clearance showed that, on average, fractional oxidation CL_formation increased <15 % when plotted against weight or postnatal age.

CONCLUSIONS

The parent-metabolite model successfully characterized the pharmacokinetics of intravenous paracetamol and its metabolites in neonates. Maturational changes in the fraction of paracetamol undergoing oxidation were small relative to between-subject variability.

Pharmacokinetic Study of Intravenous Acetaminophen Administered to Critically Ill Multiple-Trauma Patients at the Usual Dosage and a New Proposal for Administration

The pharmacokinetic profile of intravenous acetaminophen administered to critically ill multiple-trauma patients was studied after 4 consecutive doses of 1 g every 6 hours. Eleven blood samples were taken (predose and 15, 30, 45, 60, 90, 120, 180, 240, 300, and 360 minutes postdose), and urine was collected (during 6-hour intervals between doses) to determine serum and urine acetaminophen concentrations. These were used to calculate the following pharmacokinetic parameters: maximum and minimum concentrations, terminal half-life, area under serum concentration-time curve from 0 to 6 hours, mean residence time, volume of distribution, and serum and renal clearance of acetaminophen. Daily doses of acetaminophen required to obtain steady-state minimum (bolus dosing) and average plasma concentrations (continuous infusion) of 10 μg/mL were calculated (10 μg/mL is the presumed lower limit of the analgesic range). Data are expressed as median [interquartile range]. Twenty-two patients were studied, mostly young (age 44 [34-64] years) males (68%), not obese (weight 78 [70-84] kg). Acetaminophen concentrations and pharmacokinetic parameters were these: maximum concentration 33.6 [25.7-38.7] μg/mL and minimum concentration 0.5 [0.2-2.3] μg/mL, all values below 10 μg/mL and 8 below the detection limit; half-life 1.2 [1.0-1.9] hours; area under the curve for 6 hours 34.7 [29.7-52.7] μg·h/mL; mean residence time 1.8 [1.3-2.6] hours; steady-state volume of distribution 50.8 [42.5-66.5] L; and serum and renal clearance 28.8 [18.9-33.7] L/h and 15 [11-19] mL/min, respectively. Theoretically, daily doses for a steady-state minimum concentration of 10 μg/mL would be 12.2 [7.8-16.4] g/day (166 [112-202] mg/[kg·day]); for an average steady-state concentration of 10 μg/mL, they would be 6.9 [4.5-8.1] g/day (91 [59-111] mg/[kg·day]). In conclusion, administration of acetaminophen at the recommended dosage of 1 g per 6 hours to critically ill multiple-trauma patients yields serum concentrations below 10 μg/mL due to increased elimination. To reach the 10 μg/mL target, and from a strictly pharmacokinetic point of view, continuous infusion may be more feasible than bolus dosing. Such a change in dosing strategy requires appropriate, pharmacokinetic-pharmacodynamic and specific safety study.

A Non-Narcotic Pathway for the Management of Postoperative Pain Following Pediatric Robotic Pyeloplasty

PURPOSE

The purpose of this study is twofold: first, to describe the non-narcotic pathway (NNP) for the management of postoperative pain after robotic pyeloplasty (RP); second, to compare perioperative outcomes for children undergoing RP whose postoperative pain was managed with and without the NNP.

PATIENTS AND METHODS

A retrospective review was performed on 96 consecutive patients from October 2011 to December 2015 who underwent RP by three primary surgeons at a single pediatric institution. Children managed with an NNP received alternating doses of scheduled intravenous acetaminophen and ketorolac every 3 hours throughout the postoperative course. Perioperative outcomes were compared after grouping patients according to the type of postoperative pain management pathway. Continuous variables were compared using the Mann-Whitney U test, and categorical variables were compared using the two-tailed chi-squared test.

RESULTS

A total of 49 (51.0%) patients were managed with the NNP, and 47 (49.0%) patients were managed without the NNP. A larger proportion of patients in the NNP did not receive postoperative narcotic medications (71.4% vs 25.5%; p < 0.001). Patients in the NNP were administered less narcotics (median 0.000 mg vs 0.041 mg morphine equivalents/kg/day; p < 0.001) and had a shorter length of stay (median 1.0 day vs 2.0 days; p < 0.001). There was no significant difference in the proportion of patients with postoperative complications (p = 0.958) or surgical success (p = 0.958).

CONCLUSIONS

An NNP following pediatric RP is a viable and effective analgesic regimen that is associated with less narcotic use. It may also facilitate a shorter hospital stay. The majority of patients managed with this pathway had adequate pain control without being subject to the potential adverse effects of narcotic medications.

Comparative Study of the Effect of Intravenous Paracetamol and Tramadol in Relieving of Postoperative Pain after General Anesthesia in Nephrectomy Patients

Aim:

The aim of this study was to compare the effect of intravenous paracetamol and tramadol in relieving of postoperative pain after general anesthesia for nephrectomy in prospective donor patients for kidney transplantation.

Materials and Methods:

A randomized study was conducted on 100 adult patients scheduled for nephrectomy aged from 35 to 55 years of both sexes and divided into two groups and were administered intravenous paracetamol and tramadol for postoperative pain relief and assessed with visual analog scale score and variations in vital parameters to assess extent of pain relief.

Results:

After statistical interpretation of collected data, the observations were extrapolated. There was a statistically significant difference in the pain intensity scores obtained between the paracetamol and tramadol groups.

Conclusion:

On the basis of the present study, it is concluded that tramadol due to its lesser onset of action time was superior to paracetamol in providing acute postoperative pain relief.

Laparoscopic surgery: a narrative review of pharmacotherapy in pain management

Laparoscopic surgery is widespread, and an increasing number of surgeries are performed laparoscopically. Early pain after laparoscopy can be similar or even more severe than that after open surgery. Thus, proactive pain management should be provided. Pain after laparoscopic surgery is derived from multiple origins; therefore, a single agent is seldom sufficient. Pain is most effectively controlled by a multimodal, preventive analgesia approach, such as combining opioids with non-opioid analgesics and local anaesthetics. Wound and port site local anaesthetic injections decrease abdominal wall pain by 1-1.5 units on a 0-10 pain scale. Inflammatory pain and shoulder pain can be controlled by NSAIDs or corticosteroids. In some patient groups, adjuvant drugs, ketamine and α2-adrenergic agonists can be helpful, but evidence on gabapentinoids is conflicting. In the present review, the types of pain that need to be taken into account while planning pain management protocols and the wide range of analgesic options that have been assessed in laparoscopic surgery are critically assessed. Recommendations to the clinician will be made regarding how to manage acute pain and how to prevent persistent postoperative pain. It is important to identify patients at the highest risk for severe and prolonged post-operative pain, and to have a proactive strategy in place for these individuals.

Intramolecular interactions, isomerization and vibrational frequencies of two paracetamol analogues: A spectroscopic and a computational approach

The aim of this investigation was to determine the molecular properties and provide an interpretation of the vibrational mode couplings of these two paracetamol analogues: 2-bromo-2-methyl-N-(4-nitrophenyl)-propanamide and 2-bromo-2-methyl-N-p-tolyl-propanamide. E/Z isomers, keto/enol unimolecular rearrangement and prediction of the transition state structures in each mechanism were also assessed using the Density Functional Theory (DFT). The DFT estimates a high energy gap between E and Z isomers (9-11 kcal·mol(-1)), with barrier heights ranging from 16 to 19 kcal·mol(-1). In contrast, the barrier energies on the keto/enol isomerization are almost 10 kcal·mol(-1) higher than those estimated for the E/Z rearrangement. The kinetic rate constant was also determined for each reaction mechanism. Natural bond orbital analysis and the quantum theory of atoms in molecules were used to interpret the intramolecular hydrogen bonds and to understand the most important interactions that govern the stabilization of each isomer. Furthermore, an analysis of the atomic charge distribution using different population methodologies was also performed.

Intravenous acetaminophen analgesia after cardiac surgery: A randomized, blinded, controlled superiority trial

BACKGROUND

Pain after cardiac surgery traditionally has been controlled by intravenous opioids and nonsteroidal antiinflammatory drugs. An intravenous analgesic with fewer adverse effects is needed. Therefore, we tested the primary hypothesis that intravenous acetaminophen is more effective than placebo for pain management, which was defined a priori as superior on either pain intensity score and/or opioid consumption and not worse on either.

METHODS

In this single-center, double-blind trial, 147 patients having cardiac surgery via median sternotomy were randomized to receive either 1 g of intravenous acetaminophen (73 patients) every 6 hours for 24 hours or comparable placebo (74 patients) starting in the operating room after sternal closure. Cumulative opioid consumption (in morphine equivalents) and pain intensity scores (on a 0-10 Numeric Rating Scale) were measured at 4, 6, 8, 12, 16, 20, and 24 hours after surgery. We estimated ratio of mean opioid consumption by using multivariable linear regression (noninferiority delta = 1.15) and pain score difference by using repeated measures regression (noninferiority delta = 1).

RESULTS

Acetaminophen was superior to placebo on mean pain intensity scores and noninferior on opioid consumption, with estimated difference in mean pain (95% confidence interval) of -0.90 (-1.39, -0.42), P < .001 (superior), and estimated ratio of means in opioid consumption (90% confidence interval) of 0.89 (0.73-1.10), P = .28 (noninferior; not superior).

CONCLUSIONS

Intravenous acetaminophen reduced pain after cardiac surgery, but not opioid consumption. Intravenous acetaminophen can be an effective analgesic adjunct in patients recovering from median sternotomy.

Analgesic effect of paracetamol combined with low-dose morphine versus morphine alone on patients with biliary colic: a double blind, randomized controlled trial

BACKGROUND

Numerous drugs have been proposed to alleviate pain in patients with biliary colic, especially opioids, but still there is a tendency to use less narcotics because of their side effects and the unwillingness of some patients. The present study aimed to compare the analgesic effect of paracetamol combined with low-dose morphine versus morphine alone in patients with biliary colic.

METHODS

A randomized double-blind controlled trial was performed in 98 patients with biliary colic, recruited from two emergency departments from August 2012 to August 2013. Eleven patients were excluded and the remaining were randomized into two groups: group A received 0.05 mg/kg morphine+1 000 mg paracetamol in 100 mL normal saline and group B received 0.1 mg/kg morphine+normal saline (100 mL) as placebo. Pain scores were recorded using visual analogue scale (VAS) at baseline and 15 and 30 minutes after drug administration. Adverse effects and the need for rescue medication (0.75 µg/kg intravenous fentanyl) were also reported within 60 minutes of drug administration.

RESULTS

Before the infusion, the mean±SD VAS scores were 8.73±1.57 in group A and 8.53±1.99 in group B. At 15 minutes after drug administration, the mean±SD VAS scores were 2.16±1.90 in group A vs. 2.51±1.86 in group B; mean difference was -0.35, and 95%CI -1.15 to 0.45 (P=0.38). At 30 minutes the mean±SD VAS scores were 1.66±1.59 in group A vs. 2.14±1.79 in group B; mean difference was -0.48, and 95%CI -1.20 to 0.24 (P=0.19). The mean pain scores in the two groups at 15 and 30 minutes demonstrated no significant difference.

CONCLUSION

Paracetamol combined with low-dose morphine may be effective for pain management in patients with biliary colic.

Population Pharmacokinetics of Intravenous Paracetamol (Acetaminophen) in Preterm and Term Neonates: Model Development and External Evaluation

OBJECTIVES

The aims of this study were to develop a population pharmacokinetic model for intravenous paracetamol in preterm and term neonates and to assess the generalizability of the model by testing its predictive performance in an external dataset.

METHODS

Nonlinear mixed-effects models were constructed from paracetamol concentration-time data in NONMEM 7.2. Potential covariates included body weight, gestational age, postnatal age, postmenstrual age, sex, race, total bilirubin, and estimated glomerular filtration rate. An external dataset was used to test the predictive performance of the model through calculation of bias, precision, and normalized prediction distribution errors.

RESULTS

The model-building dataset included 260 observations from 35 neonates with a mean gestational age of 33.6 weeks [standard deviation (SD) 6.6]. Data were well-described by a one-compartment model with first-order elimination. Weight predicted paracetamol clearance and volume of distribution, which were estimated as 0.348 L/h (5.5 % relative standard error; 30.8 % coefficient of variation) and 2.46 L (3.5 % relative standard error; 14.3 % coefficient of variation), respectively, at the mean subject weight of 2.30 kg. An external evaluation was performed on an independent dataset that included 436 observations from 60 neonates with a mean gestational age of 35.6 weeks (SD 4.3). The median prediction error was 10.1 % [95 % confidence interval (CI) 6.1-14.3] and the median absolute prediction error was 25.3 % (95 % CI 23.1-28.1).

CONCLUSIONS

Weight predicted intravenous paracetamol pharmacokinetics in neonates ranging from extreme preterm to full-term gestational status. External evaluation suggested that these findings should be generalizable to other similar patient populations.