Tolerance and analgesic efficacy of a new i.v. paracetamol solution in children after inguinal hernia repair

A study of the regional differences in propacetamol-related adverse events using VigiBase data of the World Health Organization

Upon withdrawal of propacetamol, an injectable formulation of the paracetamol prodrug, in Europe due to safety concerns, South Korea's regulatory body requested a post-marketing surveillance study exploring its safety profile. We characterized regional disparities in adverse events (AE) associated with propacetamol between Asia and Europe using the World Health Organization's pharmacovigilance database, VigiBase. We performed disproportionality analyses using reporting odds ratios (rOR) and information component (IC) to determine whether five AEs (anaphylaxis, Stevens-Johnson syndrome, thrombosis, contact dermatitis/eczema, injection site reaction [ISR]) were associated with propacetamol versus non-propacetamol injectable antipyretics in Asia and Europe, separately. In Asia, there was a high reporting ratio of propacetamol-related ISR (rOR 5.72, 95% CI 5.19-6.31; IC₀₂₅ 1.27), satisfying the signal criteria; there were no reports of thrombosis and contact dermatitis/eczema. Two signals were identified in Europe, with higher reporting ratios for thrombosis (rOR 7.45, 95% CI 5.19-10.71; IC₀₂₅ 1.92) and contact dermatitis/eczema (rOR 16.73, 95% CI 12.48-22.42; IC₀₂₅ 2.85). Reporting ratios of propacetamol-related anaphylaxis were low for Asia and Europe. While signals were found for thrombosis and contact dermatitis/eczema in Europe, these were not detected in Asia. These findings suggest potential ethnic differences in propacetamol-related AEs between Asia and Europe, which could serve as supportive data for future decision-making.

Intravenous acetaminophen for postoperative pain control after open abdominal and thoracic surgery in pediatric patients: a systematic review and meta-analysis

Pediatric opioid exposure increases short- and long-term adverse events (AE). The addition of intravenous acetaminophen (IVA) to pediatric pain regimes to may reduce opioids but is not well studied postoperatively. Our objective was to quantify the impact of IVA on postoperative pain, opioid use, and AEs in pediatric patients after major abdominal and thoracic surgery. Medline, Embase, CINAHL, Web of Science, and Cochrane Library were searched systematically for randomized controlled trials (RCTs) comparing IVA to other modalities. Five RCTs enrolling 443 patients with an average age of 2.12 years (± 2.81) were included. Trials comparing IVA with opioids to opioids alone were meta-analyzed. Low to very low-quality evidence demonstrated equivalent pain scores between the groups (-0.23, 95% CI -0.88 to 0.40, p 0.47) and a reduction in opioid consumption (-1.95 morphine equivalents/kg/48 h, 95% CI -3.95 to 0.05, p 0.06) and minor AEs (relative risk 0.39, 95% CI 0.11 to 1.43, p 0.15). We conclude that the addition of IVA to opioid-based regimes in pediatric patients may reduce opioid use and minor AEs without increasing postoperative pain. Given the certainty of evidence, further research featuring patient-important outcomes and prolonged follow-up is necessary to confirm these findings.

Guidelines for Opioid Prescribing in Children and Adolescents After Surgery: An Expert Panel Opinion

IMPORTANCE

Opioids are frequently prescribed to children and adolescents after surgery. Prescription opioid misuse is associated with high-risk behavior in youth. Evidence-based guidelines for opioid prescribing practices in children are lacking.

OBJECTIVE

To assemble a multidisciplinary team of health care experts and leaders in opioid stewardship, review current literature regarding opioid use and risks unique to pediatric populations, and develop a broad framework for evidence-based opioid prescribing guidelines for children who require surgery.

EVIDENCE REVIEW

Reviews of relevant literature were performed including all English-language articles published from January 1, 1988, to February 28, 2019, found via searches of the PubMed (MEDLINE), CINAHL, Embase, and Cochrane databases. Pediatric was defined as children younger than 18 years. Animal and experimental studies, case reports, review articles, and editorials were excluded. Selected articles were graded using tools from the Oxford Centre for Evidence-based Medicine 2011 levels of evidence. The Appraisal of Guidelines for Research & Evaluation (AGREE) II instrument was applied throughout guideline creation. Consensus was determined using a modified Delphi technique.

FINDINGS

Overall, 14 574 articles were screened for inclusion, with 217 unique articles included for qualitative synthesis. Twenty guideline statements were generated from a 2-day in-person meeting and subsequently reviewed, edited, and endorsed externally by pediatric surgical specialists, the American Pediatric Surgery Association Board of Governors, the American Academy of Pediatrics Section on Surgery Executive Committee, and the American College of Surgeons Board of Regents. Review of the literature and guideline statements underscored 3 primary themes: (1) health care professionals caring for children who require surgery must recognize the risks of opioid misuse associated with prescription opioids, (2) nonopioid analgesic use should be optimized in the perioperative period, and (3) patient and family education regarding perioperative pain management and safe opioid use practices must occur both before and after surgery.

CONCLUSIONS AND RELEVANCE

These are the first opioid-prescribing guidelines to address the unique needs of children who require surgery. Health care professionals caring for children and adolescents in the perioperative period should optimize pain management and minimize risks associated with opioid use by engaging patients and families in opioid stewardship efforts.

Comparison of the effects on lameness of orally administered acetaminophen-codeine and carprofen in dogs with experimentally induced synovitis

OBJECTIVE

To compare the ability of acetaminophen-codeine (AC; 15.5 to 18.5 mg/kg and 1.6 to 2.0 mg/kg, respectively) or carprofen (4.2 to 4.5 mg/kg) administered PO to attenuate experimentally induced lameness in dogs.

ANIMALS

7 purpose-bred dogs.

PROCEDURES

A blinded crossover study was performed. Dogs were randomly assigned to receive AC or carprofen treatment first and then the alternate treatment a minimum of 21 days later. Synovitis was induced in 1 stifle joint during each treatment by intra-articular injection of sodium urate (SU). Ground reaction forces were assessed, and clinical lameness was scored at baseline (before lameness induction) and 3, 6, 9, 12, 24, 36, and 48 hours after SU injection. Plasma concentrations of acetaminophen, carprofen, codeine, and morphine were measured at various points. Data were compared between and within treatments by repeated-measures ANOVA.

RESULTS

During AC treatment, dogs had significantly higher lameness scores than during carprofen treatment at 3, 6, and 9 hours after SU injection. Peak vertical force and vertical impulse during AC treatment were significantly lower than values during carprofen treatment at 3, 6, and 9 hours. Plasma concentrations of carprofen (R)- and (S)-enantiomers ranged from 2.5 to 19.2 μg/mL and 4.6 to 25.0 μg/mL, respectively, over a 24-hour period. Plasma acetaminophen concentrations ranged from 0.14 to 4.6 μg/mL and codeine concentrations from 7.0 to 26.8 ng/mL, whereas plasma morphine concentrations ranged from 4.0 to 58.6 ng/mL.

CONCLUSIONS AND CLINICAL RELEVANCE

Carprofen as administered was more effective than AC at attenuating SU-induced lameness in dogs.

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

Postoperative pain might be different after intravenous vs. oral paracetamol. We systematically reviewed randomised controlled trials in patients >15 years that compared intravenous with oral paracetamol for postoperative pain. We identified 14 trials with 1695 participants. There was inconclusive evidence for an effect of route of paracetamol administration on postoperative pain at 0–2 h (734 participants), 2–6 h (766 participants), 6–24 h (1115 participants) and >24 h (248 participants), with differences in standardised mean (95%CI) pain scores for intravenous vs. oral of −0.17 (−0.45 to 0.10), −0.09 (−0.24 to 0.06), 0.06 (−0.12 to 0.23) and 0.03 (−0.22 to 0.28), respectively. Trial sequential analyses suggested that a total of 3948 participants would be needed to demonstrate a meaningful difference in pain or its absence at 0–2 h. There were no differences in secondary outcomes. Intravenous paracetamol is more expensive than oral paracetamol. Substitution of oral paracetamol in half the patients given intravenous paracetamol in our hospital would save around £ 38,711 (€ 43,960 or US$ 47,498) per annum.

Intraoperative Single-Dose Intravenous Acetaminophen for Postoperative Analgesia After Skin Laser Irradiation Surgery in Paediatric Patients: A Small Prospective Study

Objective

Acetaminophen is an analgesic that shows efficacy in postoperative pain relief in children. Many drugs such as opioids, non-steroidal anti-inflammatory drugs, and/or acetaminophen have been used in paediatric skin laser irradiation surgery for postoperative pain relief. However, acetaminophen has some advantages over opioids, and opioids are being used less often. We aimed to demonstrate the effectiveness of intravenous (IV) acetaminophen during surgery for postoperative pain in paediatric skin laser irradiation.

Methods

The present study is a small, prospective, double-blinded, randomized controlled trial. Paediatric patients (1-12 years old with an American Society of Anesthesiologists physical Status I and II), scheduled for skin laser irradiation for a nevus or haemangioma between October 2014 and April 2016 were randomized into the acetaminophen (n=9) and placebo (saline, n=8) groups. The observational face scale (FS) and the Behavioural Observational Pain Scale (BOPS) scores were recorded on emergence from anaesthesia, and 1, 2, and 4 hr post-surgery.

Results

Patient characteristics were not significantly different except with regard to the irradiation area and surgery time. The observational FS and BOPS scores of the acetaminophen group were lower than those of the placebo group; median (minimum-maximum) at each recording time: 1 (0-2) - 0 (0-2) - 0 (0-1) - 0 (0-2) vs. 2 (0-4) - 0 (0-2) - 0 (0-2) - 0 (0-1) and 1 (0-3) - 1 (0-3) - 1 (0-2) - 0 (0-1) vs. 2 (0-4) - 3 (0-5) - 1 (0-4) - 0 (0-3), p=0.07 and p=0.003, respectively. No differences in post-surgical analgesic use or adverse events were observed.

Conclusion

In this study, we showed that the IV acetaminophen group had lower observational FS and BOPS scores in the early postoperative period; however, further studies including a large number of patients are required to confirm our findings.

Introduction and Audit of Intravenous Paracetamol at a Tertiary Paediatric Teaching Hospital

Although intravenous (IV) paracetamol is an attractive analgesic, there is little information on its paediatric use. During an introduction phase with limited prescribing rights, an audit was performed to assess its use and cost impact at a tertiary paediatric centre. Patients receiving IV paracetamol prescribed by two pain specialists for restricted indications had their medical records retrospectively reviewed for age, weight, diagnosis, indications/dose for IV (and other route) paracetamol/other analgesics/antiemetics, vomiting/oral intake and liver function tests if performed. One-hundred-and-twenty-one children and five neonates received 1216 (median 8 each) doses of paracetamol IV. Audited expenditure for IV paracetamol was 3.9 times the rectal alternative ($3435 vs. $875). Indications were appropriate, with 97% of patients nil oral, 41% vomiting, 17% having rectal route replaced and 3% avoiding parenteral morphine. Only five patients received incorrect dosing: three through prescription errors and two as guideline deviations; none were considered dangerous. No liver function test derangements could be directly attributed to paracetamol.

This data facilitated our application to extend prescribing rights for IV paracetamol within our institution. As there is limited information or local experience with the use of IVparacetamol in paediatric settings in Australia, our data may be of use to other centres considering the introduction of the IV form of this agent.

Safety and Efficacy of Off-label and Unlicensed Medicines in Children

BACKGROUND

The aim of this study was to explore the use of off-label/unlicensed drugs to confirm the safety and efficacy of their prescription in children in Korea.

METHODS

In this retrospective study, we analyzed data of patients who received any of the 32 drugs between January-December 2014 in tertiary hospitals in Korea, including demographics, diagnoses, reasons for the medication, administration route, and details of adverse drug reactions. Additionally, the mortality in the cohort was assessed. The primary outcomes were efficacy and safety, including mortality, of these drugs in pediatric patients. The secondary outcomes were the current statuses of the use of off-label/unlicensed drugs in two centers.

RESULTS

Totally, 5,130 prescriptions were found in 2,779 patients. Age (73.5%) and indication (11.7%) were the most frequent reasons for prescriptions being off-labeled/unlicensed. Approximately 88% of the prescriptions were effective, and 19% of the patients developed adverse drug reactions. The number of prescriptions was significantly higher in children with adverse drug reactions than it was in those without (2.8 vs. 1.5; P < 0.001). The number of prescribed off-label/unlicensed medicines and age at prescription were independently associated with adverse drug events (odds ratio, 1.55 and 1.1; P < 0.001 and 0.034, respectively).

CONCLUSION

Children are still prescribed medicines that are not authorized in terms of age, weight, indications, or routes of administration. Therefore, many old products require re-assessment of authorization. More prospective clinical studies should be performed to confirm the efficacy and safety of drugs in the pediatric population.

Single dose intravenous paracetamol or intravenous propacetamol for postoperative pain

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 10, 2011. Paracetamol (acetaminophen) is the most commonly prescribed analgesic for the treatment of acute pain. It may be administered orally, rectally, or intravenously. The efficacy and safety of intravenous (IV) formulations of paracetamol, IV paracetamol, and IV propacetamol (a prodrug that is metabolized to paracetamol), compared with placebo and other analgesics, is unclear.

OBJECTIVES

To assess the efficacy and safety of IV formulations of paracetamol for the treatment of postoperative pain in both adults and children.

SEARCH METHODS

We ran the search for the previous review in May 2010. For this update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 1), MEDLINE (May 2010 to 16 February 2016), EMBASE (May 2010 to 16 February 2016), LILACS (2010 to 2016), a clinical trials registry, and reference lists of reviews for randomized controlled trials (RCTs) in any language and we retrieved articles.

SELECTION CRITERIA

Randomized, double-blind, placebo- or active-controlled single dose clinical trials of IV paracetamol or IV propacetamol for acute postoperative pain in adults or children.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, which included demographic variables, type of surgery, interventions, efficacy, and adverse events. We contacted study authors for additional information. We graded each included study for methodological quality by assessing risk of bias and employed the GRADE approach to assess the overall quality of the evidence.

MAIN RESULTS

We included 75 studies (36 from the original review and 39 from our updated review) enrolling a total of 7200 participants.Among primary outcomes, 36% of participants receiving IV paracetamol/propacetamol experienced at least 50% pain relief over four hours compared with 16% of those receiving placebo (number needed to treat to benefit (NNT) = 5; 95% confidence interval (CI) 3.7 to 5.6, high quality evidence). The proportion of participants in IV paracetamol/propacetamol groups experiencing at least 50% pain relief diminished over six hours, as reflected in a higher NNT of 6 (4.6 to 7.1, moderate quality evidence). Mean pain intensity at four hours was similar when comparing IV paracetamol and placebo, but was seven points lower on a 0 to 100 visual analog scale (0 = no pain, 100 = worst pain imaginable, 95% CI -9 to -6, low quality evidence) in those receiving paracetamol at six hours.For secondary outcomes, participants receiving IV paracetamol/propacetamol required 26% less opioid over four hours and 16% less over six hours (moderate quality evidence) than those receiving placebo. However, this did not translate to a clinically meaningful reduction in opioid-induced adverse events.Meta-analysis of efficacy comparisons between IV paracetamol/propacetamol and active comparators (e.g., opioids or nonsteroidal anti-inflammatory drugs) were either not statistically significant, not clinically significant, or both.Adverse events occurred at similar rates with IV paracetamol or IV propacetamol and placebo. However, pain on infusion occurred more frequently in those receiving IV propacetamol versus placebo (23% versus 1%). Meta-analysis did not demonstrate clinically meaningful differences between IV paracetamol/propacetamol and active comparators for any adverse event.

AUTHORS' CONCLUSIONS

Since the last version of this review, we have found 39 new studies providing additional information. Most included studies evaluated adults only. We reanalyzed the data but the results did not substantially alter any of our previously published conclusions. This review provides high quality evidence that a single dose of either IV paracetamol or IV propacetamol provides around four hours of effective analgesia for about 36% of patients with acute postoperative pain. Low to very low quality evidence demonstrates that both formulations are associated with few adverse events, although patients receiving IV propacetamol have a higher incidence of pain on infusion than both placebo and IV paracetamol.

Procedural sedation and analgesia in pediatric patients

A spectrum of conditions requires sedation and analgesia in pediatric population. Ineffective treatment of pain may result in physiological and behavioral responses that can adversely affect the developing nociceptive system. The recognition of pain in children can be facilitated by different pain scales. This article reviews the procedural sedation and analgesia (PSA) practices in children along with pharmacology of the drugs used for this purpose.

Comparison of paracetamol (apotel®) and morphine in reducing post pure head trauma headache

Background:

This randomized, clinical trial evaluates the analgesic and safety of paracetamol and Morphine in management of headache.

Objectives:

This study aimed to evaluate the analgesic and safety effects of intravenous single dose of paracetamol, versus morphine in post trauma headache in emergency departments.

Patients and Methods:

This study was a single-center, prospective, randomized, double-blind clinical trial conducted on two groups treated with intravenous paracetamol and intravenous morphine. Thirty patients were enrolled in each group. Patients (18-55 years-old adults) complaining from headaches due to pure trauma were included in the study. The inclusion criteria required patients to have headachesof more than 40 mm on a 100 mm visual analogue scale without any pathological findings in their clinical examinations and imaging studies.

Results:

Mean duration required to treat the headache was 37.43 and 71.93 minutes in the groups administered paracetamol (group A) and morphine (group B), respectively. After 15 minutes of treatment, this changed to 31.7 ± 18.0 mm (95% CI 8.2 to 25.2) and 48.3 ± 14.1 mm (95% CI 8.2 to 25.2) in groups A and B, respectively. Headache of the patients of group A significantly mitigated in comparison with group B (P < 0.005). Headache of group Apatients was significantly mitigated 30 minutes after treatment (P < 0.005).

Conclusions:

Intravenous paracetamol is an effective and safe treatment for patients admitted to the emergency department with headaches caused by head trauma.

Effects of single-dose injectable paracetamolversus propacetamol in pain management after minor gynecologic surgery: A multicenter, randomized, double-blind, active-controlled, two-parallel-group study

BACKGROUND

Intravenous administration is the route of choice for drug therapy in the immediate postoperative period. Propacetamol (ProAPAP), an injectable prodrug of paracetamol requiring reconstitution, has demonstrated efficacy in managing acute pain and fever. However, it has been associated with pain at the injection site. A stable, ready-to-use formulation of paracetamol solution infused intravenously (IV-APAP) has been developed and might be associated with less pain at the injection site compared with ProAPAR.

OBJECTIVE

The objective of this study was to assess the tolerability and efficacy of a single dose of IV APAP 1 g compared with those of a single dose of ProAPAP 2 g in patients with moderate to severe pain after minor gynecologic surgery.

METHODS

This single-dose, randomized, double-blind, active-controlled,2-parallel-group study was conducted at 23 hospitals and outpatient clinics in France. After minor gynecologic surgery, patients reporting moderate to severe pain were randomized to receive a single 15-minute infusion of IV-APAP 1 g or ProAPAP 2 g (bioeyuivalent doses). Tolerability was monitored using local and systemic adverse event (AE) reporting, clinical examination including vital sign measurement, and patients' ratings of acceptability of the infusion. Efficacy end points included pain intensity at 0, 1, 2, 4, and 6 hours; median time to rescue medication (defined as the time at which 50% of patients requested rescue medication); and percentage of patients requesting rescue medication. Patients' satisfaction with the study drugs was assessed using patient's global evaluation (PGE) and the percentage of patients willing to receive the treatment again.

RESULTS

Of the 163 women who were randomized, 161 received the studymedication. The IV-APAP group comprised 80 patients (mean [SD] age, 38.3 [12.8] years [range, 18.0-69.0 years]; mean [SD] weight, 61.1 [11.0] kg [range, 49.0-90.0 kg]), and the ProAPAP group comprised 81 patients (mean [SD] age, 33.9 [12.0] years [range, 18.0-67.0 years]; mean [SD] weight, 61.6 [10.2] kg [range, 42.0-95.5 kg]); the difference in mean age between the 2 groups was statistically significant (P < 0.05). The incidence of local treatment-emergent AEs (TEAEs) was significantly lower in the IV-APAP group compared with that in the ProAPAP group (7.5% vs 38.3%; P < 0.001). No between-group differences in the incidence of systemic TEAEs was found. All patients in the IV-APAP group found the infusion tolerable, compared with 95% of patients in the ProAPAP group. The median time to rescue medication was not evaluated because <50% of the patients in each group requested it. No significant differences in mean pain intensity score or percentage of patients requesting rescue medication were found between the 2 groups at any time point. The percentages of patients in the IV-APAP and ProAPAP groups who rated the study medication as good or excellent on the PGE (83.6% vs 75.6%; P < 0.05) and who were willing to receive the same treatment again (96.0% vs 81.0%; P = 0.005) were significantly higher with IV-APAP compared with ProAPAP.

CONCLUSION

In these patients with moderate to severe pain after minor gynecologic surgery, a single dose of IV-APAP was associated with better local tolerability, similar analgesic efficacy, and greater patient satisfaction compared with a single bioequivalent dose of ProAPAP.

Intravenous paracetamol and dipyrone for postoperative analgesia after day-case tonsillectomy in children: a prospective, randomized, double blind, placebo controlled study

Tonsillectomy is associated with severe postoperative pain for which, several drugs are employed for management.

Objective

In this double-blind, placebo-controlled study we aimed to evaluate the efficacy of intravenous paracetamol and dipyrone when used for post-tonsillectomy analgesia in children.

Method

120 children aged 3-6 yr, undergoing tonsillectomy with or without adenoidectomy and/ or ventilation tube insertion were randomized to receive intraoperative infusions of paracetamol (15 mg/kg), dipyrone (15 mg/kg) or placebo (0.9% NaCl). Evaluation was carried out at 0.25, 0.50, 1, 2, 4, 6h postoperatively. Pethidine 0.25 mg/kg was utilized as rescue analgesic. Cumulative pethidine requirement was the primary outcome. Pain intensity measurement, pain relief, sedation level, nausea and vomiting, postoperative bleeding and any other adverse effects were noted.

Results

No significant difference was found in pethidine requirement between paracetamol and dipyrone groups. Cumulative pethidine requirement was significantly less in paracetamol and dipyrone groups vs. placebo. No significant difference was observed between groups in postoperative pain intensity scores throughout the study.

Conclusion

Intravenous paracetamol is found to have a similar analgesic efficacy as intravenous dipyrone and they both help to reduce the opioid requirement for postoperative analgesia in pediatric day-case tonsillectomy.

S. Pediatric Otolaryngology

Otolaryngologic procedures are commonly performed on children. In fact, pressure equalizing tube placement (ear tubes) and adenotonsillectomy are among the most frequent surgical interventions in the pediatric population. Therefore, every anesthesiologist who manages children undergoing otolaryngologic procedures must be familiar with the special implications of sharing the pediatric airway with an otolaryngologist working in the head and neck region. In addition, it is imperative to be skilled in the challenges of compassionately yet safely managing anxious young patients and their parents from the time of preoperative assessment until discharge from the post anesthesia care unit.

Recent advances in the pharmaceutical management of pain

Pain is an unpleasant sensory and emotional experience for patients. Management of pain is the most frequent issue encountered by clinicians and treatment is usually with pharmacological therapy. This review discusses recent pharmaceutical advances in pain management with respect to new modes of analgesic delivery, as well as new analgesic agents and adjuvants that are currently being investigated for their analgesic properties. New modes of administration include transdermal delivery in the form of skin patches, transmucosal delivery, inhalational administration, various patient-controlled devices and extended-release analgesic formulations. Up-to-date research is presented on classical analgesics, such as opioids, anti-inflammatory agents, including cyclo-oxygenase-2 inhibitors and paracetamol (acetaminophen), local anesthetics and ketamine. In addition, newer agents such as antidepressants and antiepileptic drugs as well as medicinal cannabinoids are discussed. As our understanding of the multiple pain pathways involved in the pathogenesis of pain expands, further compounds with analgesic properties will be developed.

Role of intravenous acetaminophen in postoperative pain management

SUMMARY The need to safely treat the postoperative pain of patients is apparent. Opioids, although effective, have multiple morbidities associated with their use. A multimodal approach to postoperative pain management can serve to minimize the undesirable effects of opioids. Intravenous acetaminophen (paracetamol) has recently become available in the USA where many practitioners are not familiar with this drug. This article reviews the history, pharmacology and clinical uses of intravenous acetaminophen in the treatment of perioperative pain.

Acetaminophen injection: a review of clinical information including forms not available in the United States

Acetaminophen injection is an antipyretic and analgesic agent recently marketed in the United States as Ofirmev. A recent review published in the Journal of Pain & Palliative Care Pharmacotherapy focused on the labeled uses of acetaminophen injection in the United States. A variety of studies were excluded that may be of interest to clinicians. This addendum provides these citations and further insight into the strategy used to develop the review. Acetaminophen injection represents another agent for multimodal pain management.

Population pharmacokinetics of single-dose intravenous paracetamol in children

BACKGROUND

To determine the pharmacokinetics (PK) of a new i.v. formulation of paracetamol (Perfalgan) in children ≤15 yr of age.

METHODS

After obtaining written informed consent, children under 16 yr of age were recruited to this study. Blood samples were obtained at 0, 15, 30 min, 1, 2, 4, 6, and 8 h after administration of a weight-dependent dose of i.v. paracetamol. Paracetamol concentration was measured using a validated high-performance liquid chromatographic assay with ultraviolet detection method, with a lower limit of quantification (LLOQ) of 900 pg on column and an intra-day coefficient of variation of 14.3% at the LLOQ. Population PK analysis was performed by non-linear mixed-effect modelling using NONMEM.

RESULTS

One hundred and fifty-nine blood samples from 33 children aged 1.8-15 yr, weight 13.7-56 kg, were analysed. Data were best described by a two-compartment model. Only body weight as a covariate significantly improved the goodness of fit of the model. The final population models for paracetamol clearance (CL), V(1) (central volume of distribution), Q (inter-compartmental clearance), and V(2) (peripheral volume of distribution) were: 16.51×(WT/70)(0.75), 28.4×(WT/70), 11.32×(WT/70)(0.75), and 13.26×(WT/70), respectively (CL, Q in litres per hour, WT in kilograms, and V(1) and V(2) in litres).

CONCLUSIONS

In children aged 1.8-15 yr, the PK parameters for i.v. paracetamol were not influenced directly by age but were by total body weight and, using allometric size scaling, significantly affected the clearances (CL, Q) and volumes of distribution (V(1), V(2)).

Single dose intravenous propacetamol or intravenous paracetamol for postoperative pain

BACKGROUND

Paracetamol (acetaminophen) is the most commonly prescribed analgesic for the treatment of acute pain. It may be administered orally or intravenously. The efficacy and safety of intravenous (IV) formulations of paracetamol, IV paracetamol and IV propacetamol, compared with placebo and other analgesics, is unclear.

OBJECTIVES

To assess the efficacy and safety of IV formulations of paracetamol for treatment of postoperative pain in both adults and children.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE (1950 to May 2010), EMBASE (1980 to 2010, Week 18), LILACS (1992 to May 2010) and reference lists of retrieved articles.

SELECTION CRITERIA

Randomized, double-blind, placebo- or active-controlled single dose clinical trials of IV propacetamol or IV paracetamol for acute postoperative pain in adults or children.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data. We contacted study authors for additional information. We collected adverse event information from the studies.

MAIN RESULTS

Thirty-six studies (3896 participants) were included. Thirty-seven percent of participants receiving IV propacetamol/paracetamol experienced at least 50% pain relief over four hours compared with 16% of those receiving placebo (number needed to treat to benefit (NNT = 4.0; 95% confidence interval 3.5 to 4.8). The proportion of participants in IV propacetamol/paracetamol groups experiencing at least 50% pain relief diminished over six hours, as reflected in a higher NNT of 5.3 (4.2 to 6.7). Participants receiving IV propacetamol/paracetamol required 30% less opioid over four hours than those receiving placebo. However, this did not translate to a reduction in opioid-induced adverse events.Meta-analysis of efficacy comparisons between IV propacetamol/paracetamol and active comparators (opioids or nonsteroidal anti-inflammatories (NSAIDs)) were either not statistically significant, not clinically significant, or both.Adverse events occurred at similar rates with IV propacetamol or IV paracetamol and placebo. However, pain on infusion occurred more frequently in those receiving IV propacetamol versus placebo (23% versus 1%).Meta-analysis did not demonstrate statistically significant differences between IV propacetamol/paracetamol and active comparators for any adverse event except a reduction in the rate of hypotension versus NSAIDs and a reduction in the rate of gastrointestinal disorders versus opioids.

AUTHORS' CONCLUSIONS

A single dose of both IV propacetamol and IV paracetamol provides around four hours of effective analgesia for about 37% of patients with acute postoperative pain. Both formulations are associated with few adverse events, although patients receiving IV propacetamol have a higher incidence of pain on infusion than both placebo and IV paracetamol.

Is there a role for intravenous acetaminophen in pediatric emergency departments?

BACKGROUND

As a nonopioid parenteral analgesic intravenous (IV) acetaminophen is potentially attractive for emergency department (ED) use. However, there is little experience with its use in the pediatric ED setting. We introduced the agent into a pediatric ED with a preliminary restrictive prescribing regimen and describe its use.

METHODS

This is a retrospective record review of all patients who had received IV acetaminophen over 12 months. Prescribing indications were for analgesia only (not for fever management) in patients at risk of opioid-related adverse events. We assessed the demographics, dosing, presenting complaints, discharge diagnoses, and indications for IV acetaminophen use.

RESULTS

Thirty-one patients received IV acetaminophen (mean age, 10 years). All patients were at least moderately sick according to their triage assessment. The median dose was 15 mg/kg with a median of 1 dose administered. Presenting complaints were mainly trauma, abdominal complaints, and sepsis/fever/neutropenia. Thirty-nine percent of patients had severe underlying conditions. Two patients died: 1 patient had a chronic neurological condition, and the other was undergoing palliative treatment for cancer. Physicians complied with prescribing indications for half the patients: 53% were at risk of opioid-related adverse events. Physicians prescribed outside the initial indications as part of multimodal analgesia (13%), for complex patients with fever and pain (7%), and for fever only in patients unable to tolerate enteral administration (27%).

CONCLUSIONS

In the setting of an initial restrictive prescribing regimen, IV acetaminophen was used in a small number of pediatric ED patients. In addition to use in patients at risk of opioid adverse events, the medication was also used in complex patients who were unable to tolerate an enteral formulation. Emergency department prescribing guidelines have been modified accordingly.

Single-dose intravenous paracetamol or propacetamol for prevention or treatment of postoperative pain: a systematic review and meta-analysis

Paracetamol is the most commonly prescribed analgesic for the treatment of acute pain. The efficacy and safety of i.v. formulations of paracetamol is unclear. We performed a systematic search (multiple databases, bibliographies, any language, to May 2010) for single-dose, randomized, controlled clinical trials of propacetamol or i.v. paracetamol for acute postoperative pain in adults or children. Thirty-six studies involving 3896 patients were included. For the primary outcome, 37% of patients (240/367) receiving propacetamol or i.v. paracetamol experienced at least 50% pain relief over 4 h compared with 16% (68/527) receiving placebo (number needed to treat=4.0; 95% confidence interval, 3.5-4.8). The proportion of patients in propacetamol or i.v. paracetamol groups experiencing at least 50% pain relief diminished over 6 h. Patients receiving propacetamol or paracetamol required 30% less opioid over 4 h and 16% less opioid over 6 h than those receiving placebo. However, this did not translate to a reduction in opioid-induced adverse events (AEs). Similar comparisons between propacetamol or i.v. paracetamol and active comparators were either not statistically significant, not clinically significant, or both. AEs occurred at similar rates with propacetamol or i.v. paracetamol and placebo. However, pain on infusion occurred more frequently in those receiving propacetamol compared with placebo (23% vs 1%). A single dose of either propacetamol or i.v. paracetamol provides around 4 h of effective analgesia for about 37% of patients with acute postoperative pain. Both formulations are associated with few AEs, although patients receiving propacetamol have a higher incidence of pain on infusion.

Acetaminophen Intravenous

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Intravenous acetaminophen

Acetaminophen has unique analgesic and antipyretic properties. It is globally recommended as a first-line agent for the treatment of fever and pain due to its few contraindications. Acetaminophen lacks the significant gastrointestinal and cardiovascular side effects associated with nonsteroidal anti-inflammatory drugs and narcotics. An intravenous formulation of acetaminophen is available in Europe and is currently undergoing extensive clinical development for use in the United States. This use may have important implications for management of postoperative pain and fever. This review summarizes recent clinical trial experiences with intravenous acetaminophen for the treatment of postoperative pain and fever in adult and pediatric subjects.

Pharmacotherapy for acute pain in children: current practice and recent advances

INTRODUCTION

Acute pain in children may be undertreated. Improved understanding of developmental neurobiology and paediatric pharmacokinetics should facilitate better management of pharmacotherapy. The objective of this review is to discuss current paediatric practice and recent advances with these analgesic agents by using an evidence-based approach.

AREAS COVERED

Using PubMed an extensive literature review was conducted on the commonly used analgesic agents in children from 2000 to April 2010.

EXPERT OPINION

A multimodal analgesic regimen provides better pain control and functional outcome in children. The choice of pharmacological treatment is determined by the severity and type of pain. However, more research and evidence is required to determine the optimal drug combinations.

Pharmacologic management of acute pediatric pain

The accurate assessment and effective treatment of acute pain in children in the hospital setting is a high priority. During the past 2 to 3 decades, pediatric pain management has gained tremendous knowledge with respect to the understanding of developmental neurobiology, developmental pharmacology the use of analgesics in children, the use of regional techniques in children, and of the psychological needs of children in pain. A wide range of medications is available to treat a variety of pain types. This article provides an overview of the most common analgesic medications and techniques used to treat acute pain in children.

Intravenous paracetamol (acetaminophen)

Intravenous paracetamol (rINN)/intravenous acetaminophen (USAN) is an analgesic and antipyretic agent, recommended worldwide as a first-line agent for the treatment of pain and fever in adults and children. In double-blind clinical trials, single or multiple doses of intravenous paracetamol 1 g generally provided significantly better analgesic efficacy than placebo treatment (as determined by primary efficacy endpoints) in adult patients who had undergone dental, orthopaedic or gynaecological surgery. Furthermore, where evaluated, intravenous paracetamol 1 g generally showed similar analgesic efficacy to a bioequivalent dose of propacetamol, and a reduced need for opioid rescue medication. In paediatric surgical patients, recommended doses of intravenous paracetamol 15 mg/kg were not significantly different from propacetamol 30 mg/kg for the treatment of pain, and showed equivocal analgesic efficacy compared with intramuscular pethidine 1 mg/kg in several randomized, active comparator-controlled studies. In a randomized, noninferiority study in paediatric patients with an infection-induced fever, intravenous paracetamol 15 mg/kg treatment was shown to be no less effective than propacetamol 30 mg/kg in terms of antipyretic efficacy. Intravenous paracetamol was well tolerated in clinical trials, having a tolerability profile similar to placebo. Additionally, adverse reactions emerging from the use of the intravenous formulation of paracetamol are extremely rare (<1/10 000). [table: see text].

Survey of i.v. paracetamol (acetaminophen) use in neonates and infants under 1 year of age by UK anesthetists

BACKGROUND

The license for i.v. paracetamol has recently been extended to include term neonates and infants aged 1 year, at a uniform dose across this age range of 7.5 mg.kg(-1), total daily dose 30 mg.kg(-1).day(-1). We were interested to survey current i.v. paracetamol prescribing practices of anesthetists in the UK, in neonates and infants under 1 year of age.

METHODS

We conducted an online survey of 94 linkmen of the Association of Pediatric Anesthetists of Great Britain and Ireland Linkmen representing both general and specialist hospitals and 90 members of the British Pediatric Pain Travelling Club representing the pediatric acute pain teams throughout the UK and Ireland.

RESULTS

A total of 105/184 (57%) responded to the survey on behalf of 78 regions and 27 pediatric acute pain teams. Over half (54%) of the respondents indicated i.v. paracetamol use in infants under 1 year of age. A wide range of loading and maintenance doses were used. Total daily doses exceeded the license for age 1-12 months in 70% of cases; for the 36 week postconceptional age (PCA)-1 month age range the proportion was 50%. Over 80% of total daily dosing from age 36 weeks PCA to 1 year fell within dosing suggested by pharmacokinetic studies. Close to 40% of respondents who used i.v. paracetamol in infants, also indicated use in preterm age groups. The total daily dose used in preterm neonates was within the range suggested by pharmacokinetic studies, in over 90% of cases in the age range 32-36 weeks PCA, and for 60% in the under 32 weeks PCA age group.

CONCLUSIONS

This survey demonstrates i.v. paracetamol dosing in infants in the UK and Ireland is frequently above the licensed dose and outside the licensed age range but is in keeping with doses suggested by pharmacokinetic studies.

The preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy in pediatric patients

BACKGROUND

Both ketorolac and propacetamol are used postoperatively to control mild to moderate pain. This study compared the analgesic efficacy of ketorolac and propacetamol delivered either preoperatively or postoperatively, and assessed the preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy.

METHODS

One hundred and two pediatric patients were divided randomly into four groups. The K1 and P1 groups received ketorolac 1 mg/kg or propacetamol 30 mg/kg after induction, respectively, whereas the K2 and P2 groups received each drug at the end of the operation, respectively. After adenotonsillectomy, we measured the NRS (Numerical Rating Scale), FPS (Faces Pain Scale) and OPS (Objective Pain scale) at 15, 30 and 60 min after arriving at the postanesthesia care unit.

RESULTS

There were no significant differences in the NRS, FPS and OPS between K1 and K2 and between P1 and P2 for 60 min after operation at the postanesthesia care unit.

CONCLUSIONS

These results suggest that both ketorolac (1 mg/kg) and propacetamol (30 mg/kg) have no preemptive analgesic effects during 1 hour after adenotonsillectomy.

Paracetamol and fever management

Paracetamol is one of the most commonly used legal drugs in the western world. Its availability is good, cost is low, and its uses include `over-the-counter' (OTC) distribution, primary care prescribed therapy, secondary care `post-operative' application and emergency treatment. Stated benefits of paracetamol include: the drug's analgesic effects, preference to aspirin in avoidance of Reye's syndrome, good patient tolerance, and iatrogenic complications are infrequent and minor. Stated cautions include hepatotoxic effect following minor doses and short duration use and users may incur compromised immune integrity. This paper is concerned with paracetamol's role in fever management. Public concern regarding, in particular, childhood fever and febrile convulsions is largely unwarranted. Despite paracetamol's reputation as a popular fever-reducing agent the drug is poorly effective in the control of febrility and febrile convulsions showing no important advantage compared with placebo. Paracetamol is probably grossly over-prescribed for fever management and its value more perceived than real. Greater efforts are needed to inform patients of the natural benefits of the biological strategy of fever and of the highly limited and in some cases contraindicated use of paracetamol in fever management.

The perioperative management of pain from intracranial surgery

Analgesic therapy following intracranial procedures remains a source of concern and controversy. Although opioids are the mainstay of the "balanced" general anesthetic techniques frequently used during intracranial procedures, neurosurgeons and others have been reluctant to administer opioid analgesics to patients following such procedures. This practice is supported by the concern that the sedation and miosis associated with opioid administration could mask the early signs of intracranial catastrophe, or even exacerbate it through decreased ventilatory drive, elevated arterial carbon dioxide levels, and increased cerebral blood flow. This reluctance to use opioids following intracranial surgery is enabled by decades of training and anecdote emphasizing that pain is minimal following these procedures. However, recent data suggests otherwise, and raises the question of how to provide safe and effective analgesia for these patients. Here, this data is reviewed along with the relevant pain pathways, analgesic drugs and techniques, and the available data on their use following intracranial surgery. Although pain following intracranial surgery appears to be more intense than initially believed, it is readily treated safely and effectively with techniques that have proven useful following other types of surgery, including patient-controlled administration of opioids. The use of multimodal analgesic therapy is emphasized not only for its effectiveness, but to reduce dosages and, therefore, side effects, primarily of the opioids, that could be of legitimate concern to physicians and affect the comfort of their patients.

I.V. acetaminophen pharmacokinetics in neonates after multiple doses

BACKGROUND

Pharmacokinetics of an i.v. prodrug of acetaminophen (propacetamol) in neonates after repeat dosing are reported, with scant data for i.v. acetaminophen formulation.

METHODS

Neonates from an intensive care unit received 6-hourly prn i.v. acetaminophen dosed according to postmenstrual age (PMA): 28-32 weeks, 10 mg kg(-1); 32-36 weeks, 12.5 mg kg(-1); and > or =36 weeks, 15 mg kg(-1). A maximum of five blood samples for assay and liver function tests (LFTs) were collected. A one-compartment linear disposition model (zero-order input; first-order elimination) was used to describe time-concentration profiles using population modelling (NONMEM).

RESULTS

Fifty neonates, median (range) PMA 38.6 (32-45) weeks, mean (SD) weight 2.9 (0.7) kg, received a mean of 15 doses over a median 4 days with 189 serum acetaminophen and 231 LFT measurements. Standardized population parameter estimates for a term neonate were clearance (CL) 5.24 (CV 30.5%) litre h(-1) 70 kg(-1) and volume of distribution (V) 76 (29.6%) litre 70 kg(-1). CL increased with PMA from 4.4 litre h(-1) 70 kg(-1) at 34 weeks to 6.3 litre h(-1) 70 kg(-1) at 46 weeks. The presence of unconjugated hyperbilirubinaemia was associated with reduced CL: 150 micromol litre(-1) associated with 40% CL reduction. Acetaminophen concentrations between 10 and 23 mg litre(-1) at steady state are predicted after 15 mg kg(-1) 6-hourly for a neonate of PMA 40 weeks. Hepatic enzyme analysis of daily samples changed significantly for one patient whose alanine aminotransferase concentration tripled.

CONCLUSIONS

The parameter estimates are similar to those described for propacetamol. There was no evidence of hepatotoxicity. Unconjugated hyperbilirubinaemia impacts upon CL, dictating dose reduction.

Hepatic tolerance of repeated intravenous paracetamol administration in neonates

INTRODUCTION

An intravenous (i.v.) formulation of paracetamol is available, but reports on its hepatic tolerance in neonates are limited. We therefore assessed hepatic tolerance of i.v. paracetamol in neonates.

METHODS

In a single centre retrospective study, clinical data and hepatic enzyme profiles (ALT, AST, gammaGT) were collected in neonates treated with i.v. paracetamol between January 1, 2006 and October 1, 2007. Hepatic enzyme profiles were retrieved from 2 days before until 2 days after i.v. paracetamol administration. Mann-Whitney U-test was used to compare hepatic enzymes before, during, and after i.v. treatment. Correlations (Spearman rank) of hepatic enzymes with duration of treatment during i.v. administration were investigated.

RESULTS

In 189 cases, 2360 administrations {postmenstrual age 38 (range 30-55) weeks, postnatal age 5 (1-182) days} were documented and 1132 hepatic enzyme observations were available in 149/189 cases. There was no significant increase in ALT, AST, or gammaGT when pretreatment observations (n = 310) were compared with observations during (n = 649) or during with after (n = 173) treatment, nor was there a significant increase during administration.

CONCLUSIONS

This retrospective study on hepatic tolerance provides evidence on safety aspects of i.v. paracetamol in neonates. Future studies should focus on dose-findings and pharmacodynamics of this formulation in neonates.

Randomized controlled trial of duration of analgesia following intravenous or rectal acetaminophen after adenotonsillectomy in children

BACKGROUND

Doses of acetaminophen 40 mg kg(-1) rectally and 15 mg kg(-1) i.v. produce similar effect-site concentrations. However, the clinical effectiveness of these routes has not been compared. The aim of this study was to compare duration and efficacy of analgesia in children following adenotonsillectomy after acetaminophen either 40 mg kg(-1) rectally or 15 mg kg(-1) i.v.

METHODS

Fifty children aged between 2 and 5 yr were recruited. They received a standardized anaesthetic, including 2 microg kg(-1) of fentanyl. Children were randomized to receive either rectal or i.v. acetaminophen. Postoperative pain was assessed regularly with the Children and Infants Postoperative Pain Scale score and rescue analgesia provided if scores were 4 or greater. The primary outcome measure was time to first analgesia. Results were plotted with a Kaplan-Meier analysis and median time to rescue analgesia compared between the groups.

RESULTS

The protocol was successfully completed in 46 children. Forty-five children required rescue medication. The time to first rescue analgesia was longer in children receiving rectal acetaminophen (median 10 h, inter-quartile range 9-11 h) compared with those receiving i.v. acetaminophen (7, 6-10 h) with a P-value of 0.01 by log-rank test for equality in survivor function. Few children in either group required rescue analgesia within the first 6 h with differences between the groups being most prominent in the period from 6 to 10 h.

CONCLUSIONS

Rectal acetaminophen 40 mg kg(-1) provides longer analgesia for moderately painful procedures when compared with 15 mg kg(-1) acetaminophen i.v.

Intravenous paracetamol: a review of efficacy and safety in therapeutic use

Paracetamol is well established as a leading nonprescription antipyretic analgesic drug and is available in oral, rectal or intravenous forms. However, except for oral paracetamol, there is a marked discrepancy between the extent to which paracetamol is used and the available evidence for an analgesic effect in postoperative pain. This review mainly focuses on intravenous paracetamol. Its efficacy and safety are analyzed, as well as its use in therapeutics, alone or in combination. The morphine-sparing, additive and antihyperalgesia effects of intravenous paracetamol are also reviewed. The analyses are divided into several sections, comparing the efficacy of intravenous paracetamol with placebo, other forms of paracetamol or analgesic agents and analyzing its efficacy in multimodal therapy combined with NSAIDs or a morphinic agent.

Paracetamol (acetaminophen) penetrates readily into the cerebrospinal fluid of children after intravenous administration

INTRODUCTION

The main action of paracetamol (acetaminophen) is presumed to be in the central nervous system. The central nervous system penetration of paracetamol has been described in children with intracranial pathologies but not in children with an intact blood-brain barrier.

OBJECTIVE

We investigated the cerebrospinal fluid penetration of paracetamol in 32 healthy children, aged 3 months to 12 years, who were undergoing surgery in the lower body using spinal anesthesia.

MATERIALS AND METHODS

In this open-label prospective study, children were given a single intravenous injection of paracetamol (15 mg/kg). Cerebrospinal fluid and venous blood samples were obtained between 5 minutes and 5 hours after injection. Paracetamol concentrations were determined from the cerebrospinal fluid and plasma by using a fluorescence polarization immunoassay.

RESULTS

Paracetamol was detected in cerebrospinal fluid from the earliest sample at 5 minutes, although in this sample paracetamol concentration was below the limit of quantification of 1.0 mg/L. Subsequent paracetamol concentrations in cerebrospinal fluid ranged between 1.3 and 18 mg/L (median: 7.2 mg/L), plasma concentrations ranged between 2.4 and 33 mg/L, and cerebrospinal fluid/plasma ratios ranged between 0.06 and 2.0. The highest CSF paracetamol concentration was detected at 57 minutes.

CONCLUSIONS

Paracetamol permeates readily into the cerebrospinal fluid of children. This fast and extensive transfer enables the rapid central analgesic and antipyretic action of intravenous paracetamol.