Role of Paracetamol in Acute Pain Management

Paracetamol (acetaminophen) use in infants and children was never shown to be safe for neurodevelopment: a systematic review with citation tracking

Although widely believed by pediatricians and parents to be safe for use in infants and children when used as directed, increasing evidence indicates that early life exposure to paracetamol (acetaminophen) may cause long-term neurodevelopmental problems. Furthermore, recent studies in animal models demonstrate that cognitive development is exquisitely sensitive to paracetamol exposure during early development. In this study, evidence for the claim that paracetamol is safe was evaluated using a systematic literature search. Publications on PubMed between 1974 and 2017 that contained the keywords "infant" and either "paracetamol" or "acetaminophen" were considered. Of those initial 3096 papers, 218 were identified that made claims that paracetamol was safe for use with infants or children. From these 218, a total of 103 papers were identified as sources of authority for the safety claim.   Conclusion: A total of 52 papers contained actual experiments designed to test safety, and had a median follow-up time of 48 h. None monitored neurodevelopment. Furthermore, no trial considered total exposure to drug since birth, eliminating the possibility that the effects of drug exposure on long-term neurodevelopment could be accurately assessed. On the other hand, abundant and sufficient evidence was found to conclude that paracetamol does not induce acute liver damage in babies or children when used as directed. What is Known: • Paracetamol (acetaminophen) is widely thought by pediatricians and parents to be safe when used as directed in the pediatric population, and is the most widely used drug in that population, with more than 90% of children exposed to the drug in some reports. • Paracetamol is known to cause liver damage in adults under conditions of oxidative stress or when used in excess, but increasing evidence from studies in humans and in laboratory animals indicates that the target organ for paracetamol toxicity during early development is the brain, not the liver. What is New: • This study finds hundreds of published reports in the medical literature asserting that paracetamol is safe when used as directed, providing a foundation for the widespread belief that the drug is safe. • This study shows that paracetamol was proven to be safe by approximately 50 short-term studies demonstrating the drug's safety for the pediatric liver, but the drug was never shown to be safe for neurodevelopment. Paracetamol is widely believed to be safe for infants and children when used as directed, despite mounting evidence in humans and in laboratory animals indicating that the drug is not safe for neurodevelopment. An exhaustive search of published work cited for safe use of paracetamol in the pediatric population revealed 52 experimental studies pointing toward safety, but the median follow-up time was only 48 h, and neurodevelopment was never assessed.

Canadian Urological Association best practice report on chronic scrotal pain

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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.

Evaluation of gabapentin and dexamethasone alone or in combination for pain control after adenotonsillectomy in children

Background:

Different methods and many drugs have been used to control the post-operative pain. In this study, we evaluate the role of gabapentin premedication and/or dexamethasone in management of post-operative pain following adenotonsillectomy in children.

Materials and Methods:

In a double-blind randomized study, 120 children were subjected for adenotonsillectomy classified into three equal groups. Group G: Gabapentin 10 mg/kg was given orally 2 h before induction of anesthesia (Gabapentin syrup 250 mg/5 ml. Group D: Children in this group received placebo pre-operatively and received dexamethasone 0.15 mg/kg intravenously after induction of anesthesia, but before surgery. Group C: Children in this group received combination of oral gabapentin 10 mg/kg 2 h before induction of anesthesia and intra-operative 0.15 mg/kg dexamethasone intravenously. All children underwent general anesthesia. Pain score was assisted post-operatively 2 h, 4 h, 6 h, 8 h, 12 h and 18 h after recovery using face, legs, activity, cry, consolability scale.

Results:

Pain score in Group C and Group G was significantly less at 4 h, 6 h and 8 h post-operatively than in Group D (P < 0.05). At 12 h, the pain score in Group C was significantly less than Group G and Group D (P < 0.05). And no significant changes were observed in pain score at 18 h post-operatively between all groups (P > 0.05). The time to first analgesia was longer in the Group C than in Group G and Group D and the time to first analgesia was significantly longer in Group G than in Group D (P < 0.05). The total amount of pethidine was less in Group C and Group G than in Group D (P < 0.05). The incidence of post-operative nausea and vomiting was statically insignificant among all groups and no reported post-operative bleeding.

Conclusion:

Gabapentin 10 mg/kg premedication combined with intra-operative dexamethasone 0.15 mg/kg prolongs the post-operative analgesia following adenotonsillectomy in children and decreases the amount of pethidine used post-operatively with no reported adverse effects or increase in the incidence of post-operative bleeding.

Administration of paracetamol versus dipyrone by intravenous patient-controlled analgesia for postoperative pain relief in children after tonsillectomy

BACKGROUND AND OBJECTIVE

We compared the efficacy of intravenous (IV) paracetamol versus dipyrone via patient-controlled analgesia (PCA) for postoperative pain relief in children.

METHODS

The study was composed of 120 children who had undergone elective tonsillectomy after receiving general anesthesia. Patients were divided into 3 groups according to the dosage of postoperative intravenous-patient-controlled analgesia: paracetamol, dipyrone, or placebo. Pain was evaluated using a 0- to 100-mm visual analog scale and 1- to 4-pain relief score at 30 min, 1, 2, 4, 6, 12, and 24h postoperatively. Pethidine (0.25 mg kg(-1)) was administered intravenously to patients requiring rescue analgesia. Pethidine requirements were recorded during the first 24h postoperatively, and treatment related adverse effects were noted.

RESULTS

Postoperative visual analog scale scores were significantly lower with paracetamol group compared with placebo group at 6h (p<0.05), dipyrone group compared with placebo group at 30 min and 6h (p<0.05). No significant differences regarding visual analog scale values at 1, 2, 4, 12, and 24h were found. No significant differences were found between groups with respect to pain relief score (p>0.05). Postoperative pethidine requirements were significantly lower with paracetamol and dipyrone groups compared with placebo group (62.5%, 68.4% vs 90%, p<0.05). No significant differences were found between groups with respect to nausea, vomiting and the any other adverse effects of the drugs (p>0.05).

CONCLUSIONS

Paracetamol and dipyrone have well tolerability profile and effective analgesic properties when administered IV-PCA for postoperative analgesia in children after tonsillectomy.

Comparison of a novel fast-dissolving acetaminophen tablet formulation (FD-APAP) and standard acetaminophen tablets using gamma scintigraphy and pharmacokinetic studies

CONTEXT

Acetaminophen (paracetamol, APAP) is widely used to relieve mild-to-moderate pain and reduce fever. Absorption of the drug can be impacted by dosage form; this may have implications for pain relief in some individuals, potentially accounting for suboptimal efficacy in analgesia.

OBJECTIVE

To assess the disintegration and dissolution of a new fast-dissolving acetaminophen tablet formulation (FD-APAP) and the impact on pharmacokinetic and pharmacodynamic parameters.

MATERIALS AND METHODS

Two randomized, single-center, open-label, single-dose, two-way crossover studies in healthy subjects to compare FD-APAP (2 × 500 mg tablets) with standard acetaminophen (2 × 500 mg tablets). Gamma scintigraphy was used to assess tablet disintegration (Study 1, N = 24), and plasma profiles were evaluated in the fasted state (Study 2, N = 40).

RESULTS

In Study 1, the mean time to complete disintegration (12.9 vs. 69.6 min, P < 0.0001) and onset of disintegration were both significantly faster with FD-APAP than with standard acetaminophen (P < 0.0001). For Study 2, median T(max) was significantly faster for FD-APAP (0.50 vs. 0.67 h, P < 0.01) and AUC(0-30 min) was significantly greater (4.51 vs. 2.74, P < 0.05). AUC(0-t) and AUC(0-inf) were comparable between the two study treatments.

DISCUSSION

Despite the absence of comparative clinical data, the FD-APAP formulation may be expected to overcome some of the issues associated with the slow and variable absorption of standard acetaminophen tablet formulations, improving therapeutic outcome and avoiding the need to switch to alternative therapeutic options.

CONCLUSION

Compared with standard acetaminophen, the FD-APAP formulation results in significantly faster onset of disintegration and more rapid absorption.

Intravenous paracetamol reduced the use of opioids, extubation time, and opioid-related adverse effects after major surgery in intensive care unit

BACKGROUND

This study assessed the analgesic efficacy, side effects, and time to extubation of intravenous paracetamol when administered as an adjuvant to intravenous meperidine after major surgery in intensive care unit (ICU).

MATERIAL

Patients were randomized postoperatively into 2 groups in ICU. Patients received either 100 mL of serum saline intravenous (IV) every 6 hours and IV meperidine (n = 20 group M) or IV paracetamol 1 g every 6 hours and IV meperidine (n = 20, group MP) into a peripheral vein for 24 hours. Behavioral Pain Scale (BPS) is used until extubation, and visual analog score (VAS) is used after extubation. When BPS and VAS values were more than 4, meperidine, 1 mg/kg IV, was administered and noted in 2 groups. Pain scores, total meperidine consumption, time to extubation, sedation scores, and side effects are 24-hour postoperatively noted.

RESULTS

Behavioral Pain Scale and VAS scores are significantly lower in group paracetamol-meperidine at 24 hours (P < .05). In group MP, postoperative meperidine consumption (76.75 ± 18.2 mg vs. 198 ± 66.4 mg) and extubation time (64.3 ± 40.6 min vs. 204.5 ± 112.7 min) were lower than in group M (P < .01). In addition to, postoperative nausea-vomiting and sedation scores were significantly lower in group MP when compared with group M (P < .05).

CONCLUSION

We have demonstrated important clinical benefits by the addition of 4 g/d of paracetamol to meperidine after major surgery. This benefit has been shown in a range of patients under routine clinical conditions and therefore has important practical consequences in ICU. These data suggest that intravenous paracetamol is a useful component of the multimodal analgesia model, especially after major surgery.

Paracetamol versus metamizol in the treatment of postoperative pain after breast surgery: a randomized, controlled trial

BACKGROUND AND OBJECTIVE

Intravenously administered paracetamol is an effective analgesic in postoperative pain management. However, there is a lack of data on the effect of intravenous (i.v.) paracetamol on pain following soft tissue surgery.

METHODS

Eighty-seven patients undergoing elective breast surgery with total i.v. anaesthesia (propofol/remifentanil) were randomized to three groups. Group para received 1 g i.v. paracetamol 20 min before and 4, 10 and 16 h after the end of the operation. Group meta and plac received 1 g i.v. metamizol or placebo, respectively, scheduled at the same time points. All patients had access to i.v. morphine on demand to achieve adequate pain relief.

RESULTS

No significant difference in total morphine consumption between groups was detectable. The proportion of patients who did not receive any morphine in the postoperative period was significantly higher in group para (42%) than in group plac (4%). Ambulation was significantly (P < 0.05) earlier in group para (4.0 +/- 0.2 h) than in groups meta (4.6 +/- 0.2 h) and plac (5.5 +/- 1.0 h). No differences were observed between groups meta and plac. There were no differences between groups with regard to incidence of postoperative nausea and vomiting or changes in vigilance.

CONCLUSION

Neither i.v. paracetamol nor i.v. metamizol provided a significant reduction in total postoperative morphine consumption compared with placebo in the management of postoperative pain after elective breast surgery. Administration of paracetamol resulted in a significant reduction in the number of patients needing opioid analgesics to achieve adequate postoperative pain relief.

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].

[Drugs for postoperative analgesia: routine and new aspects. Part 1: non-opioids]

In part 1 of this review the perioperative aspects of the use of non-opioids (acetaminophen, dipyrone, traditional NSAR, coxibs) and in part 2 of opioids (weak opioids: tramadol, tilidine with naloxone, strong opioids: morphine, piritramide, oxycodone, hydromorphone, fentanyl, methadone, buprenorphine) and coanalgesics (gabapentinoids, ketamine) will be discussed. The main aim is to describe the relationship between analgesic efficacy and side effects to make clinical decisions easier in patients with preoperative renal, gastrointestinal, cardiovascular and other diseases. Some new aspects concerning perioperative administration of gabapentinoids and ketamine in patients with perioperative neuropathic pain are discussed.

[Post-operative pain management in orthopaedic surgery and traumatology]

Provision of sufficient post-operative pain therapy is an obligation in the clinical management of patients. A wide range of medical, technical and organizational options is used to improve post-operative pain management in orthopaedic surgery. Measurement of pain is as important as the correct use of analgesics and application techniques. Standardized pain therapy algorithms should facilitate autonomous treatment of patients. Additional procedures like patient-controlled analgesia or local catheter for pain are necessary for individualized or operation-specific pain therapy. The balanced combination in postoperative pain therapy could reduce side effects and complication rates, increase mobility and enhance patient satisfaction.

Multimodal Analgesia Techniques and Postoperative Rehabilitation

The concept of multimodal analgesia involves the use of different classes of analgesics and different sites of analgesic administration to provide superior dynamic pain relief with reduced analgesic-related side effects. Although multimodal analgesia techniques have assumed increasing importance in the management of perioperative pain, it has become increasingly apparent that postoperative outcome may not be improved. Nevertheless, the integration of multimodal analgesia techniques with a multimodal and multidisciplinary rehabilitation program may enhance recovery, reduce hospital stay, and facilitate early convalescence.