Effect of 3 g of intravenous paracetamol on post-operative analgesia, platelet function and liver enzymes in patients undergoing tonsillectomy under local anaesthesia

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.

Not all (N)SAID and done: Effects of nonsteroidal anti-inflammatory drugs and paracetamol intake on platelets

Platelets are key mediators of hemostasis and thrombosis and can be inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). As a result, platelet donors are temporarily deferred from donating if they have recently taken NSAIDs such as aspirin or ibuprofen. Despite these measures, a proportion of platelet donations show exposure to these drugs; however, little is known about the effect of NSAIDs and their metabolites on platelet quality in vivo and during storage. In this review, the effect of NSAIDs on platelet function is summarized, with a focus on the widely consumed over-the-counter (OTC) medications aspirin, ibuprofen, and the non-NSAID paracetamol. Aspirin and ibuprofen have well-defined antiplatelet effects. In comparison, studies regarding the effect of paracetamol on platelets report variable findings. The timing and order of NSAID intake is important, as concurrent NSAID use can inhibit or potentiate platelet activation depending on the drug taken. NSAID deferral periods and maximum platelet shelf-life is set by each country and are revised regularly. Reduced donor deferral periods and longer platelet storage times may affect the quality of platelet products, and it is therefore important to identify the possible impact of NSAID intake on platelet quality before and after storage.

Oral Diclofenac Potassium Versus Intravenous Acetaminophen in Acute, Isolated, Closed-Limb Trauma

Pain control is an important concern in limb trauma. The most ideal agent for this purpose varies among different hospitals. The objective of this study was to compare the analgesic effect of oral diclofenac potassium versus intravenous acetaminophen in patients with limb trauma. This was a double-blind randomized clinical trial conducted on 60 adult patients. Oral diclofenac potassium (50 mg) was given in Group D, and intravenous acetaminophen (1 g in 500 ml normal saline over 20 min) was administered in Group A. Patients' pain scores (visual analogue scale) were recorded and compared at baseline, 5, 15, 30, 60 min, and 4 hr after drug administration. The mean age was 42.62 ± 15.42 and 38.04 ± 17.48 years in Group A and Group D, respectively. No significant change was observed between the 2 groups (p = 0.11). In this study, both drugs could decrease the pain score effectively and safely in isolated limb trauma.

Randomized Prospective Evaluation of Intraoperative Intravenous Acetaminophen in Pediatric Adenotonsillectomy

Objective

To establish the safety and efficacy of single-dose intraoperative intravenous (IV) acetaminophen in postoperative pain management following adenotonsillectomy in addition to a standardized regimen of oral pain medication.

Study Design

Randomized, controlled prospective clinical trial.

Setting

Single academic medical center.

Subjects and Methods

Patients between the ages of 3 and 17 years scheduled for tonsillectomy or adenotonsillectomy by a single surgeon between December 2014 and November 2016 were recruited. Patients were randomly assigned to 1 of 2 groups; group 1 received a single intraoperative dose of IV acetaminophen, and group 2 did not. Induction and maintenance of anesthesia, as well as operative technique, were standardized. Nursing pain scores, pain medications administered, and recovery times were reviewed during the 24-hour postoperative period. Postoperative pain regimen included standing alternating oral acetaminophen and ibuprofen.

Results

In total, 260 patients were included in the study, and 131 (50.4%) received a single intraoperative dose of IV acetaminophen. Patients receiving IV acetaminophen were more likely to experience postoperative nausea and vomiting than patients who did not receive IV acetaminophen (1.53% vs 0.00%, P = .016). There were no significant differences noted for postoperative pain scores, requirements for breakthrough pain medications, time to discharge from the recovery room or hospital, or postoperative complications.

Conclusion

The use of a single intraoperative dose of IV acetaminophen was associated with minimal additional adverse effects. However, a single intraoperative IV dose of acetaminophen added to standard narcotic and nonnarcotic pain medication does not provide a statistically significant improvement in pain control.

Expression of glutathione S-transferase A1, a phase II drug-metabolizing enzyme in acute hepatic injury on mice

In the present study, three models of acute liver injury in mice were induced via the administration of CCl₄ (35 mg/kg, 24 h), acetyl-para-aminophenol (APAP; 200 mg/kg, 12 h) and ethanol (14 ml/kg, 8 h) to study the effect of glutathione S-transferase A1 (GSTA1) on acute liver injury. The serum levels of alanine transaminase, aspartate transaminase and liver homogenate indicators (superoxide dismutase, glutathione and glutathione peroxidase) were significantly lower in model groups compared with the control group (P<0.01), whereas the liver homogenate indicator malondialdehyde was significantly increased (P<0.01). The expression of GSTA1 in liver was significantly decreased in the model groups compared with the control group (P<0.01). GSTA1 protein content was 3.8, 1.3 and 2.6 times lower in the CCl_4, APAP and ethanol model groups, respectively. Furthermore, GSTA1 mRNA expression levels decreased by 4.9, 2.1 and 3.7 times in the CCl_4, APAP and ethanol model groups, respectively. Among the three models, the injury induced by CCl₄ was the most marked, followed by ethanol and finally APAP. These results suggest that GSTA1 may be released by the liver and serve as an antioxidant in the prevention of liver damage.

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.

Single-dose systemic acetaminophen to prevent postoperative pain: a meta-analysis of randomized controlled trials

OBJECTIVES

The effect of a single-dose systemic acetaminophen to treat postoperative pain has been previously quantified, but the effect of systemic acetaminophen to prevent postoperative pain is currently not well defined. The preventive analgesic effect of acetaminophen has yet to be quantified in a meta-analysis. The objective of the current investigation was to evaluate the effect of a single preventive dose of systemic acetaminophen on postoperative pain outcomes.

MATERIALS AND METHODS

A wide search was performed to identify randomized controlled trials that evaluated the effects of a single dose of systemic acetaminophen on pain outcomes in a large variety of surgical procedures. Meta-analysis was performed using a random-effect model.

RESULTS

Eleven randomized clinical trials evaluating 740 patients were included in the analysis. The weighted mean difference (95% confidence interval [CI]) of the combined effects favored acetaminophen over control for early pain at rest (≤4 h, -1.1 (-2.0 to -0.2)) and early pain at movement (24 h, -1.9 (-2.8 to -1.0)) Postoperative opioid consumption was decreased in the systemic acetaminophen group compared with control. Weighted mean difference (95% CI) of -9.7 (-13.0 to -6.4) mg morphine intravenous equivalents systemic acetaminophen also reduced postoperative nausea and vomiting compared with control, odds ratio (95% CI) of 0.25 (0.13 to 0.47), numbers needed to treat (95% CI)=3.3 (2.3 to 5.9).

DISCUSSION

Systemic acetaminophen, when used as a single-dose preventive regimen, is an effective intervention to reduce postoperative pain. It also reduces postoperative nausea and/or vomiting. Doses >1 g were not associated with greater reduction in pain outcomes.

Impairment of aspirin antiplatelet effects by non-opioid analgesic medication

Aspirin is the mainstay in prophylaxis of cardiovascular diseases. Impaired aspirin antiplatelet effects are associated with enhanced incidence of cardiovascular events. Comedication with non-opioid analgesic drugs has been described to interfere with aspirin, resulting in impaired aspirin antiplatelet effects. Additionally, non-opioid analgesic medication has been shown to enhance the risk of cardiovascular events and death. Pain is very frequent and many patients rely on analgesic drugs to control pain. Therefore effective analgesic options without increased risk of cardiovascular events are desirable. This review focuses on commonly used non-opioid analgesics, interactions with aspirin medication and impact on cardiovascular risk.

Median effective dose (ED₅₀) of paracetamol and morphine for postoperative pain: a study of interaction

BACKGROUND

Paracetamol is widely used to treat postoperative pain and is well known for its morphine-sparing effect. Therefore, the effect of morphine-paracetamol combination can be synergistic, additive, or infra-additive. The primary aim of our study is to define the median effective analgesic doses (ED₅₀s) of paracetamol, morphine, and the combination of both. Also, the nature of the interaction for postoperative pain after moderately painful surgery using an up-and-down method and isobolographic analysis was determined.

METHODS

Ninety patients, undergoing moderately painful surgery, were included in one of the three groups. Determination of the median ED₅₀s was performed by the Dixon and Mood up-and-down method. Initial doses were 1.5 g and 5 mg, with dose adjustment intervals of 0.5 g and 1 mg, in the paracetamol and morphine groups, respectively. The initial doses of paracetamol and morphine were 1.5 g and 3 mg, in the paracetamol-morphine combination group with dose adjustment intervals of 0.25 g for paracetamol and 0.5 mg for morphine. Analgesic efficacy was defined as a reduction to or <3 on a 0-10 numeric rating scale, 45 min after the beginning of drug administration. Isobolographic analysis was used to define the nature of their interaction.

RESULTS

The median ED₅₀s of paracetamol and morphine were 2.1 g and 5 mg, respectively. The median ED₅₀ of the combination was 1.3 g for paracetamol and 2.7 mg for morphine.

CONCLUSIONS

Our study showed that the combination of the paracetamol and morphine produces an additive analgesic effect. Clinical trial registration NCT01366313.

General anaesthetic considerations for haemostasis in orbital surgery

Orbital surgery is often conducted in areas with limited exposure where vital structures are tightly crowded together. A bloodless field is paramount in orbital surgery for the proper identification of normal and pathologic tissue and even minimal bleeding can obscure the surgical field, making surgery more difficult and increasing the risk of complications. Surgery for highly vascular orbital lesions is an additional situation where maintaining an adequate surgical field is often challenging but paramount. The role of the anaesthetist in controlling surgical blood loss has been increasingly recognized in the last few decades. Various techniques including hypotensive anaesthesia have been described, but the control of intraoperative bleeding does not rely on a single particular technique, but a series of well-designed interventions that result in optimal conditions. An understanding of the anaesthetic considerations pertinent to haemostasis is invaluable for oculoplastic surgeons. Additionally, with the growing use of endonasal approaches to medial wall decompression and accessing the medial orbit, it has become increasingly important that orbital surgeons understand the anaesthetic requirements of their colleagues in other disciplines.

How to make tonsillectomy a safer procedure: the anaesthetist's view

Anaesthetists use specific drugs peri-operatively to try to decrease the incidence and severity of postoperative pain and of postoperative nausea and vomiting. These drugs are usually administered pre-operatively with the premedication, or intra-operatively when the patient is still anaesthetised. The aim of this approach is to prevent the occurrence of intolerable pain or to avoid any nausea or vomiting symptoms which may be clearly unpleasant for the patient and which interfere with the patient's well-being, recovery and satisfaction. However, since most of these drugs are given prophylactically, and since not all patients will actually be suffering from intolerable pain or severe nausea and vomiting symptoms postoperatively, many patients will receive these drugs unnecessarily. Thus, for the individual patient, the risk of suffering from drug-related adverse reactions without profiting from any benefit may be relevant. Perhaps a 'wait-and-see' approach should be considered; especially non-steroidal anti-inflammatory drugs or dexamethasone should not be given pre-operatively to all patients but should be provided exclusively to those in whom alternative analgesics (for instance, paracetamol combined with a weak opioid) or alternative anti-emetics (for instance, a setron or droperidol) have failed or are associated with unacceptable adverse effects. There is no evidence that prophylactic administration of an analgesic or an anti-emetic is more efficacious than the therapeutic administration. An interesting alternative to achieve satisfactory posttonsillectomy analgesia may be with local anaesthesia swabs that are applied onto the wound.

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.

Clinical and economic evidence for intravenous acetaminophen

Intravenous acetaminophen received United States Food and Drug Administration approval in November 2010 for the management of mild-to-moderate pain, management of moderate-to-severe pain with adjunctive opioid analgesics, and reduction of fever. Although intravenous acetaminophen generally improved pain relief and demonstrated opioid-sparing effects compared with placebo, it did not consistently reduce the frequency of opioid-related adverse events (e.g., postoperative nausea and vomiting). The safety and efficacy of intravenous acetaminophen as an antipyretic agent have been documented in adults and children; however, its cost is several-fold higher than that of the oral and rectal formulations. Although use of intravenous acetaminophen has reduced other postoperative resource utilization (e.g., hospital length of stay) in some studies outside the United States in patients undergoing abdominal surgery, a full economic evaluation in the United States has yet to be undertaken. In addition, its administration time (15-min infusion) and packaging (glass, single-use vial) have the potential to adversely affect patient flow in the postanesthesia care unit, create burden on patient care units, and lead to drug waste. Furthermore, 1 g of intravenous acetaminophen is formulated in 100 ml of solution, which may be an issue for patients with fluid restrictions. Given the clinical and economic evidence currently available, intravenous acetaminophen should not replace oral or rectal acetaminophen, but its use may be considered in a limited number of patients who cannot receive drugs orally and rectally and who cannot tolerate other parenteral nonopioid analgesic or antipyretic agents.

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.

Continuous multimechanistic postoperative analgesia: a rationale for transitioning from intravenous acetaminophen and opioids to oral formulations

Good surgical outcomes depend in part on good pain relief, allowing for early mobilization, optimal recovery, and patient satisfaction. Postsurgical pain has multiple mechanisms, and multimechanistic approaches to postoperative analgesia are recommended and may be associated with improved pain relief, lowered opioid doses, and sometimes a lower rate of opioid-associated side effects. Acetaminophen (paracetamol) is a familiar agent for treating many types of pain, including postsurgical pain. Oral acetaminophen has been shown to be safe and effective in a variety of acute pain models. Combination products using a fixed-dose of acetaminophen and an opioid have also been effective in treating postsurgical pain. Combination products with acetaminophen have demonstrated an opioid-sparing effect, which inconsistently results in a reduced rate of opioid-associated side effects. Intravenous (IV) acetaminophen and an opioid analgesic administered in the perioperative period may be followed by an oral acetaminophen and opioid combination in the postoperative period. Transitioning from an IV acetaminophen and opioid formulation to a similar but oral formulation of the same drugs appears to be a reasonable step in that both analgesic therapies are known to be safe and effective. For postsurgical analgesia with any acetaminophen product, patient education is necessary to be sure that the patient does not concurrently take any over-the-counter products containing acetaminophen and accidentally exceed dose limits.

What do we (not) know about how paracetamol (acetaminophen) works?

WHAT IS KNOWN AND BACKGROUND

Although paracetamol (acetaminophen), N-(4-Hydroxyphenyl)acetamide, is one of the world's most widely used analgesics, the mechanism by which it produces its analgesic effect is largely unknown. This lack is relevant because: (i) optimal pain treatment matches the analgesic mechanism to the (patho)physiology of the pain and (ii) modern drug discovery relies on an appropriate screening assay.

OBJECTIVE

To review the clinical profile and preclinical studies of paracetamol as means of gaining insight into its mechanism of analgesic action.

METHODS

A literature search was conducted of clinical and preclinical literature and the information obtained was organized and reviewed from the perspective of its contribution to an understanding of the mechanism of analgesic action of paracetamol.

RESULTS

Paracetamol's broad spectrum of analgesic and other pharmacological actions is presented, along with its multiple postulated mechanism(s) of action. No one mechanism has been definitively shown to account for its analgesic activity.

WHAT IS NEW AND CONCLUSION

Further research is needed to uncover the mechanism of analgesic action of paracetamol. The lack of this knowledge affects optimal clinical use and impedes drug discovery efforts.

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.

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.