Pharmacokinetics and Bioavailability of a Fixed-Dose Combination of Ibuprofen and Paracetamol after Intravenous and Oral Administration

Acetaminophen/Ibuprofen Injection

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Simultaneous determination of plasma protein binding of five C-glycosylflavones from TFDS by rapid equilibrium dialysis

The total flavonoids of Desmodium styracifolium (TFDS) are flavonoid-rich extracts obtained from Desmodii Styracifolii Herba, which is approved for the treatment of urolithiasis in China. C-glycosylflavones including schaftoside, vicenin-1, vicenin-2, vicenin-3, and isovitexin are the main active constituents. In this study, the plasma protein binding of these compounds was determined for the first time in rat and human plasma by rapid equilibrium dialysis combined with HPLC-MS/MS method. The developed method was validated in terms of specificity, linearity, accuracy, precision, extraction effect, matrix effect, and stability. Schaftoside, vicenin-1, vicenin-2, and vicenin-3 exhibited moderate plasma protein binding, ranging from 56.6% to 61.5% in rat plasma and 55.0%-62.9% in human plasma. In comparison, isovitexin demonstrated a higher plasma protein binding in the range of 92.3-93.1% and 95.1-96.2% in rat and human plasma, respectively. Furthermore, the potential interactions mediated via plasma protein binding between isovitexin and nonsteroidal anti-inflammatory drugs (NSAIDs) were investigated by rapid equilibrium dialysis. No significant changes were observed, indicating a lower likelihood of interaction between TFDS and NSAIDs due to plasma protein binding in the treatment of urinary system disorders.

Rapid identification of potential nonsteroidal anti-inflammatory drug overdose-induced liver toxicity and prediction of follow-up exposure: Integrating bioanalytical and population pharmacokinetic assay

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used drugs that can cause liver toxicity. The aim of this study was to integrate bioanalytical and population pharmacokinetic (PopPK) assay to rapidly screen and quantify the concentrations of NSAIDs in plasma and monitor clinical safety. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetaminophen (APAP), flurbiprofen (FLB), aspirin (ASP), and ibuprofen (IBP), four commonly used NSAIDs. The PopPK model of the signature toxicant was analyzed based on the published literature. The LC-MS/MS method was successfully validated and applied to determine NSAID concentrations in patient plasma samples. APAP, ASP, and IBP data were best fitted using a one-compartment model, and FLB data were best fitted using a two-compartment model. Bootstrapping and visual predictive checks suggested that a robust and reliable pharmacokinetic model was developed. A fast, simple, and sensitive LC-MS/MS method was developed and validated for determining APAP, FLB, ASP, and IBP in human plasma. Combined with the PopPK model, this method was applied to rapidly analyze the concentrations of NSAIDs in clinical samples from patients presenting to the emergency department with acute liver dysfunction and monitored NSAIDs clinical safety.

Carbon fiber-sampling combined flame ionization mass spectrometry for direct analysis of drugs in oral fluid

Drug-impaired driving poses a significant risk of collisions and other hazardous accidents, emphasizing the urgent need for simple and rapid roadside detection methods. Oral fluid, as an easily collectible and non-invasive test material, has gained widespread use in detecting drug-impaired driving. In this study, we have devised a method for direct sampling using a carbon fiber bundle combined with flame ionization mass spectrometry. The essence of this method lies in the synergy between the adsorption properties of carbon fiber and the plasma characteristics of the flame. Leveraging the strong adsorption capabilities of the carbon fiber bundle allows for the use of a minimal sample size (<100 μL) during sampling, presenting a distinct advantage in the roadside inspection and sampling process. Throughout the flame ionization process, proteins and salts within the oral fluid matrix adhere well to the carbon fiber bundle, while small molecule targets can be efficiently desorbed and react with charged species in the flame, leading to ionization. The results demonstrate the successful development of carbon fiber-sampling combined flame ionization mass spectrometry, capable of qualitative and quantitative analysis of drugs in oral fluid without the need for sample pre-treatment. Its quantitative capabilities are sufficient for real sample detection, providing an effective analytical method for the roadside detection of drugs in oral fluids.

Postoperative pain management using an intravenous combination of ibuprofen and acetaminophen compared with acetaminophen alone after thyroidectomy: A prospective randomized controlled trial

BACKGROUND

Multiple medications are more effective than single agents for postoperative pain management. We investigated the analgesic effects of an intravenous combination of acetaminophen and ibuprofen immediately after thyroidectomy.

METHODS

In this double-blind clinical trial, 62 patients who underwent thyroidectomies were randomized to either the treatment (1000 mg acetaminophen, 300 mg ibuprofen) or control (1000 mg acetaminophen) group. Postoperative pain intensity was assessed using the visual analog scale (VAS) 0, 15, and 30 min after recovery room admission. Opioid rescue consumption was also recorded.

RESULTS

The VAS scores were significantly lower in the treatment than in the control group 15 [3 (2-4.3) vs. 5 (3-6); p = 0.015] and 30 [3 (2-4.3) vs. 4 (3-5); p = 0.018] min after recovery room admission, as were the opioid rescue dose requirements (p = 0.033).

CONCLUSIONS

Combined intravenous acetaminophen and ibuprofen may be better than acetaminophen alone for immediately acute postoperative pain after thyroidectomy.

The evaluation of the efficacy of etofenamate spray in postoperative cesarean pain: Randomized, double-blind, placebo-controlled trial

OBJECTIVE

It was aimed to investigate the effect of etofenamate spray to be applied around the postoperative incision on pain control in cesarean section in this trial.

MATERIAL AND METHODS

This was a prospective, randomized, double-blind, and placebo-controlled trial. 187 patients (93 cases and 94 controls) were recruited for the study. In the trial group, we applied the etofenamate spray (Doline® 50 ml) after closing the cesarean skin incision and go on four times a day on the skin incision for 24 h. In the control group, we applied a placebo. All patients received paracetamol IV (Paracerol®) as standard analgesic doses. If analgesia was insufficient, tramadol (Contramal®) 50 mg IV doses were added and recorded. A visually analog pain scale (VAS) was performed on both groups at 6-12-18-24th hours. Independent t-tests were performed for data showing normal distributions.

RESULTS

There were no significant differences in the mean of differences VAS scores between the two groups at 6-12, and 6-18 h. However, a significant difference was obtained in the mean of differences VAS score at the 6-24th hour (p < 0.05). When the groups were compared in terms of additional paracetamol need, a significant difference was found again (p < 0.05). There was no significant difference between the groups in terms of tramadol need.

CONCLUSION

Postoperative administration of etofenamate spray provided an analgesic effect at 24 h and additional analgesic usage decreased. Postoperative analgesia can also be used by administering NSAIDs around the cesarean section incision. In this way, the side effects of other systemic analgesics are avoided.

CLINICAL TRIAL ID

PACTR201811864509898. CLINICAL TRIAL WEB LINK: https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=5745.

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

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

Usefulness of the Beagle Model in the Evaluation of Paracetamol and Ibuprofen Exposure after Oral Administration to Pediatric Populations: An Exploratory Study

The present study aimed to explore the usefulness of beagle dogs in combination with physiologically based pharmacokinetic (PBPK) modeling in the evaluation of drug exposure after oral administration to pediatric populations at an early stage of pharmaceutical product development. An exploratory, single-dose, crossover bioavailability study in six beagles was performed. A paracetamol suspension and an ibuprofen suspension were coadministered in the fasted-state conditions, under reference-meal fed-state conditions, and under infant-formula fed-state conditions. PBPK models developed with GastroPlus v9.7 were used to inform the extrapolation of beagle data to human infants and children. Beagle-based simulation outcomes were compared with published human-adult-based simulations. For paracetamol, fasted-state conditions and reference-meal fed-state conditions in beagles appeared to provide adequate information for the applied scaling approach. Fasted-state and/or reference-meal fed-state conditions in beagles appeared suitable to simulate the performance of ibuprofen suspension in pediatric populations. Contrary to human-adult-based translations, extrapolations based on beagle data collected under infant-formula fed-state conditions appeared less useful for informing simulations of plasma levels in pediatric populations. Beagle data collected under fasted and/or reference-meal fed-state conditions appeared to be useful in the investigation of pediatric product performance of the two investigated highly permeable and highly soluble drugs in the upper small intestine. The suitability of the beagle as a preclinical model to understand pediatric drug product performance under different dosing conditions deserves further evaluation with a broader spectrum of drugs and drug products and comparisons with pediatric in vivo data.

Harmonizing Biopredictive Methodologies Through the Product Quality Research Institute (PQRI) Part I: Biopredictive Dissolution of Ibuprofen and Dipyridamole Tablets

Assessing in vivo performance to inform formulation selection and development decisions is an important aspect of drug development. Biopredictive dissolution methodologies for oral dosage forms have been developed to understand in vivo performance, assist in formulation development/optimization, and forecast the outcome of bioequivalence studies by combining them with simulation tools to predict plasma profiles in humans. However, unlike compendial dissolution methodologies, the various biopredictive methodologies have not yet been harmonized or standardized. This manuscript presents the initial phases of an effort to develop best practices and move toward standardization of the biopredictive methodologies through the Product Quality Research Institute (PQRI, https://pqri.org ) entitled "The standardization of in vitro predictive dissolution methodologies and in silico bioequivalence study Working Group." This Working Group (WG) is comprised of participants from 10 pharmaceutical companies and academic institutes. The project will be accomplished in a total of five phases including assessing the performance of dissolution protocols designed by the individual WG members, and then building "best practice" protocols based on the initial dissolution profiles. After refining the "best practice" protocols to produce equivalent dissolution profiles, those will be combined with physiologically based biopharmaceutics models (PBBM) to predict plasma profiles. In this manuscript, the first two of the five phases are reported, namely generating biopredictive dissolution profiles for ibuprofen and dipyridamole and using those dissolution profiles with PBBM to match the clinical plasma profiles. Key experimental parameters are identified, and this knowledge will be applied to build the "best practice" protocol in the next phase.

The Three W's of Acetaminophen In Children: Who, Why, and Which Administration Mode

Acetaminophen is one of the oldest medications commonly administered in children. Its efficacy in treating fever and pain is well accepted among clinicians. However, the available evidence supporting the use of acetaminophen's different modes of administration remains relatively scarce and poorly known. This short report summarizes the available evidence and provides a framework to guide clinicians regarding a rational use of acetaminophen in children.

Fixed Dose Versus Loose Dose: Analgesic Combinations

Combinations of drugs may be fixed (two or more entities in a single product) or loose (two or more agents taken together but as individual agents) to help address multimechanistic pain. The use of opioids plus nonopioids can result in lower opioid consumption without sacrificing analgesic benefits. Drug combinations may offer additive or synergistic benefits. A variety of fixed-dose combination products are available on the market such as diclofenac plus thiocolchicoside, acetaminophen and caffeine, acetaminophen and opioid, ibuprofen and acetaminophen, tramadol and acetaminophen, and others. Fixed-dose combination products offer predictable pharmacokinetics and pharmacodynamics, known adverse events, and can reduce the pill burden. However, they are limited to certain drug combinations and doses; loose dosing allows prescribers the versatility to meet individual patient requirements as well as the ability to titrate as needed. Not all drug combinations offer synergistic benefits, which depend on the drugs and their doses. Certain drugs offer dual mechanisms of action in a single molecule, such as tapentadol, and these may further be used in combination with other analgesics. New technology allows for co-crystal productions of analgesic agents which may further improve drug characteristics, such as bioavailability. Combination analgesics are important additions to the analgesic armamentarium and may offer important benefits at lower doses than monotherapy.

Testing Topical Products Specifically to Reduce Inflammatory Pain from Gout: Transdermal NSAID Delivery and Monosodium Urate Solubility

Purpose

Gout is caused by crystals of monosodium urate (MSU) in the joints. Topical nonsteroidal anti-inflammatory drug products (NSAIDs) are often the first-choice immediate treatment. This study examined the effect of commercially available and newly developed transdermal NSAID products on the solubility of MSU in a physiologically relevant system, alongside the efficacy of transdermal NSAID delivery.

Materials and Methods

Drug permeability of 7 commercially available topical NSAID products, alongside 3 newly developed “Gout Buster” products, was evaluated in vitro using pig’s ear skin in Franz diffusion cells. The standard Franz cell experimental protocol was adapted to include assessment of MSU solubility in phosphate buffered saline for each product. Some materials were also tested via direct solubility studies.

Results

The amount of drug delivered transdermally varied significantly between different formulations, with the best ibuprofen delivery being ~5 times higher than the lowest, and best diclofenac delivery being ~3.5 times higher than the lowest. Changes in formulations and the drug concentration in the product both affected the amount of drug delivered. Overall ibuprofen permeation was higher than diclofenac. The commercially available products showed little or no effect on the MSU solubility (99–103% vs control). The Gout Buster products showed significant improvement in the MSU solubility after permeation through skin (120–126%). Increased sodium levels reduced the solubility of MSU in direct solubility studies.

Conclusion

In these trials, the Gout Buster products showed significantly improved permeation of both ibuprofen and diclofenac over the commercial products at similar drug concentrations, and showed significant improvement for MSU solubility. Increased sodium levels reduced the solubility of MSU and could cause more crystallisation in vivo. Therefore, topical NSAID products with the Gout Buster formulation may have the best likelihood of both reducing inflammation and helping re-dissolve the MSU crystals that cause gout.

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Effect of intravenous acetaminophen on postoperative outcomes in hip fracture patients: a systematic review and narrative synthesis

PURPOSE

Hip fractures are debilitating in older adults because of their impact on quality of life. Opioids are associated with adverse effects in this population, so oral acetaminophen is commonly prescribed to minimize opioid use. Intravenous (iv) acetaminophen has been reported to have superior efficacy and bioavailability than oral acetaminophen. Nevertheless, its effect on postoperative outcomes in emergency hip fractures is unclear. This systematic review assessed the effect of iv acetaminophen on postoperative outcomes in older hip fracture patients.

SOURCE

We searched multiple databases from inception to June 2021 for studies on adults > 50 yr of age undergoing emergency hip fracture surgery who received iv acetaminophen (or paracetamol) and that reported postoperative outcomes. Relevant titles, abstracts, and full texts were screened based on the eligibility criteria. The Newcastle-Ottawa scale was used to assess the quality of the selected papers.

PRINCIPAL FINDINGS

Of 3,510 initial studies, four met the inclusion criteria. One was a prospective cohort study and three were retrospective cohort studies. All four studies used historical control groups. Three studies reported a significantly lower mean opioid dose with iv acetaminophen than with oral acetaminophen. Three studies also reported a significantly shorter hospital stay. One study each reported a significant decrease in the number of missed physical therapy sessions, the need for one-to-one supervision, and episodes of delirium.

CONCLUSION

There is very limited low-level evidence that iv acetaminophen improves preoperative and postoperative analgesia and shortens hospital stay in older hip fracture patients. Nevertheless, our results should be interpreted with caution since there are no prospective randomized trials investigating whether iv acetaminophen improves postoperative outcomes in this patient population.

STUDY REGISTRATION

PROSPERO (CRD42021198174); registered 15 August 2021.

Re-writing Oral Pharmacokinetics Using Physiologically Based Finite Time Pharmacokinetic (PBFTPK) Models

PURPOSE

To develop physiologically based finite time pharmacokinetic (PBFTPK) models for the analysis of oral pharmacokinetic data.

METHODS

The models are based on the passive drug diffusion mechanism under the sink conditions principle. Up to three drug successive input functions of constant rate operating for a total time τ are considered. Differential equations were written for all these models assuming linear one- or two-compartment-model disposition. The differential equations were solved and functions describing the concentration of drug as a function of time for the central and the peripheral compartment were derived. The equations were used to generate simulated data and they were also fitted to a variety of experimental literature oral pharmacokinetic data.

RESULTS

The simulated curves resemble real life data. The end of the absorption processes τ is either equal to t_max or longer than t_max at the descending portion of the concentration time curve. Literature oral pharmacokinetic data of paracetamol, ibuprofen, almotriptan, cyclosporine (a total of four sets of data), and niraparib were analyzed using the PBFTPK models. Estimates for τ corresponding to a single or two or three different in magnitude input rates were derived along with the other model parameters for all data analyzed.

CONCLUSIONS

The PBFTPK models are a powerful tool for the analysis of oral pharmacokinetic data since they rely on the physiologically sound concept of finite absorption time.

Population Pharmacokinetic Modelling of Acetaminophen and Ibuprofen: the Influence of Body Composition, Formulation and Feeding in Healthy Adult Volunteers

BACKGROUND AND OBJECTIVE

Combined acetaminophen and ibuprofen are common antipyretic and analgesic drugs. Formulation and feeding affect drug absorption. Drug clearance has a nonlinear relationship with total body weight. The covariate effect of fat mass on acetaminophen and ibuprofen pharmacokinetics remains unexplored. This study sought to quantify acetaminophen and ibuprofen pharmacokinetics with intravenous, tablet, sachet and oral suspension formulations in fed and fasted states.

METHODS

Pooled time-concentration data for acetaminophen and ibuprofen were available from fasting and fed healthy adults. Data from intravenous, tablet, sachet and suspension formulations were analysed using nonlinear mixed-effects models. Body composition was considered as a covariate on clearances and volumes of distribution (V_d). Size metrics investigated were total body weight, fat and fat-free mass. Theory-based allometry was used to scale pharmacokinetic parameters to a 70 kg individual. A factor on absorption half-life and lag time quantified delays due to feeding for oral formulations. Pharmacokinetic-pharmacodynamic simulations were used to explore the time courses of pain response for acetaminophen and ibuprofen for each formulation.

RESULTS

Pooled data included 116 individuals (18-49 years, 49-116 kg) with 6095 acetaminophen and 6046 ibuprofen concentrations available for analysis. A two-compartment pharmacokinetic model with first-order elimination described disposition for both drugs. Normal fat mass was the best covariate to describe acetaminophen clearance (CL), with a factor for fat contribution (FFATCL) of 0.816. Acetaminophen volume of distribution was described using total body weight. Normal fat mass was the best covariate to describe ibuprofen clearance (FFATCL = 0.863) and volume of distribution: (FFATV = 0.718). Clearance and central volume of distribution were 24.0 L/h/70 kg and 43.5 L/h/70 kg for acetaminophen. Ibuprofen clearance and central volume of distribution were 3.79 L/h/70 kg and 10.5 L/h/70 kg. Bioavailability and absorption half-life were 86% and 12 min for acetaminophen and 94% and 27 min for ibuprofen. Absorption lag times were 5.3 min and 6.7 min for acetaminophen and ibuprofen, respectively. Feeding increased both absorption half-life and absorption lag time when compared to the tablet formulation under fasting conditions. Feeding had the most pronounced effect on the lag time associated with tablet formulation for both drugs. Time to a pain score reduction of 2 points (visual analogue score, 0-10) differed by only 5-10 min across all formulations for acetaminophen and ibuprofen.

CONCLUSION

Fat mass was an important covariate to describe acetaminophen and ibuprofen pharmacokinetics. The absorption half-lives of acetaminophen and ibuprofen were increased in fed states. The delay in absorption, quantified by a lag time, was protracted for both drugs.

Pharmacokinetics of oral versus intravenous ibuprofen for closure of patent ductus arteriosus: A pilot randomised controlled study

AIM

This pilot study aimed to compare the pharmacokinetic profiles of oral (PO) and intravenous (IV) ibuprofen for treatment of patent ductus arteriosus (PDA) in preterm neonates.

METHODS

In a single-centre, parallel, randomised open-label trial, neonates ≤35 weeks, weight <1800 g with haemodynamically significant PDA during the first week of life were recruited between June 2017 and February 2019 and randomised to receive either PO or IV ibuprofen at standard dosage of 10, 5 and 5 mg/kg every 24 h for three consecutive days. Plasma concentrations of ibuprofen were quantified using a validated high-performance liquid chromatography method and pharmacokinetic parameters were calculated. Treatment outcomes were recorded.

RESULTS

Eleven neonates participated in the trial, six and five patients receiving PO and IV ibuprofen, respectively. Pharmacokinetic analysis reveals similar ibuprofen exposure levels in treatment groups. Median dose- and weight-normalised C_max values of PO and IV groups were 2.12 and 2.53 g/mL respectively (P = 0.082) and median AUC_0-24 levels were comparable (PO: 34.6 g*h/mL vs. IV: 50.7.6 g*h/mL, P = 0.25).

CONCLUSION

This exploratory study demonstrates comparable pharmacokinetics of PO and IV formulations of ibuprofen in preterm neonates. Larger prospective studies are required to validate these findings.

A novel approach to calculating the kinetically derived maximum dose

The kinetically derived maximal dose (KMD) provides a toxicologically relevant upper range for the determination of chemical safety. Here, we describe a new way of calculating the KMD that is based on sound Bayesian, theoretical, biochemical, and toxicokinetic principles, that avoids the problems of relying upon the area under the curve (AUC) approach that has often been used. Our new, mathematically rigorous approach is based on converting toxicokinetic data to the overall, or system-wide, Michaelis–Menten curve (which is the slope function for the toxicokinetic data) using Bayesian methods and using the “kneedle” algorithm to find the “knee” or “elbow”—the point at which there is diminishing returns in the velocity of the Michaelis–Menten curve (or acceleration of the toxicokinetic curve). Our work fundamentally reshapes the KMD methodology, placing it within the well-established Michaelis–Menten theoretical framework by defining the KMD as the point where the kinetic rate approximates the Michaelis–Menten asymptote at higher concentrations. By putting the KMD within the Michaelis–Menten framework, we leverage existing biochemical and pharmacological concepts such as “saturation” to establish the region where the KMD is likely to exist. The advantage of defining KMD as a region, rather than as an inflection point along the curve, is that a region reflects uncertainty and clarifies that there is no single point where the curve is expected to “break;” rather, there is a region where the curve begins to taper off as it approaches the asymptote (V_max in the Michaelis–Menten equation).

Pain management after complex spine surgery: A systematic review and procedure-specific postoperative pain management recommendations

BACKGROUND

Complex spinal procedures are associated with intense pain in the postoperative period. Adequate peri-operative pain management has been shown to correlate with improved outcomes including early ambulation and early discharge.

OBJECTIVES

We aimed to evaluate the available literature and develop recommendations for optimal pain management after complex spine surgery.

DESIGN AND DATA SOURCES

A systematic review using the PROcedure SPECific postoperative pain managemenT methodology was undertaken. Randomised controlled trials and systematic reviews published in the English language from January 2008 to April 2020 assessing postoperative pain after complex spine surgery using analgesic, anaesthetic or surgical interventions were identified from MEDLINE, EMBASE and Cochrane Databases.

RESULTS

Out of 111 eligible studies identified, 31 randomised controlled trials and four systematic reviews met the inclusion criteria. Pre-operative and intra-operative interventions that improved postoperative pain were paracetamol, cyclo-oxygenase (COX)-2 specific-inhibitors or non-steroidal anti-inflammatory drugs (NSAIDs), intravenous ketamine infusion and regional analgesia techniques including epidural analgesia using local anaesthetics with or without opioids. Limited evidence was found for local wound infiltration, intrathecal and epidural opioids, erector spinae plane block, thoracolumbar interfascial plane block, intravenous lidocaine, dexmedetomidine and gabapentin.

CONCLUSIONS

The analgesic regimen for complex spine surgery should include pre-operative or intra-operative paracetamol and COX-2 specific inhibitors or NSAIDs, continued postoperatively with opioids used as rescue analgesics. Other recommendations are intra-operative ketamine and epidural analgesia using local anaesthetics with or without opioids. Although there is procedure-specific evidence in favour of intra-operative methadone, it is not recommended as it was compared with shorter-acting opioids and due to its limited safety profile. Furthermore, the methadone studies did not use non-opioid analgesics, which should be the primary analgesics to ultimately reduce overall opioid requirements, including methadone. Further qualitative randomised controlled trials are required to confirm the efficacy and safety of these recommended analgesics on postoperative pain relief.

Comparison of Monotherapy Versus Combination of Intravenous Ibuprofen and Propacetamol (Acetaminophen) for Reduction of Postoperative Opioid Administration in Children Undergoing Laparoscopic Hernia Repair: A Double-Blind Randomized Controlled Trial

BACKGROUND

Extensive efforts have been made toward reducing postoperative opioid use in children. In this study, we assessed whether propacetamol, or a nonsteroidal anti-inflammatory drug (NSAID), or their combination could effectively reduce opioid use in children after laparoscopic inguinal hernia repair.

METHODS

This randomized, double-blind clinical trial included 159 children aged 6 months to 6 years. Children were allocated into 1 of the following 3 groups: group I was treated with 10 mg·kg-1 ibuprofen, group P was treated with 30 mg·kg-1 propacetamol, and group I + P was treated with both drugs in their respective concentrations. If the face-legs-activity-crying-consolability (FLACC) score was ≥4 during the postanesthesia care unit stay, 1.0 µg·kg-1 fentanyl was administered as a rescue analgesic. The number of patients who received rescue fentanyl in the postanesthesia care unit was defined as the primary outcome; this was analyzed using the χ2 test. The secondary outcomes included the FLACC and the parents' postoperative pain measure (PPPM) scores until the 24-hour postoperative period.

RESULTS

Among the 144 enrolled patients, 28.6% in group I, 66.7% in group P, and 12.8% in group I + P received rescue fentanyl in the postanesthesia care unit (P < .001). The highest FLACC score was lower in group I + P than in either group I or P (P = .007 and P < .001, respectively). Group I + P presented significantly lower PPPM scores than group P at 4 and 12 hours postoperative (P = .03 and .01, respectively).

CONCLUSIONS

The use of ibuprofen plus propacetamol immediately following laparoscopic hernia repair surgery in children resulted in the reduced use of an opioid drug compared with the use of propacetamol alone.

Extending the safety profile of the post-operative administration of an intravenous acetaminophen/ibuprofen fixed dose combination: An open-label, multi-center, single arm, multiple dose study

PURPOSE

Postoperative pain is typically treated with multimodal analgesia, using systemic acetaminophen and/or nonsteroidal anti-inflammatory drugs in conjunction with opioids as required. The present study aimed to determine the safety and tolerability of repeated doses of an intravenous fixed-dose combination (FDC) of acetaminophen and ibuprofen.

METHODS

This multicenter, open-label, single arm, multiple dose study was conducted at 4 centers across New Zealand and the United States between July 2019 and July 2020. Adults (>18 years) requiring multiple doses of parenteral nonopioid analgesics over multiple days following non-laparoscopic general, plastic or orthopedic surgery were eligible. The study drug (acetaminophen 1000 mg+ibuprofen 300 mg) was administered 6-hourly as a 5 min infusion for between 48 h and 5 days. Adverse event data was collected throughout the study, in addition to scheduled vital sign assessments, laboratory tests and electrocardiograms. Participants completed a global evaluation of the FDC at the end of the treatment period.

FINDINGS

232 participants received ≥ 1 dose of the FDC. Most were female (62.1%), White (56.5%) or Black or African American (39.2%), and had undergone orthopedic surgery (85.3%). There was a broad age range (19-87 years), with a mean age of 53.4 years, and 26.3% of participants aged ≥ 65 years. The FDC was safe when used for 48 h to 5 days. Treatment-emergent adverse events (TEAEs) affected 56.0% of participants, the most common were infusion site pain, nausea, infusion site extravasation, constipation, and headache. Minimal changes in vital signs were observed at scheduled timepoints. No clinically significant changes in electrocardiogram assessments occurred. Transient elevations in the hepatic enzymes ALT and AST to < 3 times the upper limit of normal (ULN) affected 10.5% and 9.6% of subjects, elevations to ≥ 3 times the ULN affected 2.6% and 2.2% of subjects, respectively. There were no apparent differences in the safety profile of the FDC in older participants. The FDC was well tolerated; most TEAEs were mild or moderate in severity. Five participants discontinued treatment due to TEAEs, none were considered treatment-related. The FDC was perceived well by study participants; the majority rated their experience as 'excellent' (40.1%) or 'very good' (35.3%).

IMPLICATIONS

The safety profile was comparable to previous studies with no novel safety concerns. The FDC was safe, well tolerated, and perceived positively by participants treated for acute pain between 48 h and 5 days following orthopedic or plastic surgery, supporting a favorable risk benefit profile.

Enteral Acetaminophen Bioavailability in Pediatric Intensive Care Patients Determined With an Oral Microtracer and Pharmacokinetic Modeling to Optimize Dosing

OBJECTIVES

Decreasing morbidity and mortality by rationalizing drug treatment in the critically ill is of paramount importance but challenging as the underlying clinical condition may lead to large variation in drug disposition and response. New microtracer methodology is now available to gain knowledge on drug disposition in the intensive care. On the basis of studies in healthy adults, physicians tend to assume that oral doses of acetaminophen will be completely absorbed and therefore prescribe the same dose per kilogram for oral and IV administration. As the oral bioavailability of acetaminophen in critically ill children is unknown, we designed a microtracer study to shed a light on this issue.

DESIGN

An innovative microtracer study design with population pharmacokinetics.

SETTING

A tertiary referral PICU.

PATIENTS

Stable critically ill children, 0-6 years old, and already receiving IV acetaminophen.

INTERVENTIONS

Concomitant administration of an oral C radiolabeled acetaminophen microtracer (3 ng/kg) with IV acetaminophen treatment (15 mg/kg every 6 hr).

MEASUREMENTS

Blood was drawn from an indwelling arterial or central venous catheter up to 24 hours after C acetaminophen microtracer administration. Acetaminophen concentrations were measured by liquid chromatography-mass spectrometry and C concentrations by accelerated mass spectrometry.

MAIN RESULTS

In 47 patients (median age of 6.1 mo; Q1-Q3, 1.8-20 mo) the mean enteral bioavailability was 72% (range, 11-91%). With a standard dose (15 mg/kg 4 times daily), therapeutic steady-state concentrations were 2.5 times more likely to be reached with IV than with oral administration.

CONCLUSIONS

Microtracer studies present a new opportunity to gain knowledge on drug disposition in the intensive care. Using this modality in children in the pediatric intensive care, we showed that enteral administration of acetaminophen results in less predictable exposure and higher likelihood of subtherapeutic blood concentration than does IV administration. IV dosing may be preferable to ensure adequate pain relief.

A Mechanistic Physiologically-Based Biopharmaceutics Modeling (PBBM) Approach to Assess the In Vivo Performance of an Orally Administered Drug Product: From IVIVC to IVIVP

The application of in silico modeling to predict the in vivo outcome of an oral drug product is gaining a lot of interest. Fully relying on these models as a surrogate tool requires continuous optimization and validation. To do so, intraluminal and systemic data are desirable to judge the predicted outcomes. The aim of this study was to predict the systemic concentrations of ibuprofen after oral administration of an 800 mg immediate-release (IR) tablet to healthy subjects in fasted-state conditions. A mechanistic oral absorption model coupled with a two-compartmental pharmacokinetic (PK) model was built in Phoenix WinNonlinWinNonlin^® software and in the GastroPlus™ simulator. It should be noted that all simulations were performed in an ideal framework as we were in possession of a plethora of in vivo data (e.g., motility, pH, luminal and systemic concentrations) in order to evaluate and optimize these models. All this work refers to the fact that important, yet crucial, gastrointestinal (GI) variables should be integrated into biopredictive dissolution testing (low buffer capacity media, considering phosphate versus bicarbonate buffer, hydrodynamics) to account for a valuable input for physiologically-based pharmacokinetic (PBPK) platform programs. While simulations can be performed and mechanistic insights can be gained from such simulations from current software, we need to move from correlations to predictions (IVIVC → IVIVP) and, moreover, we need to further determine the dynamics of the GI variables controlling the dosage form transit, disintegration, dissolution, absorption and metabolism along the human GI tract. Establishing the link between biopredictive in vitro dissolution testing and mechanistic oral absorption modeling (i.e., physiologically-based biopharmaceutics modeling (PBBM)) creates an opportunity to potentially request biowaivers in the near future for orally administered drug products, regardless of its classification according to the Biopharmaceutics Classification System (BCS).

A target concentration strategy to determine ibuprofen dosing in children

BACKGROUND

Ibuprofen is widely used for ductus arteriosus closure in premature neonates and for analgesia in children and adults. There are no maturation descriptors of clearance. This lack of maturation understanding limits dosing recommendations from premature neonates to adulthood.

METHODS

Published clearance estimates from different aged patients determined after administration from time-concentration profiles were used to construct a maturation model based on size and age. Curve fitting was performed using nonlinear mixed-effects models. A target concentration strategy was used to estimate maintenance dose at different ages.

RESULTS

There were three publications reporting an estimate of individual clearance estimates in premature neonates, three reporting population clearances in infants, 11 in children 2-15 years (1 with individual and 9 with population clearances), and 13 adult studies (1 with individual and 12 with population clearances). Clearance maturation, standardized to a 70 kg person was described using the Hill equation. Mature clearance was 3.81 (CV 15.5%, 95%CI 3.72, 3.92) L/h/70 kg. The maturation half-time was 36.8 (CV 9.2%, 95%CI 34.7, 40.9) weeks postmenstrual age and the Hill coefficient 11.5 (95%CI 8.1, 15). A target effect of four units (visual analogue scale 0-10) correlated with an effect site concentration of 6.3 mg/L: a concentration achieved at trough after 400 mg 8 hourly in adults.

CONCLUSION

Previously published pharmacokinetic parameters can be used to develop maturation models that address gaps in current knowledge regarding the influence of age on a drug's disposition. Maturation of ibuprofen clearance was rapid and was 90% of adult values by the first month of life in term neonates (ie, 44 weeks postmenstrual age) and 98% of standardized adult estimates by 3 months of age (53 weeks postmenstrual age). Clearance informed dosing predictions in all ages (premature neonate to adult) and matched those doses in common use in children older than 3 months.

Efficacy and Safety of an Intravenous Acetaminophen/Ibuprofen Fixed-dose Combination After Bunionectomy: a Randomized, Double-blind, Factorial, Placebo-controlled Trial

PURPOSE

Multimodal analgesia with acetaminophen and/or nonsteroidal anti-inflammatory drugs is recommended for the treatment of postoperative pain. Although oral fixed-dose combinations (FDCs) are available, parenteral administration may be clinically justified. The goal of this study was to investigate the clinical efficacy and safety of an intravenous FDC of ibuprofen and acetaminophen after bunionectomy.

METHODS

This study was a prospective, randomized, double-blind, multicenter, placebo-controlled factorial clinical trial conducted at 2 clinical research centers in the United States between November 2016 and June 2017. Eligible patients (male and female subjects, aged 18-65 years, reporting pain intensity levels ≥40 mm on a 100-mm visual analog scale (VAS) after distal, first metatarsal bunionectomy) were randomized (3:3:3:2) to receive the FDC (ibuprofen 300 mg + acetaminophen 1000 mg), ibuprofen 300 mg, acetaminophen 1000 mg, or placebo (vehicle), administered as 15-minute intravenous infusions every 6 hours for 48 hours. The primary efficacy end point was the time-adjusted sum of pain intensity differences from baseline over 48 hours (SPID₄₈). In addition to VAS pain intensity scores, pain relief scores, time to perceptible and meaningful pain relief, the use of rescue medication, and participant's global evaluations of the study drug were recorded. Adverse events occurring during the 48-hour treatment period were included in the safety analysis.

FINDINGS

A total of 276 participants were enrolled; most were female (82%), the mean age was 42.4 years, and the median baseline VAS was 67 mm, indicating moderate to severe pain. SPID₄₈ was significantly higher for the FDC (23.4 [2.5] mm) than for ibuprofen (9.5 [2.5] mm), acetaminophen (10.4 [2.5] mm), and placebo (-1.3 [3.1] mm; all, P < 0.001). The superior analgesic effect of the FDC was supported by a range of secondary end points, including reduced opioid usage rates (75% for FDC, 92% for ibuprofen, 93% for acetaminophen, and 96% for placebo; all, P < 0.005). The safety profile of the FDC was comparable to that of intravenous ibuprofen or acetaminophen alone. Three participants withdrew from the study due to adverse events: 2 in the ibuprofen group and 1 in the acetaminophen group.

IMPLICATIONS

The study found that repeated administration of an intravenous FDC of ibuprofen and acetaminophen provided statistically significant improvement in SPID₄₈ over comparable doses of either monotherapy without an increase in adverse events. ClinicalTrials.gov identifier: NCT02689063.

Acetaminophen, ibuprofen, and tramadol analgesic interactions after adenotonsillectomy

BACKGROUND

The impact of tramadol in children given acetaminophen-ibuprofen combination therapy is uncertain in acute pediatric pain management. A model describing the interaction between these three drugs would be useful to understand the role of supplemental analgesic therapy.

METHODS

Children undergoing tonsillectomy were given oral paracetamol and ibuprofen perioperatively. Blood was taken for paracetamol and ibuprofen drug assay on up to six occasions over 6 h after the initial dose. Tramadol was administered by caregivers for unacceptable postoperative pain. Pain was measured using the Parent's Postoperative Pain Measurement rating two hourly on the first postoperative day. A first-order absorption, one-compartment linear model with first-order elimination was used to describe acetaminophen and ibuprofen disposition. Analgesia was described using an E_MAX model extended for three drugs, assuming additive effects. Curve fitting was performed using nonlinear mixed effects models.

RESULTS

Pharmacodynamic parameter estimates, expressed using fractional Hill equation, were maximum effect (E_MAX ) 0.65 (95%CI 0.54, 0.74), the concentration of acetaminophen associated with 50% of the maximal drug effect (C_50,ACET ) 7.06 (95%CI 7.03, 7.72) mg/L, and the ibuprofen C₅₀ (C_50,IBU ) 3.95 (95%CI 2.57, 7.53) mg/L. The Hill coefficient was 1.48 (95%CI 0.92, 2.62) and an interaction term was fixed at zero (additivity). The half-time (t_1/2 keo) for equilibration between the plasma and effect site was 0.34 hour (95%CI 0.23, 1.98) for acetaminophen and 1.04 hour (95%CI 0.75, 1.77) for ibuprofen. Tramadol had a C_50,TRAM of 0.07 (95%CI 0.048, 1.07) mg/L with a t_1/2 keo,_TRAM 1.78 hour (95%CI 1.06, 1.96).

CONCLUSION

Ibuprofen has an EC₅₀ for analgesia in children similar to that of adults (3.95 mg/L; 95%CI 2.57-7.53, vs 5-10 mg/L adults). The maximum effect from combination therapy (ie, 65% reduction in pain score) achieves satisfactory analgesia with commonly used doses but increased dose adds little additional benefit. The addition of tramadol to this analgesic mixture prolongs analgesia duration.

The Influence of Diabetes Mellitus on Glucuronidation and Sulphation of Paracetamol in Patients with Febrile Neutropenia

BACKGROUND AND OBJECTIVES

Numerous studies have confirmed the influence of diabetes mellitus on the pharmacokinetics of drugs. Paracetamol (APAP) is an antipyretic that is commonly used in febrile neutropenia (FN) therapy. APAP is chiefly metabolised by glucuronidation and sulphation. This study assessed the influence of diabetes on the pharmacokinetics of paracetamol and its metabolites: glucuronide (APAP-glu) and sulfate (APAP-sulfate) in FN patients.

METHODS

Patients with FN received single intravenous dose 1000 mg of APAP. The FN patients were allocated to one of two groups: diabetics (DG, n = 7) or non-diabetics (NDG, n = 11). The plasma concentrations of paracetamol and its metabolites were measured with the validated high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection.

RESULTS

Pharmacokinetic parameters (mean [SD]) of APAP in the DG and NDG groups were as follows: C_max (maximum comcentration) = 21.50 [11.23] vs. 23.42 [9.79] mg/L, AUC_0-t (area under the concentration-time curve) = 44.23 [17.93] vs. 41.43 [14.57] mg·h/L, t_1/2kel (elimination half-life) = 2.28 [0.80] vs. 2.11 [0.80] h. In both groups the exposure to APAP was comparable. The study did not reveal differences between the two groups in the pharmacokinetics of APAP-glu and APAP-sulfate. The C_max and AUC_0-t ratio between the metabolites and APAP were similar.

CONCLUSIONS

No differences in the pharmacokinetics of APAP, APAP-glu and APAP-sulfate in patients with FN indicates that diabetes does not influence glucuronidation and sulfatation of paracetamol.

The comparison of single-dose preemptive intravenous ibuprofen and paracetamol on postoperative pain scores and opioid consumption after open septorhinoplasty: a randomized controlled study

PURPOSE

Septorhinoplasty is performed in combination with septoplasty and rhinoplasty operations and is characterized by severe postoperative pain. The aim of this study is to evaluate preemptive effects of intravenous (IV) ibuprofen and IV paracetamol on opioid consumption and pain scores after open septorhinoplasty.

METHODS

The study included 150 patients who had undergone elective open septorhinoplasty. Patients were randomly assigned into three groups; Group Control (Group C, n = 50) received 100 ml saline solution, Group Paracetamol (Group P, n = 50) received 1000 mg IV paracetamol in 100 ml solution, and Group Ibuprofen (Group I, n = 50) received 800 mg IV ibuprofen in 100 ml saline before surgery. Postoperative analgesia was achieved by opioid administration via patient-controlled analgesia. Visual analog scores (VASs), postoperative opioid consumption, additional analgesic requirements, and side effects were recorded.

RESULTS

Compared with Group C, VASs in Group P and Group I were statistically lower at all time points (p < 0.05). VAS was lower in Group I than in Group P at postoperative, 1st and 6th hours (p < 0.05). Opioid consumption in Group C was highest in all groups at all time periods (p < 0.05). At the 0-6 and 6-12 time intervals, total opioid consumption was significantly lower in Group I compared to Group P (p < 0.05). Total opioid consumption was highest in Group C (p < 0.05).

CONCLUSIONS

This study has indicated that ibuprofen has more analgesic effect than paracetamol during first 12 h, but there is a non-inferiority between ibuprofen and paracetamol after first 12 h.

Simultaneous determination of acetaminophen and oxycodone in human plasma by LC-MS/MS and its application to a pharmacokinetic study

A simple and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous determination of acetaminophen and oxycodone in human plasma. Acetaminophen-d4 and oxycodone-d3 were used as internal standards. The challenge encountered in the method development that the high plasma concentration level of acetaminophen made the MS response saturated while the desired lower limit of quantification (LLOQ) for oxycodone was hard to reach was well solved. The analytes were extracted by protein precipitation using acetonitrile. The matrix effect of the analytes was avoided by chromatographic separation using a hydrophilic C₁₈ column coupled with gradient elution. Multiple reaction monitoring in positive ion mode was performed on tandem mass spectrometer employing electrospray ion source. The calibration curves were linear over the concentration ranges of 40.0–8000 ng/mL and 0.200–40.0 ng/mL for acetaminophen and oxycodone, respectively. This method, which could contribute to high throughput analysis and better clinical drug monitoring, was successfully applied to a pharmacokinetic study in healthy Chinese volunteers.

Formulation and delivery strategies of ibuprofen: challenges and opportunities

Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), is mostly administered orally and topically to relieve acute pain and fever. Due to its mode of action this drug may be useful in the treatment regimens of other, more chronic conditions, like cystic fibrosis. This drug is poorly soluble in aqueous media and thus the rate of dissolution from the currently available solid dosage forms is limited. This leads to poor bioavailability at high doses after oral administration, thereby increasing the risk of unwanted adverse effects. The poor solubility is a problem for developing injectable solution dosage forms. Because of its poor skin permeability, it is difficult to obtain an effective therapeutic concentration from topical preparations. This review aims to give a brief insight into the status of ibuprofen dosage forms and their limitations, particle/crystallization technologies for improving formulation strategies as well as suggesting its incorporation into the pulmonary drug delivery systems for achieving better therapeutic action at low dose.