Pseudomonas aeruginosa gene PA4880 encodes a Dps-like protein with a Dps fold, bacterioferritin-type ferroxidase centers, and endonuclease activity.

We report the biochemical, structural, and functional characterization of the protein coded by gene PA4880 in the P. aeruginosa PAO1 genome. The PA4880 gene had been annotated as coding a probable bacterioferritin. Our structural work shows that the product of gene PA4880 is a protein that adopts the Dps subunit fold, which oligomerizes into a 12-mer quaternary structure. Unlike Dps, however, the ferroxidase di-iron centers and iron coordinating ligands are buried within each subunit, in a manner identical to that observed in the ferroxidase center of P. aeruginosa bacterioferritin. Since these structural characteristics correspond to Dps-like proteins, we term the protein as P. aeruginosa Dps-like, or Pa DpsL. The ferroxidase centers in Pa DpsL catalyze the oxidation of Fe2+ utilizing O2 or H2O2 as oxidant, and the resultant Fe3+ is compartmentalized in the interior cavity. Interestingly, incubating Pa DpsL with plasmid DNA results in efficient nicking of the DNA and at higher concentrations of Pa DpsL the DNA is linearized and eventually degraded. The nickase and endonuclease activities suggest that Pa DpsL, in addition to participating in the defense of P. aeruginosa cells against iron-induced toxicity, may also participate in the innate immune mechanisms consisting of restriction endonucleases and cognate methyl transferases.

9-Step synthesis of (-)-larikaempferic acid methyl ester enabled by skeletal rearrangement.

We report here a concise synthesis of the anti-tumor-promoting (-)-larikaempferic acid methyl ester, a novel and rearranged abietane-type diterpene natural product containing a unique tetracyclic skeleton with a trans-hydrindane, an oxabicyclo[3.2.1]octane, and six stereogenic centers. Our synthesis starts with the cheap and abundant abietic acid and features an oxidative C-C bond cleavage followed by a transannular aldol reaction to skeletally rearrange the 6-6-6 tricyclic carbon skeleton of abietic acid to the desired 6-5-7 tricyclic carbon skeleton and an intramolecular oxa-Michael addition to form the oxa bridge. This skeletal rearrangement strategy enabled us to synthesize (-)-larikaempferic acid methyl ester in 9 steps.

Mobilization of iron stored in bacterioferritin, a new target for perturbing iron homeostasis and developing antibacterial and antibiofilm molecules.

Antibiotic resistance is a global public health threat. The care of chronic infections is complicated by bacterial biofilms. Biofilm embedded cells can be up to 1000-fold more tolerant to antibiotic treatment than planktonic cells. Antibiotic tolerance is a condition which does not involve mutation and enables bacteria to survive in the presence of antibiotics. The antibiotic tolerance of biofilm-cells often renders antibiotics ineffective, even against strains that do not carry resistance-impairing mutations. This review discusses bacterial iron homeostasis and the strategies being developed to target this bacterial vulnerability, with emphasis on a recently proposed approach which aims at targeting the iron storage protein bacterioferritin (Bfr) and its physiological partner, the ferredoxin Bfd. Bfr regulates cytosolic iron concentrations by oxidizing Fe2+ and storing Fe3+ in its internal cavity, and by forming a complex with Bfd to reduce Fe3+ in the internal cavity and release Fe2+ to the cytosol. Blocking the Bfr-Bfd complex in P. aeruginosa cells causes an irreversible accumulation of Fe3+ in BfrB and simultaneous cytosolic iron depletion, which leads to impaired biofilm maintenance and biofilm cell death. Recently discovered small molecule inhibitors of the Bfr-Bfd complex, which bind Bfr at the Bfd binding site, inhibit iron mobilization, and elicit biofilm cell death.

Objective and self-reported evidence of dextromethorphan antitussive efficacy in children, aged 6-11 years, with acute cough due to the common cold.

OBJECTIVE: To determine objective and subjective endpoints most suitable for evaluating antitussive efficacy of dextromethorphan hydrobromide (DXM) in children. Spontaneous resolution of acute cough and large placebo effects are impediments to evaluating antitussive efficacy. Another impediment is paucity of age-appropriate, validated cough assessment tools. METHODS: This was a multiple-dose, double-blind, placebo-controlled, randomized, pilot clinical study in children, aged 6-11 years, with cough due to the common cold. Eligible subjects met entry criteria and qualified by completing a run-in period where coughs were recorded with a cough monitor after they were dosed with sweet syrup. They were subsequently randomized to receive DXM or placebo over 4 days. Coughs were recorded during the initial 24 h; subjective assessments of cough severity and frequency were self-reported daily during treatment. RESULTS: Data from 128 evaluable subjects (67 DXM; 61 placebo) were analyzed. Total coughs over 24-hours (primary endpoint) and cough frequency during daytime were reduced by 21.0% and 25.5%, respectively, with DXM relative to placebo. Also, greater reductions in cough severity and frequency were self-reported with DXM. These findings were statistically significant and medically relevant. No effects were detected between treatments for nighttime cough rates or impact of cough on sleep. Multiple doses of DXM and placebo were generally well-tolerated. CONCLUSION: Evidence of DXM antitussive efficacy was shown in children using objective and subjective assessment tools validated in pediatric populations. Diurnal variation of cough frequency over 24 h reduced the assay sensitivity needed to detect treatment differences at nighttime, as coughs/hour decreased during sleep for both groups.

Modular and practical diamination of allenes.

Vicinal diamines are privileged scaffolds in medicine, agrochemicals, catalysis, and other fields. While significant advancements have been made in diamination of olefins, diamination of allenes is only sporadically explored. Furthermore, direct incorporation of acyclic and cyclic alkyl amines onto unsaturated π systems is highly desirable and important, but problematic for many previously reported amination reactions including the diamination of olefins. Herein, we report a modular and practical diamination of allenes, which offers efficient syntheses of ß,γ-diamino carboxylates and sulfones. This reaction features broad substrate scope, excellent functional group tolerability, and scalability. Experimental and computational studies support an ionic reaction pathway initiated with a nucleophilic addition of the in situ formed iodoamine to the electron deficient allene substrate. An iodoamine activation mode via a halogen bond with a chloride ion was revealed to substantially increase the nucleophilicity of the iodoamine and lower the activation energy barrier for the nucleophilic addition step.

Optimization of Host Cell-Compatible, Antimicrobial Peptides Effective against Biofilms and Clinical Isolates of Drug-Resistant Bacteria.

Here, we describe the continued synthetic molecular evolution of a lineage of host-compatible antimicrobial peptides (AMP) intended for the treatment of wounds infected with drug-resistant, biofilm-forming bacteria. The peptides tested are variants of an evolved AMP called d-amino acid CONsensus with Glycine Absent (d-CONGA), which has excellent antimicrobial activities in vitro and in vivo. In this newest generation of rational d-CONGA variants, we tested multiple sequence-structure-function hypotheses that had not been tested in previous generations. Many of the peptide variants have lower antibacterial activity against Gram-positive or Gram-negative pathogens, especially variants that have altered hydrophobicity, secondary structure potential, or spatial distribution of charged and hydrophobic residues. Thus, d-CONGA is generally well tuned for antimicrobial activity. However, we identified a variant, d-CONGA-Q7, with a polar glutamine inserted into the middle of the sequence, that has higher activity against both planktonic and biofilm-forming bacteria as well as lower cytotoxicity against human fibroblasts. Against clinical isolates of Klebsiella pneumoniae, innate resistance to d-CONGA was surprisingly common despite a lack of inducible resistance in Pseudomonas aeruginosa reported previously. Yet, these same isolates were susceptible to d-CONGA-Q7. d-CONGA-Q7 is much less vulnerable to AMP resistance in Gram-negative bacteria than its predecessor. Consistent with the spirit of synthetic molecular evolution, d-CONGA-Q7 achieved a critical gain-of-function and has a significantly better activity profile.

Pseudomonas aeruginosa Dps (PA0962) Functions in H2O2 Mediated Oxidative Stress Defense and Exhibits In Vitro DNA Cleaving Activity.

We report the structural, biochemical, and functional characterization of the product of gene PA0962 from Pseudomonas aeruginosa PAO1. The protein, termed Pa Dps, adopts the Dps subunit fold and oligomerizes into a nearly spherical 12-mer quaternary structure at pH 6.0 or in the presence of divalent cations at neutral pH and above. The 12-Mer Pa Dps contains two di-iron centers at the interface of each subunit dimer, coordinated by conserved His, Glu, and Asp residues. In vitro, the di-iron centers catalyze the oxidation of Fe2+ utilizing H2O2 (not O2) as an oxidant, suggesting Pa Dps functions to aid P. aeruginosa to survive H2O2-mediated oxidative stress. In agreement, a P. aeruginosa Δdps mutant is significantly more susceptible to H2O2 than the parent strain. The Pa Dps structure harbors a novel network of Tyr residues at the interface of each subunit dimer between the two di-iron centers, which captures radicals generated during Fe2+ oxidation at the ferroxidase centers and forms di-tyrosine linkages, thus effectively trapping the radicals within the Dps shell. Surprisingly, incubating Pa Dps and DNA revealed unprecedented DNA cleaving activity that is independent of H2O2 or O2 but requires divalent cations and 12-mer Pa Dps.

Concise Synthesis of (-)-GA18 Methyl Ester.

Gibberellins (GAs) are important plant hormones, but some of their family members are in extremely limited natural supply including GA18. Herein, we report a concise synthesis of (-)-GA18 methyl ester, a member of the C20 gibberellins, from commercially available and cheap andrographolide. Our synthesis features an intramolecular ene reaction to form the C ring, an oxidative cleavage followed by aldol condensation to realize a ring contraction and form the challenging trans-hydrindane (AB ring), and a photochemical [2+2] cycloaddition accompanied by a subsequent SmI2-mediated skeletal rearrangement to construct the methylenebicyclo[3.2.1]octanol moiety (CD ring).

Siderosis idiopática del sistema nervioso central y asociación con atrofia óptica e infarto cerebral. Caso clínico / Superficial siderosis of the central nervous system. Report of one case

Superficial siderosis of the central nervous system is produced by the deposit of hemosiderin within the subpial layers of the central nervous system and central parts of the cranial nerves, leading to progressive degeneration. We report a 55-year-old male who consulted for hearing loss and long-standing progressive decrease in visual acuity, associated with sudden onset of left hemiparesis. A brain CAT scan showed subacute ischemic lesions in the territory of the right posterior cerebral artery (thalamus and right subcortical temporal regions), old ischemic lesions in the right subcortical occipital regions and cerebellar atrophy. A magnetic resonance confirmed the lesions and the presence of superficial diffuse siderosis. A cerebrospinal fluid analysis showed slight xanthochromia, 26 leukocytes/mm3, glucose 51 mg/dL and proteins 1.23 g/L. He was managed with aspirin in low doses and statins. His motor function improved and was discharged two weeks after admission.

An unprecedented function for a tungsten-containing oxidoreductase.

Five tungstopterin-containing oxidoreductases were characterized from the hyperthermophile Pyrococcus furiosus. Each enzyme catalyzes the reversible conversion of one or more aldehydes to the corresponding carboxylic acid, but they have different specificities. The physiological functions of only two of these enzymes are known: one, termed GAPOR, is a glycolytic enzyme that oxidizes glyceraldehyde-3-phosphate, while the other, termed AOR, oxidizes multiple aldehydes generated during peptide fermentation. Two of the enzymes have known structures (AOR and FOR). Herein, we focus on WOR5, the fifth tungstopterin enzyme to be discovered in P. furiosus. Expression of WOR5 was previously shown to be increased during cold shock (growth at 72 â„ƒ), although the physiological substrate is not known. To gain insight into WOR5 function, we sought to determine both its structure and identify its intracellular substrate. Crystallization experiments were performed with a concentrated cytoplasmic extract of P. furiosus grown at 72 â„ƒ and the structure of WOR5 was deduced from the crystals that were obtained. In contrast to a previous report, WOR5 is heterodimeric containing an additional polyferredoxin-like subunit with four [4Fe-4S] clusters. The active site structure of WOR5 is substantially different from that of AOR and FOR and the significant electron density observed adjacent to the tungsten cofactor of WOR5 was modeled as an aliphatic sulfonate. Biochemical assays and product analysis confirmed that WOR5 is an aliphatic sulfonate ferredoxin oxidoreductase (ASOR). A catalytic mechanism for ASOR is proposed based on the structural information and the potential role of ASOR in the cold-shock response is discussed.

Key Concepts Surrounding Cardiogenic Shock.

Cardiogenic shock (CS) is the final common pathway of impaired cardiovascular performance that results in ineffective forward cardiac output producing clinical and biochemical signs of organ hypoperfusion. CS represents the most common cause of shock in the cardiac intensive care unit (CICU) and accounts for a substantial proportion of CICU patient deaths. Despite significant advances in revascularization techniques, pharmacologic therapeutics and mechanical support devices, CS remains associated with a high mortality rate. Indeed, the prevalence of CS within the CICU appears to be increasing. CS can be differentiated as phenotypes reflecting different metabolic, inflammatory, and hemodynamic profiles, depending also on anatomic substrate and congestion profile. Future prospective studies and clinical trials may further characterize these phenotypes and apply targeted intervention for each phenotype and SCAI SHOCK stage rather than a one-size-fits-all approach. Overall, there are 8 key concepts of CS; 1) the mortality associated with CS; 2) Shock attributed to AMI may be declining in both incidence and associated mortality; 3) providers should think about hemodynamic, metabolic, inflammation and cardiac function in totality to assess CS; 4) CS is a dynamic process; 5) no randomized trials evaluating use of the PAC in patients with CS; 6) most data supporting neosynephrine as first line agent in CS; 7) most registries suggest that almost half of CS patients do not have any mechanical support, and the vast majority of the remainder utilize the IABP; and 8) patients with AMI CS should receive emergent PCI of the culprit vessel.

Pseudomonas aeruginosa Bacterioferritin Is Assembled from FtnA and BfrB Subunits with the Relative Proportions Dependent on the Environmental Oxygen Availability.

Ferritins are iron storage proteins assembled from 24 subunits into a spherical and hollow structure. The genomes of many bacteria harbor genes encoding two types of ferritin-like proteins, the bacterial ferritins (Ftn) and the bacterioferritins (Bfr), which bind heme. The genome of P. aeruginosa PAO1 (like the genomes of many bacteria) contains genes coding for two different types of ferritin-like molecules, ftnA (PA4235) and bfrB (PA3531). The reasons for requiring the presence of two distinct types of iron storage protein in bacterial cells have remained largely unexplained. Attempts to understand this issue in P. aeruginosa through the recombinant expression of the ftnA and bfrB genes in E. coli host cells, coupled to the biochemical and structural characterization of the recombinant 24-mer FtnA and 24-mer BfrB molecules, have shown that each of the recombinant molecules can form an Fe3+-mineral core. These observations led to the suggestion that 24-mer FtnA and 24-mer BfrB molecules coexist in P. aeruginosa cells where they share iron storage responsibilities. Herein, we demonstrate that P. aeruginosa utilizes a single heterooligomeric 24-mer Bfr assembled from FtnA and BfrB subunits. The relative content of the FtnA and BfrB subunits in Bfr depends on the O2 availability during cell culture, such that Bfr isolated from aerobically cultured P. aeruginosa is assembled from a majority of BfrB subunits. In contrast, when the cells are cultured in O2-limiting conditions, the proportion of FtnA subunits in the isolated Bfr increases significantly and can become the most abundant subunit. Despite the variability in the subunit composition of Bfr, the 24-mer assembly is consistently arranged from FtnA subunit dimers devoid of heme and BfrB subunit dimers each containing a heme molecule.

[Superficial siderosis of the central nervous system. Report of one case]. / Siderosis idiopática del sistema nervioso central y asociación con atrofia óptica e infarto cerebral. Caso clínico.

Superficial siderosis of the central nervous system is produced by the deposit of hemosiderin within the subpial layers of the central nervous system and central parts of the cranial nerves, leading to progressive degeneration. We report a 55-year-old male who consulted for hearing loss and long-standing progressive decrease in visual acuity, associated with sudden onset of left hemiparesis. A brain CAT scan showed subacute ischemic lesions in the territory of the right posterior cerebral artery (thalamus and right subcortical temporal regions), old ischemic lesions in the right subcortical occipital regions and cerebellar atrophy. A magnetic resonance confirmed the lesions and the presence of superficial diffuse siderosis. A cerebrospinal fluid analysis showed slight xanthochromia, 26 leukocytes/mm3, glucose 51 mg/dL and proteins 1.23 g/L. He was managed with aspirin in low doses and statins. His motor function improved and was discharged two weeks after admission.

Efficacy of a Fixed-Dose Combination of Ibuprofen and Acetaminophen Compared With Individual Monocomponents in Adult Male Subjects With Endotoxin-Induced Fever: A Randomized Controlled Trial.

PURPOSE: This study evaluated antipyretic efficacy and onset of a novel fixed-dose combination (FDC) of ibuprofen (IBU; 250 mg) and acetaminophen (APAP; 500 mg) compared with placebo and IBU or APAP monocomponents. MET: This single-center, randomized, double-blind, placebo-controlled, full-factorial study was conducted in healthy males aged 18 to 55 years with pyrexia induced by intravenous administration of reference standard endotoxin (RSE). After attainment of an oral temperature ≥38.1°C, subjects were randomized 3:3:3:1 to a double-blind single oral dose of FDC IBU/APAP 250 mg/500 mg, APAP 500 mg, IBU 250 mg, or placebo. Oral temperature was measured every 10 minutes for 2 hours, then every 30 minutes until 8 hours postdose. Time-weighted sum of temperature differences from baseline to 8 hours (WSTD0-8) after study medication administration was the primary efficacy end point. Secondary end points included WSTD scores from 0 to 2 hours, 0 to 4 hours, 0 to 6 hours, and 6 to 8 hours; time to return to "normal" temperature; time to rescue medication use; and global drug evaluation. Safety was assessed via adverse events (AEs). FINDINGS: Two hundred ninety subjects were randomized; 273 were included in the primary efficacy analysis. WSTD0-8 was significantly better for FDC IBU/APAP 250 mg/500 mg (P = 0.002), IBU 250 mg (P = 0.030), and APAP 500 mg (P = 0.023) versus placebo; there were no significant differences between active treatments. For WSTD0-2, only the FDC was statistically significant versus placebo (P = 0.004). All active treatments were significantly better (P < 0.05) for WSTD0-4 and WSTD0-6 versus placebo; there were no differences in WSTD6-8 between cohorts. Temperature returned to normal during the 8-hour treatment period in ∼50% of subjects in each cohort. Only 1 subject (IBU cohort) took rescue medication. Post hoc analyses at early time points revealed significant treatment differences favoring FDC versus placebo and IBU for the WSTD from baseline during the 50- to 110-minute posttreatment window; for WSTD from baseline during the 80- to 110-minute posttreatment window, FDC provided significant treatment differences versus placebo and both monocomponents. Overall, 223 (76.9%) of 290 subjects experienced AEs related to RSE; only 2 subjects experienced treatment-related AEs (FDC, rash; placebo, ear pain). IMPLICATIONS: Although the primary end point was not met, these results suggest that FDC IBU/APAP 250 mg/500 mg provides effective antipyresis with a faster onset versus equal doses of IBU and APAP alone. ClinicalTrials.gov identifier: NCT02761980.

Safety and tolerability of fixed-dose combinations of ibuprofen and acetaminophen: pooled analysis of phase 1-3 clinical trials.

OBJECTIVES: An ibuprofen (IBU)/acetaminophen (APAP) fixed-dose combination (FDC) for over-the-counter (OTC) use was developed with the goal of providing the same effective analgesic activity as full doses of the individual monocomponents, while reducing individual monocomponent drug exposures. Here, the safety and tolerability of the FDC is characterized using pooled safety data from phase 1-3 clinical trials in the FDC development program. METHODS: We conducted a pooled safety analysis of data from 7 clinical trials: three phase 1 pharmacokinetic trials, a phase 2 proof-of-concept trial, and three phase 3 trials (a single- and a multiple-dose trial in a dental pain model and a single-dose trial in an induced-fever model). Safety and tolerability of the FDC were assessed by adverse events (AEs) for the total group and subgroups (age, sex, race). RESULTS: A total of 1,477 participants were enrolled in the 7 trials; 715 were treated with FDC IBU/APAP, 432 with IBU monotherapy, 330 with APAP monotherapy, and 156 with placebo. Most subjects were white (86.5%), and 44% were female. Two trials enrolling 195 adolescents accounted for 13.2% of the overall study population. All-causality treatment-emergent AEs (TEAEs) occurred in 19.7% of the 1477 participants. Nausea (13.5%), vomiting (7.4%), dizziness (4.5%), headache (1.2%), and feeling hot (1.0%) were the only TEAEs reported in ≥1% of subjects. Treatment-related AEs occurred in 1.8% of the subjects in the overall population. The incidence of AEs, including treatment-related AEs, was consistently lower in all active treatment groups than in the placebo group; this also applied to subgroups according to sex, race, and age, including adolescents aged 12-17 years. The higher rate of AEs with placebo was likely due to lack of pain/fever control. CONCLUSION: Single-dose or short-course FDC IBU/APAP OTC use was well tolerated, with an AE profile similar to its IBU and APAP monocomponents. CLINICALTRIALS.GOV REGISTRATION: NCT01559259; NCT02912650; NCT02837952; NCT02761980. The pharmacokinetic studies (n = 3) did not require registration.

Small Molecule Inhibitors of the Bacterioferritin (BfrB)-Ferredoxin (Bfd) Complex Kill Biofilm-Embedded Pseudomonas aeruginosa Cells.

Bacteria depend on a well-regulated iron homeostasis to survive adverse environments. A key component of the iron homeostasis machinery is the compartmentalization of Fe3+ in bacterioferritin and its subsequent mobilization as Fe2+ to satisfy metabolic requirements. In Pseudomonas aeruginosa Fe3+ is compartmentalized in bacterioferritin (BfrB), and its mobilization to the cytosol requires binding of a ferredoxin (Bfd) to reduce the stored Fe3+ and release the soluble Fe2+. Blocking the BfrB-Bfd complex in P. aeruginosa by deletion of the bfd gene triggers an irreversible accumulation of Fe3+ in BfrB, concomitant cytosolic iron deficiency and significant impairment of biofilm development. Herein we report that small molecules developed to bind BfrB at the Bfd binding site block the BfrB-Bfd complex, inhibit the mobilization of iron from BfrB in P. aeruginosa cells, elicit a bacteriostatic effect on planktonic cells, and are bactericidal to cells embedded in mature biofilms.

Mobilization of Iron Stored in Bacterioferritin Is Required for Metabolic Homeostasis in Pseudomonas aeruginosa.

Iron homeostasis offers a significant bacterial vulnerability because pathogens obtain essential iron from their mammalian hosts, but host-defenses maintain vanishingly low levels of free iron. Although pathogens have evolved mechanisms to procure host-iron, these depend on well-regulated iron homeostasis. To disrupt iron homeostasis, our work has targeted iron mobilization from the iron storage protein bacterioferritin (BfrB) by blocking a required interaction with its cognate ferredoxin partner (Bfd). The blockade of the BfrB-Bfd complex by deletion of the bfd gene (Δbfd) causes iron to irreversibly accumulate in BfrB. In this study we used mass spectrometry and NMR spectroscopy to compare the proteomic response and the levels of key intracellular metabolites between wild type (wt) and isogenic ΔbfdP. aeruginosa strains. We find that the irreversible accumulation of unusable iron in BfrB leads to acute intracellular iron limitation, even if the culture media is iron-sufficient. Importantly, the iron limitation and concomitant iron metabolism dysregulation trigger a cascade of events that lead to broader metabolic homeostasis disruption, which includes sulfur limitation, phenazine-mediated oxidative stress, suboptimal amino acid synthesis and altered carbon metabolism.

A Paleogenomic Reconstruction of the Deep Population History of the Andes.

There are many unanswered questions about the population history of the Central and South Central Andes, particularly regarding the impact of large-scale societies, such as the Moche, Wari, Tiwanaku, and Inca. We assembled genome-wide data on 89 individuals dating from ∼9,000-500 years ago (BP), with a particular focus on the period of the rise and fall of state societies. Today's genetic structure began to develop by 5,800 BP, followed by bi-directional gene flow between the North and South Highlands, and between the Highlands and Coast. We detect minimal admixture among neighboring groups between ∼2,000-500 BP, although we do detect cosmopolitanism (people of diverse ancestries living side-by-side) in the heartlands of the Tiwanaku and Inca polities. We also highlight cases of long-range mobility connecting the Andes to Argentina and the Northwest Andes to the Amazon Basin. VIDEO ABSTRACT.

Efficacy and Safety of Single and Multiple Doses of a Fixed-dose Combination of Ibuprofen and Acetaminophen in the Treatment of Postsurgical Dental Pain: Results From 2 Phase 3, Randomized, Parallel-group, Double-blind, Placebo-controlled Studies.

OBJECTIVES: A previous pilot study demonstrated that various fixed-dose combinations (FDCs) of ibuprofen (IBU) and acetaminophen (APAP) provided analgesic efficacy comparable to a higher dose of IBU, with the same safety profile. These studies further evaluated the chosen FDC IBU/APAP 250/500 mg formulation. MATERIALS AND METHODS: Two phase 3 dental pain studies enrolled healthy young patients with ≥moderate pain after ≥3 third molar extractions who received single-dose FDC IBU/APAP 250/500 mg, IBU 250 mg, APAP 650 mg, or placebo evaluated over 12 hours (study 1) or multiple-dose FDC or placebo every 8 hours, evaluated over 48 hours (study 2). Time-weighted sum of pain intensity differences over 8 (SPID[11]0-8) and 24 (SPID[11]0-24) hours were primary outcomes, respectively. Time to meaningful pain relief and duration of pain relief were assessed; tolerability was evaluated by adverse events. RESULTS: Five hundred sixty-eight patients were randomized in study 1; 123 in study 2. Study 1: SPID[11]0-8 favored FDC significantly over placebo, IBU, and APAP (P<0.001, P=0.008, and P<0.001, respectively); study 2: SPID[11]0-24 significantly favored FDC over placebo (P<0.001), with sustained efficacy during multiple dosing. Time to meaningful pain relief occurred within 1 hour; pain relief duration was >8 hours in both studies. Adverse event rates were lowest with the FDC. DISCUSSION: FDC IBU/APAP 250/500 mg provides superior analgesic efficacy to individual monocomponents (IBU 250 mg and APAP 650 mg), a rapid onset of action, >8-hour duration of pain relief, is generally well tolerated, and may provide an additional nonopioid treatment option for acute pain.