Project description:Rofecoxib (Vioxx) was one of the first selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) to be approved for use in humans. Within five years after its release to the public, Vioxx was withdrawn from the market owing to the adverse cardiovascular effects of the drug. Despite the widespread knowledge of the development and withdrawal of Vioxx, relatively little is known at the molecular level about how the inhibitor binds to COX-2. Vioxx is unique in that the inhibitor contains a methyl sulfone moiety in place of the sulfonamide moiety found in other coxibs such as celecoxib and valdecoxib. Here, new crystallization conditions were identified that allowed the structural determination of human COX-2 in complex with Vioxx and the structure was subsequently determined to 2.7 Å resolution. The crystal structure provides the first atomic level details of the binding of Vioxx to COX-2. As anticipated, Vioxx binds with its methyl sulfone moiety located in the side pocket of the cyclooxygenase channel, providing support for the isoform selectivity of this drug.
Project description:BackgroundOrganismal Performance Assays (OPAs) are a unique toxicity quantification method used to assess the safety of potentially toxic compounds, such as pharmaceuticals. OPAs utilize genetically diverse wild mice (Mus musculus) housed in semi-natural enclosures wherein exposed individuals compete directly with controls for resources. Previously, OPAs have been successful in detecting adverse effects in mice that were exposed to paroxetine. Here, we further test OPAs utility in pharmaceutical safety assessment by testing OPAs with rofecoxib, a drug with known adverse effects in humans.MethodsWe exposed mice to rofecoxib (~37.5 mg/kg/day) during gestation and into early adulthood. Exposure ceased when individuals were released into enclosures. Five independent populations were established and rofecoxib-exposed individuals (n = 58) competed directly with control individuals (n = 58) over 28 weeks. Organismal performance was determined by quantifying reproduction, survival and male competitive ability.ResultsIn enclosures, rofecoxib-exposed males had equal reproduction, survival and competitive ability. Rofecoxib-exposed females had equal survival compared to controls but experienced 40% higher reproductive output.ConclusionsThe adverse health effects of rofecoxib seen in humans escaped detection by OPAs, just as they had during traditional preclinical assays. These results may be explained by the exposure design (in enclosures, all animals were on the control diet), the relatively short duration of exposure, species differences, or because the health benefits of the drug negated the side effects. Similarly to numerous assays used in preclinical trials, OPAs cannot reveal all maladies, despite their demonstrated sensitivity in detecting cryptic toxicity from numerous exposures.
Project description:BackgroundThere is a variation in dialysis withdrawal rates, but reasons for this variation across European countries are largely unknown. We therefore surveyed nephrologists' perceptions of factors concerning dialysis withdrawal and palliative care and explored relationships between these perceptions and reports of whether withdrawal actually occurred in practice.MethodsWe developed a 33-item electronic survey, disseminated via an email blast to all European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) members. In our data analyses, we distinguished those respondents who reported occurrence from those reporting no dialysis withdrawal in their unit. With multilevel logistic regression, we investigated the association between respondents' characteristics and perceptions and whether they reported occurrence of dialysis withdrawal or not.ResultsFive hundred and twenty-eight nephrologists from 45 countries completed the questionnaire; 42% reported occurrence of withdrawal in their unit in the past year, and 56% perceived that stopping life-prolonging treatment in terminally ill patients was allowed. Few respondents reported presence in their unit of protocols on withdrawal decision making (7%) or palliative care (10%) or the common involvement of a geriatrician in withdrawal decisions (10%). The majority stated that palliative care had not been part of their core curriculum (74%) and that they had not recently attended continuous medical education sessions on this topic (73%). Respondents from Eastern and Southern Europe had a 42 and 40% lower probability, respectively, of reporting withdrawal compared with those from North European countries. Working in a public centre [odds ratio (OR), 2.41; 95% confidence interval (CI), 1.36-4.25] and respondents' perception that stopping life-prolonging treatment in terminally ill patients was allowed (OR, 1.96; 95% CI, 1.23-3.12), that withdrawal decisions were commonly shared between doctor and patient (OR, 1.97; 95% CI, 1.26-3.08) and that palliative care was reimbursed (OR, 1.81; 95% CI, 1.16-2.83) increased the odds of reporting occurrence of withdrawal.ConclusionReports of dialysis withdrawal occurrence varied between European countries. Occurrence reports were more likely if respondents worked in a public centre, if stopping life-prolonging treatments was perceived as allowed, if withdrawal decisions were considered shared between doctors and patients and if reimbursement of palliative care was believed to be in place. There is room for improvement regarding protocols on withdrawal and palliative care processes and regarding nephrologists' training and education on end-of-life care.
Project description:The cyclooxygenase-2 receptor is a therapeutic target for planning potential drugs with anti-inflammatory activity. The selective cyclooxygenase-2 (COX-2) inhibitor rofecoxib was selected as a pivot molecule to perform virtual ligand-based screening from six commercial databases. We performed the search for similarly shaped Rapid Overlay of Chemical Structures (ROCS) and electrostatic (EON) compounds. After, we used pharmacokinetic and toxicological parameters to determine the best potential compounds, obtained through the softwares QikProp and Derek, respectively. Then, the compounds proceeded to the molecular anchorage study, which showed promising results of binding affinity with the hCOX-2 receptor: LMQC72 (∆G = -11.0 kcal/mol), LMQC36 (∆G = -10.6 kcal/mol), and LMQC50 (∆G = -10.2 kcal/mol). LMQC72 and LMQC36 showed higher binding affinity compared to rofecoxib (∆G = -10.4 kcal/mol). Finally, molecular dynamics (MD) simulations were used to evaluate the interaction of the compounds with the target hCOX-2 during 150 ns. In all MD simulation trajectories, the ligands remained interacting with the protein until the end of the simulation. The compounds were also complexing with hCOX-2 favorably. The compounds obtained the following affinity energy values: rofecoxib: ΔGbind = -45.31 kcal/mol; LMQC72: ΔGbind = -38.58 kcal/mol; LMQC36: ΔGbind = -36.10 kcal/mol; and LMQC50: ΔGbind = -39.40 kcal/mol. The selected LMQC72, LMQC50, and LMQC36 structures showed satisfactory pharmacokinetic results related to absorption and distribution. The toxicological predictions of these compounds did not display alerts for possible toxic groups and lower risk of cardiotoxicity compared to rofecoxib. Therefore, future in vitro and in vivo studies are needed to confirm the anti-inflammatory potential of the compounds selected here with bioinformatics approaches based on rofecoxib ligand.
Project description:BACKGROUND: Rofecoxib is a cyclo-oxygenase 2 selective inhibitor. This systematic review of rofecoxib in acute pain examined studies in adults of analgesic efficacy over six hours, the amount and quality of the evidence on extended duration of analgesia, and the quality and quantity of evidence on adverse events. METHODS: Cochrane Library (issue 4, 2001), Biological Abstracts (March 2002), MEDLINE (March 2002) and PubMed (March 2002) were searched using rofecoxib as a free text term. The area under the pain relief versus time curve was dichotomized using validated equations to derive the proportion of patients on rofecoxib 50 mg or placebo with at least 50% pain relief over six hours. This was used to calculate the number needed to treat for at least 50% pain relief over six hours for rofecoxib compared with placebo. Information on duration of analgesia and adverse events was also collected. RESULTS: Five included trials investigated 1,118 patients, of whom 211 received placebo and 464 received rofecoxib 50 mg. The NNT for rofecoxib 50 mg was 2.3 (95% confidence interval 2.0 to 2.6). The weighted mean remedication time was 1.9 hours for placebo (126 patients), 7.4 hours for ibuprofen 400 mg (97 patients) and 13.6 hours for rofecoxib 50 mg (322 patients). CONCLUSION: Rofecoxib at 2-4 times the standard daily dose for chronic pain is an effective single dose oral analgesic in acute pain. Limitations in trial reporting constrain conclusions about longer duration of analgesia and adverse event profile.
Project description:Cardiac adverse effects are among the leading causes of the discontinuation of clinical trials and the withdrawal of drugs from the market. The novel concept of 'hidden cardiotoxicity' is defined as cardiotoxicity of a drug that manifests in the diseased (e.g. ischemic/reperfused), but not in the healthy heart or as a drug-induced deterioration of cardiac stress adaptation (e.g. ischemic conditioning). Here, we aimed to test if the cardiotoxicity of a selective COX-2 inhibitor rofecoxib that was revealed during its clinical use, i.e., increased occurrence of proarrhythmic and thrombotic events, could have been revealed in early phases of drug development by using preclinical models of ischemia/reperfusion (I/R) injury. Rats that were treated with rofecoxib or vehicle for four weeks were subjected to 30 min. coronary artery occlusion and 120 min. reperfusion with or without cardioprotection that is induced by ischemic preconditioning (IPC). Rofecoxib increased overall the arrhythmias including ventricular fibrillation (VF) during I/R. The proarrhythmic effect of rofecoxib during I/R was not observed in the IPC group. Rofecoxib prolonged the action potential duration (APD) in isolated papillary muscles, which was not seen in the simulated IPC group. Interestingly, while showing hidden cardiotoxicity manifested as a proarrhythmic effect during I/R, rofecoxib decreased the infarct size and increased the survival of adult rat cardiac myocytes that were subjected to simulated I/R injury. This is the first demonstration that rofecoxib increased acute mortality due to its proarrhythmic effect via increased APD during I/R. Rofecoxib did not interfere with the cardiprotective effect of IPC; moreover, IPC was able to protect against rofecoxib-induced hidden cardiotoxicity. These results show that cardiac safety testing with simple preclinical models of I/R injury uncovers hidden cardiotoxicity of rofecoxib and might reveal the hidden cardiotoxicity of other drugs.
Project description:New insights into the biological properties of cyclooxygenase-2 (COX-2) and its response pathway challenge the hypothesis that COX-2 is simply pro-inflammatory and inhibition of COX-2 solely prevents the development of inflammation and ameliorates inflammatory pain. The present study performed a comprehensive analysis of gene/protein expression induced by a selective inhibitor of COX-2, rofecoxib, compared with a non-selective COX inhibitor, ibuprofen, and placebo in a clinical model of acute inflammatory pain (the surgical extraction of impacted third molars) using microarray analysis followed by quantitative RT-PCR verification and Western blotting. Inhibition of COX-2 modulated gene expression related to inflammation and pain, the arachidonic acid pathway, apoptosis/angiogenesis, cell adhesion and signal transduction. Compared to placebo, rofecoxib treatment increased the gene expression of ANXA3 (annexin 3), SOD2 (superoxide dismutase 2), SOCS3 (suppressor of cytokine signaling 3) and IL1RN (IL1 receptor antagonist) which are associated with inhibition of phospholipase A(2) and suppression of cytokine signaling cascades, respectively. Both rofecoxib and ibuprofen treatment increased the gene expression of the pro-inflammatory mediators, IL6 and CCL2 (chemokine C-C motif ligand 2), following tissue injury compared to the placebo treatment. These results indicate a complex role for COX-2 in the inflammatory cascade in addition to the well-characterized COX-dependent pathway, as multiple pathways are also involved in rofecoxib-induced anti-inflammatory and analgesic effects at the gene expression level. These findings may also suggest an alternative hypothesis for the adverse effects attributed to selective inhibition of COX-2.
Project description:Owing to the involvement of cyclooxygenase-2 (COX-2) in carcinogenesis, COX-2-selective inhibitors are increasingly studied for their potential cytotoxic properties. Moreover, the incorporation of carboranes in structures of established anti-inflammatory drugs can improve the potency and metabolic stability of the inhibitors. Herein, we report the synthesis of carborane-containing derivatives of rofecoxib that display remarkable cytotoxic or cytostatic activity in the micromolar range with excellent selectivity for melanoma and colon cancer cell lines over normal cells. Furthermore, it was shown that the carborane-modified derivatives of rofecoxib showed different modes of action that were dependent on the cell type.