Clinical pharmacokinetics and pharmacodynamics of celecoxib: a selective cyclo-oxygenase-2 inhibitor

Potent cell growth inhibitory effects in hepatitis B virus X protein positive hepatocellular carcinoma cells by the selective cyclooxygenase-2 inhibitor celecoxib

Hepatitis B virus (HBV) X protein (HBx) and cyclooxygenase-2 (COX-2) are all playing roles in hepatocellular carcinoma (HCC), but the reversing effects of COX-2 inhibitors on the neoplastic features caused by HBx protein is still unclear. To further evaluate the therapeutic potential of celecoxib on HBx mediated transformation, HCC cells transfected with HBx gene were treated with COX-2 selective inhibitor, celecoxib. The amount the main metabolite of COX-2, prostaglandin E2 (PGE2), was determined by using high sensitivity ELISA. Electron microscope and flow cytometry was used to analyze cell apoptosis and cell cycle distribution. RT-PCR and Western blot were used to identify the molecules involved in celecoxib induced cell apoptosis. The results showed that celecoxib inhibited cell growth more significantly and also induced more cell apoptosis in HBx over-expression cells than in control cells. Celecoxib could selectively inhibited COX-2 expression and PGE2 production. Celecoxib also inhibited p(473Ser)Akt, raf and p53 expression, and induced apoptosis by release of cytochrome c and activation of caspase 9, 3, and 6, which were more remarkably in HBx positive cells than in control cells. These results suggest that celecoxib had potent cell growth inhibitory effects on HBx positive HCC cells mainly through inducing more cell apoptosis, and these findings provide a new insight into the anticancer effects of celecoxib against HBx related HCC.

Effect of folic acid on methotrexate induction of sulfotransferases in rats

Our earlier investigation showed that MTX is an inducer of rat and human sulfotransferases. Here we report that folic acid treatment inhibited MTX induction of aryl sulfotransferase (AST-IV) in female rat liver and hydroxysteroid sulfotransferase (STa) in male rat liver. This is important for understanding the clinical mechanisms of MTX.

The effect of selective cyclooxygenase-2 inhibitor on human osteoclast precursors to influence osteoclastogenesis in vitro

The inducible prostaglandin synthesis enzyme, cyclooxygenase-2 (COX-2), is involved in bone resorption and osteoclastogenesis, and acts indirectly through prostaglandin E2 (PG E2) produced by osteoblastic cells. This study was undertaken to investigate whether celecoxib (a selective COX-2 inhibitor) has a direct effect on human osteoclast precursors to influence osteoclastogenesis in vitro. Human peripheral blood mononuclear cells (PBMCs) were cultured on glass coverslips and dentine slices with soluble receptor activator of NF-kB ligand (sRANKL) and macrophage colony stimulating factor (M-CSF). COX inhibitors including celecoxib were added to the cultures. Osteoclast formation was assessed as the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the functional evidence of lacunar resorption pits on dentine slices was assessed. Celecoxib and indomethacin inhibited osteoclast formation and the extent of lacunar resorption in a dose-dependent manner, but the effect of indomethacin was less than that of celecoxib. Mofezolac affected neither the number of TRAP-positive MNCs nor the extent of lacunar resorption pits. These results indicate that celecoxib influences not only osteoclast formation through osteoblastic cells but also acts directly on circulating osteoclast precursors to influence human osteoclast differentiation. The effect of celecoxib on osteoclast precursors may be related to the COX-2 signal pathway.

[Down-regulation of survivin in growth inhibition of hepatoma cells induced by a selective cyclooxygenase-2 inhibitor]

BACKGROUND/AIMS

Cyclooxygenase-2 (COX-2) inhibitors reportedly inhibit the growth of hepatocellular carcinoma (HCC) via caspase-dependent or caspase-independent apoptosis, which is due to COX-2 being associated with hepatocarcinogenesis. Survivin is highly expressed in most human cancers, but the mechanism regulating survivin expression remains unclear. We investigated the regulatory expression of survivin in selective-COX-2-inhibitor-induced growth inhibition of hepatoma cells.

METHODS

After treatment with NS-398 (a selective COX-2 inhibitor) at various concentrations (10, 50, 100, 150, and 200 micrometer), the growth inhibition of Hep3B hepatoma cells was assessed by an MTT cell-viability assay, DNA fragmentation gel analysis, and flow cytometry. The expression of survivin transcript was analyzed by reverse-transcription polymerase chain reactions.

RESULTS

NS-398 inhibited the growth of hepatoma cells by an amount dependent on the concentration and the time since treatment. Apoptotic DNA ladder and flow-cytometry shifting to the sub-G1 phase were revealed in NS-398-induced growth inhibition of hepatoma cells. NS-398 suppressed the expression of the survivin gene in a concentration- and time-dependent manner.

CONCLUSIONS

Survivin was down-regulated in the growth inhibition of hepatoma cells induced by a selective COX-2 inhibitor, NS-398, in a concentration- and time-dependent manner. These results suggest the therapeutic inhibition of COX-2 via suppression of survivin in HCC.

Effects of short- and long-term celecoxib on orthodontic tooth movement

OBJECTIVE

To test the hypothesis that short- and long-term celecoxib administration has no effect on orthodontic tooth movement.

MATERIALS AND METHODS

Male Wistar rats were submitted to short- (3 days) and long-term (14 days) celecoxib administration, while the respective control groups received equivolumetric saline intraperitoneal injections. The upper left first molars of all rats were moved mesially for 14 days by a fixed orthodontic appliance exerting 50 g force upon insertion. After the experimental period, tooth movement was quantified and tissues around the first molar were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. The amount of tooth movement and the number of TRAP-positive cells on the alveolar bone surface were evaluated.

RESULTS

The amount of tooth movement was significantly reduced in rats submitted to short- and long-term celecoxib administration, while the number of osteoclasts on the alveolar bone did not differ between the four groups studied.

CONCLUSIONS

The hypothesis is rejected. Although celecoxib administration did not affect the number of osteoclasts, the osteoclast activity might be reduced, which could explain the inhibition of tooth movement observed in the celecoxib-treated animals. These results indicate that orthodontists should be aware of patients under short- and long-term therapy with celecoxib.

Cyclooxygenase-2 inhibition increases lipopolysaccharide-induced atherosclerosis in mice

AIMS

The risk of adverse cardiovascular events in humans is increased with chronic use of cyclooxygenase-2 (COX-2) inhibitors. However, the role of COX-2 in animal models of cardiovascular disease has been controversial. In humans and animal models, cardiovascular disease is increased by bacterial infection of the supporting tissue of the teeth, a condition known as periodontal disease. Periodontal disease may result in chronic exposure to pro-inflammatory mediators, such as bacterial lipopolysaccharide (LPS), thereby producing a systemic inflammatory response. The current study examined the role of COX-2 in atherosclerosis induced by LPS derived from the periodontal disease pathogen Porphyromonas gingivalis (P. gingivalis).

METHODS AND RESULTS

Porphyromonas gingivalis LPS was administered by chronic infusion for 28 days and atherosclerosis development was examined in the aortic root of ApoE (apolipoprotein E)-deficient mice. The extent of atherosclerosis was compared between mice receiving control diet or diet containing the COX-2 inhibitor celecoxib. The role of COX-2 in P. gingivalis LPS-induced inflammatory cell activation was examined in peritoneal macrophages. Porphyromonas gingivalis LPS infusion significantly increased atherosclerosis development. In mice infused with P. gingivalis LPS, administration of the COX-2 inhibitor celecoxib further increased the extent of atherosclerotic lesion area. In peritoneal macrophages, P. gingivalis LPS increased the expression of COX-2 mRNA (messenger ribonucleic acid) and the production of prostaglandin (PG) E(2) (PGE(2)), the latter of which was inhibited by celecoxib. Porphyromonas gingivalis LPS-induced expression of tumour necrosis factor alpha (TNFalpha) was enhanced by inactivation of COX-2 and was attenuated by treatment with PGE(2).

CONCLUSION

The inhibition of COX-2-derived PGE(2) may enhance P. gingivalis LPS-induced atherosclerosis by increasing macrophage production of TNFalpha.

Celecoxib-Cyclodextrin Systems: Characterization and Evaluation of In Vitro and In Vivo Advantage

Solid dispersions of Celecoxib were prepared with hydroxypropyl beta cyclodextrin by various methods such as physical mixture, cogrinding, kneading, and coevaporation. The dispersions were characterized by differential scanning calorimetry (DSC), X-ray diffraction patterns, infrared spectroscopy, and nuclear magnetic resonance studies. The DSC thermograms of the dispersions indicated potential of heat-induced interaction between Celecoxib and cyclodextrin that could influence in vitro drug dissolution. The dispersions exhibited faster rates of dissolution compared to that of Celecoxib. The kneaded dispersion with the fastest in vitro dissolution rate when compressed into tablets showed a better release profile compared to the tablets of pure Celecoxib. In vivo studies revealed that the kneaded dispersion provided for quicker response and was more effective in inhibiting rat paw edema as compared to Celecoxib alone, thus confirming the advantage of improved pharmacological activity of Celecoxib when administered as a solid dispersion with cyclodextrin.

Novel CYP2C9 promoter variants and assessment of their impact on gene expression

There are a considerable number of reports identifying and characterizing genetic variants within the CYP2C9 coding region. Much less is known about polymorphic promoter sequences that also might contribute to interindividual differences in CYP2C9 expression. To address this problem, approximately 10,000 base pairs of CYP2C9 upstream information were resequenced using 24 DNA samples from the Coriell Polymorphism Discovery Resource. Thirty-one single-nucleotide polymorphisms (SNPs) were identified; nine SNPs were novel, whereas 22 were reported previously. Using both sequencing and multiplex single-base extension, individual SNP frequencies were determined in 193 DNA samples obtained from unrelated, self-reported Hispanic Americans of Mexican descent, and they were compared with similar data obtained from a non-Latino white cohort. Significant interethnic differences were observed in several SNP frequencies, some of which seemed unique to the Hispanic population. Analysis using PHASE 2.1 inferred nine common (>1%) variant haplotypes, two of which included the g.3608C>T (R144C) CYP2C9(*)2 and two the g.42614A>C (I359L) CYP2C9(*)3 SNPs. Haplotype variants were introduced into a CYP2C9/luciferase reporter plasmid using site-directed mutagenesis, and the impact of the variants on promoter activity assessed by transient expression in HepG2 cells. Both constitutive and pregnane X receptor-mediated inducible activities were measured. Haplotypes 1B, 3A, and 3B each exhibited a 65% decrease in constitutive promoter activity relative to the reference haplotype. Haplotypes 1D and 3B exhibited a 50% decrease and a 40% increase in induced promoter activity, respectively. These data suggest that genetic variation within CYP2C9 regulatory sequences is likely to contribute to differences in CYP2C9 phenotype both within and among different populations.

Neuroinflammatory response to lipopolysaccharide is exacerbated in mice genetically deficient in cyclooxygenase-2

Background

Cyclooxygenases (COX) -1 and -2 are key mediators of the inflammatory response in the central nervous system. Since COX-2 is inducible by inflammatory stimuli, it has been traditionally considered as the most appropriate target for anti-inflammatory drugs. However, the specific roles of COX-1 and COX-2 in modulating a neuroinflammatory response are unclear. Recently, we demonstrated that COX-1 deficient mice show decreased neuroinflammatory response and neuronal damage in response to lipopolysaccharide (LPS).

Methods

In this study, we investigated the role of COX-2 in the neuroinflammatory response to intracerebroventricular-injected LPS (5 μg), a model of direct activation of innate immunity, using COX-2 deficient (COX-2^-/-) and wild type (COX-2^+/+) mice, as well as COX-2^+/+ mice pretreated for 6 weeks with celecoxib, a COX-2 selective inhibitor.

Results

Twenty-four hours after LPS injection, COX-2^-/- mice showed increased neuronal damage, glial cell activation, mRNA and protein expression of markers of inflammation and oxidative stress, such as cytokines, chemokines, iNOS and NADPH oxidase. Brain protein levels of IL-1β, NADPH oxidase subunit p67^phox, and phosphorylated-signal transducer and activator of transcription 3 (STAT3) were higher in COX-2^-/- and in celecoxib-treated mice, compared to COX-2^+/+ mice. The increased neuroinflammatory response in COX-2^-/- mice was likely mediated by the upregulation of STAT3 and suppressor of cytokine signaling 3 (SOCS3).

Conclusion

These results show that inhibiting COX-2 activity can exacerbate the inflammatory response to LPS, possibly by increasing glial cells activation and upregulating the STAT3 and SOCS3 pathways in the brain.

Effects of celecoxib on ionic currents and spontaneous firing in rat retinal neurons

Accumulating evidence suggests that the side effects of celecoxib, widely used to treat muscle and joint pain, may be mediated in part through cyclooxygenase-2 (COX-2) independent mechanisms, such as inhibition of ion channels. In this study we report effects of celecoxib on ionic currents and neuronal activity in isolated rat retinal neurons. We found that celecoxib suppressed voltage-gated potassium currents in retinal bipolar cells with an effective concentration to inhibit 50% of function (EC(50)) of 5.5 microM. In retinal amacrine and ganglion cells, celecoxib inhibited voltage-dependent sodium channels with an EC(50) of 5.2 microM, and voltage-dependent transient and sustained potassium currents with EC(50)s of 16.3 and 9.1 microM, respectively. Notably, the rate of spontaneous spike activity was dramatically suppressed in ganglion and amacrine cells with an EC(50) of 0.76 microM. All actions of celecoxib on ionic currents and action potentials occurred from the extracellular side and were completely reversible. These findings indicate that inhibition of ion channels by celecoxib in the CNS may affect neuronal function at clinically relevant concentrations.

Celecoxib and ankylosing spondylitis

It is now over 100 years since the arrival of aspirin and, from the mid-20th Century onwards, we have seen numerous attempts at providing society with safer and more efficacious nonsteroidal drugs. Ironically, while aspirin went from strength to strength with an ever-increasing pharmaceutical profile, new nonsteroidal anti-inflammatory drugs arrived and disappeared with rapid succession. Finally, there appears to have been a breakthrough with the development of the coxibs but concern has recently developed because of potential toxic cardiovascular reactions. Although originally studied in rheumatoid arthritis and degenerative arthropathy, the coxibs have now been investigated in ankylosing spondylitis and efficacy appears to be favorable and, to date, there is little evidence of toxicity, although problems in the nonspondylarthropathic arena may spill over into the seronegative spondylarthritides.

A study of the pharmacokinetic interactions of the direct renin inhibitor aliskiren with allopurinol, celecoxib and cimetidine in healthy subjects

OBJECTIVE

Aliskiren is the first in a new class of orally effective direct renin inhibitors approved for the treatment of hypertension. This multiple-dose study investigated the potential for pharmacokinetic interactions between aliskiren and three drugs, each predominantly eliminated by a different clearance/metabolic pathway: allopurinol (glomerular filtration), celecoxib (cytochrome P450 metabolism) and cimetidine (P-glycoprotein and organic anion/cation transporters).

RESEARCH DESIGN AND METHODS

Three open-label, multiple-dose studies in healthy subjects investigated possible pharmacokinetic interactions between aliskiren 300 mg od and allopurinol 300 mg od (n = 20), celecoxib 200 mg bid (n = 22), or cimetidine 800 mg od (n = 22). Subjects received aliskiren alone or co-administered with allopurinol, celecoxib or cimetidine. Allopurinol and celecoxib were also administered alone and in combination with aliskiren. Plasma drug concentrations were determined by LC/MS/MS.

RESULTS

Co-administration of aliskiren with allopurinol had no effect on allopurinol AUC(tau) (ratio of geometric means 0.93 [90% CI, 0.88, 0.98]) or oxypurinol AUC(tau) (mean ratio 1.12 [90% CI, 1.08, 1.16]) and C(max) (mean ratio 1.08 [90% CI, 1.04, 1.13]), with 90% CI within the bioequivalence range 0.80-1.25, and a minor effect on allopurinol C(max) (mean ratio 0.88 [90% CI, 0.78, 1.00]). Aliskiren co-administration had no effect on AUC(tau) or C(max) of celecoxib (mean ratios and 90% CI within range 0.80-1.25). Neither allopurinol nor celecoxib significantly altered aliskiren AUC(tau) or C(max) (geometric mean ratios 0.88-1.02 with 90% CI including 1.00, but with some 90% CI outside the 0.80-1.25 range due to high variability). Co-administration of aliskiren with cimetidine increased aliskiren AUC(tau) by 20% (mean ratio 1.20 [90% CI, 1.07, 1.34]) and C(max) by 25% (mean ratio 1.25 [90% CI, 0.98, 1.59]).

CONCLUSIONS

In this multiple-dose study, aliskiren showed no clinically relevant pharmacokinetic interactions when co-administered with allopurinol, celecoxib or cimetidine in healthy subjects.

Effect of phenytoin on celecoxib pharmacokinetics in patients with glioblastoma

Cyclooxygenase-2 (COX-2) expression has been linked to the prognosis, angiogenesis, and radiation sensitivity of many malignancies. Celecoxib, a selective COX-2 inhibitor, is predominantly eliminated by hepatic metabolism. This study was conducted to determine the effects of hepatic enzyme-inducing antiseizure drugs (EIASDs) on the pharmacokinetics of celecoxib. The safety of celecoxib administered with radiation for glioblastoma and the effect of the combined treatment on survival were also evaluated. Patients were stratified based on concomitant use of EIASDs. Celecoxib (400) mg was administered orally twice a day until tumor progression or dose-limiting toxicity. Standard radiation was administered without adjuvant chemotherapy. Sampling was performed to define the plasma concentration/time profile for the initial dose of celecoxib and steady-state trough concentrations. Thirty-five patients (22 +EIASD, 13 -EIASD) were enrolled. There were no significant differences in age, performance status, extent of surgery, or Mini Mental State Exam scores between the two cohorts. The treatment was well tolerated. All patients in the +EIASD arm were taking phenytoin. There were no significant differences in any celecoxib pharmacokinetic parameters between 15 +EIASD and 12 -EIASD patients. With 31 of 35 patients deceased, estimated median survival time for all patients was 12 months (+EIASD, 11.5 months; - EIASD, 16 months; p = 0.11). The pharmacokinetics of celecoxib is not significantly affected by the concomitant administration of phenytoin. Celecoxib administered during and after radiation is well tolerated. The potential difference in survival between the +EIASD and -EIASD groups deserves further evaluation.

Celecoxib inhibits proliferation of retinal pigment epithelial and choroid-retinal endothelial cells by a cyclooxygenase-2-independent mechanism

Age-related macular degeneration (ARMD) is a leading cause of blindness. The major reason for severe vision loss in ARMD is choroidal neovascularization due to an elevation in the expression of angiogenic factors such as vascular endothelial growth factor (VEGF). Drugs with anti-VEGF and antiproliferative activities can be beneficial for the treatment of this disorder. We have previously demonstrated that celecoxib [a selective cyclooxygenase (Cox)-2 inhibitor] inhibits VEGF expression in retinal pigment epithelial cells. In this study, we investigated the antiproliferative effects of celecoxib in adult retinal pigment epithelial (ARPE-19) and choroidal endothelial (RF/6A) cells. The results indicate that celecoxib 1) causes a dose-dependent antiproliferative effect in ARPE-19 and RF/6A cells (IC(50) of 23 and 13 microM, respectively); 2) leads to a G(2)-M phase cell cycle arrest in these cell types; and 3) inhibits VEGF-induced proliferation of RF/6A cells (IC(50) of 20 microM). In addition, 4) the concentrations of celecoxib required for antiproliferative effects are lower than those required for the cytotoxicity. These effects of celecoxib are by mechanisms independent of its Cox-2 inhibitory activity because rofecoxib (another Cox-2 inhibitor) had no effects on the proliferation or cell cycle distribution of the two cell types, and flurbiprofen (an inhibitor of Cox-1 and Cox-2) had weak antiproliferative effects on ARPE-19 cells, with IC(50) of 90 microM. In summary, celecoxib has potent antiproliferative effects in RF/6A and ARPE-19 cells; thus, it can be a potential new treatment in proliferative disorders of the choroid-retina such as choroidal neovascularization in age-related macular degeneration.

Clinical use and pharmacological properties of selective COX-2 inhibitors

Selective COX-2 inhibitors (coxibs) are approved for the relief of acute pain and symptoms of chronic inflammatory conditions such as osteoarthritis (OA) and rheumatoid arthritis (RA). They have similar pharmacological properties but a slightly improved gastrointestinal (GI) safety profile if compared to traditional nonsteroidal anti-inflammatory drugs (tNSAIDs). However, long-term use of coxibs can be associated with an increased risk for cardiovascular (CV) adverse events (AEs). For this reason, two coxibs were withdrawn from the market. Currently celecoxib, etoricoxib, and lumiracoxib are used. These three coxibs differ in their chemical structure and selectivity for COX-2, which might explain some of their pharmacological features. Following oral administration, the less lipophilic celecoxib has a lower bioavailability (20-40%) than the other two coxibs (74-100%). All are eliminated by hepatic metabolism involving mainly CYP2C9 (celecoxib, lumiracoxib) and CYP3A4 (etoricoxib). Elimination half-life varies from 5 to 8 h (lumiracoxib), 11 to 16 h (celecoxib) and 19 to 32 h (etoricoxib). In patients with liver disease, plasma levels of celecoxib and etoricoxib are increased about two-fold. Clinical efficacies of the coxibs are comparable to tNSAIDs. There is an ongoing discussion about whether the slightly better GI tolerability (which is lost if acetylsalicylic acid is coadministered) of the coxibs is offset by their elevated risks for CV AEs (also seen with tNSAIDs other than naproxen), which apparently increase with dose and duration of exposure. In addition, the higher costs for coxibs (if compared to tNSAIDs, even when a "gastroprotective" proton pump inhibitor is coadministered) should be taken into consideration, if a coxib will be selected for certain patients with a high risk for GI complications. For such treatment, the lowest effective dose should be used for a limited time. Monitoring of kidney function and blood pressure appears advisable. It is hoped that further controlled studies can better define the therapeutic place of the coxibs.

Altered GABAergic neurotransmission is associated with increased kainate-induced seizure in prostaglandin-endoperoxide synthase-2 deficient mice

Excitotoxicity involves over activation of brain excitatory glutamate receptors and has been implicated in neurological, neurodegenerative and neuropsychiatric diseases. Metabolism of arachidonic acid (AA) through the phospholipase A(2) (PLA(2))/prostaglandin-endoperoxide synthase (PTGS) pathway is increased after excitotoxic stimulation. However, the individual roles of the PTGS isoforms in this process are not well established. We assessed the role of the PTGS isoforms in the process of excitotoxicity by exposing mice deficient in either PTGS-1 (PTGS-1(-/-)) or PTGS-2 (PTGS-2(-/-)) to the prototypic excitotoxin, kainic acid (KA). Seizure intensity and neuronal damage were significantly elevated in KA-exposed PTGS-2(-/-), but not in PTGS-1(-/-), mice. The increased susceptibility was not associated with an alteration in KA receptor binding activity or mediated through the CB1 endocannabinoid receptor. The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) was decreased in the CA1 pyramidal neurons of PTGS-2(-/-) mice, suggesting an alteration of GABAergic function. In wild-type mice, six weeks treatment with the PTGS-2 selective inhibitor celecoxib recapitulated the increased susceptibility to KA-induced excitotoxicity observed in PTGS-2(-/-) mice, further supporting the role of PTGS-2 in the excitotoxic process. The increased susceptibility to KA was also associated with decreased brain levels of PGE(2), a biomarker of PTGS-2 activity. Our results suggest that PTGS-2 activity and its specific products may modulate neuronal excitability by affecting GABAergic neurotransmission. Further, inhibition of PTGS-2, but not PTGS-1, may increase the susceptibility to seizures.

Inhibition of delayed rectifier potassium channels and induction of arrhythmia: a novel effect of celecoxib and the mechanism underlying it

Selective inhibitors of cyclooxygenase-2 (COX-2), such as rofecoxib (Vioxx), celecoxib (Celebrex), and valdecoxib (Bextra), have been developed for treating arthritis and other musculoskeletal complaints. Selective inhibition of COX-2 over COX-1 results in preferential decrease in prostacyclin production over thromboxane A2 production, thus leading to less gastric effects than those seen with nonselective COX inhibitors such as acetylsalicylic acid (aspirin). Here we show a novel effect of celecoxib via a mechanism that is independent of COX-2 inhibition. The drug inhibited the delayed rectifier (Kv2) potassium channels from Drosophila, rats, and humans and led to pronounced arrhythmia in Drosophila heart and arrhythmic beating of rat heart cells in culture. These effects occurred despite the genomic absence of cyclooxygenases in Drosophila and the failure of acetylsalicylic acid, a potent inhibitor of both COX-1 and COX-2, to inhibit rat Kv2.1 channels. A genetically null mutant of Drosophila Shab (Kv2) channels reproduced the cardiac effect of celecoxib, and the drug was unable to further enhance the effect of the mutation. These observations reveal an unanticipated effect of celecoxib on Drosophila hearts and on heart cells from rats, implicating the inhibition of Kv2 channels as the mechanism underlying this effect.

CCAAT/enhancer binding protein homologous protein-dependent death receptor 5 induction and ubiquitin/proteasome-mediated cellular FLICE-inhibitory protein down-regulation contribute to enhancement of tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by dimethyl-celecoxib in human non small-cell lung cancer cells

2,5-Dimethyl-celecoxib (DMC) is a derivative of celecoxib, a cyclooxygenase-2 (COX-2) inhibitor with anticancer activity in both preclinical studies and clinical practice, and lacks COX-2-inhibitory activity. Several preclinical studies have demonstrated that DMC has better apoptosis-inducing activity than celecoxib, albeit with undefined mechanisms, and exhibits anticancer activity in animal models. In this study, we primarily investigated DMC's cooperative effect with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the induction of apoptosis and the underlying mechanisms in human non-small-cell lung cancer (NSCLC) cells. We found that DMC was more potent than celecoxib in decreasing the survival and inducing apoptosis of NSCLC cells. When combined with TRAIL, DMC exerted enhanced or synergistic effects on the induction of apoptosis, indicating that DMC cooperates with TRAIL to augment the induction of apoptosis. To determine the underlying mechanism of the synergy between DMC and TRAIL, we have demonstrated that DMC induces a CCAAT/enhancer binding protein homologous protein-dependent expression of DR5, a major TRAIL receptor, and reduces the levels of cellular FLICE-inhibitory protein (c-FLIP) (both the long and short forms), key inhibitors of death receptor-mediated apoptosis, by facilitating c-FLIP degradation through a ubiquitin/proteasome-dependent mechanism. It is noteworthy that enforced expression of c-FLIP or silencing of DR5 expression using DR5 small interfering RNA abrogated the enhanced effects on induction of apoptosis by the combination of DMC and TRAIL, indicating that both DR5 up-regulation and c-FLIP reduction contribute to cooperative induction of apoptosis by the combination of DMC and TRAIL. Together, we conclude that DMC sensitizes human NSCLC cells to TRAIL-induced apoptosis via induction of DR5 and down-regulation of c-FLIP.

The select cyclooxygenase-2 inhibitor celecoxib reduced the extent of atherosclerosis in apo E-/- mice

Many investigators have suggested that immune activation may trigger the atherosclerotic process. The benefits of aspirin in preventing myocardial infarction have been attributed, in part, to its anti-inflammatory effects. Several reports have documented that cyclooxygenase (COX)-2 is up-regulated in human and mouse atherosclerotic lesions. To clarify the role of COX-2 in atherosclerosis, we conducted a study to test whether the COX-2 inhibitor, celecoxib, prevents the development and progression of the atherosclerotic process. We have used the apo E-/- mouse, a relevant animal model of atherosclerosis that develops fibrofatty lesions similar to human atherosclerosis. Treatment of 4-wk old apo E-/- mice with a standard rodent no. 5020 diet supplemented with 900 ppm of celecoxib for 16 wk led to an 81% reduction in lesion size. The mean lesion area per section (mean +/- SD) of proximal aorta from the apo E-/- mice fed the diet with celecoxib (33,991 +/- 7863 microm2, P < 0.001) was significantly less than that of the untreated apo E-/- mice (183,401 +/- 36,212 microm2). There were no lesions detected in the C57B1/6 mice. Immunohistochemistry of the ileum revealed that there was 80% reduction in staining for intercellular adhesion molecule and 60% reduction in staining for vascular cell adhesion molecule in the celecoxib treated mice. The protective effect of celecoxib was not maintained when the mice were switched after feeding the celecoxib-supplemented diet to the control 5020 diet for an additional 10 wk. These findings demonstrate that selective inhibition of the COX-2 enzyme with celecoxib prevented the development of atherosclerotic lesions in the proximal aortas from apo E-/- mice. One of the possible mechanisms is reduction in expression of the endothelial cell adhesion cell molecules intercellular adhesion molecule and vascular cell adhesion molecule, which plays a key role in the recruitment of inflammatory cells during the early stages of atherogenesis.

A critical appraisal of COX-2 selective inhibition and analgesia: how good so far?

The development of COX-2 selective inhibitors has opened a new era of clinical investigation in NSAIDs. Discussion of the established concepts of inflammation and therapeutical uses of these drugs has changed the rationale for its clinical use and therapeutic labeling of these drugs. A comprehensive discussion across basic science and clinical areas involved in each of these concepts is presented. This led to a remarkable re-evaluation of our insights on their traditionally proposed mechanisms of analgesia, their side-effects, and the clinical indication of NSAIDs as "over the counter" pain killers. This may shift physicians toward a more rational use of this drug class.

Celecoxib inhibits Na+ currents in rat dorsal root ganglion neurons

Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor used in the treatment of osteoarthritis and rheumatoid arthritis with fewer gastrointestinal toxicities compared to traditional non-steroidal anti-inflammatory drugs. Voltage-gated Na(+) channels in primary sensory neurons play an important role in the pathogenesis of various pain conditions. We examined the effects of celecoxib on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na(+) currents in acutely dissociated rat dorsal root ganglion neurons. Celecoxib suppressed both currents in dose- and frequency-dependent manner. The apparent dissociation constants (K(d)) for TTX-S and TTX-R Na(+) currents measured at 0 mV from a holding potential of -80 mV were estimated to be 5.6 and 19.5 microM, respectively. Celecoxib slightly slowed inactivation kinetics of TTX-S Na(+) current, but made it much faster in TTX-R Na(+) current. Celecoxib shifted the activation voltage of TTX-S Na(+) current to a depolarizing direction, but not that of TTX-R Na(+) current. Celecoxib caused a hyperpolarizing shift of the steady-state inactivation curve in both Na(+) currents to a great extent. In addition celecoxib reduced the maximal availability of both Na(+) channels. Thus celecoxib appears to bind to both inactivated and resting Na(+) channels. Celecoxib slowed the recovery of both Na(+) channels from inactivation. All these effects combined would suppress the excitability of sensory neurons. Thus, beside COX-2 inhibition, the Na(+) channel inhibition is considered to contribute to celecoxib analgesia.

A comparison of the effectiveness of selected non-steroidal anti-inflammatory drugs and their derivatives against cancer cells in vitro

PURPOSE

Previously, we reported in vitro observations suggesting that ibuprofen is an effective non-prescription non-steroidal anti-inflammatory drug (NSAID) to reduce the survival of human prostate cancer cells (Andrews et al. in Cancer Chemother Pharmacol 502:77-284, 2002), and that this observed effectiveness is mediated by an up-regulation of the p75 NTR tumor suppressor (Khwaja et al. in Cancer Res 646:207-6213, 2004). However, other NSAIDs and their derivatives have received significant attention with regard to their anti-cancer effectiveness and have been selected for clinical trials to treat a variety of human cancers. In this investigation, we compared celecoxib, sulindac sulfone, nitric oxide linked NSAIDs, and R-flurbiprofen with ibuprofen in their ability to inhibit the growth of a variety of human cancer cells lines including cells lines with multi-drug resistance. We also evaluated whether, like ibuprofen, an up-regulation of p75 NTR is a molecular mechanism that mediates the anti-growth effectiveness of these drugs.

MATERIALS AND METHODS

Selected dosages for each drug were evaluated for their ability to reduce the growth (MTT analysis) and induce apoptosis (Hoechst staining) of a variety of different cancer cell lines, including an ovarian cell line expressing multidrug resistance-1 glycoprotein (MDR-1). The drugs were then analyzed using immunoblot, RT-PCR and siRNA to study the role of p75 NTR in their anti-growth effectiveness.

RESULTS

Our study revealed consistency in the drug dosages that inhibit the survival of different human cancer cell lines. While NO-linked aspirin and celecoxib were most effective in decreasing cell growth and inducing apoptosis at the lowest dosages, R-flurbiprofen and ibuprofen were most effective at clinically relevant dosages. A multidrug resistant ovarian cell line is more resistant to growth inhibition by the drugs tested than its non-drug resistant parental counterpart. There was no correlation between the expression of cyclooxygenase-2 (COX-2) and the ability of the drugs to reduce cancer cell survival. All the drugs tested induced an up-regulation in p75 NTR tumor suppressor gene expression in concert with their observed growth inhibiting ability. Inhibition of p75 NTR expression with siRNA reduced the cell growth inhibiting effects of all the drugs tested.

CONCLUSIONS

The method of chemotherapy (i.e., intravascular, intrathecal, oral) might dictate the choice of NSAID/NSAID derivative used to treat/prevent a given type of cancer. Also, the p75 NTR tumor suppressor appears to be a common molecular mechanism that mediates the growth inhibiting effectiveness of these drugs.

The cytotoxicity of celecoxib towards cardiac myocytes is cyclooxygenase-2 independent

The cyclooxygenase (COX)-2 inhibitors celecoxib and rofecoxib were studied for their effects on neonatal rat cardiac myocytes as a possible model for the adverse cardiovascular effects that this class of compounds have shown in their clinical use. Celecoxib, but not rofecoxib, as measured by lactate dehydrogenase release was toxic to myocytes in the low micromolar concentration range. This toxicity shown by celecoxib was also associated with a high degree of myofibrillar disruption similar to that caused by doxorubicin. As measured by induction of caspase-3/7 activity and by changes in nuclear morphology, neither celecoxib nor rofecoxib strongly induced apoptosis in myocytes. The stable prostacyclin analog iloprost was unable to reduce celecoxib-induced damage, which suggested that celecoxib exerted its cytotoxicity through prostacyclin-independent pathways. Celecoxib treatment did not increase intracellular oxidation of 2',7'-dichlorofluorescin in myocytes, which suggested that its cytotoxicity was not due to reactive oxygen species generation. The evidence supports the conclusion that celecoxib exerts its cytotoxicity towards myocytes through COX-2-independent mediated pathways.

Calcium-activated endoplasmic reticulum stress as a major component of tumor cell death induced by 2,5-dimethyl-celecoxib, a non-coxib analogue of celecoxib

A drawback of extensive coxib use for antitumor purposes is the risk of life-threatening side effects that are thought to be a class effect and probably due to the resulting imbalance of eicosanoid levels. 2,5-Dimethyl-celecoxib (DMC) is a close structural analogue of the selective cyclooxygenase-2 inhibitor celecoxib that lacks cyclooxygenase-2-inhibitory function but that nonetheless is able to potently mimic the antitumor effects of celecoxib in vitro and in vivo. To further establish the potential usefulness of DMC as an anticancer agent, we compared DMC and various coxibs and nonsteroidal anti-inflammatory drugs with regard to their ability to stimulate the endoplasmic reticulum (ER) stress response (ESR) and subsequent apoptotic cell death. We show that DMC increases intracellular free calcium levels and potently triggers the ESR in various tumor cell lines, as indicated by transient inhibition of protein synthesis, activation of ER stress-associated proteins GRP78/BiP, CHOP/GADD153, and caspase-4, and subsequent tumor cell death. Small interfering RNA-mediated knockdown of the protective chaperone GRP78 further sensitizes tumor cells to killing by DMC, whereas inhibition of caspase-4 prevents drug-induced apoptosis. In comparison, celecoxib less potently replicates these effects of DMC, whereas none of the other tested coxibs (rofecoxib and valdecoxib) or traditional nonsteroidal anti-inflammatory drugs (flurbiprofen, indomethacin, and sulindac) trigger the ESR or cause apoptosis at comparable concentrations. The effects of DMC are not restricted to in vitro conditions, as this drug also generates ER stress in xenografted tumor cells in vivo, concomitant with increased apoptosis and reduced tumor growth. We propose that it might be worthwhile to further evaluate the potential of DMC as a non-coxib alternative to celecoxib for anticancer purposes.

Pharmacokinetics and bioavailability of nimesulide in goats

The pharmacokinetic properties and bioavailability of cyclooxygenase (COX)-2 selective nonsteroidal anti-inflammatory drug nimesulide were investigated in female goats following intravenous (i.v.) and intramuscular (i.m.) administration at a dose of 4 mg/kg BW. Blood samples were collected by jugular venipuncture at predetermined times after drug administration. Plasma concentrations of nimesulide were determined by a validated high-performance liquid chromatography method. Plasma concentration-time data were subjected to compartmental analysis and pharmacokinetic parameters for nimesulide after i.v. and i.m. administration were calculated according to two- and one-compartment open models respectively. Following i.v. administration, a rapid distribution phase was followed by the slower elimination phase. The half-lives during the distribution phase (t1/2alpha) and terminal elimination phase (t1/2beta) were 0.11+/-0.10 and 7.99+/-2.23 h respectively. The steady-state volume of distribution (Vd(ss)), total body clearance (ClB) and mean residence time (MRT) of nimesulide were 0.64+/-0.13 L/kg, 0.06+/-0.02 L/h/kg and 11.72+/-3.42 h respectively. After i.m. administration, maximum plasma concentration (Cmax) of nimesulide was 2.83+/-1.11 microg/mL attained at 3.6+/-0.89 h (tmax). Plasma drug levels were detectable up to 72 h. Following i.m. injection, the t1/2beta and MRT of nimesulide were 1.63 and 1.73 times longer, respectively, than the i.v. administration. The bioavailability of nimesulide was 68.25% after i.m. administration at 4 mg/kg BW. These pharmacokinetic data suggest that nimesulide given intramuscularly may be useful in the treatment of inflammatory disease conditions in goats.

Dose and time-dependent effects of cyclooxygenase-2 inhibition on fracture-healing

BACKGROUND

Fracture-healing is impaired in mice lacking a functional cyclooxygenase-2 (COX-2) gene or in rats continuously treated with COX-2 inhibitors. These observations indicate that COX-2 is a critical regulator of fracture repair. Nonsteroidal anti-inflammatory drugs are commonly used to treat pain associated with musculoskeletal trauma and disease. Nonsteroidal anti-inflammatory drugs inhibit COX-2 function and in so doing can impair fracture-healing. The goal of the present study was to determine how variations in nonsteroidal anti-inflammatory drug therapy ultimately affect fracture-healing.

METHODS

Closed femoral fractures were made in female Sprague-Dawley rats. The rats were treated with different doses of celecoxib (a COX-2-selective nonsteroidal anti-inflammatory drug) or were treated for different periods before or after fracture with celecoxib. Eight weeks after the fracture, healing was assessed with radiography and destructive torsional mechanical testing. The effect of celecoxib treatment on fracture callus prostaglandin E2 and F(2alpha) levels was determined as a measure of cyclooxygenase activity.

RESULTS

Celecoxib doses as small as 2 mg/kg/day reduced fracture callus mechanical properties and caused a significant increase in the proportion of nonunions. Similarly, treatment with celecoxib at a dose of 4 mg/kg/day for just five days reduced fracture callus mechanical properties and significantly increased the proportion of nonunions. Conversely, celecoxib therapy prior to fracture or initiated fourteen days after fracture did not significantly increase the proportion of nonunions. Celecoxib treatment at a dose of 4 mg/kg/day reduced fracture callus prostaglandin E2 and F(2alpha) levels by >60%.

CONCLUSIONS

COX-2-selective nonsteroidal anti-inflammatory drug therapy during the early stages of fracture repair significantly reduced fracture callus mechanical properties at later stages of healing and increased the proportion of nonunions in this animal model.

The effects of COX-2 selective and non-selective NSAIDs on the initiation and progression of atherosclerosis in ApoE−/− mice

In this study, we investigated the effects of prolonged administration of the selective COX-2 inhibitors celecoxib and rofecoxib and the non-selective NSAID naproxen on the initiation and progression of atherosclerosis. ApoE(-/-) mice, as well as corresponding wild-type mice, were fed either a normal chow or a high fat Western diet with or without addition of the respective drugs over a period of 16 weeks. Thereafter, aortic lesion size, plasma lipid levels, and COX-2 expression in the plaques were determined. The results showed that neither the COX-2 selective inhibitors nor naproxen had a significant impact on the initiation and progression of atherosclerosis in diet-fed ApoE(-/-) mice, although both celecoxib and rofecoxib showed a tendency to reduce plaque size. This slight effect may be due to selective inhibition of COX-2 activity because the COX-2 expression was not altered in the plaque. Plasma lipid levels were also not significantly influenced by these drugs. Interestingly, in ApoE(-/-) mice that have been fed with normal chow, we found an increased incidence of plaque formation after treatment with celecoxib and rofecoxib, indicating that coxibs may promote the initiation of atherosclerosis. This effect was probably masked in diet-fed mice by the more pronounced effects of the high cholesterol diet. In conclusion, the reduction in diet-induced plaque size in animals fed a high fat diet and the promotion of atherosclerosis in mice on a normal diet indicate a dual role of the coxibs. In advanced stages of atherosclerosis, they may exert antithrombotic properties due to their COX-2 inhibiting activity, whereas in very early stages they may favor the initiation of atherogenesis. However, because these results were only observed in ApoE(-/-) and not in wild-type animals, coxibs may increase the risk of thrombosis in patients with a predisposition for thrombotic complications.

A novel pathway involving melanoma differentiation associated gene-7/interleukin-24 mediates nonsteroidal anti-inflammatory drug-induced apoptosis and growth arrest of cancer cells

Numerous studies show that nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in chemoprevention or treatment of cancer. Nevertheless, the mechanisms underlying these antineoplastic effects remain poorly understood. Here, we report that induction of the cancer-specific proapoptotic cytokine melanoma differentiation associated gene-7/interleukin-24 (MDA-7/IL-24) by several NSAIDs is an essential step for induction of apoptosis and G(2)-M growth arrest in cancer cells in vitro and inhibition of tumor growth in vivo. We also show that MDA-7/IL-24-dependent up-regulation of growth arrest and DNA damage inducible 45 alpha (GADD45alpha) and GADD45gamma gene expression is sufficient for cancer cell apoptosis via c-Jun NH(2)-terminal kinase (JNK) activation and growth arrest induction through inhibition of Cdc2-cyclin B checkpoint kinase. Knockdown of GADD45alpha and GADD45gamma transcription by small interfering RNA abrogates apoptosis and growth arrest induction by the NSAID treatment, blocks JNK activation, and restores Cdc2-cyclin B kinase activity. Our results establish MDA-7/IL-24 and GADD45alpha and GADD45gamma as critical mediators of apoptosis and growth arrest in response to NSAIDs in cancer cells.

Stronger inhibition by nonsteroid anti-inflammatory drugs of cyclooxygenase-1 in endothelial cells than platelets offers an explanation for increased risk of thrombotic events

Recent data have suggested that regular consumption of nonsteroid anti-inflammatory drugs (NSAIDs), particularly selective inhibitors of cyclo-oxygenase-2 (COX-2), is associated with an increased risk of thrombotic events. It has been suggested that this is due to NSAIDs reducing the release from the endothelium of the antithrombotic mediator prostaglandin I2 as a result of inhibition of endothelial COX-2. Here, however, we show that despite normal human vessels and endothelial cells containing cyclo-oxygenase-1 (COX-1) without any detectable COX-2, COX-1 in vessels or endothelial cells is more readily inhibited by NSAIDs and COX-2-selective drugs than COX-1 in platelets (e.g., log IC50+/-SEM values for endothelial cells vs. platelets: naproxen -5.59+/-0.07 vs. -4.81+/-0.04; rofecoxib -4.93+/-0.04 vs. -3.75+/-0.03; n=7). In broken cell preparations, the selectivities of the tested drugs toward endothelial cell over platelet COX-1 were lost. These observations suggest that variations in cellular conditions, such as endogenous peroxide tone and substrate supply, and not the isoform of cyclo-oxygenase present, dictate the effects of NSAIDs on endothelial cells vs. platelets. This may well be because the platelet is not a good representative of COX-1 activity within the body as it produces prostanoids in an explosive burst that does not reflect tonic release from other cells. The results reported here can offer an explanation for the apparent ability of NSAIDs and COX-2-selective inhibitors to increase the risk of myocardial infarction and stroke.

Blood pressure effects of COX-2 inhibitors

There has been significant recent interest in the cardiovascular effects of cyclooxygenase 2 (COX-2) selective inhibitors. Whereas much attention has been focused on the putative prothrombotic effect of these agents, their cardiorenal and blood pressure elevating actions may be of equal if not greater importance to cardiovascular risk. COX-2 is widely expressed throughout the kidney, and inhibition of this enzyme is contributory to reduced glomerular filtration, salt and water retention, and blood pressure elevation. The key issues in relation to COX-2 inhibitors and blood pressure are whether these blood pressure-elevating effects are similar to or differ from nonselective nonsteroid anti-inflammatory drugs, whether differences exist among COX-2 inhibitors in regard to blood pressure regulation, and if so, possible mechanisms underlying blood pressure differences between COX-2 inhibitors. With regard to the last issue, possible mechanisms include greater COX-2 selectivity of certain agents such as rofecoxib, the differing half-life of these agents, the carbonic anhydrase activity of celecoxib (which may offset renal-induced salt and water retention), and possible aldosterone modulation by rofecoxib. Finally, and perhaps most important, the issue arises as to whether blood pressure elevation may contribute in whole or in part to the increase in cardiovascular events observed with these agents in some but not all studies. Ultimately, adequately powered, prospective randomized clinical trials assessing relevant cardiovascular endpoints are required to address many of these outstanding questions. Such studies have recently been announced and will commence soon.

The Use of Celecoxib and Dexamethasone for the Prevention and Control of Postoperative Pain After Periodontal Surgery

BACKGROUND

Conventional non-steroidal anti-inflammatory drugs have been widely used in the control of postoperative pain, but sparse information is available on the efficacy of celecoxib, a selective cyclooxygenase-2 inhibitor, or dexamethasone, a steroidal anti-inflammatory drug, after periodontal surgeries. The purpose of the present study was to compare the use of celecoxib and dexamethasone in the management of pain after mucoperiosteal flap surgery.

METHODS

A randomized double-masked cross-over clinical trial was conducted on 20 patients from 27 to 52 years old with generalized moderate to advanced chronic periodontitis. Mucoperiosteal flap surgeries for scaling and root planing were performed under local anesthesia on at least three quadrants, with a 4-week interval between. Each quadrant was randomly assigned to one of the following medication protocols: placebo, 4 mg dexamethasone 1 hour before surgery and 8 hours after the first dose, and 200 mg celecoxib 1 hour before surgery and 12 hours after the first dose. Postoperative pain was accessed during the first 8 hours and on the following 3 days using the visual analog scale (VAS), the 101-point numerical rate scale (NRS-101), and the four-point verbal rating scale (VRS-4).

RESULTS

Pain perception was statistically significantly lower in the celecoxib group than in the placebo group during the first 4 hours using VAS (P = 0.01) and at 1, 2, 3, 4, 6, and 7 hours using NRS-101 (P = 0.03). The level of pain was lower in the dexamethasone group than in the placebo only at the 3-hour period (P = 0.001). Statistically significant differences could be found among the groups at 1 hour (P = 0.015), 3 hours (P = 0.004), 4 hours (P = 0.02), and 7 hours (P = 0.05) using VRS-4. There was no statistically significant difference between the celecoxib and dexamethasone groups.

CONCLUSION

The findings of this study suggest that the preemptive and postoperative use of celecoxib or dexamethasone were effective in the management of postoperative pain following open-flap debridement.

The role of the cylooxygenase pathway in nociception and pain

Cycloxygenase (COX) pathways have long been targeted for the treatment of inflammatory pain, initially through the use of NSAIDs. With the demonstration of two major COX isoforms, COX-1 and COX-2, involved in the production of prostanoids, but with different distribution and regulation, selective COX-2 inhibitors have been developed. This review covers factors influencing COX enzyme activity, the role of their products in the development and maintenance of pain and discusses recent safety concerns of COX-2 inhibitors.

Effects of the antifungals voriconazole and fluconazole on the pharmacokinetics of s-(+)- and R-(-)-Ibuprofen

Our objective was to study the effects of the antifungals voriconazole and fluconazole on the pharmacokinetics of S-(+)- and R-(-)-ibuprofen. Twelve healthy male volunteers took a single oral dose of 400 mg racemic ibuprofen in a randomized order either alone, after ingestion of voriconazole at 400 mg twice daily on the first day and 200 mg twice daily on the second day, or after ingestion of fluconazole at 400 mg on the first day and 200 mg on the second day. Ibuprofen was ingested 1 h after administration of the last dose of voriconazole or fluconazole. Plasma concentrations of S-(+)- and R-(-)-ibuprofen were measured for up to 24 h. In the voriconazole phase, the mean area under the plasma concentration-time curve (AUC) of S-(+)-ibuprofen was 205% (P < 0.001) of the respective control value and the mean peak plasma concentration (C(max)) was 122% (P < 0.01) of the respective control value. The mean elimination half-life (t(1/2)) was prolonged from 2.4 to 3.2 h (P < 0.01) by voriconazole. In the fluconazole phase, the mean AUC of S-(+)-ibuprofen was 183% of the control value (P < 0.001) and its mean C(max) was 116% of the control value (P < 0.05). The mean t(1/2) of S-(+)-ibuprofen was prolonged from 2.4 to 3.1 h (P < 0.05) by fluconazole. The geometric mean S-(+)-ibuprofen AUC ratios in the voriconazole and fluconazole phases were 2.01 (90% confidence interval [CI], 1.80 to 2.22) and 1.82 (90% CI, 1.72 to 1.91), respectively, i.e., above the bioequivalence acceptance upper limit of 1.25. Voriconazole and fluconazole had only weak effects on the pharmacokinetics of R-(-)-ibuprofen. In conclusion, voriconazole and fluconazole increased the levels of exposure to S-(+)-ibuprofen 2- and 1.8-fold, respectively. This was likely caused by inhibition of the cytochrome P450 2C9-mediated metabolism of S-(+)-ibuprofen. A reduction of the ibuprofen dosage should be considered when ibuprofen is coadministered with voriconazole or fluconazole, especially when the initial ibuprofen dose is high.

Cyclooxygenase-2 selective inhibition suppresses restoration of tibial trabecular bone formation in association with restriction of osteoblast maturation in skeletal reloading after hindlimb elevation of mice

To clarify the role of cyclooxygenase-2 (COX-2) in acute recovery of trabecular bone in reloaded hindlimbs of tail-suspended mice, we administered a COX-2 selective inhibitor in the mice during the reloading period after unloading. Experiments were conducted on 140 male C57BL/6J mice (8 weeks old). They were divided into ground control (GC) and unloading by tail suspension (UL) groups. On day 7, Group GC was divided into Groups GC+Vehicle (Veh) and GC+Celecoxib (Cel), while Group UL mice were fed on the ground [reloading (RL)] after 7-day unloading and were then divided into Groups RL+Veh and RL+Cel. Bone histomorphometry, osteogenic cell development, and mRNA expression of osteogenic molecules were assessed. At 5 days after reloading, the increase of bone formation rate and the ratio of osteocalcin mRNA expression per CFU-f colony in Group RL+Cel were significantly decreased compared with those in Group RL+Veh, while alkaline phosphatase-positive (ALP+) CFU-f formation and the ratios of cbfa-1, osterix, and type 1 collagen mRNA expression per CFU-f colony increased to the same levels in both RL groups. At 14 days after reloading, decreased bone volume by unloading in RL+Veh recovered to the same level as that of GC+Veh, but that in RL+Cel did not recover completely. The increase of c-fos mRNA expression in bone marrow cells at 1, 24, and 48 h after reloading, osteocalcin mRNA at 6 h, and osterix mRNA at 24 h were suppressed by COX-2 inhibitor. These data indicate that the COX-2 selective inhibitor celecoxib suppresses the restoration of tibial trabecular bone formation and the acute recovery of trabecular bone. These actions are closely related to restriction of c-fos and osteocalcin mRNA expressions and osteoblast differentiation in bone marrow cells.

Celecoxib induces anoikis in human colon carcinoma cells associated with the deregulation of focal adhesions and nuclear translocation of p130Cas

Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, is effective as chemopreventive against colon cancer and it is the only nonsteoroidal antiinflammatory drug approved by the FDA for adjuvant therapy in patients with familial adenomatous polyposis. It is also being evaluated, within Phase II and III clinical trials, in combination with standard chemotherapy to treat sporadic colorectal cancer. Nevertheless, its antitumor mechanism of action is still not fully understood. In this study, we have evaluated the in vitro growth inhibitory effect of celecoxib in colon carcinoma cells and analyzed its mechanism of action. We report that the deregulation of the focal adhesion assembly protein Crk-associated substrate 130 kDa (p130Cas) by celecoxib plays a relevant role in the cytotoxic effect of this drug. Thus, celecoxib induces the proteolysis of p130Cas and the nuclear translocation of the 31 kDa generated fragment leading to apoptosis. Furthermore, overexpression of wild-type p130Cas reverts, in part, the growth inhibitory effect of celecoxib. In contrast, FAK and AKT do not appear to be involved in this activity. Our data suggest, for the first time, that the antitumor mechanism of action of celecoxib includes the induction of anoikis, an effect that is not related to COX-2 inhibition. Besides providing new insights into the antitumor effect of celecoxib, this novel mechanism of action holds potential relevance in drug development. Indeed, our results open the possibility to develop new celecoxib derivatives that induce anoikis without COX-2 inhibition so as to avoid the cardiovascular toxicity recently described for the COX-2 inhibitors.

Downregulation of survivin expression and concomitant induction of apoptosis by celecoxib and its non-cyclooxygenase-2-inhibitory analog, dimethyl-celecoxib (DMC), in tumor cells in vitro and in vivo

Background

2,5-Dimethyl-celecoxib (DMC) is a close structural analog of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib (Celebrex^®) that lacks COX-2-inhibitory function. However, despite its inability to block COX-2 activity, DMC is able to potently mimic the anti-tumor effects of celecoxib in vitro and in vivo, indicating that both of these drugs are able to involve targets other than COX-2 to exert their recognized cytotoxic effects. However, the molecular components that are involved in mediating these drugs' apoptosis-stimulatory consequences are incompletely understood.

Results

We present evidence that celecoxib and DMC are able to down-regulate the expression of survivin, an anti-apoptotic protein that is highly expressed in tumor cells and known to confer resistance of such cells to anti-cancer treatments. Suppression of survivin is specific to these two drugs, as other coxibs (valdecoxib, rofecoxib) or traditional NSAIDs (flurbiprofen, indomethacin, sulindac) do not affect survivin expression at similar concentrations. The extent of survivin down-regulation by celecoxib and DMC in different tumor cell lines is somewhat variable, but closely correlates with the degree of drug-induced growth inhibition and apoptosis. When combined with irinotecan, a widely used anticancer drug, celecoxib and DMC greatly enhance the cytotoxic effects of this drug, in keeping with a model that suppression of survivin may be beneficial to sensitize cancer cells to chemotherapy. Remarkably, these effects are not restricted to in vitro conditions, but also take place in tumors from drug-treated animals, where both drugs similarly repress survivin, induce apoptosis, and inhibit tumor growth in vivo.

Conclusion

In consideration of survivin's recognized role as a custodian of tumor cell survival, our results suggest that celecoxib and DMC might exert their cytotoxic anti-tumor effects at least in part via the down-regulation of survivin – in a manner that does not require the inhibition of cyclooxygenase-2. Because inhibition of COX-2 appears to be negligible, it might be worthwhile to further evaluate DMC's potential as a non-coxib alternative to celecoxib for anti-cancer purposes.

Simple and rapid high-performance liquid chromatographic method for determination of celecoxib in plasma using UV detection: Application in pharmacokinetic studies

A rapid, sensitive and reproducible HPLC method was developed and validated for the analysis of celecoxib in human plasma. The analysis was carried out on a monolithic silica column using UV detection at 254 nm. The assay enables the measurement of celecoxib for therapeutic drug monitoring with a minimum quantification limit of 10 ng ml(-1). The method involves simple, one-step extraction procedure, and analytical recovery was 100.5 +/- 1.3%. The calibration curve was linear over the concentration range of 10-800 ng ml(-1). The coefficients of variation for inter-day and intra-day assay were found to be less than 8%. We also demonstrate the applicability of this method for pharmacokinetic studies in humans.

Celecoxib inhibits interleukin-12 alphabeta and beta2 folding and secretion by a novel COX2-independent mechanism involving chaperones of the endoplasmic reticulum

Celecoxib (CE) is a nonsteroidal anti-inflammatory drug (NSAID) that is a specific inhibitor of cyclooxygenase 2 (COX2). It is indicated for a variety of chronic inflammatory conditions, including rheumatoid arthritis. Over the last few years, adverse cardiovascular effects and increased risk for heart attacks have been associated with this drug. In addition, evidence is emerging for COX2-independent molecular targets. CE has been shown to induce apoptosis in various cancer cells lines through a COX2-independent mechanism that seems to involve inactivation of protein kinase Akt and inhibition of endoplasmic reticulum (ER) Ca2+ ATPase. In this study, we show that both CE and an analog devoid of COX2 inhibitory activity [1-(4-sulfamoyl phenyl)-3-trifluoromethyl-5-(4-trifluoromethylphenyl)pyrazole, CEA] inhibit the secretion of the dimeric interleukin-12 (IL-12) alphabeta and beta2 forms with identical IC50 values of 20 and 30 microM, respectively, whereas no such effect was seen with rofecoxib. Reverse transcription-polymerase chain reaction analysis showed that this inhibition was not due to a blockage of transcription of the alpha- and beta-chain expression cassettes. Secretion of the beta monomer form was less strongly inhibited, suggestive for a mechanism primarily targeting dimer assembly in the ER. Analysis of intracellular fractions revealed that both CE and CEA increased the association of IL-12 with calreticulin, an endoplasmic reticulum-resident chaperone involved in the retention of misfolded cargo proteins while blocking interaction with ERp44. Our findings reveal a previously undescribed effect of celecoxib on oligomer protein folding and assembly in the endoplasmic reticulum and ensuing secretion and suggest that celecoxib-driven alteration of the secretome may be involved in some of its clinical side effects.

Characterization of a novel polymorphic form of celecoxib

A new solid form (Form IV) of celecoxib was prepared in the presence of Polysorbate 80 and HPMC. A celecoxib suspension containing the Form IV had significantly higher bioavailability (>4 times) in dogs than the marketed capsules and the suspension containing bulk drug powders (Form III). The new form was characterized using differential scanning calorimetry, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), infrared spectroscopy, and Raman spectroscopy. The solids separated from the suspension containing the new form showed a melt onset at 145-148 degrees C, which was about 12-15 degrees less than known melting points of Form I, II ,and III of celecoxib. The PXRD pattern of the separated solids was not consistent with any of the known celecoxib crystal forms or the known excipients in the suspension. The formation of the new solid form (Form IV) was dependent upon the concentration and ratio of HPMC and Polysorbate 80. A faster dissolution rate (>2 times) of Form IV was observed compared to the thermodynamically stable form of celecoxib (Form III). There were no measurable changes in the solid state of Form IV either in dried solids or in the suspension for at least 6 months at 40 degrees C and 16 months at 25 degrees C.

Antitumor properties of dimethyl-celecoxib, a derivative of celecoxib that does not inhibit cyclooxygenase-2: implications for glioma therapy

✓ Celecoxib (Celebrex) appears to be unique among the class of selective COX-2 inhibitors (coxibs), because this particular compound exerts a second function that is independent of its celebrated ability to inhibit COX-2. This second function is the potential to inhibit cell proliferation and stimulate apoptotic cell death at much lower concentrations than any other coxibs. Intriguingly, these two functions are mediated by different moieties of the celecoxib molecule and can be separated. The author, as well as others, have generated and investigated analogs of celecoxib that retain only one of these two functions. One derivative, 2,5-dimethyl-celecoxib (DMC), which retains the antiproliferative and apoptosis-inducing function, but completely lacks the COX-2 inhibitory activity, is able to mimic faithfully all of the numerous antitumor effects of celecoxib that have been investigated so far, including reduction of neovascularization and inhibition of experimental tumor growth in various in vivo tumor models. In view of the controversy that has recently arisen regarding the life-threatening side effects of this class of coxibs, it may be worthwhile to pursue further the potential benefits of drugs such as DMC for anticancer therapy. Because DMC is not a coxib yet potently maintains celecoxib's antitumor potential, one may be inclined to speculate that this novel compound could potentially be advantageous in the management of COX-2–independent cancers. In this summary, the implications of recent findings with DMC will be presented and discussed.