Evidence of more ion channels inhibited by celecoxib: KV1.3 and L-type Ca(2+) channels

Anti-Psoriasis Effect of Diclofenac and Celecoxib Using the Tail Model for Psoriasis

Non-steroidal anti-inflammatory drugs (NSAIDs) showed effects in some hyperproliferative dermatologic pathologies. The aim of the study is the assessment of anti-psoriasis effect of diclofenac and celecoxib using a mice tail model. The topical application of substances on the proximal mice tails was performed for two weeks. The effects on the epidermal granular layer and mean epidermal thickness (excluding the stratum corneum) were evaluated using hematoxylin–eosin staining. Orthokeratosis degree and percentual drug activity were calculated. A positive control group treated with tretinoin and two negative controls (white soft paraffin and untreated mice) were used. Orthokeratosis degree significantly increased in all the NSAIDs groups (celecoxib 1%, 2% and diclofenac 1%, 2%) and in the tretinoin 0.05% group, versus negative controls. Celecoxib 1% and 2%, tretinoin 0.05% and white soft paraffin significantly increased mean epidermal thickness, versus untreated mice. The values obtained in the case of celecoxib 2% ointment regarding the orthokeratosis degree and percentual drug activity are providing premises for further investigations regarding this effect and the mechanisms of action involved. Celecoxib 2% had the greatest percentual drug activity and is a promising substance for the anti-psoriasis topical treatment. Along with the COX-2 inhibition, celecoxib might have an anti-psoriasis effect by other independent mechanisms.

Non-steroidal anti-inflammatory drugs and the risk of out-of-hospital cardiac arrest: a case-control study

AIMS

Non-steroidal anti-inflammatory drugs (NSAIDs), particularly selective COX-2 inhibitors, are associated with an increased risk of cardiovascular adverse events. However, the association between these drugs and out-of-hospital cardiac arrest with electrocardiogram-documented ventricular tachycardia/ventricular fibrillation (VT/VF-OHCA) has not been studied yet. This study was aimed to evaluate the association between the use of selective COX-2 inhibitors or conventional NSAIDs and VT/VF-OHCA compared with non-use.

METHODS AND RESULTS

A case-control study was conducted among 2483 cases with VT/VF-OHCA from the AmsteRdam REsuscitation STudies (ARREST) registry, an ongoing Dutch registry of OHCA, and 10 441 non-VT/VF-OHCA-controls from the Dutch PHARMO Database Network, containing drug dispensing records of community pharmacies, over the period July 2005-December 2011. Up to five controls were matched for age and sex to one case at the date of VT/VF-OHCA (index date). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by conditional logistic regression analysis. Of the cases, 0.5% was currently exposed at the index date to selective COX-2 inhibitors and 2.5% to conventional NSAIDs. Neither current use of selective COX-2 inhibitors nor conventional NSAIDs were associated with an increased risk of VT/VF-OHCA (adjusted OR 1.11, 95% CI: 0.79-1.56 and adjusted OR 0.97, 95% CI: 0.86-1.10, respectively) compared with non-use. Stratification for VT/VF-OHCA with presence/absence of acute myocardial infarction did not change these results.

CONCLUSION

Exposure to selective COX-2 inhibitors or conventional NSAIDs was not associated with an increased risk of VT/VF-OHCA compared with non-use.

Parecoxib, a selective blocker of cyclooxygenase-2, directly inhibits neuronal delayed-rectifier K+ current, M-type K+ current and Na+ current

Parecoxib, a prodrug of valdecoxib, is a selective inhibitor of cyclooxygenase-2 and widely used for traumatic and postoperative patients to avoid opioid-induced side effects. It is a potent analgesic and has a role in multimodal analgesic and enhanced recovery after surgery. Whether parecoxib exerts any actions on these types of ionic currents remains unclear. In this study, we investigated whether it exerts any effects on ion currents in differentiated NG108-15 neuronal cells. Cell exposure to parecoxib (1-30 μM) caused a reversible reduction in the amplitude of I_K(DR) with an IC₅₀ value of 9.7 μM. The time course for the I_K(DR) inactivation in response to a long-lasting pulse was changed to the biexponential process during cell exposure to 3 μM parecoxib. Other agents known to inhibit the cyclooxygenase activity have minimal effects on I_K(DR). Parecoxib enhanced the degree of excessive accumulative inhibition of I_K(DR) inactivation evoked by a train of brief repetitive stimuli. This compound suppressed the amplitude of M-type K⁺ current. It depressed the peak amplitude of voltage-gated Na⁺ current with no change in the current-voltage relationship of this current. However, it did not have any effect on hyperpolarization-activated cation current. No change in the expression level of K_V3.1 mRNA was detected in the presence of parecoxib. The effects of parecoxib on ion currents are direct and unrelated to its inhibition of the enzymatic activity of cyclooxygenase-2. The inhibition of these ion channels by parecoxib may partly contribute to the underlying mechanisms by which it affects neuronal function in vivo.

Advances with support vector machines for novel drug discovery

INTRODUCTION

Novel drug discovery remains an enormous challenge, with various computer-aided drug design (CADD) approaches having been widely employed for this purpose. CADD, specifically the commonly used support vector machines (SVMs), can employ machine learning techniques. SVMs and their variations offer numerous drug discovery applications, which range from the classification of substances (as active or inactive) to the construction of regression models and the ranking/virtual screening of databased compounds. Areas covered: Herein, the authors consider some of the applications of SVMs in medicinal chemistry, illustrating their main advantages and disadvantages, as well as trends in their utilization, via the available published literature. The aim of this review is to provide an up-to-date review of the recent applications of SVMs in drug discovery as described by the literature, thereby highlighting their strengths, weaknesses, and future challenges. Expert opinion: Techniques based on SVMs are considered as powerful approaches in early drug discovery. The ability of SVMs to classify active or inactive compounds has enabled the prioritization of substances for virtual screening. Indeed, one of the main advantages of SVMs is related to their potential in the analysis of nonlinear problems. However, despite successes in employing SVMs, the challenges of improving accuracy remain.

Investigation of cyclooxygenase and signaling pathways involved in human platelet aggregation mediated by synergistic interaction of various agonists

In the present study, the mechanism(s) of synergistic interaction of various platelet mediators such as arachidonic acid (AA) when combined with 5-hydroxytryptamine (5-HT) or adenosine diphosphate (ADP) on human platelet aggregation were examined. The results demonstrated that 5-HT had no or negligible effect on aggregation but it did potentiate the aggregation response of AA. Similarly, the combination of subeffective concentrations of ADP and AA exhibited noticeable rise in platelet aggregation. Moreover, the observed synergistic effect of AA with 5-HT on platelets was inhibited by different cyclooxygenase (COX) inhibitors, namely ibuprofen and celecoxib, with half maximal inhibitory effect (IC₅₀) values of 18.0±1.8 and 15.6±3.4 μmol/L, respectively. Interestingly, the synergistic effect observed for AA with 5-HT was, also, blocked by the 5-HT receptor blockers cyproheptadine (IC₅₀=22.0±7 μmol/L), ketanserin (IC₅₀=152±23 μmol/L), phospholipase C (PLC) inhibitor (U73122; IC₅₀=6.1±0.8 μmol/L), and mitogen activated protein kinase (MAPK) inhibitor (PD98059; IC₅₀=3.8±0.5 μmol/L). Likewise, the synergism of AA and ADP was, also, attenuated by COX inhibitors (ibuprofen; IC₅₀=20±4 μmol/L and celecoxib; IC₅₀=24±7 μmol/L), PLC inhibitor (U73122; IC₅₀=3.7±0.3 μmol/L), and MAPK inhibitor (PD98059; IC₅₀=2.8±1.1 μmol/L). Our observed data demonstrate that the combination of subthreshold concentrations of agonists amplifies platelet aggregation and that these synergistic effects largely depend on activation of COX/thromboxane A2, receptor-operated Ca²⁺ channels, Gq/PLC, and MAPK signaling pathways. Moreover, our data revealed that inhibition of COX pathways by using both selective and/or non-selective COX inhibitors blocks not only AA metabolism and thromboxane A2 formation, but also its binding to Gq receptors and activation of receptor-operated Ca²⁺ channels in platelets. Overall, our results show that PLC and MAPK inhibitors proved to inhibit the synergistic activation of platelets by several/multiple agonists.