COX-2抑制剂Celecoxib的合成

以对甲基苯乙酮为原料,经缩合、环合反应合成选择性ＣＯＸ－２抑制剂Ｃｅｌｅｃｏｘｉｂ,总收率３７．７％。     

Retinal toxicity of chloroquine hydrochloride administered by intraperitoneal injection

Chloroquine is quinolone derivative known to exert dose-related retinal toxicity, albeit in a variable manner. It is thought that variability in the presentation of chloroquine retinopathy may be the result of perturbations in drug bioavailability subsequent to oral ingestion. In order to better understand the ramifications of bioavailability on the development of retinal injury subsequent to chloroquine use, this study investigated the relationship between retinal injury and chloroquine administration via intraperitoneal rather than oral administration. Four-week-old C57/6J mice underwent daily intraperitoneal injection of 10 mg kg(-1) chloroquine hydrochloride for a total of 62 days. Following treatment, tissue was fixed in preparation for analysis by light and transmission electron microscopy. Treated animals demonstrated marked abnormality of the outer retinal layers described as complete loss of the outer plexiform layer as well as photoreceptors and photoreceptor nuclei. The retinal pigmented epithelium demonstrated focal atrophy, loss of nuclei and pigment irregularity. Findings in the inner retina were notable for the loss of Müller cells and the presence of membranous cytoplasmic bodies. Retinae of control animals were entirely normal. In contrast to previous studies in the murine model examining chloroquine retinopathy subsequent to oral administration, this study suggests that intraperitoneal chloroquine administration facilitates retinal toxicity, presumably due to heightened drug absorption and bioavailability. It is posited that an increased rate of drug accumulation within the retina leads to an enhanced lysosomotrophic drug effect due to inability of the lysosome to compensate for chloroquine-induced elevation in pH through re-acidification of the intra-lysosomal content.     

塞来昔布对肝癌HepG2 HepG3细胞的免疫增敏作用

目的探讨选择性环氧合酶-2（COX-2）抑制剂塞来昔布（Celecoxib）对人肝癌HepG2和HepG3细胞株对肿瘤坏死因子相关的凋亡诱导配体（TRAIL）的增敏作用及其可能机制。方法以人HepG2 HepG3肝癌细胞为研究对象,以塞来昔布和TRAIL作为干预手段,采用四甲基偶氮唑蓝（MTT）法检测塞来昔布对肝癌细胞株的增殖抑制作用,采用流式细胞术,检测塞来昔布联合TRAIL对HepG2,HepG3细胞的凋亡及DR4,DR5的表达。塞来昔布与不同效靶比的细胞因子诱导的杀伤细胞（CIK）联合作用于人肝癌细胞株,经LDH检测法检测其杀伤作用。结果塞来昔布及TRAIL对人肝癌HepG2和HepG3细胞株均有显著抑制作用,塞来昔布联合TRAIL可显著增敏TRAIL对HepG2和HepG3的杀伤,其差异具有统计学意义（P〈0.05）,经过塞来昔布预处理的肝癌细胞更易被CIK细胞杀伤。结论塞来昔布对人肝癌HepG2和HepG3细胞株具有明显细胞毒性,联合TRAIL及CIK可显著增敏后者对肝癌细胞的杀伤效应,其机制可能与塞来昔布上调DR4,DR5有关。     

塞来昔布对人乳腺癌SKBR-3细胞生长的影响

目的探讨选择性环氧化酶-2(COX-2)抑制剂塞来昔布对乳腺癌SKBR-3细胞生长的影响及机制。方法用不同浓度的塞来昔布处理SKBR-3细胞后,采用CCK-8法检测塞来昔布对SKBR-3细胞增殖活性的影响;流式细胞仪检测细胞周期;酶联免疫吸附试验(ELISA)检测前列腺素E2(PGE2)的释放水平;Western Blot法测定各浓度塞来昔布刺激SKBR-3细胞后Caspase-3被酶解激活情况。结果塞来昔布对SKBR-3细胞的增殖抑制作用呈剂量-时间依赖性;随着塞来昔布浓度的增加,G0/G1期细胞阻滞,S期细胞比例明显减少;塞来昔布明显减少PGE2的释放水平;Caspase-3在细胞凋亡早期被激活,在凋亡晚期则无表达。结论塞来昔布能有效抑制乳腺癌SKBR-3细胞的增殖,诱导其凋亡;其作用机制可能与COX-2表达下调、抑制PGE2水平和促进Caspase-3的活化有关。     

Celecoxib: a new option in the treatment of arthropathies and familial adenomatous polyposis

The discovery of the two isoenzymes of cyclooxygenase (COX) has recently lead to the development and clinical introduction of specific inhibitors of cyclooxygenase-2 (COX-2), such as celecoxib, onto the market. Celecoxib is an effective anti-inflammatory, analgesic and antipyretic agent therapeutically utilised in the management of osteoarthritis and rheumatoid arthritis. In addition, celecoxib has some novel therapeutic and pharmacological activities. Celecoxib inhibits anti-apoptotic kinase activation and is the first specific COX-2 inhibitor to be marketed for familial adenomatous polyposis, an inheritable predisposition for colorectal cancer. Celecoxib is not without gastrointestinal (GI) side effects but demonstrates markedly reduced GI ulceration in clinical trials when compared to traditional non-specific non-steroidal anti-inflammatory drugs (NSAIDs). The specific COX-2 inhibitors each have distinctive pharmacokinetic properties. Celecoxib can be given either once or twice daily. Racial differences in drug disposition, and pharmacokinetic changes in elderly patients, patients with chronic renal insufficiency and patients with mild to moderate hepatic impairment, are evident with celecoxib. Despite the specific action of these drugs, there remains the potential for significant drug interactions. Celecoxib has demonstrated interactions with fluconazole, lithium and warfarin. Increased clinical vigilance should be maintained when co-prescribing medications with celecoxib until further clinical experience is gained. Celecoxib represents a major therapeutic advance in terms of GI safety. However, long-term safety in other organ systems, safety with concomitant drug administration, and pharmacoeconomic benefits still remain to be proven.     

The Oral Route for the Administration of Cytotoxic Drugs: Strategies to Increase the Efficiency and Consistency of Drug Delivery

There is an increasing interest to administer cytotoxic drugs topatients by the oral route. Quality of life issues, treatmentadvantages and pharmaco-economics are major arguments in favorof oral therapy. However, low or moderate bioavailability incombination with considerable interpatient variability arefrequently observed which may reduce the feasibility of the oralroute for this class of drugs with a generally narrow therapeuticwindow. Until recently, investigators focused on absorptionenhancers which slightly damage the intestinal surface such assalicylates, methylxantines and surfactants to improve the oralbioavailability of drugs. To date, a shift can be seen towardsmore subtle mechanisms to enhance the absorption. This reviewarticle focuses on two important mechanisms that determine theoral bioavailability of cytotoxic drugs. These include thepresence of drug transporters in the intestinal epitheliumpumping drugs into the intestinal lumen, such as MDR1 typeP-glycoproteins, and first-pass elimination by cytochrome P450isoenzymes (e.g. 3A4 and 3A5) or other enzymes in the intestinesand/or liver. Currently preclinical and clinical studies arebeing performed to explore the feasibility of blocking thesetransporters/enzymes in order to achieve higher and less variablesystemic drug levels after oral dosing. This review gives anupdate of the results of these studies. It is concluded however,that further research to unravel the processes involved in oraldrug uptake is warranted to make the oral route a more efficientand consistent way of drug administration.     

Assessment of Patient Exposure to Leachables From Lyophilized Drug Formulations Following Reconstitution,Storage, and Administration via Polymeric Packaging/Delivery Systems

It has been demonstrated that lyophilized drug formulations have an increased propensity to leach substances from the rubber stoppers comprising their primary packaging system when compared to aqueous liquid formulations stored in the same manner. Unfortunately, patient exposure to leachables originating in lyophilized drug products is not known. To that end, the goal of this study was to assess patient exposure to these leachables after reconstitution, storage, and administration of the lyophilized drug. To achieve this goal, several leachables present in 2 commercial lyophilized drug products were quantified after contact with polyvinyl chloride and non–polyvinyl chloride medication bags as well as an infusion set for durations of 15 min to 7 days at refrigerated and ambient temperature. The results obtained from this study showed that the bag’s material of construction and the drugs formulation did not impact the mass of the leachables administered. Conversely, the mass of each leachable administered to the patient was reduced or eliminated as the contact duration with the intravenous bag and the temperature increased. However, for shorter contact durations, refrigerated storage, and higher molecular weight compounds, the patient would be exposed to a majority of the leachables originating from the vial.     

Reduced Toxicity of Shiga Toxin (Stx) Type 2c in Mice Compared to Stx2d Is Associated with Instability of Stx2c Holotoxin

Shiga toxin (Stx) is an AB₅ ribotoxin made by Stx-producing Escherichia coli (STEC). These organisms cause diarrhea, hemorrhagic colitis and the hemolytic uremic syndrome. STEC make two types of Stxs, Stx1 and/or Stx2. Stx2 has one prototype (a) and six subtypes (b–g), but only STEC that make Stx2a, and/or Stx2c, or Stx2d are associated with severe disease. However, Stx2c is about 10-fold less toxic than Stx2d in vivo despite only two amino acid differences in the A subunit at positions 291 and 297. We made mutations at these two sites to create intermediate toxins between Stx2c and Stx2d, and determined the 50% cytotoxic dose on Vero cells before and after heat treatment, and the 50% lethal dose in mice of the toxins. We found that serine 291 was associated with increased toxicity in vivo and that either amino acid change from that in Stx2c to that in Stx2d increased heat stability. We also assessed the secondary structure of Stx2c and Stx2d by circular dichroism (CD) spectroscopy. The CD studies suggest that Stx2c has a less-ordered secondary structure than Stx2d. We conclude that both amino acids at positions 291 and 297 in Stx2c contribute to its decreased stability and in vivo toxicity compared to Stx2d.     

Nipecotic Acid: Systemic Availability and Brain Delivery After Nasal Administration of Nipecotic Acid and <Emphasis Type="Italic">n</Emphasis>-Butyl Nipecotate to Rats

No HeadingPurpose. The purpose of this research was to characterize nipecotic acid pharmacokinetics in blood and brain after intravenous (i.v.) and nasal administration of nipecotic acid and its n-butyl ester.Methods. Nipecotic acid and its n-butyl ester were administered to rats i.v. and intranasally (n = 5 rats/drug per route), and nipecotic acid pharmacokinetics in blood were characterized. Nipecotic acid concentration-time profiles were determined in blood by noncompartmental and compartmental methods. Nipecotic acid was also dosed i.v. and its n-butyl ester was dosed by nasal and i.v. routes, and brain levels of nipecotic acid over the subsequent 4 h (n = 5 rats/time point per route) were assessed.Results. The absolute systemic availability of nipecotic acid after nasal dosing was 14%. After i.v. and nasal dosing of the n-butyl ester, nipecotic acid systemic availability was 97% and 92%, respectively. Both i.v. and nasal administration of the n-butyl ester resulted in a significantly longer terminal half-life and larger mean resident time and volume of distribution for nipecotic acid than was observed after an i.v. nipecotic acid dose. Total brain exposure to nipecotic acid was not significantly different after nasal and i.v. dosing of the n-butyl ester. However, the brain/blood nipecotic acid ratio declined significantly with time after i.v. and nasal dosing of the ester prodrug. Nipecotic acid was not detectable in brain after i.v. dosing of nipecotic acid.Conclusions. The use of an ester formulation was crucial to delivering nipecotic acid to the brain. Preliminary evidence strongly suggests ester hydrolysis is rate limiting to nipecotic acid brain delivery. Once nipeoctic acid was formed, it displayed tissue trapping in brain. Parenteral dosing of nipecotic acid esters is unnecessary for systemic or brain delivery of nipecotic acid and possibly other CNS active zwitterion esters.