Carboxylesterase catalyzed 18O-labeling of carboxylic acid and its potential application in LC-MS/MS based quantification of drug metabolites

LC-MS quantification of drug metabolites is sometimes impeded by the availability of internal standards that often requires customized synthesis and/or extensive purification. Although isotopically labeled internal standards are considered ideal for LC-MS/MS based quantification, de novo synthesis using costly isotope-enriched starting materials makes it impractical for early stage of drug discovery. Therefore, quick access to these isotope-enriched compounds without chemical derivatization and purification will greatly facilitate LC-MS/MS based quantification. Herein, we report a novel ¹⁸O-labeling technique using metabolizing enzyme carboxylesterase (CES) and its potential application in metabolites quantification study. Substrates of CES typically undergo a two-step oxygen exchange with H₂¹⁸O in the presence of the enzyme, generating singly- and doubly-¹⁸O-labeled carboxylic acids; however, unexpected hydrolytic behavior was observed for three of the test compounds – indomethacin, piperacillin and clopidogrel. These unusual observations led to the discovery of several novel hydrolytic mechanisms. Finally, when used as internal standard for LC-MS/MS based quantification, these in situ labeled compounds generated accurate quantitation comparable to the conventional standard curve method. The preliminary results suggest that this method has potential to eliminate laborious chemical synthesis of isotope-labeled internal standards for carboxylic acid-containing compounds, and can be developed to facilitate quantitative analysis in early-stage drug discovery.     

双氯芬酸钠肠溶片的血药浓度测定及人体药代动力学研究

目的 :研究双氯芬酸在正常志愿者的血药浓度及体内的药代动力学 ,为临床用药提供依据。方法 :16名健康男性志愿者 ,单剂量口服双氯芬酸钠肠溶片 10 0 mg,在不同时间点取静脉血 ,血药浓度采用高效液相色谱法 (HPL C)测定。由血药浓度数据获得各自的主要药动力学参数。结果 :志愿者单次服用 10 0 mg双氯芬酸钠肠溶片后的药代动力学参数 AUC0→∞ 、AU C0→ 8、Cmax、Tmax分别为 (5 .98± 1.4 7) mg.h/ L、(6 .15± 1.5 2 ) mg.h/ L、(2 .96± 0 .84 ) m g.h/ L、(2 .2 5± 0 .32 ) h。结论 :双氯芬酸钠肠溶片在我国正常志愿者的药代动力学参数与国外的相似。     

双氯芬酸钠滴眼液稳定性研究

采用高效液相色谱法测定双氯芬酸钠滴眼液的含量，方法简便，准确，能将药与杂质峰完全分离。应用化学动力学原理以恒温加试验预测双氯芬酸钠滴眼液稳定性及有效期，室温下有效期ｔ＾２５℃０．９约为２．５７年，与留样观察结果相符。     

Non-steroidal anti-inflammatory drug (NSAID)-induced colonic strictures and perforation: A case report

Although non-steroidal anti-inflammatory drug-induced colopathy is well described, colonic perforations complicating non-steroidal anti-inflammatory drug intake are rare. We report a patient with rheumatoid arthritis who was on long-term diclofenac and presented with early colonic stricture formation and a caecal perforation, which to the best of our knowledge, has only been reported once before. It is important to suspect this diagnosis in patients on non-steroidal anti-inflammatory drug therapy who present with an acute abdomen.     

Efficacy and tolerability of a topical NSAID patch (local action transcutaneous flurbiprofen) and oral diclofenac in the treatment of soft-tissue rheumatism

Summary The efficacy and safety of local action transcutaneous flurbiprofen 40 mg [flurbiprofen LAT] patches and diclofenac sodium tablets, 50 mg b.d., were compared in an open, multicentre, randomized, parallel-group study in patients with soft-tissue rheumatism. Patches were replaced at 12-hourly intervals. Clinical assessments were performed after 7 and 14 days of treatment. Fifty-six patients were treated with flurbiprofen LAT and 53 with diclofenac. Six withdrawals (three from each group) occurred during the treatment period.A statistically significant difference was observed in favour of flurbiprofen LAT for the principal measure, namely the investigator's opinion of overall change in clinical condition: 49/53 (92%) patients treated with flurbiprofen LAT had improved by day 14 compared with 36/49 (73%) patients receiving diclofenac sodium (p=0.03; eligible dataset). There were also statistically significant differences in favour of flurbiprofen LAT for the investigator's assessments of the overall severity of the clinical condition (p=0.03; eligible dataset), for the severity of pain at the region treated (p=0.04; intent-to-treat), and for the severity of tenderness (p<0.001; intent-to-treat). Supplementary analgesia (paracetamol) was required by two patients in the flurbiprofen LAT group and by eight diclofenac-treated patients. The difference in favour of flurbiprofen LAT group and by eight diclofenac-treated patients. The difference in favour of flurbiprofen LAT in the average daily consumption of paracetamol was significant (p=0.04). The patients' assessment of severity of pain on movement also favoured flurbiprofen LAT (p =0.049; eligible dataset), but there were no statistically significant differences in day or night pain or quality of sleep. For the patients' opinion of treatment there was, however, a statistically significant difference in favour of flurbiprofen LAT (p=0.02). Of the patients receiving flurbiprofen LAT, 94% regarded it as a convenient form of treatment.With respect to tolerability 8/56 (14%) patients applying flurbiprofen patches reported a total of nine adverse effects (AEs) (mainly local, mild skin irritations), vs 9/52 (17%) patients receiving diclofenac, who reported 12 AEs. Most AEs in the enteric-coated diclofenac group were of a gastrointestinal nature (one of which was severe). In terms of the proportion of patients reporting AEs related to the digestive system, there was a statistically significant difference in favour of flurbiprofen LAT (p=0.011).In conclusion, local treatment of soft-tissue rheumatism with flurbiprofen LAT was demonstrably superior to benchmark oral therapy with diclofenac sodium over a 2-week period in terms of both efficacy and gastrointestinal tolerability. Flurbiprofen LAT provided both an effective and convenient form of topical SAID treatment.     

双氯灭痛药膜体外透皮速率的实验研究

作者选择乙基纤维素、聚乙烯醇等高分子材料制成涂膜剂，用大鼠皮进行双氯灭痛药膜的体外透皮速率测定。结果表明，氮酮与丙二醇可以促进药物渗透。不同的高分子材料可影响药物的扩散与释放，从而影响其透皮速率。与无膜无促透剂处方相比，药物在乙基纤维素中的透皮速率没有增加，在聚乙烯醇膜中的透皮速率有显著增加。     

双氯灭痛缓释片在中国人体内药代动力学和相对生物利用度

八名健康男性志愿者单剂量随机交叉服用１００ｍｇ双氯灭痛缓释片及肠溶衣片后，用ＨＰＬＣ法测定血药浓度。体内药物浓度符合一室开放模型。肠溶衣片及缓释片的Ｔ＿１／２（Ｋｅ）分别为２．１５±０．１７及ｌｌ．６０±ｌ．９５ｈ；药物浓度曲线下面积分别为５．８±０．６７及５．５５±０．５７μｇ·ｈ／ｍｌ。缓释片对肠溶衣片的相对生物利用度为０．９５（Ｐ＞０．０５）。     

示差导数光谱法测定感冒通片中双氯灭痛和扑尔敏的含量

本文利用示差导数光谱法对感冒通片中双氯灭痛和扑尔敏进行定量测定。本法用同一样品液,在同一测定条件下完成,具有操作简便、快速、灵敏度高和重现性好等特点,双氯灭痛和扑尔敏的平均回收率分别为99.5%和97.3%,变异系数分别为0.42%和0.63%.     

Diclofenac and oxycodone in treatment of postoperative pain: a double-blind trial

The effects of a prostaglandin synthesis inhibitor (diclofenac, Voltaren) and an opiate (oxycodone, Oxanest) on postoperative pain were compared. Included in the study were 85 candidates for various operations. Patients requesting an analgesic were given either 75 mg of diclofenac or 10 mg of oxycodone as an intramuscular injection. The onset of analgesic effect occurred within 13 +/- 4 min with oxycodone and within 16 +/- 8 min with diclofenac. The analgesic effect of diclofenac was slightly weaker than that of oxycodone (on a pain scale of 1-4, 1.6/2.1 after 0.5 h and 1.5/1.8 after 1 h). The patients again asked for an analgesic after an average of 4.6 h in the oxycodone group and after an average of 6.1 h in the diclofenac group. The average number of injections required until the first postoperative morning was 2.5 in the oxycodone group and 1.8 in the diclofenac group. Side-effects: 21 patients in the oxycodone group reported a total of 39 side-effects and eight patients in the diclofenac group a total of 10 side-effects. Diclofenac is an alternative to opiates in the management of postoperative pain. It is especially useful in patients in whom opiates cause side-effects.