Discovery of 5-(1-benzyl-1H-imidazol-4-yl)-1,2,4-oxadiazole derivatives as novel RIPK1 inhibitors via structure-based virtual screening.

RIPK1 plays a key role in necroptosis and is associated with various inflammatory diseases. Using structure-based virtual screening, a novel hit with 5-(1-benzyl-1H-imidazol-4-yl)-1,2,4-oxadiazole scaffold was identified as an RIPK1 inhibitor with an IC50 value of 1.3 µM. Further structure-activity relationship study was performed based on similarity research and biological evaluation. The molecular dynamics simulation of compound 2 with RIPK1 indicated that it may act as a type II kinase inhibitor. This study provides a highly efficient way to discover novel scaffold RIPK1 inhibitors for further development.

Pharmacokinetic interactions between the potential COVID-19 treatment drugs lopinavir/ritonavir and arbidol in rats.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has occasioned worldwide alarm. Globally, the number of reported confirmed cases has exceeded 84.3 million as of this writing (January 2, 2021). Since there are no targeted therapies for COVID-19, the current focus is the repurposing of drugs approved for other uses. In some clinical trials, antiviral drugs such as remdesivir (Grein et al., 2020), lopinavir/ritonavir (LPV/r) (Cao et al., 2020), chloroquine (Gao et al., 2020), hydroxychloroquine (Gautret et al., 2020), arbidol (Wang et al., 2020), and favipiravir (Cai et al., 2020b) have shown efficacy in COVID-19 patients. LPV/r combined with arbidol, which is the basic regimen in some regional hospitals in China including Zhejiiang Province, has shown antiviral effects in COVID-19 patients (Guo et al., 2020; Xu et al., 2020). A retrospective cohort study also reported that this combination therapy showed better efficacy than LPV/r alone for the treatment of COVID-19 patients (Deng et al., 2020).

Elevation of Serum Cytokine Profiles and Liver Metabolomic Normalization in Early Convalescence of COVID-19 Patients.

Coronavirus disease 2019 (COVID-19) has become a global public health concern. We aimed to study the cytokine profile during the convalescent phase and its association with liver functions. We performed a retrospective study to investigate the longitudinal dynamic serum cytokine, liver function, and metabolomic profiles, as well as their potential correlations, from the viral replication phase to early convalescence. Our results demonstrated that liver injury was common. Liver injury was significantly associated with higher levels of interleukin (IL)-6 and IL-10 (p < 0.05). However, alanine aminotransferase levels decreased during the first week after hospital discharge (p < 0.01). In parallel, T-cell and B-cell immune response-stimulating cytokine IL-4, but not IL-2, was significantly elevated (p < 0.05). Furthermore, interferon-γ (IFN-γ) and tumor necrosis factor-α (TFN-α) levels increased, in contrast to the decrease in IL-6 and IL-10 levels; liver function returned to normal. The metabolomic analysis supported active recovery during early convalescence of COVID-19 patients that had distinct metabolic profiles associated with the hepatic tricarboxylic acid cycle, amino acid metabolism, and lipid metabolism. In addition, we identified a metabolomic association of IL-4 with liver repair. Our findings suggest that discharged patients continue to recover from the physiological effects of COVID-19, and the association of IL-4, IL-6, and IL-10 levels with metabolic changes and liver function repair may have important implications for clinical manifestations and treatment of COVID-19.

Efficacy and safety of thrombolysis for acute ischemic stroke with atrial fibrillation: a meta-analysis.

BACKGROUND: The efficacy and safety of intravenous thrombolysis (IVT) for acute ischemic stroke with atrial fibrillation (AF) is still controversial. METHODS: We conducted a meta-analysis of all relevant studies, retrieved through systematic search of PubMed, Embase, and Cochrane databases up to December 31, 2019. Modified Rankin Scale (mRS) scores of 0-1 at 90 days, mRS of 0-2 at 90 days, overall mortality, and incidence of symptomatic intracranial hemorrhage (sICH) were collected as outcome measures. Fixed- and random-effects meta-analytical models were applied, and between-study heterogeneity was assessed. RESULTS: A total of 8509 patients were enrolled in 18 studies. A comparison of IVT treatment in AF versus non-AF patients showed that AF was associated with a significantly lower proportion of patients with mRS of 0-1 (24.1% vs. 34.5%; OR 0.59; 95% CI 0.43-0.81; P < 0.001), mRS of 0-2 (33.6% vs. 47.8%; OR 0.55; 95% CI 0.43-0.70; P < 0.001), as well as significantly higher mortality (19.4% vs. 11.5%; OR 2.05; 95% CI 1.79-2.36; P < 0.001) and higher incidence of sICH (6.4% vs. 4.1%; OR 1.60; 95% CI 1.27-2.01; P < 0.001). A comparison of AF patients who were subjected or not to IVT showed that thrombolysis carried a higher risk of sICH (5.7% vs. 1.6%; OR 3.44; 95% CI 2.04-5.82; P < 0.001) and was not associated with a better prognosis. Subgroup analysis in prospective studies also suggested a poorer functional prognosis and higher mortality in AF patients treated with IVT compared with those who did not receive IVT. Some heterogeneity was present in this meta-analysis. CONCLUSIONS: Acute IS patients with AF had worse outcomes than those without AF after thrombolytic therapy, and had a higher incidence of sICH after thrombolysis than those without thrombolysis. Thrombolysis in ischemic stroke patients with AF should be carefully considered based on clinical factors such as NIHSS score, age, and the type of AF.

Antiviral Agent Therapy Optimization in Special Populations of COVID-19 Patients.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now a global outbreak of disease. The antiviral treatment acts as one of the most important means of SARS-CoV-2 infection. Alteration of physiological characteristics in special populations may lead to the change in drug pharmacokinetics, which may result in treatment failure or increased adverse drug reactions. Some potential drugs have shown antiviral effects on SARS-CoV-2 infections, such as chloroquine, hydroxychloroquine, favipiravir, lopinavir/ritonavir, arbidol, interferon alpha, and remedsivir. Here, we reviewed the literature on clinical effects in COVID-19 patients of these antiviral agents and provided the potential antiviral agent options for pregnant women, elderly patients, liver or renal dysfunction patients, and severe or critically ill patients receiving renal replacement therapy or ECMO after SARS-CoV-2 infection.

Liver Injury in Critically Ill and Non-critically Ill COVID-19 Patients: A Multicenter, Retrospective, Observational Study.

Background: Liver injury commonly occurs in patients with COVID-19. There is limited data describing the course of liver injury occurrence in patients with different disease severity, and the causes and risk factors are unknown. We aim to investigate the incidence, characteristics, risk factors, and clinical outcomes of liver injury in patients with COVID-19. Methods: This retrospective observational study was conducted in three hospitals (Zhejiang, China). From January 19, 2020 to February 20, 2020, patients confirmed with COVID-19 (≥18 years) and without liver injury were enrolled and divided into non-critically ill and critically ill groups. The incidence and characteristics of liver injury were compared between the two groups. Demographics, clinical characteristics, treatments, and treatment outcomes between patients with or without liver injury were compared within each group. The multivariable logistic regression model was used to explore the risk factors for liver injury. Results: The mean age of 131 enrolled patients was 51.2 years (standard deviation [SD]: 16.1 years), and 70 (53.4%) patients were male. A total of 76 patients developed liver injury (mild, 40.5%; moderate, 15.3%; severe, 2.3%) with a median occurrence time of 10.0 days. Critically ill patients had higher and earlier occurrence (81.5 vs. 51.9%, 12.0 vs. 5.0 days; p < 0.001), greater injury severity (p < 0.001), and slower recovery (50.0 vs. 61.1%) of liver function than non-critically ill patients. Multivariable regression showed that the number of concomitant medications (odds ratio [OR]: 1.12, 95% confidence interval [CI]: 1.05-1.21) and the combination treatment of lopinavir/ritonavir and arbidol (OR: 3.58, 95% CI: 1.44-9.52) were risk factors for liver injury in non-critically ill patients. The metabolism of arbidol can be significantly inhibited by lopinavir/ritonavir in vitro (p < 0.005), which may be the underlying cause of drug-related liver injury. Liver injury was related to increased length of hospital stay (mean difference [MD]: 3.2, 95% CI: 1.3-5.2) and viral shedding duration (MD: 3.0, 95% CI: 1.0-4.9). Conclusions: Critically ill patients with COVID-19 suffered earlier occurrence, greater injury severity, and slower recovery from liver injury than non-critically ill patients. Drug factors were related to liver injury in non-critically ill patients. Liver injury was related to prolonged hospital stay and viral shedding duration in patients with COVID-19. Clinical Trial Registration: World Health Organization International Clinical Trials Registry Platform, ChiCTR2000030593. Registered March 8, 2020.

Interactions between clopidogrel and traditional Chinese medicine.

The use of traditional Chinese medicine (TCM) has obtained more and more acceptance all over the world due to its multi-target and multi-level function characteristics. Clopidogrel is a major therapeutic option to reduce atherothrombotic events in patients with acute coronary syndrome, recent myocardial infarction, recent stroke or established peripheral arterial disease. These patients probably take TCM. Are there any interactions between clopidogrel and TCM? Whether TCM will affect the efficacy of clopidogrel or increase the adverse reactions of bleeding? Clarifying this information will help physicians make better use of TCM. A literature search was carried out using Web of Science, PubMed and the Cochrane Library to analyze the pharmacokinetic or pharmacodynamic interactions of clopidogrel and TCM. Some herbs can increase the AUC or Cmax of clopidogrel, such as Scutellarin, Danggui, Gegen, Sauchinone and Dengzhan Shengmai capsules. Whereas others can decrease clopidogrel, for example, Ginkgo and Danshen. Furthermore, some herbs can increase the AUC or Cmax of clopidogrel active metabolite, including Ginkgo and Xuesaitong tablet. And others can decrease the clopidogrel active metabolite, such as Scutellarin, Danshen, Fufang Danshen Dripping Pill and Dengzhan Shengmai capsules. Additionally, Schisandra chinensis, Danggui, Gegen and Fufang Danshen Dripping Pill can decrease the AUC or Cmax of the clopidogrel inactive metabolite, while Curcumin on the contrary. The pharmacodynamics of Panax notoginseng, Notoginsenoside Ft1, Hypericum perforatum, Shexiang baoxin pills, Naoxintong capsule increased the antiplatelet activity compared with clopidogrel alone, while Danshen decreased the platelet inhibition. In adverse reactions, Danggui can enhance the adverse effects of clopidogrel on the bleeding time. With more awareness and understanding on potential drug-herb interactions of clopidogrel and TCM, it may be possible to combine clopidogrel with TCM herbs to yield a better therapeutic outcome.

Predictors of functional outcome and hemorrhagic complications in acute ischemic stroke patients treated with intravenous thrombolysis - A retrospective analysis
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Intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator (rt-PA) within 4.5 hours is an effective and routine therapy for acute ischemic stroke (AIS). The purpose of the study was to identify predictors of functional outcome at 3 months and hemorrhagic complications after IVT. A total of 123 AIS patients treated with intravenous alteplase within 4.5 hours after stroke were enrolled. Baseline clinical characteristics, medication and disease history, radiographic and laboratory data were collected. The clinical functional outcome at 3 months was measured by the modified Rankin Scale dichotomized at 0 - 1 (favorable) vs. 2 - 6 (unfavorable). Hemorrhagic complications were measured within 36 hours after IVT. Univariate and multivariate analysis was applied in the study, and the logistic regression identified the predictors for functional outcome at 3 months and hemorrhagic complications within 36 hours. In univariate analysis, the favorable outcome was significantly associated with short hospitalization, low initial National Institute of Health Stroke Scale scores, previous smoking, previous statin use, and absence of post-stroke cerebral edema or pneumonia. Hemorrhagic complications were significantly associated with high initial NIHSS scores, low platelet count, high D-dimer level, previous atrial fibrillation, and onset seasons (except summer). Multivariate regression analyses identified that seasons (spring and summer), short hospital stays, and absence of post-stroke cerebral edema or pneumonia were the predictors of a favorable functional outcome. Meanwhile, seasons (except summer), low platelet count, and high D-dimer levels were correlation factors for prognosis of high hemorrhagic complications.
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Clinical pharmacist interventions on a Chinese neurology ward: a 2-year service evaluation.

A prospective observational study of clinical pharmacist interventions was conducted over a 2-year period from November 2012 to October 2014 to evaluate the clinical activity of pharmacists in the care they provide to patients and to promote safe and effective medication therapy by quantifying medicine-related interventions on a Chinese neurology ward. All pharmacist interventions made in the department of neurology were recorded, categorized, and assessed for potential patient harm if the intervention had not taken place. The quantity, outcomes, and potential severity of clinical pharmacists' interventions were recorded. 619 interventions were made in 385 patients over the 2-year observational period. The mean severity of potential harm assessment was 3.7 (1.12), range 0.8 - 7.0. 87 of the 619 interventions (14.0%) were classified as medication errors. The results of the clinical pharmacist intervention study demonstrated that pharmacists play an important role in the care of neurological patients by improving patient care and reducing clinical risk.

Design, synthesis and evaluation of rivastigmine and curcumin hybrids as site-activated multitarget-directed ligands for Alzheimer's disease therapy.

A series of novel 2-methoxy-phenyl dimethyl-carbamate derivatives were designed, synthesized and evaluated as site-activated MTDLs based on rivastigmine and curcumin. Most of them exhibited good to excellent AChE and BuChE inhibitory activities with sub-micromolar IC50 values. Among all the compounds, 6a demonstrated the most potent AChE inhibition with IC50 value of 0.097µM, which is about 20-fold than that of rivastigmine. In addition, the three selected compounds 5a, 6a and 6e demonstrated inhibitory activity against Aß self-aggregation similar to cucurmin in TEM assay, which is obviously different from the weak activity of rivastigmine. Moreover, the hydrolysate of 6a (compound 7) also showed potent ABTS(+) scavenging and moderate copper ion chelating activity in vitro.

Epidemiological and clinical characteristics of 266 cases of intracerebral hemorrhage in Hangzhou, China.

Ethnicity and socioeconomic factors can influence disease susceptibility, clinical presentation, and outcome. We investigated the clinical characteristics (age, sex, seasonal variation, lesion site, symptoms, complications, prognosis, and sequelae) and risk factors for intracerebral hemorrhage (ICH) in 266 cases treated at our hospital in Hangzhou City, China, from January 2011 to December 2011. Risk of ICH increased dramatically with age; only 4.3% of cases were <30 years old, while 44.4% were >60 years of age. Men outnumbered women by 2:1 (67.3% vs. 32.7%). Single hemorrhage was most often located in the cerebral lobes (37.2% of cases), basal ganglia (34.2%), thalamus (8.3%), cerebellum (6.8%), ventricle (1.5%), and brainstem (1.1%), while 10.9% of cases exhibited hemorrhages at multiple sites. Hypertension was also a major risk factor for ICH, as 47% of all patients were hypertensive and the percentage increased with age. In hypertensive patients, the most common hemorrhage site was the basal ganglia and ICH was often associated with thrombopenia. In patients with leukemia (all forms), most hemorrhages were lobar. Warfarin- and encephalic operation-associated ICHs were all lobar. Headache was the major symptom of occipital, temporal, and frontal lobe hemorrhage. Dizziness, nausea, and vomiting were the major symptoms of cerebellum hemorrhage. Limb dysfunction was the major symptom of thalamic and basal ganglia hemorrhage. Disturbed level of consciousness was the major symptom in multisite, ventricular, parietal lobe, and brainstem hemorrhage. Hyperspasmia occurred most often in lobar hemorrhage and blurred vision in occipital lobe hemorrhage. Hospital mortality was 24.4% (n=65) with a mean delay from presentation to death of (10.5±18.5) d. The majority of fatalities were cerebral hernia cases (58.5%) and these patients also had the shortest time to death [(2.9±3.5) d]. Mortality was 100% in brainstem ICH and hemorrhagic conversion of cerebral infarct. Thrombopenia-associated ICH also had a high mortality rate (81.0%), while patients with cerebrovascular malformations and cerebral aneurysms demonstrated a much better prognosis (46.2% recovery).

Thrombocytopenia induced by both aspirin and clopidogrel in the same patient.

Aspirin and clopidogrel are used widely as antiplatelet agents due to their efficacy, safety, and tolerability. In rare cases, these agents can cause thrombotic thrombocytopenic purpura, but no report has documented severe thrombocytopenia in response to both drugs in the same patient. A 73-year old female developed severe thrombocytopenia following treatment with clopidogrel. Platelet count recovered within 6 months of drug withdrawal without additional thrombopoietic therapies. Seven months after the last dose of clopidogrel, thrombocytopenia recurred on aspirin therapy. Again, platelet count rebounded gradually and independently. This case suggests that some patients who experience thrombocytopenia in response to one antiplatelet agent may react similarly to other antiplatelet agents.

Synthesis and biological evaluation of 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives as hypoxic selective anti-tumor agents.

A series of 3-aryl-2-quinoxaline-carbonitrile 1,4-di-N-oxide derivatives were designed, synthesized and evaluated for hypoxic and normoxic cytotoxic activity against human SMMC-7721, K562, KB, A549 and PC-3 cell lines. Many of these new compounds displayed more potent hypoxic cytotoxic activity compared with TX-402 and TPZ in the tumor cells based evaluation, which confirmed our hypothesis that the replacement of the 3-amine with the substituted aryl ring of TX-402 increases the hypoxic anti-tumor activity. The preliminary SAR revealed that 3-chloro was a favorable substituent in the phenyl ring for hypoxic cytotoxicity and 7-methyl or 7-methoxy substituted derivatives exhibited better hypoxic selectivity against most of the tested cell lines. The most potent compound, 7-methyl-3-(3-chlorophenyl)-quinoxaline-2-carbonitrile 1,4-dioxide (9h) was selected for further anti-tumor evaluation and mechanistic study. It also exhibited significant cytotoxic activity against BEL-7402, HepG2, HL-60, NCI-H460, HCT-116 and CHP126 cell lines in hypoxia with IC50 values ranging from 0.31 to 3.16 µM, and preliminary mechanism study revealed that 9h induced apoptosis in a caspase-dependent pathway.

[Metabolism-based interaction of diphenytriazol and flavone compounds].

OBJECTIVE: To observe the metabolism-based interaction of diphenytriazol and flavone compounds. METHODS: Flavone compounds kaempferol, isoharmnten and Elsholtzia blanda benth extract were chosen as the substrate of glucuronidation in the phase II metabolism. The metabolism was investigated in different rat liver microsome incubates pretreated with beta-naphthoflavone (BNF), diphenytriazol and tea oil (control). The concentrations of residual substrate were determined by HPLC. Quercetin and kaempferol were coincubated with diphenytriazol in control microsome to evaluate the inhibition for phase I metabolism. The concentration of diphenytriazol was determined by HPLC. RESULT: The phase II metabolic activity of kaempferol, isoharmnten and Elsholtzia blanda benth extract in diphenytriazol-treated microsome was more potent than that in BNF-treated microsome (P<0.01). The phase I metabolism of diphenytriazol was markedly inhibited by quercetin and kaempferol, with the inhibition constants (Ki) (12.41 +/-0.26)microg . ml(-1) and (7.97 +/-0.08)microg . ml(-1), respectively. CONCLUSION: Diphenytriazol demonstrates metabolism-based interaction with flavone compounds in vitro.

[In vitro metabolic interaction between diphenytriazol and steroid hormone drugs].

AIM: To observe the metabolic interaction between diphenytriazol and steroid hormone drugs, and provide some useful information for clinical medication. METHODS: The steroid hormone drugs which may be co-administrated with diphenytriazol were selected, such as mifepriston, estradiol, medroxyprogesterone acetate, progesterone, norethisterone and so on. Diphenytriazol was incubated with each drug in rat liver microsome. The residual concentration of diphenytriazol or steroid hormone drugs in the microsomal incubates was determined by reversed-phase high-performance liquid chromatography, separately. The inhibition constants (K(i)) for each of them were calculated. RESULTS: The inhibition constant K(is) of diphenytriazol for the metabolism of mifepristone, estradiol, medroxyprogesterone acetate, progesterone and norethisterone were (201.3 +/- 1.0), (94 +/- 4), (128.7 +/- 2.2), (64 +/- 5) and (80 +/- 4) micromol x L(-1), respectively. The inhibition constants K(i) of steroid hormone drugs for the metabolism of diphenytriazol was (66.9 +/- 2.2) micromol x L(-1) for estradiol, (60.0 +/- 2.3) micromol x L(-1) for medroxyprogesterone acetate, (163 +/- 10) micromol x L(-1) for progesterone and (88 +/- 5) micromol x L(-1) for norethisterone, respectively. CONCLUSION: Diphenytriazol shows metabolism interaction with steroid hormone drugs such as estradiol, medroxyprogesterone acetate, progesterone and norethisterone.

Induction of diphenytriazol on cytochrome CYP1A.

AIM: To study the effects of diphenytriazol on cytochrome P-450 (CYP) enzymes. METHODS: SD rats were pretreated with diphenytriazol. The catalytic activities of rat liver microsomes were determined by assaying ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-dealkylase. Phenacetin and aminopyrine were selected as the substrate of CYP1A and CYP2B, respectively. The concentration of remaining substrate in microsomal incubates was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). The inhibition of fluvoxamine or alpha-naphthoflavone on phenacetin metabolism was measured. RESULTS: Phenacetin was significantly metabolized in the diphenytriazol-treated microsomes and the metabolic degree increased according to the diphenytriazol-treatment days. There existed a significant correlation between the metabolic degree of phenacetin and EROD in the microsomes pretreated with diphenytriazol. Both fluvoxamine and alpha-naphthoflavone inhibited the metabolism of phenacetin significantly, and the inhibition constants (K(i)) were (5.4+/-1.0) micromol/L and (10.4+/-0.5) micromol/L, respectively. The activity of microsomes pretreated with diphenytriazol for 4 d was similar to that in b-naphthoflavone group, but was significantly different from those in control group and phenobarbital group. CONCLUSION: These results reveal that diphenytriazol is a novel inducer of CYP1A.

In vitro metabolism and inductive or inhibitive effect of DL111 on rat cytochrome P4501A enzyme.

In vitro metabolism and the inductive or inhibitive effect of DL111, a non-hormonal early pregnancy-terminating agent, toward cytochrome P450 (CYP) enzymes in rat liver microsomes were studied. In vitro metabolism of DL111 was performed in different rat liver microsomes (pretreated with phenobarbital (PB), dexamethasone (Dex), beta-naphthoflavone (BNF), DL111, respectively) and the catalytic abilities of these microsomes for DL111 were compared with control group. DL111 was well metabolized in microsomes pretreated with beta-naphthoflavone and itself. The K(m) and V(max) was 41.76 +/- 3.26 microM and 15.34 +/- 1.03 nM min(-1) mg(-1) protein for beta-naphthoflavone group, 48.17 +/- 6.06 microM and 17.54 +/- 1.79 nM min(-1)mg(-1) protein for DL111 group, 77.81 +/- 4.73 microM and 3.087 +/- 0.202 nM min(-1)mg(-1) protein for control group, respectively. The rats were pretreated intraperitoneally with the same daily dose of DL111 for different days. The DL111-pretreated microsomal enzymatic activities were evaluated by measuring the metabolic abilities for specific substrates of various enzymes. The results showed that DL111 had the same inductive function as beta-naphthoflavone (the specific inducer of CYP1A) toward rat liver microsomes. The inhibitive effect of DL111 on CYP1A was investigated by coincubating DL111 with the specific substrates of CYP1A-ethoxyresorufin or phenacetin in the microsome induced by beta-naphthoflavone, and the inhibitive level was compared with fluvoxamine (Flu), the specific inhibitor of CYP1A. DL111 inhibited significantly the metabolism of phenacetin and ethoxyresorufin with the inhibition constant (K(i)) 6.836 +/- 0.10 and 1.222 +/- 0.230 microM, respectively and its inhibition potential on CYP1A was higher than fluvoxamine.

[HPLC determination of zolmitriptan and its related substances].

OBJECTIVE: To develop an analytical method and quality control for determination of zolmitriptan and related substances. METHODS: Zolmitriptan and related substances were separated and determined on a shimadzu CLC-C(8) column (150 mm x 6 mm, 10 microm) with a mobile phase of acetonitrile-10 mmol/L phosphate buffer (25:75 pH 7.5) and a flow-rate of 1 ml/min; the UV-VIS detector was operated at 229 nm. RESULT: The limit of detection for the related substances was 0.5 ng on the zolmitriptan basis (S/N >3). Linear calibration curve was gene rated from 4 - 40 microg/ml with a correlation coefficient of 0.9999. The recovery rate of zolmitriptan was 99.1% with a standard deviation of 0.2%. The results of HPLC method were consistent with those of nonaqueous titration method. CONCLUSION: HPLC method is a rapid sensitive and accurate method for the determination of zolmitriptan and its related substances.

[RP-HPLC determination of diphenytriazol in rat liver microsomal incubates and its application in in vitro metabolism].

AIM: To establish a RP-HPLC method for determination of diphenytriazol (DL111-IT) in rat hepatic microsomes. METHODS: DL111-IT in rat hepatic microsomal incubates was extracted with chloroform, using diazepam as internal standard. The determination was performed on a Lichrospher ODS-C18 reversed column (25 cm x 0.46 cm ID) with mobile phase of methanol-pH 7.5 phosphate buffer (70:30) at a flow-rate of 1.0 mL.min-1. A UVVIS detector was operated at 235 nm. RESULTS: The assaywas linear from 1.01-101.0 micrograms.mL-1 for DL111-IT. The limit of detection was 0.15 microgram.mL-1 (signal-to-noise ratio 3) and the limit of quantification was 1.01 micrograms.mL-1(RSD < 10%, n = 4). The method afforded average recoveries of (100.3 +/- 1.9)% (n = 5), and intra-day and inter-day RSD were less than 5.0%(n = 5). The method allowed study of the in vitro phase I metabolism of DL111-IT in rat liver microsomal incubates. The microsomes induced by beta-naphthoflavone showed high enzymatic activity for DL111-IT phase I metabolism. CONCLUSION: The method is simple, accurate and can be used to study the metabolism of DL111-IT in rat hepatic microsomes.