Pharmacokinetics, Tissue Distribution, and Druggability Prediction of the Natural Anticancer Active Compound Cytisine N-Isoflavones Combined with Computer Simulation.

Cytisine N-methylene-(5,7-dihydroxy-4'-methoxy)-isoflavone (CNF2) is a new compound isolated from the Chinese herbal medicine Sophora alopecuroides. Preliminary pharmacodynamic studies demonstrated its activity in inhibiting breast cancer cell metastasis. This study examined the pharmacokinetics, absolute bioavailability, and tissue distribution of CNF2 in rats, and combined computer-aided technology to predict the druggability of CNF2. The binding site of CNF2 and the breast cancer target human epidermal growth factor receptor-2 (HER2) were examined with molecular docking technology. Next, ACD/Percepta software was used to predict the druggability of CNF2 based on the quantitative structure-activity relationship (QSAR). Finally, a simple and effective HPLC method was used to determine plasma pharmacokinetics and tissue distribution of CNF2 in rats. Prediction and experimental results show that compared with the positive control HER2 inhibitor SYR127063, CNF2 has a stronger binding affinity with HER2, suggesting that its efficacy is stronger; and the structure of CNF2 complies with the Lipinski's Rule of Five and has good drug-likeness. The residence time of CNF2 in rats is less than 4 h, and the metabolic rate is relatively fast; But the absolute bioavailability of CNF2 in rats was 6.6%, mainly distributed in the stomach, intestine, and lung tissues, where the CNF2 contents were 401.20, 144.01, and 245.82 µg/g, respectively. This study constructed rapid screening and preliminary evaluation of active compounds, which provided important references for the development and further research of such compounds.

A Validated Ultra-Performance Liquid Chromatographic Method for the Simultaneous Determination of Nadifloxacin, Mometasone Furoate and Miconazole Nitrate in Their Combined Dosage Form and Spiked Human Plasma Samples.

Nadifloxacin, mometasone furoate and miconazole nitrate are formulated together as a topical antifungal dosage form. In this work, a reversed-phase ultra-performance liquid chromatographic method coupled with a diode array detector (RP-UPLC-DAD) was developed and validated to determine nadifloxacin, mometasone furoate and miconazole nitrate simultaneously in their bulk powder, in pharmaceutical preparation and in spiked human plasma samples. Separation was achieved on an ACQUITY UPLC C18 column of 2.2 µm particle size (2.1 × 100 mm) via isocratic elution using a mobile phase consisting of methanol, acetonitrile and water with ratio (50:20:30; v/v/v) and 0.1 g ammonium acetate, then pH was adjusted to (7.00) using acetic acid, flow rate 0.6 mL/min, temperature 30°C and UV detection at 220 nm. The method is linear in a range from 5 to 400 µg/mL for both nadifloxacin and miconazole nitrate and from 20 to 500 µg/mL for mometasone furoate. The method was validated according to the ICH guidelines then applied successfully to determine the mentioned drugs in their pharmaceutical preparation and spiked human plasma samples. For plasma samples, the results showed that the method can determine nadifloxacin, mometasone furoate and miconazole nitrate in human plasma samples with high accuracy and precision.

Ascending single dose pharmacokinetics of cytisine in healthy adult smokers.

1. Cytisine, a partial agonist for the α4ß2-nAChR, is used as a smoking cessation medication. Cytisine's current dosing is complex and involves taking 1.5 mg several times a day. The aim of this study was to explore the effect of dose on the pharmacokinetics and safety of cytisine after a single dose in healthy adult smokers. 2. Participants were assigned to one of three groups (n = 6 in each group) to receive a single oral dose of 1.5, 3 or 4.5 mg of cytisine. Blood samples were collected up to 24 h post dose. Pulse, blood pressure and respiratory rate were measured. Adverse effects were recorded. 3. Cytisine reached peak plasma concentration 1-2 h post dose in all participants irrespective of dose, with no dose-dependent changes in the elimination phase. Mean (SD) cytisine exposure (AUC0-24h) were 81.9 (15.8), 181.9 (40.8) and 254.5 (48.1) ng.h/mL following 1.5, 3 and 4.5 mg, respectively. 4. Cytisine appears to have predictable pharmacokinetics following a single dose of up to 4.5 mg and may be safe given as a single 4.5 mg dose, which is threefold greater than the recommended dose taken at one time. This study is registered in ClinicalTrials.gov (ID:NCT02585024).

Preliminary pharmacokinetics of intravenous and subcutaneous dolasetron and pharmacodynamics of subcutaneous dolasetron in healthy cats.

Objectives The objectives were to evaluate the pharmacokinetics (PK) of subcutaneous (SC) and intravenous (IV) dolasetron and the pharmacodynamics (PD) of SC dolasetron in healthy cats. Methods Five cats with unremarkable complete blood count, serum biochemistry and urinalyses were utilized. In the PK study, cats received 0.8 mg/kg SC and IV dolasetron in a crossover format. Serum samples were obtained via a jugular catheter at 0, 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36 and 48 h after the administration of dolasetron. Dolasetron and the active metabolite hydrodolasetron were measured using liquid chromatography/tandem mass spectrometry. Non-compartmental PK analysis was performed. In the PD study, SC dolasetron (0.8 mg/kg and 1.0 mg/kg) and saline were administered 30 mins prior to administration of 0.44 mg/kg intramuscular xylazine in a randomized three-way crossover. Number of emetic events, lip licks, time to onset of emesis and visual nausea score were scored by a blinded observer. Results In the PK study, dolasetron was quickly metabolized to the active metabolite hydrodolasetron, limiting assessment of dolasetron PK parameters. Median (range) PK parameters for IV hydrodolasetron were as follows: maximum serum concentration (Cmax) 116 ng/ml (69-316 ng/ml), time to maximum concentration (Tmax) 0.5 h (0.3-0.5 h), half-life 3.3 h (2.9-7.2 h) and area under the curve until the last measurable concentration (AUClast) 323 h/ng/ml (138-454 h/ng/ml). Median (range) PK parameters for SC hydrodolasetron were as follows: Cmax 67.9 ng/ml (60.4-117 ng/ml), Tmax 0.5 h (0.5-1.0 h), half-life 3.8 h (2.9-5.3 h) and AUClast 437 h/ng/ml (221.5-621.8 h/ng/ml). There was no significant difference in exposure to hydrodolasetron between the routes of administration. With regard to PD, when dolasetron was administered prior to xylazine, there was no significant difference in the mean number of emetic events, lip licks, time to onset of emesis or visual nausea score when compared with saline. Conclusions and relevance Administration of 0.8 mg/kg dolasetron does not maintain serum concentrations of active metabolite for 24 h. Administration of dolasetron at 0.8 mg/kg and 1 mg/kg did not prevent xylazine-induced vomiting. Additional feline dose studies are needed to determine if a higher dose is efficacious.

Determination of N-methylcytisine in rat plasma by UPLC-MS/MS and its application to pharmacokinetic study.

In this work, a sensitive and selective UPLC-MS/MS method for determination of N-methylcytisine in rat plasma is developed. After addition of hordenine as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH HILIC (2.1 mm×100mm, 1.7µm) with acetonitrile (containing 10mM ammonium formate) and water (containing 0.1% formic acid and 10mM ammonium formate) as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring (MRM) mode was used for quantification using target fragment ions m/z 205.1→58.0 for N-methylcytisine, and m/z 166.1→121.0 for IS. Calibration plots were linear throughout the range 2-2000ng/mL for N-methylcytisine in rat plasma. Mean recoveries of N-methylcytisine in rat plasma ranged from 86.1% to 94.8%. RSD of intra-day and inter-day precision were both<13%. The accuracy of the method was between 94.5% and 109.4%. The method was successfully applied to pharmacokinetic study of N-methylcytisine after either oral or intravenous administration. For the first time, the absolute bioavailability of N-methylcytisine was reported as high as 55.5%.

Pharmacokinetics of cytisine, an α4 ß2 nicotinic receptor partial agonist, in healthy smokers following a single dose.

Cytisine, an α4 ß2 nicotinic receptor partial agonist, is a plant alkaloid that is commercially extracted for use as a smoking cessation medication. Despite its long history of use, there is very little understanding of the pharmacokinetics of cytisine. To date, no previous studies have reported cytisine concentrations in humans following its use as a smoking cessation agent. A high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed and validated for analysis of Tabex® and nicotine-free oral strips, two commercial products containing cytisine. A sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the quantification of cytisine in human plasma and for the detection of cytisine in urine. Single-dose pharmacokinetics of cytisine was studied in healthy smokers. Subjects received a single 3 mg oral dose administration of cytisine. Cytisine was detected in all plasma samples collected after administration, including 15 min post-dose and at 24 h. Cytisine was renally excreted and detected as an unchanged drug. No metabolites were detected in plasma or urine collected in the study. No adverse reactions were reported.

Chemopreventive effect of a mixture of Chinese Herbs (antitumor B) on chemically induced oral carcinogenesis.

In this study, we evaluated chemopreventive efficacy of Antitumor B, a Chinese herbal mixture of six plants (Sophora tonkinensis, Polygonum bistorta, Prunella vulgaris, Sonchus arvensis L., Dictamnus dasycarpus, and Dioscorea bulbifera) on the development of 4-nitroquinoline-1-oxide (4NQO) induced oral squamous cell carcinomas in A/J mice. Antitumor B, delivered through diet, inhibited 4NQO-induced oral cancer development by 59.19%. The reduction of cell proliferation appears to be associated with efficacy of Antitumor B against 4NQO-induced oral cancer in A/J mice. The expression of epidermal growth factor receptor (EGFR) and phosphorylated EGFR (Tyr1173) were down-regulated by Antitumor B. Tissue distribution of Antitumor B was determined using obacunone, matrine, and maackiain as marker chemicals. We found significant amounts of obacunone, matrine, and maackiain in the blood after 1-wk treatment. The concentrations of these three compounds did not increase further at 18 wk, suggesting that plasma concentrations had reached a steady-state level at 1 wk. There was no significant body weight loss and there was no other obvious sign of toxicity in Antitumor B-treated mice. These results suggest that Antitumor B is a promising agent for human oral cancer chemoprevention.

Biopharmaceutical and pharmacokinetic characterization of matrine as determined by a sensitive and robust UPLC-MS/MS method.

The purpose of this research was to develop a sensitive and reproducible UPLC-MS/MS method to analyze matrine, an anticancer compound, and to use it to investigate its biopharmaceutical and pharmacokinetic behaviors in rats. A sensitive and fast UPLC-MS/MS method was successfully applied to determine matrine in rat plasma, intestinal perfusate, bile, microsomes, and cell incubation media. The absolute oral bioavailability of matrine is 17.1+/-5.4% at a dose of 2mg/kg matrine. Matrine at 10microM was shown to have good permeability (42.5x10(-6)cm/s) across the Caco-2 cell monolayer, and the ratio of P(A-B) to P(B-A) was approximately equal to 1 at two different concentrations (1 and 10microM). Perfusion study showed that matrine displayed significant differences (P<0.05) in permeability at different intestinal regions. The rank order of permeability was ileum (highest, P(w)=6.18), followed by colon (P(w)=2.07), duodenum (P(w)=0.61) and jejunum (P(w)=0.52). Rat liver microsome studies showed that CYP and UGTs were not involved in matrine metabolism. In conclusion, a sensitive and reliable method capable of measuring matrine in a variety of matrixes was developed and successfully used to determine absolute oral bioavailability of matrine in rats, transport across Caco-2 cell monolayers, absorption in rat intestine, and metabolism in rat liver microsomes.

Determination of oxymatrine and its metabolite matrine in rat blood and dermal microdialysates by high throughput liquid chromatography/tandem mass spectrometry.

Oxymatrine (OMT) and matrine (MT) are the major quinolizidine alkaloids found in certain Sophora plants, which have been extensively used in China for the treatment of viral hepatitis, cancer, cardiac diseases and skin diseases (such as atopic dermatitis and eczema). A precise, sensitive and high throughput LC-MS/MS was developed to determine OMT and its metabolite MT in rat blood and dermis collected using microdialysis technique. Microdialysis probes were inserted into the jugular vein/right atrium and dermis of Wistar rats, and 3% OMT gel (1g) was administered via topical application. The samples were collected and then injected into the LC-MS/MS system after adding the internal standard (codeine, CDN). Chromatographic separation was achieved in a run time of 2min on a reversed phase short-column (50mmx2.1mm, 3.5microm). The mobile phase for column separation was methanol-ammonium formate (pH 5.0; 25mM) (70:30, v/v) with a flow rate of 0.3mL/min. A diverter valve was installed post-LC column for desalting. Detection of analytes and IS was done by tandem mass spectrometry, operating in positive ion and multiple reaction monitoring (MRM) acquisition mode. The protonated precursor to product ion transitions monitored for OMT, MT and IS was m/z 265.0-->247.3, 249.1-->148.3 and 300.0-->215.2, respectively. The lower limit of quantification (LLOQ) for OMT and MT was 0.5ng/mL. The calibration curves were linear over the range of 0.5-1000ng/mL for OMT and MT with a coefficient of determination >0.999. This selective and sensitive method is useful for the determination of OMT and MT and in the pharmacokinetic studies of these compounds. The blood and dermal concentration-time profile of OMT and its metabolite MT suggest that the limiting factor for dermal metabolism is the low capacity of enzymes in the skin rather than the quantity of penetrated OMT.

Pharmacokinetics of intravenous dolasetron in cancer patients receiving high-dose cisplatin-containing chemotherapy.

Dolasetron mesylate (MDL 73,147, Anzemet, Hoechst Marion Roussel, Kansas City, MO) is a 5-HT ( 3 ) receptor antagonist undergoing clinical evaluation as an antiemetic agent. Dolasetron is rapidly metabolized to form hydrodolasetron (MDL 74,156). The pharmacokinetics of hydrodolasetron were studied after administration of a single intravenous infusion of 0.6 mg/kg (group I) or 1.8 mg/kg (group II) in 21 cancer patients participating in a randomized, double-blind, parallel-group, multicenter trial of the drug in patients receiving their first course of high-dose (>/=75 mg/m ( 2 ) ) cisplatin-containing chemotherapy. The intent of this study was to obtain preliminary data on the pharmacokinetics of the active metabolite, hydrodolasetron, in cancer patients. The reduced metabolite, hydrodolasetron, was formed rapidly with peak plasma concentrations (group I, mean = 128.6 ng/mL; group II, mean = 505.3 ng/mL) occurring at or shortly after the end of the infusion. Plasma concentrations of hydrodolasetron remained quantifiable for up to 24 hours. Increases in peak plasma concentrations and AUC of hydrodolasetron were proportional to dose, suggesting linear pharmacokinetics over this dose range. Apparent clearance, apparent volume of distribution, elimination rate, and terminal elimination half-life of the reduced metabolite were similar at both doses. The results support a pharmacokinetic basis for the prolonged duration of antiemetic efficacy after a single intravenous dose.

Human dolasetron pharmacokinetics: II. Absorption and disposition following single-dose oral administration to normal male subjects.

Dolasetron is a 5-hydroxytryptamine antagonist active at type III receptors; it is presently undergoing clinical evaluation for the reduction/prevention of cancer chemotherapy-induced nausea and vomiting. A previous study demonstrated that following intravenous administration to healthy male subjects, dolasetron disappeared extremely rapidly from plasma, and less than 1 per cent of the dose appeared in the urine. A major plasma metabolite, reduced dolasetron, peaked rapidly in the plasma. In this study, dolasetron was administered orally to healthy male subjects at doses ranging from 50 to 400 mg (mesylate monohydrate). Plasma concentrations of dolasetron were low and sporadic, and there was little excreted in urine; this prevented dolasetron pharmacokinetic analysis. Reduced metabolite concentrations peaked rapidly, with a median value of 1.00 h. The median terminal disposition half-life was 7.80 h. Median values for fraction of dose excreted in urine and renal clearance were 22.2 per cent and 2.56 ml min-1 kg-1. Whereas areas under the plasma concentration-time curves were proportional to dose, renal clearance increased with dose (p < 0.05). However, given dose proportionality to AUC, this is probably of little therapeutic consequence. Since reduced dolasetron has significant anti-emetic activity in the ferret model, it appears that this metabolite may play a significant role in pharmacodynamic activity.

Development of a sensitive enzyme immunoassay for OPC-7251, a novel antimicrobial agent for percutaneous application.

A sensitive enzyme immunoassay for OPC-7251, a novel pyridone carboxylic acid antimicrobial agent, was developed and applied for the determination of human plasma levels. OPC-7251 was coupled to bovine serum albumin through a formation of N-hydroxysuccinimide ester. By immunization of rabbits, highly specific antiserum was raised. Using the antiserum and beta-D-galactosidase-labeled hapten, the homologous assay system allowed the detection of 2 pg of this compound. Plasma samples were precisely analyzed down to the minimum value of 200 pg/ml after heat treatment. The system was further validated by the recovery test and correlation with the HPLC analyses. Percutaneous application of 10 g of 1% OPC-7251 cream to healthy volunteers resulted in the peak plasma value of 1.6 ng/ml about 8 hours after dosing, indicating extremely low absorption efficiency through a transdermal system.

[Tissue diffusion of flumequine into human renal and prostatic tissues. Assay of flumequine by high performance liquid chromatography after administration of 800 mg/day over 48 hours, the sampling being done 12 hours after the last ingestion]. / Etude de la diffusion tissulaire de la fluméquine chez l'homme dans les tissus rénaux et prostatiques. Dosage de la fluméquine par chromatographie liquide haute performance aprés administration de 800 mg/jour pendant 48 heures, le prélèvement étant fait 12 heures aprés la derniére prise.

Diffusion of flumequine into human renal and prostatic tissues was studied. Chemical characteristics and the natural antibacterial spectrum of the compound are described and its rapidity of absorbtion emphasized, blood levels being detected 30 minutes after administration. Maximum plasma levels were reached after 2 to 3 hours and were of the order of 17 mcg/ml, half-life being approximately 10 hours. Plasma protein binding capacity was 60 to 70%, indicating liposolubility enabling diffusion into prostatic parenchyma. Flumequine was recovered in the urine 2 hours after oral administration, maximum urinary concentrations being reached after between 3 and 6 hours, and being of the order of 280 mg/ml after single-dose 40 mg administration. The product was still recovered from the urine 12 hours later, and 60 to 70% of the dose administered after 24 hours, including 20.6% of active form. To evaluate renal and prostatic tissue diffusion 2 series of patients were studied 10 after renal surgery and 14 prostatic operations. Diffusion was excellent into renal parenchyma since the mean ratio between renal tissue and plasma concentrations was 2.41. Urine concentrations were even more extraordinary since the ratio was 136. In contrast, prostatic tissue concentrations were lower than plasma concentrations, the ratio between the two being 0.26, although levels is prostatic tissue were still sufficiently elevated to be effective against germs sensitive to flumequine.