Redispersible dry emulsion system as novel oral dosage form of oily drugs: in vivo studies in beagle dogs.

The absorption characteristics of vitamin E acetate (VEA) formulated into a dry emulsion system after its oral administration to beagle dogs were determined and compared to those of two different dosage forms (an oily mixture of the drug with cottonseed oil and an oil (drug)-in-water emulsion). The three dosage forms were administered in a crossover fashion to six nonfasting subjects, and the drug absorption was assessed from the plasma concentration of the major metabolite (free vitamin E). VEA formulated in the dry emulsion was rapidly absorbed, which suggested that a considerable amount was released as reformed emulsion droplets in the gastrointestinal tract as well as in water in vitro. Based on the analysis of variance, no significant differences in bioavailability parameters (AUC, Cmax or Tmax) were observed among the three dosage forms.     

Development of a differential pulse voltammetric method for the determination of Silymarin/Vitamin E acetate mixture in pharmaceuticals

Differential pulse voltammetric method was developed for determination of Silymarin (SMR)/Vitamin E acetate (VEA) mixture in pharmaceuticals. SMR and VE gave well-resolved diffusion-controlled anodic peaks at +756 and +444mV, respectively (versus Ag/AgCl) in Britton-Robinson buffer at pH 2.8. The solution conditions and instrumental parameters were optimized for their quantitative determination. The linear response was obtained in the range 0.1-4.0mgL(-1) with a detection limit of 0.03mgL(-1) for SMR and 0.05-4.0mgL(-1) with a detection limit of 0.01mgL(-1)for VEA.     

Preparation and evaluation of eudragit gels. V. Rectal gel preparations for sustained release and avoidance of first-pass metabolism of lidocaine.

The release of lidocaine from hydrogel and xerogel preparations was remarkably suppressed compared with polyethylene glycol (PEG) 2000 suppository. The release rate of lidocaine from hydrogel and xerogel increased with the increase in the amount of sodium hydroxide incorporated within the range of 3 to 7 milliequivalent (meq). After an oral administration of lidocaine HCl solution, the plasma concentration of lidocaine was considerably lower than that after intravenous administration for all time periods. The absolute bioavailability (F(oral)) was 5.63%. For the Witepsol S-55 and PEG 2000 suppositories, the plasma levels of lidocaine were higher than those for the oral preparation, and Cmax and area under the concentration-time curve (AUC) values significantly improved (p < 0.01). The absolute bioavailabilities were 21.3 and 29.6%, respectively. On the other hand, Eudispert hv-hydrogel and xerogel preparations showed the characteristics of a sustained-release preparation, especially the xerogel preparation with 5 meq NaOH. Absolute bioavailability for hydrogel and xerogel preparations increased significantly (p < 0.05) by approximately 1.7-3.4 folds compared with those of Witepsol S-55 and PEG 2000 suppositories.     

Isolation of 6-mercaptopurine in human plasma by aluminum ion complexation for high-performance liquid chromatographic analysis

A sample preparation technique and a high-performance liquid chromatographic method for 6-mercaptopurine (6-MP) that is simple, sensitive and without interference from its metabolites is described. 6-Thioguanine (6-TG) is added as an internal standard to the plasma sample, which is then treated with an aqueous solution of aluminum perchlorate to denature the plasma proteins and form complexes with 6-TG, 6-MP and its major metabolite, 6-thiouric acid (6-TUA). These complexes coprecipitate with proteins on centrifugation. 6-MP and its analogues are then extracted from the precipitate with perchloric acid containing sodium hydrosulfite and the extract is chromatographed on an Ultrasphere ODS column eluted with 0.1 M phosphoric acid and 0.001 M dithiothreitol in deionized water. The eluate is monitored at 340 nm. No interfering peak was encountered in over 300 clinical plasma samples. 6-TUA was separated from 6-MP and was found to be present in much higher concentration than 6-MP itself throughout the sampling time (6 h) following oral administration of the drug.     

Isolation of 6-mercaptopurine in human plasma by aluminum ion complexation for high-performance liquid chromatographic analysis

A sample preparation technique and a high-performance liquid chromatographic method for 6-mercaptopurine (6-MP) that is simple, sensitive and without interference from its metabolites is described. 6-Thioguanine (6-TG) is added as an internal standard to the plasma sample, which is then treated with an aqueous solution of aluminum perchlorate to denature the plasma proteins and form complexes with 6-TG, 6-MP and its major metabolite, 6-thiouric acid (6-TUA). These complexes coprecipitate with proteins on centrifugation. 6-MP and its analogues are then extracted from the precipitate with perchloric acid containing sodium hydrosulfite and the extract is chromatographed on an Ultrasphere ODS column eluted with 0.1 M phosphoric acid and 0.001 M dithiothreitol in deionized water. The eluate is monitored at 340 nm. No interfering peak was encountered in over 300 clinical plasma samples. 6-TUA was separated from 6-MP and was found to be present in much higher concentration than 6-MP itself throughout the sampling time (6 h) following oral administration of the drug.     

HPLC determination and pharmacokinetic studies of salvianolic acid B in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract

A precise and reproducible HPLC method has been established and validated for determination of salvianolic acid B (SalB) in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract. Liquid-liquid extraction was adopted for the sample preparation. Separation was accomplished on a C(18) column with a linear gradient elution consisting of acetonitrile and aqueous phosphoric acid. Ultraviolet detection was at 280 nm. The method was validated over the concentration range 10.8-259.4 microg/mL using 1 mL of plasma. The assay was linear over this concentration range with a coefficient of variation less than 7%. The extraction recovery of SalB was within the range 71-83% with RSD 11%. The mean recovery of the internal standard was 84% (n = 6) with RSD of 5.6%. This method is suitable to determine SalB in plasma and to investigate the pharmacokinetics of SalB.     

Development and validation of a UHPLC‐qTOF‐MS method for quantification of fuziline in rat plasma and its application in a pharmacokinetic study

A specific and sensitive UHPLC‐qTOF‐MS method was developed and validated for quantification of fuziline in rat plasma after oral administration of three dosages. The analyte was separated on an Acquity UPLC BEH C₁₈ column with a total running time of 3 min using a mobile phase of 0.1% formic acid aqueous solution and methanol (80:20, v/v) at a flow‐rate of 0.25 mL/min. The calibration curves for fuziline showed good linearity in the concentrations ranging from 1 to 200 ng/mL with correlation coefficients >0.997. The precision, accuracy, recovery and stability were deemed acceptable. The method was applied to a pharmacokinetics study of fuziline in rats. The mean half‐life was 5.93, 6.13 and 5.12 h for 1, 2 and 4 mg/kg oral administration of fuziline, respectively. The peak concentration and area under the concentration–time curve increased linearly with the doses. The sum of these results indicated that, in the range of the doses examined, the pharmacokinetics of fuziline in rat was based on first‐order kinetics. Copyright © 2014 John Wiley & Sons, Ltd.     

Design of polyvinyl alcohol hydrogel as a controlled-release vehicle for rectal administration of dl-propranolol-HCl and atenolol

Preparations of beta-blockers, propranolol-HCl and atenolol, in poly(vinyl alcohol) (PVA) hydrogel were designed for the therapeutic treatment of hypertension by transrectal delivery. In vitro release characteristics and plasma drug concentration profiles after rectal administration in rats and dogs were examined. The PVA hydrogels containing beta-blockers were prepared by a low-temperature crystallization method. The release of beta-blockers from hydrogel preparations was consistent with Fickian diffusion (Higuchi model); the drug release versus the square root of release time profile gave a straight line over 60% of the total release process. The release of beta-blockers from hydrogel preparations increased at higher concentrations of PVA in the hydrogel preparations and was not affected by the pH of hydrogel preparations. Plasma concentrations of beta-blockers after rectal administration of hydrogels were higher than those after administration of suppositories (Witepsol H-15) in rats and dogs. The drug plasma concentrations increased at higher concentrations of PVA in hydrogel preparations. In the case of propranolol, which is a hepatic high-clearance drug, area under the blood concentration curve, 0-8 h after rectal administration of a hydrogel preparation (20% w/w PVA, pH 7.0) was 2.16 times and 5.26 times higher than those obtained with Witepsol H-15 suppository and oral administration, respectively. Rectal administration with PVA hydrogels is a favorable route for a hepatic high-clearance drug such as propranolol.     

Mixtures of mucin and oppositely charged surfactant aggregates with varying charge density. Phase behavior, association, and dynamics

The nonionic surfactant Tween80 is a commonly used excipient in drug formulations containing an active substance with low aqueous solubility. Model drug vehicles with varying charge density were obtained by mixing Tween80 (PS-80) with the cationic surfactant Tetradecyltrimethylammonium chloride (TTAC), thus forming mixed micelles. The micelles were mixed with the negatively charged polyelectrolyte mucin, which is a component in the protective mucus layer covering epithelial cell linings. Depending on the composition of the mixture, complex-formation could be followed by precipitation. Using X-ray diffraction, it was found that the precipitate contained a lamellar phase with properties sensitive to the proportion of PS-80. Higher amounts of PS-80 were found to oppose phase separation. Further analysis in the one-phase region, or alternatively of the supernatant of two-phase samples, by (1)H NMR, HPLC, and diffusion measurements with PGSE-NMR led to the conclusions that at low proportion of PS-80 aggregates composed of mixed (PS-80 and TTAC) micelles and mucin were formed, whereas increased concentrations of PS-80 favored the dissolution of the precipitate and limited the interactions between mixed micelles and the polymer.     

Pharmacokinetics of aconitine in rat skin after oral and transdermal gel administrations

The purpose of this study was to evaluate percutaneous penetration and arrhythmogenic effects of aconitine after transdermal administration, compared with the oral route. Skin penetration of aconitine was tested by a microdialysis technique in rats and in vivo recovery was determined by retrodialysis. After oral and transdermal administration of aconitine, dialysate was sampled at 20 min intervals until the end of the experiment for the determination of concentration of aconitine in skin. Blood samples were collected and analyzed using a validated HPLC‐MS/MS method. In addition, we concurrently recorded the electrocardiogram (ECG). The in vivo recovery of aconitine in the skin was calculated to be 39.59%. The C_max values for aconitine absorbed into the skin after oral and transdermal administration were 1.51 ± 0.53 and 2723.8 ± 848.8 ng/mL, respectively, and within the plasma, 215.86 ± 79.29 and 20.92 ± 3.15 ng/mL. The C_max value for the plasma concentration of aconitine after oral administration was approximately 10 times higher than with the transdermal route. For oral administration, the ECG revealed various types of arrhythmias at a period of T_max, which is normal in transdermal gel administration. These results indicate that transdermal aconitine gel is a safe formulation that can deliver the drug in sufficient amounts and safe concentrations to produce therapeutic action in rats. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of trace vitamin C by ion-pair HPLC with UV detection in calcium gluconate and vitamin C compound oral solution

A sensitive and specific reversed-phase high-performance liquid chromatographic method with ultraviolet detection was developed for the determination of vitamin C, using tetrabutylammonium hydroxide as an ion-pair reagent in a compound oral solution containing 100 mg/mL calcium gluconate and 1.25 mg/mL vitamin C. The aqueous phase contained 0.005 mol/L tetrabutylammonium hydroxide and the mobile phase consisted of a mixture of the aqueous phase-methanol (80:20, v/v, pH 6.0 adjusted by phosphoric acid). The linearity, sensitivity and specificity, accuracy, and stability of the procedure were evaluated. The calibration curves for vitamin C were linear in the range of 10.0-100.0 μg/mL. The percentage coefficient of variation of the quantitative analysis of the vitamin C in the products analysis was within 5%. The method was successfully applied to determine the stability of vitamin C in the compound oral solution. It was found that the vitamin C peak was symmetrical and the column efficiency was high. The method is simple and suitable for stability testing of a low concentration of vitamin C preparation.     

超高效液相色谱-串联质谱法测定人血浆中盐酸氨溴索及其制剂的生物等效性评价

采用超高效液相色谱-串联质谱（UHPLC-MS/MS）技术,建立了快速、简单、灵敏的测定人血浆中盐酸氨溴索含量的方法,并用于盐酸氨溴索人体生物等效性预试验研究。取50 μL血浆样品,采用蛋白沉淀法处理,以盐酸氨溴索-d5为内标。采用Waters XBridge BEH C18色谱柱（50 mm×2.1 mm,2.5 μm）,以0.1%（v/v）甲酸水-含0.1%（v/v）甲酸的甲醇为流动相,在0.4 mL/min流速下进行梯度洗脱。采用电喷雾电离（ESI）源以正离子模式进行MRM检测。结果显示,盐酸氨溴索在2~400 ng/mL范围内线性关系良好,相关系数（r）为0.998,准确度为97.1%~108.7%,精密度为1.0%~5.6%。将该方法用于6名健康受试者口服盐酸氨溴索受试制剂和参比制剂30 mg后血药浓度的测定,结果显示二者相对生物利用度为（102.3±14.8）%,血药浓度-时间曲线下面积（AUC_0-t、AUC_0-∞）和最大血药浓度（C_max）的90%置信区间均在80.0%~125.0%范围内,两种制剂生物等效。     

Application of a sensitive and specific LC‐MS/MS method for determination of eriodictyol‐8‐C‐β‐d‐glucopyranoside in rat plasma for a bioavailability study

This study is the first to detail the development and validation of a rapid, sensitive and specific LC‐ESI‐MS/MS method for the determination of eriodictyol‐8‐C‐β‐d ‐glucopyranoside (EG) in rat plasma. A simple protein precipitation method was used for plasma sample preparation. Chromatographic separation was successfully achieved on an Agilent Zorbax XDB C₁₈ column (2.1 × 50 mm, 3.5 µm) using a step gradient program with the mobile phase of 0.1% formic acid aqueous solution and acetonitrile with 0.1% formic acid. EG and the internal standard (IS) were detected using an electrospray negative ionization mass spectrometry in the multiple reaction monitoring mode. This method demonstrated good linearity and did not show any endogenous interference with the active compound and IS peaks. The lower limit of quantification of EG was 0.20 ng/mL in 50 μL rat plasma. The average recoveries of EG and IS from rat plasma were both above 80%. The inter‐day precisions (relative standard deviation) of EG determined over 5 days were all within 15%. The present method was successfully applied to a quantification and bioavailability study of EG in rats after intravenous and oral administration. The oral absolute bioavailability of EG in rats was estimated to be 7.71 ± 1.52%. Copyright © 2014 John Wiley & Sons, Ltd.     

Study on colon-specific 5-Fu pH-enzyme Di-dependent chitosan microspheres

Colon-specific drug delivery systems (CDDS) can improve the bioavailability of drug through the oral route. A novel formulation for oral administration using pH-enzyme Di-dependent chitosan mcirospheres (MS) and 5-Fu as a model drug has been investigated for colon-specific drug delivery by the emulsification/chemical cross-linking and coating technique, respectively. The influence of polymer concentration, ratio of drug to polymer, the amount of crosslinking agent and the stirring speed on the encapsulation efficiency, particle size in microspheres were evaluated. The best formulation was optimized by an orthogonal design. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released in the physiological environment of the stomach and small intestine. The plasma concentrations of 5-Fu after oral administration of coated chitosan MS to rats were determined and compared with that of 5-Fu solution. The in vivo pharmacokinetics study of 5-Fu loaded pH-enzyme Di-dependent chitosan MS showed sustained plasma 5-Fu concentration-time profile. The in vitro release correlated well with the pharmacokinetics profile. The results clearly demonstrated that the pH-enzyme Di-dependent chitosan MS is potential system for colon-specific drug delivery of 5-Fu.     

Quantitation of glucosamine sulfate in plasma by HPLC-MS/MS after administration of powder for oral solution formulation

A rapid method for the quantification of glucosamine in human plasma using high‐performance liquid chromatography coupled to tandem mass spectrometry was developed and validated. The sample preparation includes a simple deproteinization step, using d ‐[1‐¹³C] glucosamine hydrochloride as an internal standard. Chromatographic separation was performed on an ACE Ciano column using isocratic elution with acetonitrile and aqueous 2 mm ammonium acetate containing 0.025% formic acid (80:20). Selected reaction monitoring was performed using the transitions m/z 180.1 → m/z 72.1 and m/z 181.0 → m/z 74.6 to quantify glucosamine and internal standard, respectively. The method was validated and proved to be linear, accurate and precise over the range 50–5000 ng/mL of glucosamine. Recovery rates higher than 90% were obtained for both glucosamine and internal standard. No matrix effect was detected in the samples. The validated method was successfully applied to a pharmacokinetic study after oral administration of a powder for oral solution formulation containing glucosamine sulfate. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of bupleurum nasal spray and evaluation on its safety and efficacy

Radix Bupleuri is widely used in traditional medicine for the treatment of fever, pain, and inflammation associated with influenza or the common cold. The essential oil extracted from the herb is generally claimed to play the major role in the efficacious treatment of fever. The purpose of the present study was to formulate an intranasal delivery system for the essential oil in an aqueous solution used in the form of nasal spray. From 450 g Radix Bupleuri was extracted the essential oil in the amount of about 0.2 ml, which was slightly water-soluble and viscous with low-fluidity. In order to dissolve the essential oil evenly in the aqueous solution, tween-80 (TW-80, used in 10% (w/v) solution), propylene glycol (PG) and diethylene glycol monoethyl ether (TC) were selected as the favorable solubilizing agents, whose amount was respectively determined by L16(4(5)) orthogonal design. An aqueous solution with clarity and no ciliotoxicity was prepared when TW-80 8% (v/v), PG 14.4% (v/v) and TC 14.4% (v/v) were added. Employed to evaluate the acute toxicity, the rats grew well and were kept active and healthy within 14 d after an intranasal administration of this preparation at the dose of oil from 10 g Bupleuri/kg (50-fold higher than the clinical dose), indicating that there would be no serious toxicity at the normal dose. Intranasal administration of this preparation to 2 kg rabbits with fever induced by subcutaneous injection of turpentine decreased body temperature markedly (0.5, 0.8 and 1.0 degrees C respectively at the dose of oil from 1, 2 and 4 g Bupleuri/body). In addition, the administration significantly reduced fever in 200 g rats induced by intramuscular injection of colicine suspension (0.6 degrees C at the dose of oil from 0.8 g Bupleuri/body). The results suggest that the formulation of nasal spray for the essential oil from Radix Bupleuri can be potentially effective in the treatment of fever.     

Determination of hydroxysafflor yellow A in rat plasma and tissues by high-performance liquid chromatography after oral administration of safflower extract or safflor yellow

A simple and reproducible HPLC method for quantification of hydroxysafflor yellow A (HSYA) in rat plasma and tissues after oral administration of safflower extract or safflor yellow (SY) was developed. Sample preparation was achieved by protein precipitation of plasma and tissue homogenates with three volumes of methanol. p-Hydroxybenzaldehyde was used as the internal standard (IS). HSYA and IS were separated on a Hypersil BDS-C(18) column with a gradient elution system composed of acetonitrile and aqueous acetic acid. UV detection was used at 320 nm. The calibration curves were linear in all matrices (r(2) > 0.999) in the concentration ranges 0.51-101.36 microg/mL for plasma, 12.27-2454.46 microg/g for intestines and 0.96-192.20 microg/g for lung. The intra-day and inter-day precision were all less than 12.5%, and the extract recovery was in the range 64.1-103.7% with RSD less than 15.6% for HSYA in all matrices. The method was used successfully to quantify HSYA in rat plasma and tissue samples to support a pharmacokinectic study.     

Mechanisms of pharmacokinetic interaction between propranolol and quinidine in rats.

In order to study the mechanism of propranolol-quinidine interaction, the effects of quinidine on propranolol pharmacokinetics were examined in male Wistar rats. The concurrent oral administration of quinidine (10 mg/kg) markedly increased the plasma concentration of propranolol (2.5 mg/kg), and the area under the propranolol concentration-time curve increased about 3.6-fold. These results are consistent with previous observations in man and indicate the possible usefulness of the male Wistar rat as an animal model for investigating the mechanisms of the drug interaction. When propranolol was given intravenously, a concurrent administration of quinidine increased the apparent distribution volume of propranolol, mainly by decreasing its plasma protein binding. However, the systemic clearance of propranolol was not significantly altered by quinidine. Thus, quinidine increased the availability of oral propranolol from 13.8 +/- 2.2 to 44.2 +/- 4.6% (p less than 0.01). Furthermore, quinidine delayed the elimination of propranolol from the isolated perfused rat liver. These results indicate that quinidine reduces the presystemic elimination of propranolol in the liver, thereby increasing its systemic availability after oral administration.     

超高效液相色谱-串联质谱法测定人血浆中苯海索

建立了灵敏、高通量的超高效液相色谱-串联质谱（UPLC-MS/MS）定量测定人血浆中苯海索的方法,用于盐酸苯海索片生物等效性研究,并确证食物对苯海索体内药代动力学行为的影响。以甲醇为沉淀剂进行蛋白质沉淀,苯海索-d11为内标,采用Waters Acquity UPLC BEH C8色谱柱（50 mm×2.1mm,1.7 μm）,以0.1%（v/v）甲酸水溶液（含5 mmol/L醋酸铵）和乙腈-水（95：5,v/v）为流动相进行梯度洗脱;采用电喷雾电离（ESI）源,在正离子模式下进行多反应监测（MRM）扫描。苯海索在0.1~40 ng/mL范围内线性关系良好。应用该方法测定中国健康受试者空腹及餐后单次口服2 mg盐酸苯海索片后的血药浓度,结果显示最大血药浓度（C_max）、血药浓度-时间曲线下面积（AUC_0-t、AUC_0-∞）的90%置信区间均在80.0%~125.0%范围内,表明两种制剂在空腹和餐后均生物等效。     

UHPLC‐ESI‐MS/MS determination and pharmacokinetics of pinoresinol glucoside and chlorogenic acid in rat plasma after oral administration of Eucommia ulmoides Oliv extract

This study aimed to develop a specific UHPLC‐ESI‐MS/MS method for simultaneous determination and pharmacokinetics of pinoresinol glucoside and chlorogenic acid in rat plasma after oral administration of Eucommia ulmoides . The chromatographic separation was achieved on a Hypersil GOLD column with gradient elution by using a mixture of 0.1% formic acid aqueous solution and acetonitrile as the mobile phase at a flow rate of 200 μL/min. A tandem mass spectrometric detection was conducted using multiple‐reaction monitoring via an electrospray ionization source in negative ionization mode. Samples were pre‐treated by a single‐step protein precipitation with acetonitrile, and bergenin was used as internal standard. After oral administration of 3 mL/kg E. ulmoides extract in rats, the maximum plasma concentrations of pinoresinol glucoside and chlorogenic acid were 57.44 and 61.04 ng/mL, respectively. The times to reach the maximum plasma concentration were 40.00 and 23.33 min for pinoresinol glucoside and chlorogenic acid, respectively. The intra‐ and inter‐day precision (RSD) values for the two analytes were <2.46 and 5.15%, respectively, and the accuracy (RE) values ranged from −12.76 to 0.00. This is the first study on pharmacokinetics of bioactive compounds in rat plasma after oral administration of E. ulmoides extract.