盐酸二甲双胍的毛细管电泳法快速测定

建立了毛细管电泳高频电导法快速测定片剂中盐酸二甲双胍的方法。考察了缓冲溶液、有机溶剂添加剂、毛细管长度以及分离电压和进样条件等因素对分离检测的影响。在最佳条件下5.0 min内即可实现盐酸二甲双胍分离检测,盐酸二甲双胍的线性范围为1.50μg/mL~130μg/mL,检出限为1.0μg/mL。该方法成功地测定了盐酸二甲双胍片剂中的盐酸二甲双胍。     

盐酸二甲双胍药物中杂质测定方法研究进展

对近年来盐酸二甲双胍类药物中杂质的测定方法进行综述.盐酸二甲双胍类药物中的杂质主要有双氰胺、二甲胺以及由二甲胺形成的亚硝胺类基因毒性杂质等.测定方法主要有高效液相色谱(HPLC)法、离子色谱(IC)法、高效液相色谱–串联质谱(HPLC–MS/MS)法和气相色谱–串联质谱(GC–MS/MS)法,其中高效液相色谱法主要用于...     

Estimation of pioglitazone hydrochloride and metformin hydrochloride in tablets by derivative spectrophotometry and liquid chromatographic methods

Two simple and accurate methods of analysis to determine pioglitazone hydrochloride (PIO) and mefformin hydrochloride (MET) in combined dosage forms were developed using second-derivative spectrophotometry and reversed-phase liquid chromatography (LC). PIO and MET in combined preparations (tablets) were quantified using the second-derivative responses at 227.55 nm for PIO and 257.25 nm for MET in spectra of their solutions in a mixture of methanol and acetonitrile (30 + 70). The calibration curves were linear [correlation coefficient (r) = 0.9984 for PIO and 0.9986 for MET] in the concentration range of 8-40 microg/mL for PIO and 4-12 microg/mL for MET. In the LC method, analysis was performed on a Hypersil ODS-C18 column with 5 microm particle size using the mobile phase acetonitrile-water-acetic acid (75 + 25 + 0.3), adjusted to pH 5.5 with liquor ammonia, at a flow rate of 0.5 mL/min. Measurement was made at a wavelength of 230 nm. Both the drugs were well resolved on the stationary phase, and the retention times were 8.5 min for PIO and 16.0 min for MET. The calibration curves were linear (r = 0.9933 for PIO and 0.9958 for MET) in the concentration range of 4-20 microg/mL for PIO and MET. Both methods were validated, and the results were compared statistically. They were found to be accurate, precise, and specific. The methods were successfully applied to the estimation of PIO and MET in combined tablet formulations.     

Stability-indicating capillary electrophoresis method for the simultaneous determination of metformin hydrochloride,saxagliptin hydrochloride,and dapagliflozin in pharmaceutical tablets

A capillary electrophoretic method coupled to a diode array detector (CE-DAD) was developed and validated for the simultaneous determination of metformin hydrochloride (MET), the dipeptidyl peptidase-4 (DPP-4) inhibitor saxagliptin hydrochloride (SAX), and the sodium glucose co-transporter (SGLT 2) inhibitor dapagliflozin (DAP). The proposed method was used for the determination of these drugs in binary antidiabetic combinations namely, SAX/MET, combination I, DAP/MET, combination II, and SAX/DAP, combination III. CE separation was performed on a fused silica capillary with background electrolyte consisting of 30?mM phosphate buffer (pH 6.0) with a high voltage of 30?kV, a pressure of 20 mbar, and an injection time of 40?s. The compounds were detected at 203?nm for SAX/DAP and 250?nm for MET. The method was linear in the concentration range of 10–200?µ?g/mL (SAX), 1.25–50?µ?g/mL (DAP), and 7.5–1000?µ?g/mL (MET). Full validation of the proposed method was performed as per the ICH guidelines. The obtained errors and deviation values did not exceed 2% assessing good accuracy and precision, respectively. The stability-indicating potential of the proposed method was proved under different stress-degradation conditions. The proposed method was successfully applied to the analysis of the three binary combinations in their tablets.     

Simultaneous estimation of metformin hydrochloride, pioglitazone hydrochloride, and glimepiride by RP-HPLC in tablet formulation

A simple, precise, rapid, and reproducible reversed-phase high-performance liquid chromatography method is developed for the simultaneous estimation of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO), and glimepiride (GLP) present in multicomponent dosage forms. Chromatography is carried out isocratically at 25 degrees C +/- 0.5 degrees C on an Inertsil-ODS-3 (C-18) Column (250 x 4.60 mm, 5 microm) with a mobile phase composed of methanol-phosphate buffer (pH 4.3) in the ratio of 75:25 v/v at a flow rate of 1 mL/min. Detection is carried out using a UV-PDA detector at 258 nm. Parameters such as linearity, precision, accuracy, recovery, specificity, and ruggedness are studied as reported in the International Conference on Harmonization guidelines. The retention times for MET, PIO, and GLP are 2.66 + 0.5 min, 7.12 + 0.5 min, and 10.17 + 0.5 min, respectively. The linearity range and percentage recoveries for MET, PIO, and GLP are 10-5000, 10-150, and 1-10 microg/mL and 100.4%, 100.06%, and 100.2%, respectively. The correlation coefficients for all components are close to 1. The relative standard deviations for three replicate measurements in three concentrations of samples in tablets are always less than 2%.     

Determination of metformin hydrochloride in tablets by nuclear magnetic resonance spectrometry

The ¹H-n.m.r. signal of the drug (10–35 mg ml^?1) in deuterium oxide, with maleic acid as internal reference standard, is used. The integral of the peak at 3.06 ppm with respect to 3-trimethylsilylpropionic acid is compared with that at 6.3 ppm for the internal standard. The method is quantitative and free from interference by tablet excipients.     

串联双柱固相萃取-高效液相色谱-电喷雾多级质谱法测定盐酸二甲双胍制剂中的盐酸二甲双胍及残留物三聚氰胺和双氰胺

建立了串联双柱固相萃取-高效液相色谱-电喷雾多级质谱（HPLC-ESI-MSⁿ）确认及测定盐酸二甲双胍制剂中的盐酸二甲双胍及残留物三聚氰胺和双氰胺的方法。盐酸二甲双胍制剂样品在超声辅助下,采用含0.1%（v/v）乙酸的无水乙醇溶液提取,选择Cleanert PCX-C18串联固相萃取双柱净化富集,以5%（v/v）氨水甲醇溶液为洗脱剂进行洗脱。采用Kromasil-C18色谱柱（100 mm×4.6 mm,3.5 μm）分离,梯度洗脱,在电喷雾多级质谱、选择离子模式下检测,外标法定量。通过比较制剂残留物在不同萃取溶剂、固相萃取柱及洗脱液等条件下的回收率,优化了前处理方法。结果表明,在各自的线性范围内,3种目标物的峰面积与质量浓度呈良好的线性关系,相关系数（r²）≥0.9992;方法的检出限为1.48~13.61 μg/kg,定量限为5.96~45.67 μg/kg。3种目标物在低、中、高加标水平下的平均回收率为65.02%~118.33%,相对标准偏差（RSD）≤13.41%（n=5）。该法操作简单,净化效果好,准确度高,重现性好,适用于检测和分析不同盐酸二甲双胍制剂中盐酸二甲双胍及残留物三聚氰胺和双氰胺。     

Development of an efficient transdermal delivery system of small interfering RNA using functional peptides, Tat and AT-1002

Topical use of small interfering RNA (siRNA) as a therapeutic nucleic acid is increasingly studied for the treatment of skin diseases and for the improvement of skin properties. However, naked siRNA transdermal delivery is limited by its low stability in the body and low permeability into target cells. This is due to various skin barriers such as the stratum corneum that has multiple lipid bilayers and epidermal layers that have tight junctions. In this study, we investigate non-invasive transdermal siRNA delivery using two functional peptides: AT1002, which is a tight junction modulator and 6-mer synthetic peptide belonging to a novel class of compounds that reversibly increases paracellular transport of molecules across the epithelial barrier; and Tat, which is a cell-penetrating peptide applicable as a transdermal siRNA delivery enhancer. We examined whether expression of the tight junction protein zonula occludens protein 1 (ZO-1) was detected in mouse skin applied with AT1002. Additionally, siRNA stabilities for RNaseA using Tat and AT1002 were assessed. We also determined the intradermal delivery efficiency of siRNA using functional peptides by confocal laser microscopy of fluorescently labeled siRNA in mouse skin. We found that the Tat analog and AT1002 strongly increased siRNA stability against RNaseA. In addition, ZO-1 disappeared from the skin after treatment with AT1002, yet recovered with time after washing. Finally, we also found that Tat and AT1002 peptides accelerate transdermal siRNA delivery both widely and effectively. Thus, combination of Tat and AT1002 is expected to be a transdermal delivery enhancer of siRNA.     

Development and evaluation of a monolithic floating drug delivery system for acyclovir

Acyclovir (ACV), a model drug for this study, is one of the most effective drugs against viruses of the herpes group. Absorption of orally administered ACV is variable and incomplete, with a bioavailability of ca. 15-30%. The drug is absorbed in the duodenum after oral administration and hence, preparation of a floating drug delivery system (FDDS) for ACV may increase oral absorption of the drug. ACV matrix tablets (200?mg) containing an effervescent base (sodium bicarbonate and citric acid) and a binary combination of hydroxypropyl methylcellulose (HPMC) K4M with carbopol or sodium carboxymethyl cellulose (Na CMC) or polyvinylpyrrolidone (PVP) and/or sodium alginate were prepared by the direct compression method. The tablets were evaluated for physicochemical properties and in vitro floating ability (floating lag-time and duration), bioadhesiveness and drug release. The drug release studies were carried out in 0.1?N HCl (pH 1.2) at 37±0.5°C. At appropriate time intervals, samples were withdrawn and assayed spectrophotometrically at λ(max)=259?nm. The floating test showed tablets containing 15% effervescent base had a floating lag time of 10-30?s and a duration of floating time of 24?h. The formulations containing HPMC-PVP, HPMC-Na CMC, HPMC-carbopol, and HPMC-sodium alginate released about 60-90% of their drug content during a 12-h period. Increasing carbopol caused slower drug release. We concluded that the proposed tablets with 15% effervescent base, 20-30% HPMC, 30% Na CMC (and/or 20% PVP or 20% sodium alginate) showed good floating and drug release properties in vitro, and should be considered as FDDS for ACV.     

Development and validation of an analytical method for metformin hydrochloride and its related compound (1-cyanoguanidine) in tablet formulations by HPLC-UV

A simple, and stability-indicating liquid chromatographic method was developed and validated for the analysis of metformin hydrochloride and its related compound (1-cyanoguanidine) in tablet formulations. Liquid chromatography with a UV detector at a wavelength of 232 nm using a Nova-Pak silica column was employed in this study. Isocratic elution was employed using a mixture of ammonium dihydrogen phosphate buffer and methanol (21:79, v/v). This new method was validated in accordance with USP requirements for new methods for assay determination, which include accuracy, precision, specificity, linearity and range. The current method demonstrates good linearity over the range of 0.01-0.03 mg mL⁻¹ of metformin hydrochloride. The accuracy of the method is 100.4%. The precision of this method reflected by relative standard deviation of replicates is 0.30%. Validation of the same method for 1-cyanoguanidine determination was also performed according to USP requirements for quantitative determination of impurities which include accuracy, precision, linearity and range, selectivity, and limit of quantification (LOQ). Low LOQ of 1-cyanoguanidine using this method enables the detection and quantification of this impurity at low concentration.     

Conjugated polymer nanoparticles for small interfering RNA delivery

Loosely aggregated conjugated polymer nanoparticles (CPNs) were used as nontoxic and efficient small interfering RNA (siRNA) delivery vehicles with delivery visualization. A significant down regulation (94%) of a target gene was achieved by transfection of HeLa cells with the CPNs/siRNA complexes, supporting CPN as a promising siRNA delivery carrier.     

Study on a new precolumn derivatization method in the determination of metformin hydrochloride

Metformin hydrochloride is successfully determined by reversed-phase high-performance liquid chromatography with a new precolumn derivatization method using 9,10-anthraquinone-2-sulfonyl chloride as the derivatization agent. Several derivatization systems are tried to optimize the derivatization conditions, and a new post-derivatization treatment method is established. The derivatization product is analyzed on a Lichrosper C18 column (6.0 mm x 150 mm, 5 microm) at 256 nm with methanol-water (70:30, v/v) as the mobile phase. The calibration curves of the derivatives for the UV detector (0.01-4 mg/L) are linear with respect to peak area. The detection limit (peak area) for the metformin hydrochloride is 0.01 mg/L for a signal-to-noise ratio of 3:1. In human plasma, the detection limit is 0.02 mg/L. This assay is rapid, sensitive, and highly reproducible.     

Development of a stick-type transdermal eyelid delivery system of ketotifen fumarate for ophthalmic diseases

A transdermal eyelid delivery system for treating ocular diseases (eye-stick) has been developed. Ketotifen fumarate (KT) was used as a model drug. An in vivo study using rabbits showed that the eye-stick device maintained a constant conjunctival concentration of the drug for an extended period of time, which was equivalent or higher than the therapeutic level following eye drop administration. Moreover, the conjunctival concentration after eye-stick application was well predicted using the physicochemical parameters, diffusion coefficient and partition coefficient, obtained from in vitro hairless mouse skin permeation experiments.     

Novel nano-porous hydrogel as a carrier matrix for oral delivery of tetracycline hydrochloride

A novel nano-porous hydrogel (NPH) was synthesized via graft copolymerization of sodium acrylate (Na-AA) and acrylamide (AAm) onto salep backbones and its application as a carrier matrix for oral delivery of tetracycline hydrochloride (TH) was investigated. The Taguchi method as a strong experimental design tool was used for synthesis optimization. The swelling behavior of optimum hydrogel was measured in various media. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetrical analysis (TGA). The study of the surface morphology of the hydrogels using SEM and AFM showed a nanoporous (average pore size: 180 nm) structure for the sample obtained under optimized conditions. The drug delivery results demonstrated that this NPH could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be a good candidate as an orally administrated drug delivery system.     

A catalytic multi-pumping flow system for the chemiluminometric determination of metformin

A multi-pumping flow system for the chemiluminometric determination of the hypoglycaemic drug metformin was implemented. The developed methodology was based on the metformin-induced inhibition (metformin acts as a Cu(II) scavenger) of the catalytic effect of Cu(II) ions on the chemiluminescent reaction between luminol and hydrogen peroxide. The flow manifold configuration was based on the utilisation of multiple solenoid-actuated micro-pumps that were simultaneously accountable for sample/reagent introduction and reaction zone formation/propulsion, thus resulting in a fully automated, simple and highly selective multi-pumping flow system. A versatile sample manipulation allowed the establishment of distinct sampling strategies with low reagent consumption. The characteristic pulsed flow ensured an effective sample/reagent mixing leading to a better and faster reaction zone homogenisation and thus improved analytical signals. Linear calibration plots were obtained for metformin hydrochloride concentrations ranging from 5 to 15 mg L^–1 with a relative standard deviation lower than 2.0% (n=5). Detection limit was 0.94 mg L^–1, and the sampling rate was about 95 determinations per hour. The developed methodology was applied to the analysis of pharmaceutical formulations and the obtained results were in agreement with those furnished by the reference method with relative percentage deviations of lower than 1.5%.     

Multiparticulate chitosan-dispersed system for drug delivery

A multiparticulate chitosan-dispersed system (CDS), which is composed of the drug reservoir and the drug release-regulating layer, was developed for drug delivery. The drug release-regulating layer is a mixture of water-insoluble polymer and chitosan powder. The drug is released from CDS pellets in all regions of the gastrointestinal tract (from the stomach to the colon). CDS pellets containing chitosan powder were designed to dissolve chitosan powder partly in the release-regulating layer in the stomach and release part of drug. After passing through the stomach, the drug is released from CDS pellets at a constant speed in the small intestine. In the large intestine, CDS pellets were designed to disintegrate the remaining chitosan powder at an accelerated speed and the remaining drug in CDS pellets is released. The drug release rate can be controlled with the thickness of the chitosan-dispersed water-insoluble layer. Furthermore, for colon-specific drug delivery, an additional outer enteric coating is necessary to prevent drug release from CDS pellets in the stomach, because the chitosan-dispersed water-insoluble layer dissolves gradually under acidic conditions. The resulting enteric-coated CDS (E-CDS) pellets were found to permit colon-specific drug delivery. In this study, the multiparticulate CDS was adopted not only for colon-specific drug delivery but also for sustained drug release.     

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.     

Development of a thermal neutron-sensitive liposome for a novel drug delivery system aiming for radio-chemo-concurrent cancer therapy

A thermal neutron-sensitive liposome has been developed focusing on irradiation site-specific-controlled release of a medicine. We recommended a ¹⁰B-borocaptate dimer as a detonator of liposome in expectation of effects of low-energy heavy ions produced by ¹⁰B(n, α)⁷Li reaction. As a result, an X-ray-sensitive liposome incorporating the detonator was vulnerable enough to release an anticancer agent, carboplatin, at a dose/dose–rate near clinical use. These results reveal, moreover, that the liposomes are also applicable to a heavy-ion beam.