Pharmaceutical Analysis of β-Methyldigoxin in Dosage Forms Using RP-HPLC

Abstract

A reversed-phase high-performance liquid chromatographic method has been developed for the assay of β-methyldigoxin in Dimekor® tablets (0.1 mg) and ampules (0.2 mg/2 mL). Quantitation of cardiac glycoside in mentioned dosage forms was carried out by the incorporation of phenacetin as an internal standard. A Varian HPLC configured with a Paltisil P10 ODS1 column was used for the separation and quantitation of β-methyldigoxin in pharmaceutical preparations. The mobile phase was acetonitrile-water 38: 62 v/v with flow rate 1.6 ml/min and UV detection was set at 220 nm. The range of linearity extended from 0.01 to 0.11 mg/mL. For the quantitative analysis of β-methyldigoxin in tablets the recovery was 100.16% and for ampules 99.50%. The excipients did not interfere with the determination of the analysed substance. The proposed method is precise and sensitive for the examination of examine the content uniformity of tablets and is in a good agreement with PH.JUG.IV (1). A spectrofluorimetric method was used for the dissolution test by the method described in USP XXII (2).     

The influence of diluent on the release of theophylline from hydrophilic matrix tablets

The role of β-cyclodextrin (β-CD) on the apparent solubility of theophylline was investigated by the solubility method. Binary systems of theophylline and β-CD were prepared using the dry co-grinding method. Their characterization was performed by differential scanning calorimetry (DSC). The dissolution rate of theophylline and theophylline/β-CD and dissolution studies of matrix tablets prepared from mixtures containing theophylline and ground theophylline were carried out. It can be concluded that β-CD is related to an increase in the apparent solubility and dissolution rate of the drug, promoting improvement on the release of theophylline from matrices manufactured with hydroxypropylmethylcellulose (HPMC). This can be attributed to the amorphous state and the increased wettability of the drug.     

Inclusion Complexes of Tolnaftate with β-Cyclodextrin and Hydroxypropyl β-Cyclodextrin

Tolnaftate, an antifungal agent, was found to form inclusion complexes with both β-cyclodextrin (β-CD) and hydroxypropyl β-cyclodextrins (HPBCDs) with two different degrees of substitution [HPBCD(A)-8% and HPBCD(B)-3%]. Complex formation in the solution state was studied using phase solubility and spectral shift methods. Solid complexes were prepared by the coprecipitation method. Solubilities and dissolution rates were determined for each solid complex, its corresponding physical mixture, and free drug. The increase in solubility of tolnaftate with added HPBCD was found to be significantly greater than with added β-CD. For both HPBCD(A) and HPBCD(B), over the concentration range 0-0.05 M. 1:1 complexes with stability constants of 1460 ± 139 M^-1 and 1860 ± 165 M^-1 were observed, respectively. Over the β-CD concentration range 0-0.02 M, a 1:1 complex with a stability constant of 1190 ± 105 M^-1 was observed. At higher HPBCD concentrations, the increase in solubility was observed to show a positive deviation from linearity (type A_p phase diagram). Using the spectral method, in a 2 5% v/v methanol in water system, the stability constants were determined to be 1020 ± 150 M^-1 1110 ± 120 M^-1 and 1100 ± 260 M^-1 for HPBCD(A), HPBCD(B) and β-CD, respectively. The solid complexes prepared showed improved dissolution over physical mixtures and free drug.     

Determination of steroid hormones in oral contraceptives by high-performance liquid chromatography

The aim of this research was to standardize a high-performance liquid chromatographic method for quantitative determination of steroid hormones, like ethinylestradiol (ETE), levonorgestrel (LEVO), and gestodene (GEST), in commercially available oral contraceptives (OCs). The combination ETE- LEVO was analyzed using a LiChrospher® 100 RP-8 column (5 μm, 125×4 mm) in LiChroCART®, with a mobile phase constituted of acetonitrile: water (60:40 v/v). Using the same column, ETE-GEST was analyzed with a mobile phase constituted of acetonitrile:water (50:50 v/v) at pH 7.5 adjusted with 0.02 M ammonium hydroxide. For both methods, a flow rate of 0.8 mL/min was utilized and detection was carried out at 215 nm. All analyses were performed at room temperature (24±2°C).

Calibration curves for ETE-LEVO were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 12.0 to 300.0 μg/mL (LEVO). Calibration curves for ETE-GEST were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 9.0 to 160.0 μg/mL (GEST). Correlation coefficients obtained were from 0.9999 to 0.9990. Coefficients of variation for samples containing ETE-LEVO were 0.47% and 0.38%, respectively. For samples with ETE-GEST they were 0.39% and 0.44%, respectively. The average recovery for samples with ETE-LEVO was 103.46% and 100.78%, respectively. For samples containing ETE-GEST it was 100.89% and 101.03%, respectively.     

Development of fast-dissolving tablets of flurbiprofen-cyclodextrin complexes

The present study was aimed at developing a tablet formulation based on an effective flurbiprofen-cyclodextrin system, able to allow a rapid and complete dissolution of this practically insoluble drug. Three different cyclodextrins were evaluated: the parent β-cyclodextrin (previously found to be the best partner for the drug among the natural cyclodextrins), and two amorphous, highly soluble β-cyclodextrin derivatives, i.e., methyl-β-cyclodextrin and hydroxyethyl-β-cyclodextrin. Equimolar drug-cyclodextrin binary systems prepared according to five different techniques (physical mixing, kneading, sealed-heating, coevaporation, and colyophilization) were characterized by Differential Scanning Calorimetry, x-ray powder diffractometry, infrared spectroscopy, and optical microscopy and evaluated for solubility and dissolution rate properties. The drug solubility improvement obtained by the different binary systems varied from a minimum of 2.5 times up to a maximum of 120 times, depending on both the cyclodextrin type and the system preparation method. Selected binary systems were used for preparation of direct compression tablets with reduced drug dosage (50 mg). Chitosan and spray-dried lactose, alone or in mixture, were used as excipients. All formulations containing drug-cyclodextrin systems gave a higher drug dissolved amount than the corresponding ones with drug alone (also at a dose of 100 mg); however, the drug dissolution behavior was strongly influenced by formulation factors. For example, for the same drug-cyclodextrin product the time to dissolve 50% drug varied from less than 5 minutes to more than 60 minutes, depending on the excipient used for tableting. In particular, only tablets containing the drug kneaded with methyl-β-cyclodextrin or colyophilized with β-cyclodextrin and spray-dried lactose as the only excipient satisfied the requirements of the Food and Drug Administration (FDA) for rapid dissolving tablets, allowing more than 85% drug to be dissolved within 30 minutes. Finally, it can be reasonably expected that the obtained drug dissolution rate improvement will result in an increase of its bioavailability, with the possibility of reducing drug dosage and side effects.     

Simultaneous determination of thiabendazole and mebendazole in tablets by high-performance liquid chromatography

Reversed-phase high performance liquid chromatography using an RP 18 column (4 × 125 mm), tetrahydrofuran-acetonitrile-0.5% formic acid (5:25:70, v/v/v) as mobile phase and UV detection at 254 nm enabled the simultaneous determination of thiabendazole (TZ) and mebendazole (MZ) in tablets. The method showed linearity over 4.0 to 40.0 μg TZ/ml and 6.0 to 60.0 μg MZ/ml. The correlation coefficient r was .9999 for both TZ and MZ. The coefficient of variation (CV) was 0.59-0.80% for TZ and 0.49-0.67% for MZ. The average recovery was 100.54-101.17% for TZ and 100.35-101.13% for MZ. The excipients of the tablets did not interfere in the proposed method. The developed method is precise, accurate, and selective for the determination of both benzimidazoles analyzed.     

高效液相色谱法鉴定嫌疑药丸中西地那非

本文研究了药丸中西地那非的高效液相色谱法鉴定。色谱柱为XDB-C18,5μm,4.6×150mm,二极管阵列检测器检测230nm(带宽4nm),流动相为35%乙睛+65%0.025mmol/L KH2PO4(含0.1‰v/v乙二胺)(pH5.57),流速1mL/min。样品用水溶解,外标法定量。检出限(LOD,S/N=3)为3μg/mL,定量限(LOQ,S/N=5)为4μg/mL。1000μg/mL、600μg/mL和200μg/mL的回收率分别为98.8%、101.3%和99.9%。6次测定600μg/mL和200μg/mL的相对标准偏差(RSD%)分别为2.4%和2.6%。在20～1000μg/mL范围内线型回归方程为Y=16.692X+50.17(Y为相应信号,mAU;X为浓度,μg/mL),回归系数R2为0.9998。该方法样品处理简单,定量准确度高,干扰小,可用于药丸中西地那非的法庭科学鉴定。     

Evaluation of Stereoselective Dissolution of Racemic Salbutamol Matrices Prepared with Commonly Used Excipients and 1H-NMR Study

The purpose of this work was to examine the in vitro enantioselective dissolution of salbutamol from matrix tablets containing various chiral excipients, such as γ-cyclodextrin (γ-CD), heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), sulfobutyl-β-cyclodextrin (SBE-β-CD), hydroxypropylmethylcellulose (HPMC), and egg albumin. In this study, two types of tablets were prepared; the coated tablet contained the complex of racemic salbutamol and cyclodextrin (γ-CD, DM-β-CD, and SBE-β-CD), and the uncoated tablet was composed of the drug with either HPMC or egg albumin. Subsequently, these formulations were evaluated for enantioselective release. The results revealed that the formulations containing either SBE-β-CD, HPMC, or egg albumin had no enantioselective release, while the formulation with DM-β-CD gave slightly different release of the two enantiomers at the end of the dissolution profile. The formulation containing γ-CD provided significant stereoselectivity throughout the dissolution profile. The release of the eutomer R-salbutamol was higher than that of the distomer S-salbutamol from the γ-CD tablet. In addition, the enantioselective interaction for the γ-CD inclusion complex was investigated by ¹H-NMR (nuclear magnetic resonance) spectroscopy and gave evidence to support the enantioselectivity obtained on dissolution.     

A validated stability indicating LC method for Nateglinide

A simple, isocratic, rapid and accurate reverse phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of Nateglinide. The developed method is also applicable for determination of related substance in bulk drugs. The chromatographic separation was achieved on a Hypersil C18 (250 × 4.6 mm 5 μm) column using aqueous mixture of 0.025 M potassium hydrogen phosphate and 0.1% triethyl amine, v/v (pH 3.0 with dilute phosphoric acid)—methanol (25:75, v/v) as a mobile phase. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The chromatographic resolutions between Nateglinide and its potential impurities A and B were found to be greater than four. Forced degradation studies were performed for Nateglinide using acid (0.5 N hydrochloric acid), base (0.5 N sodium hydroxide), oxidation (3% hydrogen peroxide) heat (60°C) and UV light (254 nm). The limit of detection and limit of quantification of Nateglinide, impurities A and B were found to be 0.05 and 0.15 μg /mL, respectively for 20 μL injection volume. The percentage recovery of Nateglinide was ranged from 98.4 to 100.9. The percentage recovery of impurities in Nateglinide sample was ranged from 96.8 to 103.5. The developed RP-HPLC method was validated with respect to linearity, accuracy, precision, robustness, and forced degradation studies prove the stability indicating power of the method.     

Preliminary study on the development of nanoemulsions for carbamazepine intravenous delivery: an investigation of drug polymorphic transition

Carbamazepine (CBZ) is available on the pharmaceutical market as tablets, capsules, and oral suspensions, but not as a parenteral formulation for clinical use. Parenteral emulsions are a good alternative to poorly water-soluble drugs such as CBZ. In this way, four different emulsions containing 3 mg/mL of CBZ were developed, but during a period of storage, drug crystal precipitates appeared. To investigate this phenomenon, differential scanning calorimetry, infrared spectroscopy, and light microscopy were employed. The results suggested a polymorphic transition from β form to dehydrate form, resulting in drug precipitation, although the emulsions themselves remained stable for at least three months.     

Development of a Transdermal Delivery Device for Melatonin In Vitro Study

The present study was undertaken to develop a transdermal delivery device for melatonin and to determine the effects of system design on the release of melatonin. Melatonin(MT) diffusion characteristics from 2 solvents through a series of ethylene vinyl acetate membranes with 4.5%, 9%, 19%, 28% vinyl acetate were characterized using vertical Franz® diffusion cells. The solvent used were 40% (v/v) propylene glycol (PG) and 40%(v/v) propylene glycol with 30%(w/v) 2-hydroxypropyl-β-cytrodextrin. The best release rate (Jss = 0.795 μg/h/cm²) was obtained from the 40% PG vehicle through the 28% vinyl acetate membrane. Melatonin diffusion through this membrane with an acrylate pressure sensitive adhesive (PSA) with and without MT loading was also studied. The data revealed an interaction between MT and the PSA in the systems with MT-loaded adhesive. A MT transdermal delivery device was constructed based on the above data. Effect of storage time (1 day, 2 days, and 3 days) on the developed device was also investigated. Steady state flux values of MT did not vary significantly with storage time (p-value = 0.14). The steady state flux was 1.88 ± 0.6 μg/hr/cm²(n = 9). However, storage time did affect the burst effect of MT. Total amount of MT released in the first hour was 137.4 ± 25.7 μg after 3 days, 61.5 ± 8.9 μg after 2 days, and 43.8 ± 20.9 μg after 1 day.     

Comparative Pharmacokinetics of New Theophylline Preparations as Egifilin® 200 mg and 400 mg Retard Tablets After Single Dose in Healthy Volunteers

Pharmacokinetic properties of Egifilin® retard tablets (containing 200 or 400 mg of theophylline, EGIS Pharmaceuticals Ltd., Budapest, Hungary) were investigated in 12 healthy volunteers (six women, six men). Pharmacokinetic analysis was performed according to a one-compartment open model. The retard nature of both 200 and 400 mg tablets could be demonstrated. Comparison of the pharmacokinetic curves of women and men indicated that there was no sex difference in the pharmacokinetics of two retard tablets.

Egifilin retard tablets ensured plasma levels for almost 30 hr after single drug intake with an extremely long retard plateau between 6 and 30 hr. For study purposes, an improved rapid HPLC-UV analytical method (less than 3.5 min chromatogram) has been elaborated for the determination of theophylline in human plasma. The range of the calibration is 0.6-18 μg/ml.     

Study of Surfactants/β-Cyclodextrin Interactions Over Mequitazine Dissolution

Surfactant/β-cyclodextrin interactions were investigated by studying the dissolution of mequitazine in different binary (aqueous solutions of β-CD or surfactants) and ternary (aqueous solution of β-CD and surfactants) dissolution media. Results were compared with those obtained from binary media with 50, 250, and 500 mg of surfactants (preceding paper). Results show that there is an interaction between β-cyclodextrin and surface-active agent, and that the type and extent of interaction are controlled by the nature and the amount of the surface-active agent. A decrement in drug dissolution rate was obtained from all of the ternaly media containing β-cyclodextrin and sodium lauryl sulfate as surfactant in the ratio of 1:1 mol/mol. These facts suggest that sodium lauryl sulfate and β-cyclodextrin form an inclusion compound in the molecular ratio of 1:1.     

Investigation and physicochemical characterization of clarithromycin-citric acid-cyclodextrins ternary complexes

The purpose of this study was to investigate the effect of citric acid (CA) on the complexation of clarithromycin (CLM) with β-cyclodextrin (βCD) in aqueous solutions and in the solid state. A phase solubility study revealed a positive effect of CA on the drug solubility. A B_s-type solubility with an apparent stability constant (K_c) of 102.4 M^-1 was obtained for CLM in βCD solution and 161.2 M^-1 for CLM in 6 mM βCD solution. Solid ternary complexes were prepared by coevaporation and lyophilization. CLM-βCD-CA interactions were studied in the solid state by differential scanning calorimetry (DSC), infrared spectroscopy, scanning electron microscopy and X-ray diffractometry. A part of the guest molecule was located in the βCD host cavity. The results obtained suggest that the lyophilization method yields a higher degree of amorphous entity than coevaporation.     

Development of fixed dose combination tablets of aripiprazole plus divalproex sodium and their simultaneous determination using HPLC-UV

A vast majority of psychiatric patients are effectively treated with combination of drugs to improve efficacy and adherence, but due to limited research and development in fixed dose combination (FDC) in psychiatry, these products are not commonly available. The aim of this study is to prepare cost effective FDC tablets containing aripiprazole and divalproex sodium. Two batches of fixed dose combination tablets, FDC1 and FDC2, were successfully prepared using wet granulation technique. Furthermore, aripiprazole tablets A1 and A2 and divalproex tablets D1 were also formulated as reference to compare the in vitro availability profile. An accurate and simple isocratic HPLC method was established and validated for the simultaneous quantification of aripiprazole and valproic acid in the FDC tablets. A reversed-phase C18 (250?×?4.6?mm) column in isocratic mode was used. The mobile phase consisted of acetonitrile and 0.32% KH₂PO₄ (60:40, v/v), flow rate was set at 1.0?mL/min and the detection was performed at 210?nm. Average percent recoveries of aripiprazole and valproic acid were 96.0 and 95.5%, respectively, meeting the official requirements. The newly developed FDC product may be used for the better therapeutic outcomes of combined use of aripiprazole and valproic acid, which may improve patient adherence.     

Solubility Properties of the Serotonergic Agonist 2, 3, 4, 5- Tetrahydro-8- (Methylsulfonyl)-1H-3-Benzazepin-7-0L

The apparent solubility of S K & F 103829 (2, 3, 4, 5-Tetrahydro- 8-(methyl sulfonyl)-lH-3-benzazepin-7-0l) as a function of pH was determined in the presence of methane sulfonic,acetic and hydrochloric acids . The mesylate salt of S K & F 103829 was observed to be highly soluble in water (solubiity - 441.3 mg/mL). However, the addition of NaCl to solutions of the mesylate salt was observed to cause a dramatic decrease in solubility which was determined to be due to the formation of the poorly soluble hydrochloride salt (saturated solubility in water 1.0 mg/mL). when acetic acid was used in the studies. A plausible explanation for this unique solubility profie and the implication of the solubility data generated on development of a parenteral formulation is discussed.     

Inclusion complexation of lorazepam with different cyclodextrins suitable for parenteral use

The development of a parenteral lorazepam formulation, using cyclodextrins (CDs) as inclusion complexation agents, was investigated. CDs suitable for parenteral injection, i.e., hydroxypropyl-β-cyclodextrin (HP-β-CD), hydroxypropyl-γ-cyclodextrin (HP-γ-CD), sulfobutylether-7-β-cyclodextrin (SBE-7-β-CD), and maltosyl-β-cyclodextrin (malt-β-CD) were studied for the possibility to increase the solubility of lorazepam. Lorazepam interacted with all tested CD derivatives and 1:1 complexes are formed. HP-β-CD exerts the highest solubility improvement, reaching about 6 mg/ml lorazepam in 30% (w/v) CD solution. When using SBE-7-β-CD or malt-β-CD only half of that concentration can be dissolved. HP-γ-CD interacts much less with lorazepam. Parenteral solutions with 4 mg/ml in 30% (w/v) HP-β-CD solution, with 2 mg/ml in 30% (w/v) SBE-7-β-CD, and with 2 mg/ml lorazepam in 15% (w/v) HP-β-CD, were prepared. Sterile filtration of the formulation needs to be applied because of massive degradation of lorazepam during autoclaving. No precipitation is observed after dilution of the different formulations with (physiological) water or with 5% dextrose in water, which proves their suitability for administration with perfusions. The stability of the preparations was investigated in aqueous medium. During the first month, in all solutions more than 90% of lorazepam remained; after 3 months, less than 60% of lorazepam remained in the solutions with 15% (w/v) HP-β-CD and around 65-70% in the solutions with 30% (w/v) of CDs. Because of this short stability time, the preparations need to be lyophilized.     

The physicochemical characteristics of freeze-dried scutellarin-cyclodextrin tetracomponent complexes

In an effort to improve the solubility of the insoluble drug scutellarin, a novel complexation of scutellarin with β-cyclodextrin (β-CD) was studied. Tetracomponent freeze-dried complex was prepared with scutellarin, β-CD, Hydroxypropyl Methylcellulose (HPMC), and triethanolamine. To confirm complex formation, complex was characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction, and differential scanning calorimetry (DSC). Phase-solubility analysis suggested the soluble complexes having 1:1 stoichiometry. The β-CD solubilization of scutellarin could be improved significantly by combining water-soluble polymer and pH adjuster. Comparing the binary, ternary solid systems with tetrary systems, tetracomponent freeze-dried complex showed the best effect of solubilization. A maximal solubility of scutellarin (23.65 mg/ml) was achieved with tetracomponent freeze-dried complex, up to 148-fold increase over scutellarin solubility in water, and the solubility of scutellarin is 15.35 ug/ml (up to 6-fold) in simulated gastric fluid.     

Pharmacokinetics of doxazosin gastrointestinal therapeutic system after multiple administration in Korean healthy volunteers

Doxazosin mesylate is a selective alpha-adrenoreceptor antagonist for the treatment of hypertension and benign prostatic hyperplasia. A simple high performance liquid chromatographic method has been developed and validated for the quantitative determination of doxazosin in plasma. A reversed phase C18 column was used for the separation of doxazosin and prazosin (internal standard) with a mobile phase composed of water • acetonitrile • triethylamine (68:32:0.2 v/v, pH 5.0) at a flow rate of 1.2 mL/min. The fluorescence detector was operated at 246 (excitation) and 389 nm (emission). Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification of 1 ng/mL. Recovery of doxazosin from human plasma was greater than 93.4%. Doxazosin was stable in human plasma under various storage conditions. This method was used successfully for a pharmacokinetic study in plasma after oral administration of multiple 4-mg dose of doxazosin gastrointestinal therapeutic system formulation to 16 healthy volunteers. At steady state the mean area under the curve for a dosing interval and elimination half-life were calculated to be 367.0 ± 63.5 ng · hr/mL and 29.2 ± 4.5 hr, respectively. There was no difference in pharmacokinetic parameters between male and female.