Validation of an HPLC method on short columns to assay ketoconazole and formaldehyde in shampoo

A New Electrochemical Sensor for the Detection of Ketoconazole Using Carbon Paste Electrode Modified with Sheaf-like Ce-BTC MOF Nanostructure and Ionic Liquid

An ultrasensitive and selective voltammetric sensor with an ultratrace-level detection limit is introduced for ketoconazole (KTC) determination in real samples using a modified carbon paste electrode with a sheaf-like Ce-BTC MOF nanostructure and ionic liquid. The as-synthesized nanostructure was characterized by several techniques, including energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The electrocatalytic performance of the developed electrode was observed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and chronoamperometry. The limit of detection (LOD) of the developed sensor for KTC is 0.04 μM, and the response was found to be in the dynamic concentration range of 0.1-110.0 μM in a phosphate buffer solution. The proposed electrode exhibits acceptable electrocatalytic activity for KTC oxidation with a high sensitivity of 0.1342 μA·μM^-1. The ability of the fabricated sensor to monitor KTC in real aqueous samples is demonstrated using standard addition data.

Pharmaco-Technical Evaluation of Statistically Formulated and Optimized Dual Drug-Loaded Silica Nanoparticles for Improved Antifungal Efficacy and Wound Healing

The current research aimed at designing mesoporous silica nanoparticles (MSNs) for a controlled coadministration of salicylic acid (SA) and ketoconazole (KCZ) to effectively treat highly resistant fungal infections. The sol-gel method was used to formulate MSNs, which were further optimized using central composite rotatable design (CCRD) by investigating mathematical impact of independent formulation variables such as pH, stirring time, and stirring speed on dependent variables entrapment efficiency (EE) and drug release. The selected optimized MSNs and pure drugs were subjected to comparative in vitro/in vivo antifungal studies, skin irritation, cytotoxicity, and histopathological evaluations. The obtained negatively charged (-23.1), free flowing spherical, highly porous structured MSNs having a size distribution of 300-500 nm were suggestive of high storage stability and improved cell proliferation due to enhanced oxygen supply to cells. The physico-chemical evaluation of SA/KCZ-loaded MSNs performed through powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) indicates absolute lack of any interaction between formulation components and successful encapsulation of both drugs in MSNs. The EE_SA, EE_KCZ, SA release, and KCZ release varied significantly from 34 to 89%, 36 to 85%, 39 to 88%, and 43 to 90%, respectively, indicating the quadratic impact of formulation variables on obtained MSNs. For MSNs, the skin tolerability and cell viability percentage rate were also having an extraordinary advantage over suspension of pure drugs. The optimized SA/KCZ-loaded MSNs demonstrated comparatively enhanced in vitro/in vivo antifungal activities and rapid wound healing efficacy in histopathological evaluation without any skin irritation impact, suggesting the MSNs potential for the simultaneous codelivery of antifungal and keratolyic agents in sustained release fashion.

Experimental design in HPLC separation of pharmaceuticals

Design of Experiments (DoE) is an indispensable tool in contemporary drug analysis as it simultaneously balances a number of chromatographic parameters to ensure optimal separation in High Pressure Liquid Chromatography (HPLC). This manuscript briefly outlines the theoretical background of the DOE and provides step-by-step instruction for its implementation in HPLC pharmaceutical practice. It particularly discusses the classification of various design types and their possibilities to rationalize the different stages of HPLC method development workflow, such as the selection of the most influential factors, factors optimization and assessment of the method robustness. Additionally, the application of the DOE-based Analytical Quality by Design (AQbD) concept in the LC method development has been summarized. Recent achievements in the use of DOE in the development of stability-indicating LC and hyphenated LC-MS methods have also been briefly reported. Performing of Quantitative structure retention relationship (QSRR) study enhanced with DOE-based data collection was recomended as a future perspective in description of retention in HPLC system.

Stability-Indicating Validated Novel RP-HPLC Method for Simultaneous Estimation of Methylparaben, Ketoconazole, and Mometasone Furoate in Topical Pharmaceutical Dosage Formulation

A simple, specific, precise, and accurate RP-HPLC method has been developed and validated for simultaneous estimation of Methylparaben (MP), Ketoconazole (KT), and Mometasone Furoate (MF) topical pharmaceutical dosage formulation. The separation was achieved by Waters X Terra C18 column using mobile phase consisting of buffer (triethyl amine in water, pH adjusted to 6.5 with glacial acetic acid)-acetonitrile (40 : 60, v/v) at a flow rate of 1.5 mL/min and detection at 250 nm. The method showed linearity with correlation coefficient <0.9999 over the range of 0.12–15.2 μg/mL, 0.67–149.4 μg/mL, and 0.42–7.6 μg/mL for MP, KT, and MF, respectively. The mean recoveries were found to be in the range of 99.9–101.1% for all the components. The method was validated as per the ICH guidelines for linearity, limit of detection, limit of quantification, accuracy, precision, robustness and solution stability. Stability indicating capability of the developed method was established by analyzing forced degradation of samples in which spectral purity of MP, KT, and MF along with separation of degradation products from analytes peak was achieved. The method can be successfully applied for routine analysis of quantitative determination of MP, KT, and MF in pharmaceutical dosage form.

Formaldehyde in hair straightening products: rapid ¹H NMR determination and risk assessment

Despite official regulations, the illegal use of formaldehyde-containing or releasing hair straightening products has become a popular practice in Europe and high contents of formaldehyde in such products have been reported. In this study, a methodology utilizing (1)H NMR spectroscopy has been developed to measure the concentration of formaldehyde in hair straightening products. For sample preparation, a dilution and alkaline hydrolysis is required. The total formaldehyde content can then be quantified by a distinct peak of the CH2 group of the methanediol molecule in the δ4.84-4.82 ppm range. The developed methodology was applied for the analysis of 10 hair straightening products. Seven of these products contained detectable amounts of formaldehyde that were higher than the maximum allowed concentration of 0.2%. The formaldehyde content of these products was found to be in the range 0.42-5.83% with an average concentration of 1.46%. The accuracy and reliability of the NMR results were confirmed by the EU reference photometric method. The air formaldehyde concentrations after application of hair straightening products were estimated in ranges 20-423 ppm and 1-18 ppm (for 1 and 24 m(3) salon volume). A probabilistic exposure estimation using Monte Carlo simulation found the average formaldehyde concentration to be 6 ppm (standard deviation 15 ppm). All exposure scenarios considerably exceeded the safe level of 0.1 ppm. Our findings confirmed that the risk of cosmetic formulations with formaldehyde above 0.2% is not negligible, as these products may facilitate considerable exposure of formaldehyde for consumers especially for salon workers.

Identification of major degradation products of ketoconazole

Analytical methods were developed for the identification of major degradation products of Ketoconazole, an antifungal agent. The stressed degradation of Ketoconazole drug substance was performed under acid, base, thermal, photo and oxidative stress conditions. The major degradation was observed under acid, base and oxidative stress conditions. The degradation study was performed on Inertsil ODS-3V, length 100 X diameter 4.6 mm, particle size 3 μm column using gradient method. These degradants were identified by LC-MS technique.

Determination of trace formaldehyde in blood plasma by resonance fluorescence technology

A novel method for the determination of trace formaldehyde in blood plasma has been established by using resonance fluorimetry technique. It was based on the fact that oxidation of pyronine Y by potassium bromate was catalyzed by formaldehyde in sulfuric acid. When the wavelength interval was at Δλ=0 nm, it was found that the decreased intensity (ΔF) of resonance fluorescence at 574.6 nm was proportional to the concentration of formaldehyde in the range of 1.27×10(-2) to 2.28 μg mL(-1). The limit of detection and the average recovery for formaldehyde were 3.80 ng mL(-1) and 101.6% (n=6), respectively. The present method had been applied to the determination of trace formaldehyde in blood plasma, and the obtained results were in good agreement with those obtained by the resonance light scattering method.

Ruggedness and robustness testing

Due to the strict regulatory requirements, especially in pharmaceutical analysis, analysis results with an acceptable quality should be reported. Thus, a proper validation of the measurement method is required. In this context, ruggedness and robustness testing becomes increasingly more important. In this review, the definitions of ruggedness and robustness are given, followed by a short explanation of the different approaches applied to examine the ruggedness or the robustness of an analytical method. Then, case studies, describing ruggedness or robustness tests of high-performance liquid chromatographic (HPLC), capillary electrophoretic (CE), gas chromatographic (GC), supercritical fluid chromatographic (SFC), and ultra-performance liquid chromatographic (UPLC) assay methods, are critically reviewed and discussed. Mainly publications of the last 10 years are considered.

Fast analysis in liquid chromatography using small particle size and high pressure

In order to enhance chromatographic performances in terms of efficiency and rapidity, LC has recently evolved in the development of short columns packed with small particles (sub-2 microm) working at high pressures (> 400 bar). This approach has been described 30 years ago according to the fundamental chromatographic equations. However, systems and columns compatible with such high pressures have been introduced in the market in 2004 only. Advantages of small particles working at high pressure will be discussed in terms of sensitivity, efficiency, resolution, and analysis time. Potential problems encountered with high pressure in terms of frictional heating and solvent compressibility will also be discussed even if systems working at a maximum pressure of 1000 bar are not influenced by these parameters and give reliable and reproducible results. Several applications will highlight the potential and interest of this new technology.

Robustness study of a reversed-phase liquid chromatographic method for the analysis of carboxylic acids in industrial reaction mixtures

The robustness study of the reversed-phase liquid chromatographic method developed for the quantitative analysis of carboxylic acids is a real asset to prepare method transfer because it provides an indication of its reliability during routine use. Indeed, it was possible to predict the consequences of small variations in operating conditions on the responses. The design of experiments approach was applied to model the effects and interactions of a high number of factors varying simultaneously with a limited number of runs. First we identified the factors which potentially affect the chromatographic responses used for carboxylic acids quantitation: detection wavelength (lambda), column temperature (T), acetonitrile ratio in mobile phase (Me), duration of the plateau before the gradient (L) and gradient slope (S). Then we estimated the order of magnitude of realistic variations to assign factor levels. Finally a central composite design was carried out around the nominal conditions defined during method optimization. The statistical treatment of responses (retention factors, and concentrations) showed that the column temperature, the acetonitrile ratio in the mobile phase, the duration of the plateau before the gradient and the gradient slope were the most influent factors. The building of the robust domain from response-surfaces allowed us to give tolerance limits for the factors (216 nm< lambda <222 nm, 49.3 degrees C < T < 51.4 degrees C, 4.90% < Me < 5.18%, v/v, 4.5 min < L < 5.4 min, 9%< S <11%) for which the performances of the method were maintained.

SLN and NLC for topical delivery of ketoconazole

The clinical use of ketoconazole has been related to some adverse effects in healthy adults, specially local reactions, such as severe irritation, pruritus and stinging. The purpose of the present work is the assessment of ketoconazole stability in aqueous SLN and NLC dispersions, as well as the physicochemical stability of these lipid nanoparticles, which might be useful for targeting this drug into topical route, minimizing the adverse side effects and providing a controlled release. Lipid particles were prepared using Compritol 888 ATO as solid lipid. The natural antioxidant alpha-tocopherol was selected as liquid lipid compound for the preparation of NLC. Ketoconazole loading capacity was identical for both SLN and NLC systems (5% of particle mass). SLN were physically stable as suspensions during 3 months of storage, but the SLN matrix was not able to protect the chemically labile ketoconazole against degradation under light exposure. In contrast, the NLC were able to stabilize the drug, but the aqueous NLC dispersion showed size increase during storage. Potential topical formulations are light-protected packaged SLN or NLC physically stabilized in a gel formulation.

Flow gradient liquid chromatography using a coated anion exchange microcolumn

Ion chromatography on a 4.0-mm-long (3.0 mm ID) ion exchange column is presented. Using a 10 mM phosphate buffer (pH 2.22) the separation of up to six UV-absorbing anions was obtained using the microcolumn, containing 5 microm RP support (Phenomenex Gemini) coated with the zwitterionic surfactant, (N-dodecyl-N,N-dimethylammonio) undecanoate. The short analytical column facilitated the application of a flow gradient programme over the flow range 0.3-5 mL/min resulting in optimum resolution of nitrite, nitrate, benzoate, iodide, thiocyanate and trichloroacetate in less than 10 min. The effect of both eluent concentration and pH on the retention of six selected anions was investigated, showing a strong pH capacity dependence. The microcolumn was found to exhibit no selectivity towards chloride and so was well suited to the analysis of saline samples. To illustrate this, the rapid analysis of a concentrated iodized table salt sample (20 g/L) was carried out. Following standard addition, a concentration of 3.55 +/- 0.05 microg iodide/g and 1.05 +/- 0.02 microg iodate/g in the solid salt sample was determined.

Determination of Magnesium Stearate in Pharmaceutical Preparations Using Derivatization with 2-Nitrophenylhydrazine and HPLC

In general, spectrophotometric methods (inductively coupled plasma or atomic absorption spectrophotometry) are used for the assay of magnesium stearate (Mg-St). In this study, a new rapid, selective assay method was developed for Mg-St in pharmaceutical formulations. The method was based on isocratic reverse-phase liquid chromatography using a mobile phase of acetonitrile-water (80:20, v/v) after precolumn derivatization with 2-nitrophenyl hydrazine for sensitive UV detection. Margaric acid was used as an internal standard and the substances were detectable at 230 nm or 400 nm. Using a short (2 cm) HPLC column reduced the analytical time to 5 min. Validation of the newly developed method was performed in accordance with the International Conference on Harmonization guidelines. The linearity range for Mg-St was 0.00-0.04 mg/ml (as the concentration of injected sample solution) and their correlation factor was 0.9998. The determination and detection limits for Mg-St were 6 microg and 2 microg, respectively. The proposed method was successfully applied to the determination of trace amounts of Mg-St in commercially available tablets with a high recovery percentage, good accuracy, and precision.

Microbiological assay of ketoconazole in shampoo

Ketoconazole, an anti-fungal agent, is often incorporated in several pharmaceutical forms and in shampoo formulation it is known to be effective against fungal infection on the scalp. This paper describes a method to quantify ketoconazole in shampoo by comparing the cylinder plate assay and the HPLC method. The test organism used for the agar diffusion assay was Candida albicans ATCC 10231. Three different concentrations of ketoconazole were used for the diffusion assay. A mean zone diameter was obtained for each concentration. A standard curve was obtained by plotting the three values derived from the zone diameters. A prospective validation of the method showed that the method was linear (r = 0.9982), precise (R.S.D. = 2.57%) and accurate. The results obtained by the two methods were statistically evaluated by analysis of variance (ANOVA) and the results obtained indicate that there is no significant difference between these two methods.

Evaluating “Fast” Micellar Monolithic Liquid Chromatography for High-Throughput Quantitative Structure−Retention Relationship Screening

The recently introduced monolithic silica columns were tested for their use in micellar liquid chromatography. Micellar methods are utilized in high-throughput quantitative structure-retention relationships to estimate an indicator of the membrane permeability of drugs, namely, the octanol-water partition coefficient, log P. The monolithic column's ability to function at higher flow rates might be useful to speed up these chromatographic methods estimating the log P. Therefore, the elution behavior of diverse basic pharmaceutical substances was determined on a classical particle-based and a monolithic column, both with and without a micellar medium in the mobile phase. Utilizing among others principal component analysis, the extent to which these methods differ in retention characteristics was examined in the context of high-throughput determination of log P. Results indicate that combining monolithic columns with micellar media leads to faster log P and possibly even better permeability predictions.

Recent Advances in the Analysis of Steroid Hormones and Related Drugs

The development during the last 15 years and the state-of-the-art in the analysis of bulk steroid hormone drugs and hormone-like structures and pharmaceutical formulations made thereof are summarized. Other steroids (sterols, bile acids, cardiac glycosides, vitamins D) as well as biological-clinical aspects and pharmacokinetic and metabolic studies are excluded from this review. The state-of-the-art is summarized based on comparisons of monographs in the latest editions of the European Pharmacopoeia, United States Pharmacopoeia and the Japanese Pharmacopoeia. This is followed by sections dealing with new developments in the methodology for the fields of spectroscopic and spectrophotometric, chromatographic, electrophoretic and hyphenated techniques as well electroanalytical methods. The review is terminated by two problem-oriented sections: examples on impurity and degradation profiling as well as enantiomeric analysis.

Robustness testing of chiral separations by capillary electrophoresis using highly-sulfated cyclodextrins

The robustness of a generic method for chiral separation in capillary electrophoresis using highly-sulfated cyclodextrins in a low pH phosphate buffer and the "short-end injection technique" was studied. In this study, we focused on the robustness of the separations and not of the quantitative analysis of the enantiomers. The robustness was evaluated for the enantiomeric separation of a basic (propranolol), a neutral (praziquantel) and an acidic (warfarin) compound. The influence of eight factors which were believed to affect significantly the separations was studied using a 11-factor, 12-experiment Plackett-design. Statistical interpretation of the factor effects on different analytical responses (selectivity and resolution) was performed. The separations of the three compounds could be considered as rather robust as the factor effects were generally not significant (alpha = 0.05) and small.