Coupling of Physical and Chromatographic Separation for Analyzing Cream Containing Miconazole, Mometasone Furoate and Gentamicin Sulphate.

High-performance liquid chromatographic method was developed, validated and applied for miconazole, mometasone and gentamicin in Momenta® cream. Physical separation was applied using two extraction procedures due to different solubility of the three components. First, a methanolic extract of the cream contained miconazole and mometasone was chromatographed on ODS-3 Inertsil C18 column (150 × 4.6, 5 µm) using acetonitrile: water (80:20, v/v) as a mobile phase, flow rate 1.5 mL·min-1, scanned at 230 nm, showing tR 2.817 and 6.808 min for mometasone and miconazole, respectively. Second, an aqueous extract of the cream containing gentamicin was derivatized with o-phthalaldehyde in order to enhance the gentamicin UV detection and subjected to ion pairing chromatography on Inertsil ODS-3 C18 column (150 × 4.6, 5 µm), using methanol: 0.025 M heptane sulphonic acid: glacial acetic acid (75:20:5, by volume) as a mobile phase, flow rate 0.8 mL·min-1, scanned at 330 nm where the three active gentamicin isomers were separated at tR 11.7, 15.6 and 18.3 min. Suitability of this method for quantitative estimation of the drugs was proved by validation according to ICH guidelines. The method was selective, precise and accurate so could be used for analysis of cream formulation in QC labs.

Comparative Study of the Selectivity Power of Colorimetric Method Over Chromatographic Methods for the Analysis of Valaciclovir Hydrochloride.

BACKGROUND: Valaciclovir hydrochloride (VAL) is an essential antiviral prodrug used to cure various types of herpes. Analysis of VAL by different analytical techniques demonstrates a persuasive aspect that is favorable in quality control application. OBJECTIVE: This study describes a comparison between colorimetric and chromatographic (RP-high performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)-densitometric) methods concerning selectivity and specificity for the determination of VAL in all possible degradation products (alkali- and acid-induced degradation products, namely aciclovir [ACI] and guanine [GUA], respectively) in their synthetic mixture and pharmaceutical formulations. METHOD: The colorimetric method was accomplished by forming a highly colored complex with ferric hydroxamate reagent measured at 493 nm in the concentration range (0.20-1.60 mg/mL). Both chromatographic methods were successfully applied using ultraviolet (UV) detection at 256 nm in the concentration range (2.00-5.00 µg/mL) for the RP-HPLC method and (10.00-900.00 ng/band) for the TLC-densitometric method. RESULTS: The linearity studies, regression equations, assay parameters, and validation sheet of the proposed colorimetric and chromatographic methods to determine VAL were obtained with highly acceptable values. CONCLUSIONS: The International Council for Harmonization (ICH) guidelines were followed to validate the described methods and the statistical comparison regarding both accuracy and precision, and satisfactory results were accomplished. HIGHLIGHTS: In this study, we configure a full comparative study between different analytical methods for the analysis of challengeable mixture containing the drug of interest, VAL, along with its degradation products, ACI and GUA.

TLC-smartphone in antibiotics determination and low-quality pharmaceuticals detection.

Thin layer chromatography (TLC) is a powerful and simple technique for screening and quantifying low quality and counterfeit pharmaceutical products. The detection methods used to detect and quantify separate analytes in TLC ranges from the densitometric method to mass spectrometric or Raman spectroscopic methods. This work describes the development and optimization of a simple and sensitive TLC method utilizing a smartphone CCD camera for verification of both identity and quantity of antibiotics in dosage form, namely ofloxacin and ornidazole. Mixtures of ofloxacin and ornidazole were chromatographed on a silica gel 60 F254 plate as a stationary phase. The optimized mobile phase is n-butanol : methanol : ammonia (8 : 1 : 1.5 by volume). Iodine vapor has been used as a "universal stain" to visualize the spots on the TLC plates in order to obtain a visual image using the smartphone camera and a desk lamp as an illumination source, thus eliminating the need for a UV illumination source. The recorded images were processed to calculate the R f values (R f values for ofloxacin and ornidazole were 0.12 and 0.76, respectively) which provide identity of the drugs while spot intensity was calculated using a commercially available smartphone app and employed for quantitative analysis of the antibiotics and "acetaminophen" as an example of a counterfeit substance. The smartphone TLC method yielded a linearity of ofloxacin and ornidazole in the range of 12.5-62.5 µg/band and 500-1000 µg/band, respectively. The limit of detection was found to be 1.6 µg/spot for ofloxacin and 97.8 µg/spot for ornidazole. The proposed method was compared with the bench top densitometric method for verification using a Camag TLC Scanner 3, the spot areas were scanned at 320 nm. The R f value of ofloxacin and ornidazole was calculated to be 0.12 and 0.76, respectively. The densitometric method yielded a linearity of ofloxacin and ornidazole in the range of 5-40 µg/band and 5-50 µg/band, respectively. The limit of detection was found to be 0.8 µg/spot for ofloxacin and 1.1 µg/spot for ornidazole. The proposed method has been successfully applied for the determination of ofloxacin and ornidazole present in more than one pharmaceutical dosage form and was comparable to the densitometric method.

Monitoring of Clotrimazole Degradation Pathway in Presence of its Co-formulated Drug.

Two stability-indicating chromatographic methods for the determination of clotrimazole and its two acid induced degradation products, with dexamethasone acetate without prior separation. First method depends on RP-HPLC utilizing ODS-3 Inertsil C18 column. Mobile phase consists of acetonitrile:phosphate buffer (pH 6.0) in ratio (65:35, v/v) with flow rate 1.5 mL/min and UV-detection at 220 nm. Linearity range 1.0-75.0 µg/mL for clotrimazole and 2.0-75.0 µg/mL for dexamethasone with mean percentage recovery of 99.49 ± 1.10 for CLT and 99.60 ± 1.06 for DA. Second method depends on HP-TLC. Developing system is composed of chloroform:ethyl acetate in the ratio of (5:3.5, v/v), scanned at 220 nm. Linearity range 1.0-12.0 µg/band for clotrimazole and 1.0-20.0 µg/band for dexamethasone with mean R% of 99.33 ± 0.76 for clotrimazole and 99.77 ± 0.99 for dexamethasone. Conditions and parameters affecting the separation of the cited components without interference of the degradation products are tested and optimized. Suitability of the methods for quantization of the drugs concentrations is proven by validation as instructed from the ICH. Validation results and statistical treatment of the data demonstrate reliability of these methods. Kinetics of acid degradation process of clotrimazole are investigated by the proposed HPLC method and the order rate constant, half life and shelf life are computed.

Spectrophotometric resolution of the severely overlapped spectra of clotrimazole with dexamethasone in cream dosage form by mathematical manipulation steps.

Several spectrophotometric techniques were recently conducted for the determination of binary mixtures of clotrimazole (CLT) and dexamethasone acetate (DA) without any separation procedure. The methods were based on generation of ratio spectra of mixture then applying simple mathematic manipulation. The zero order absorption spectra of both drugs could be obtained by the constant center (CC) method. The concentration of both CLT and DA could be obtained by constant value via amplitude difference (CV-AD) method depending on ratio spectra, Ratio difference (RD) method where the difference between the amplitudes at two wavelengths (ΔP) on the ratio spectra could eliminate the contribution of the interfering substance and bring the concentration of the other, and the derivative ratio (DD1) method where the derivative of the ratio spectra was able to determine the drug of interest without any interference of the other one. While the concentration of DA could be measured after graphical manipulation as concentration using the novel advanced concentration value method (ACV). Calibration graphs were linear in the range of 75-550 µg/mL for CLT and 2-20 µg/mL for DA. The methods applied to the binary mixture under study were successfully applied for the simultaneous determination of the two drugs in synthetic mixtures and in their combined form Mycuten-D cream. The results obtained were compared statistically to each other and to the official methods.

Comparative study of the efficiency of computed univariate and multivariate methods for the estimation of the binary mixture of clotrimazole and dexamethasone using two different spectral regions.

Three methods of analysis are conducted that need computational procedures by the Matlab® software. The first is the univariate mean centering method which eliminates the interfering signal of the one component at a selected wave length leaving the amplitude measured to represent the component of interest only. The other two multivariate methods named PLS and PCR depend on a large number of variables that lead to extraction of the maximum amount of information required to determine the component of interest in the presence of the other. Good accurate and precise results are obtained from the three methods for determining clotrimazole in the linearity range 1-12 µg/mL and 75-550 µg/mL with dexamethasone acetate 2-20 µg/mL in synthetic mixtures and pharmaceutical formulation using two different spectral regions 205-240 nm and 233-278 nm. The results obtained are compared statistically to each other and to the official methods.

Evaluation of graphical and statistical representation of analytical signals of spectrophotometric methods.

Simultaneous determination of miconazole (MIC), mometasone furaoate (MF), and gentamicin (GEN) in their pharmaceutical combination. Gentamicin determination is based on derivatization with of o-phthalaldehyde reagent (OPA) without any interference of other cited drugs, while the spectra of MIC and MF are resolved using both successive and progressive resolution techniques. The first derivative spectrum of MF is measured using constant multiplication or spectrum subtraction, while its recovered zero order spectrum is obtained using derivative transformation. Beside the application of constant value method. Zero order spectrum of MIC is obtained by derivative transformation after getting its first derivative spectrum by derivative subtraction method. The novel method namely, differential amplitude modulation is used to get the concentration of MF and MIC, while the novel graphical method namely, concentration value is used to get the concentration of MIC, MF, and GEN. Accuracy and precision testing of the developed methods show good results. Specificity of the methods is ensured and is successfully applied for the analysis of pharmaceutical formulation of the three drugs in combination. ICH guidelines are used for validation of the proposed methods. Statistical data are calculated, and the results are satisfactory revealing no significant difference regarding accuracy and precision.

Mean centering of ratio spectra and concentration augmented classical least squares in a comparative approach for quantitation of spectrally overlapped bands of antihypertensives in formulations.

Two different methods manipulating spectrophotometric data have been developed, validated and compared. One is capable of removing the signal of any interfering components at the selected wavelength of the component of interest (univariate). The other includes more variables and extracts maximum information to determine the component of interest in the presence of other components (multivariate). The applied methods are smart, simple, accurate, sensitive, precise and capable of determination of spectrally overlapped antihypertensives; hydrochlorothiazide (HCT), irbesartan (IRB) and candesartan (CAN). Mean centering of ratio spectra (MCR) and concentration residual augmented classical least-squares method (CRACLS) were developed and their efficiency was compared. CRACLS is a simple method that is capable of extracting the pure spectral profiles of each component in a mixture. Correlation was calculated between the estimated and pure spectra and was found to be 0.9998, 0.9987 and 0.9992 for HCT, IRB and CAN, respectively. The methods were successfully determined the three components in bulk powder, laboratory-prepared mixtures, and combined dosage forms. The results obtained were compared statistically with each other and to those of the official methods.

Simultaneous determination of some anti-hypertensive drugs in their binary mixture by novel spectrophotometric methods.

Three simple, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Irbesartan (IRB) and Hydrochlorothiazide (HCT) without prior separation namely; ratio subtraction coupled with constant multiplication (RS-CM), ratio difference (RD) and constant center (CC). The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the cited drugs. The three methods were applied for the determination of the cited drugs in tablets and the obtained results were statistically compared with each other and with those of official methods. The comparison showed that there is no significant difference between the proposed methods and the official methods regarding both accuracy and precision.