Simultaneous determination of some cholesterol-lowering drugs in their binary mixture by novel spectrophotometric methods

Spectrum subtraction as a complementary method for six resolution techniques resolving overlapping spectra; application to multicomponent veterinary formulation with greenness and whiteness assessment

Mathematical filtration is an efficient tool to resolve the overlapping spectra of binary mixtures in zero or first order form. Herein, a comparative study was conducted between six economic, accurate and precise spectrophotometric methods for determination of Triclabendazole (TCB) and Levamisole HCl (LVM). Each component was resolved with minimum mathematical steps in its zero-order absorption spectrum by ratio subtraction, constant multiplication, and the recent factorized response method; coupled with spectrum subtraction. In addition, the mixture was resolved in its first derivative form by derivative subtraction, D1 constant multiplication, and the recent D1 factorized response method; coupled with spectrum subtraction. Results obtained were also compared to those obtained from constant value, concentration value, and derivative ratio methods. The linearity range was found to be either 1.0-10.0 µg/mL or 2.0-20.0 µg/mL for TCB, and 2.0-14.0 µg/mL for LVM with LOD of 0.08 µg/mL and 0.19 µg/mL, respectively. Validation of the proposed methods was performed according to VICH guidelines. Results obtained from the statistical data showed no significant difference regarding accuracy and precision compared to the reported methods. The developed spectrophotometric methods followed the principles of green analytical chemistry, in which the green assessment was done through four tools, called, National Environmental Methods Index (NEMI), Analytical Eco-Scale (AES), Green Analytical Procedure Index (GAPI) and Analytical greenness metric (AGREE). Also, a white assessment was performed using RGB model. The proposed methods could offer an economic alternative for the routine analysis of bulk materials and combined veterinary dosage form.

Green-assisted spectrophotometric techniques utilizing mathematical and ratio spectra manipulations to resolve severely overlapped spectra of a cardiovascular pharmaceutical mixture

Cardiovascular diseases, in particular hypertension and hypercholesterolemia, are two of the main causes of death worldwide. These conditions are silent killer syndromes that need a variety of pharmacological treatments to be effectively controlled. This study introduces novel, environmentally friendly spectrophotometric techniques for the simultaneous determination of telmisartan (TMS) and rosuvastatin calcium (RVS) in their pharmaceutical dosage forms. For the simultaneous determination of the binary mixture, the suggested methods included the dual wavelength method (DWM) which utilizes mainly the absorbance difference at 233 nm and 253 for TMS determination and, the absorbance difference at 274 nm and 310 for RVS determination as the selected wavelengths for each drug is directly proportional to the drug of interest independent on the other interfering component. The Fourier-self deconvolutions method (FSDM) depends on compressing their bandwidth to resolve the overlap. Ratio difference spectrophotometric method (RDSM) that utilizes TMS 35 μg.mL^-1 and RVS 20 μg.mL^-1, respectively as divisors to produce the ratio spectra for each drug. Further manipulation of the produced ratio spectra was applied for the determination of the two drugs. Mean centering method (MCM) where a suitable wavelength range was chosen to exclusively use the informative portions and prevent experimental spectrum noises. The investigated methods showed good levels of detection and quantification together with excellent linearity. The suggested methods' greenness was evaluated using two different greenness evaluation tools, which showed that the methods were green in terms of several factors, including the safety of the chemicals, instruments, and waste. The validity of the methodologieswas investigated by resolving prepared laboratory mixtureswith varying TMS and RVS ratios. The standard addition method also assured the newly added methods. Finally, statistical analysis using the reported method did not reveal any appreciable differences in terms of accuracy and precision. The developed methods can be employed in quality control laboratories to ascertain the binary mixture due to their high precision and affordability.

The simultaneous measurement of quaternary mixture in over-the-counter cold medications using sequential spectrophotometric resolution approach enhanced with in-lab sample enrichment

A sequential spectrophotometric resolution technique (SSRT) was developed in this study without the use of systematic separation procedures to determine drug of a quaternary combination; caffeine (CAF), pseudoephedrine (PSE), doxylamine succinate (DOX), and paracetamol (PAR). Their presence in a tablet with a gap ratio of 3:3:1:150, respectively, and their overlapping spectra with low absorptivities make their resolution and determination impossible without prior separation. successive ratio subtraction technique (SRST) and constant multiplication method were used to solve these problems. Furthermore, an in-lab sample enrichment technique was applied to increase minor components concentration and consequently their absorbanses (CAF, PSE, and DOX). The D⁰ absorption spectra were generated by successive ratios followed by subtraction and multiplication of the constants. The maximum absorbances of the drugs tested, namely (CAF, PSE, DOX and PAR) were measured at wavelengths of 272.0, 257.0, 260.0, and 248.0 nm, respectively. The limits of detection (LOD) and limits of quantification (LOQ) were 0.021, 0.124, 0.186, 0.137 and 0.070, 0.414, 0.621, 0.456 (µg/mL), respectively. The linearitiy ranges (µg/mL) were 1.0-22.0, 1.0-24.0, 10.0-90.0 and 1.0-15.0 for CAF, PSE, DOX, and PAR, respectively. The International Conference on Harmonization (ICH) guidelines were applied for method validation, and the results obtained were within the limited parameters. The finding results were compared to official and/or published analytical methods to determine the procedure's reliability. It was noted that there was no actual difference in accuracy and precision between both meyhods. The proposed technique is sensitive, selective and economic;so it can be applied to the simultaneous analysis of these drugs in their commercial tablets and/or in quality-control laboratories.

Smart UV-spectrophotometric platforms for rapid green analysis of miconazole nitrate and nystatin in their combined suppositories and in vitro dissolution testing

Miconazole nitrate (MIC) and nystatin (NYS) combination has proven its effectiveness as a prodigious therapy to cure women's common infections; vaginal candidiasis and vaginal mycosis. Herein, six smart UV-spectrophotometric platforms depending on minimal mathematical manipulation steps were first introduced for the simultaneous green analysis of MIC and NYS in their pure forms and commercial vaginal suppositories without any preliminary separation steps. These platforms included dual-wavelength, ratio difference, mean centering of ratio spectra, first derivative ratio, ratio subtraction, and absorption correction methods. All of the aforementioned platforms could estimate MIC in a linear range of 90-900 µg/ml. While NYS was computed directly by zero-order spectrophotometry at its λ_max (304 nm) in a linear range of 1-15 µg/ml without any interference by MIC even in low or high concentrations. Dual-wavelength and zero-order spectrophotometric platforms were successfully applied to study the dissolution profile of MIC and NYS in their combined formulation in compliance with FDA recommendations without excipients interference. According to ICH guidelines, all platforms were validated regarding the accuracy, precision, and selectivity producing satisfactory results within the accepted limits. Also, the suggested platforms' results were statistically compared with each other and with those of the reported HPLC platform revealing no significant difference concerning accuracy and precision at p = .05. Accordingly, all proposed platforms are regarded as economic and eco-friendly alternatives to the expensive chromatographic platforms that utilize hazardous organic solvents during the analysis of cited drugs.

Development of Ecofriendly Derivative Spectrophotometric Methods for the Simultaneous Quantitative Analysis of Remogliflozin and Vildagliptin from Formulation

Three rapid, accurate, and ecofriendly processed spectrophotometric methods were validated for the concurrent quantification of remogliflozin (RGE) and vildagliptin (VGN) from formulations using water as dilution solvent. The three methods developed were based on the calculation of the peak height of the first derivative absorption spectra at zero-crossing points, the peak amplitude difference at selected wavelengths of the peak and valley of the ratio spectra, and the peak height of the ratio first derivative spectra. All three methods were validated adapting the ICH regulations. Both the analytes showed a worthy linearity in the concentration of 1 to 60 µg/mL and 2 to 90 µg/mL for VGN and RGE, respectively, with an exceptional regression coefficient (r2 ≥ 0.999). The developed methods demonstrated an excellent recovery (98.00% to 102%), a lower percent relative standard deviation, and a relative error (less than ±2%), confirming the specificity, precision, and accuracy of the proposed methods. In addition, validated spectrophotometric methods were commendably employed for the simultaneous determination of VGN and RGE from solutions prepared in the laboratory and the formulation. Hence, these methods can be utilized for the routine quality control study of the pharmaceutical preparations of VGN and RGE in pharmaceutical industries and laboratories. The ecofriendly nature of the anticipated spectrophotometric procedures was confirmed by the evaluation of the greenness profile by a semi-quantitative method and the quantitative and qualitative green analytical procedure index (GAPI) method.

A comparative study of novel spectrophotometric methods for simultaneous determination of nitroaniline isomers in their binary mixtures with highly severe overlapping spectra

In the present work, four simple and economic spectrophotometric methods, namely constant center (CC), ratio difference (RD), H-point standard addition method (HPSAM), and ratio H-point standard addition method (RHPSAM) were employed for the simultaneous determination of meta and para-nitroaniline with severely overlapping spectra without unitizing the preliminary physical separation techniques. In each method, the parameters affecting the resolution of the spectra were optimized to determine the cited isomers in a binary mixture with a high accuracy. Under the optimized conditions, the results obtained showed that from cited methods used, the CC and RD methods have the least errors in determination of the concentration of highly spectral overlapping species. The mean percentage recovery values for the binary mixture of meta- and para-nitroaniline were found to be 95.98 and 98.78 using the RD method, and 101.85 and 100.23 using the CC method, respectively. For comparison of the powerful multivariate methods including the principal component regression (PCR) and partial least squares (PLS) were also applied. The mean percentage recovery values for the binary mixtures of the cited isomers were found to be 101.62 and 101.47 using the PCR method, and 101.00 and 101.36 using the PLS method, respectively. A statistical comparison of the methods demonstrated that there was no significant difference between the RD, CC, PCR, and PLS methods and the reported HPLC method regarding both accuracy and precision. The proposed methods have an admissible precision and accuracy for determination of the two isomers in their binary mixtures in tap water as a real sample.

Green spectrophotometric methods for the determination of a binary mixture of lidocaine hydrochloride and cetylpyridinium chloride in the presence of dimethylaniline

Three green, simple, precise, accurate and sensitive spectrophotometric methods were developed for the determination of a binary mixture of lidocaine hydrochloride (LDC) and cetylpyridinium chloride (CPC) in the presence of dimethylaniline (DMA). In the three methods, the interference of DMA spectrum is eliminated using the ratio subtraction method. Method (A) depended on determining LDC and CPC by measuring the first derivative of the ratio spectra (¹DD) at 271.0 and 268.4 nm, respectively. Method (B) was the ratio difference (RD), based on dividing the absorption spectrum of the binary mixture by a standard spectrum of CPC or LDC, then measuring the amplitude difference of the ratio spectra (∆P) between 231.2 and 240.0 nm for LDC and between 242.8 and 258.0 nm for CPC. Method (C) based on the application of dual wavelength coupled with the isoabsorptive point method. This was achieved by measuring the absorbance difference (∆A) between 243.0 and 268.6 nm for the determination of LDC, followed by application of isoabsorptive point method comprised of measurement the total content of the mixture of LDC and CPC at their isoabsorptive point at 240.0 nm. The content of CPC was obtained by subtraction. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures containing different ratios of LDC and CPC in presence of DMA. The proposed methods displayed useful analytical characteristics for the determination of LDC and CPC in bulk powder and their combined dosage form. The obtained results were statistically compared with those obtained by the official methods, showing no significant difference with respect to accuracy and precision.

The concept of Relative Absorptivity Distribution for enhancing disbanding power of spectrophotometric technique to resolve co-formulated tablets: A tool for purity index and uniformity assessment

Resolving the spectral bands of the drugs into their discrete constituents is critical for an effective mathematical spectrophotometric method. The spectral resolution is ordinarily affected by the required application. In the current work an innovative, simple and green Relative Absorptivity Distribution (RAD) concept was established for the successful assay and assessing of content uniformity and purity index of tablet co-formulation which is recommended for lowering the blood glucose level and is comprised of Cangliflozin (CGF) and Metformin CGF and MTF. From the spectrophotometric perspective, the investigation of this combination is challenging as the composition of the tablets is CGF:MTF (1:17), where CGF is not only the minor analyte but also the one of lower absorptivity. The RAD concept is based on the production of master Resolving Spectra (RS). Within the RAD concept and according to the manipulation used for the generation of the RS, three different univariate mathematic methods via spectrophotometer software were developed. The proposed methods are characterized by the ability of extracting the raw spectra of each investigated analyte separately, consequently, enabling each analyte to be determined at its λ_max without the contribution of the other. The proposed methods had analyzed CGF in the range 1.0-30.0 μg/mL and MTF within the range 1.0-20.0 μg/mL. The guidelines of the ICH were performed for the complete validation of all methods and the results confirmed satisfactory accuracy, precision and selectivity. The accomplished results together with the simplicity and low-cost of all methods suggested their suitability for the routine quality control analysis of bulk materials, assay of the pharmaceutical formulations and evaluating the content uniformity. Statistical comparison of the results with those of reported HPLC method showed good agreement. In addition, the environmental impact of the proposed methods was assessed by utilizing the National Environmental Methods Index (NEMI), the Analytical Eco-Scale and the Green Analytical Procedure Index (GAPI) where the three tools confirmed the environmentally friendly nature of all proposed methods.

Paired wavelength relevance as spectrophotometric strategy for evaluation the potency of medicine affecting human health

Paired wavelength relevance as spectrophotometric strategy was carried for simultaneous analysis of unresolved bands of doxycycline hydrochloride (DOX) and tylosin tartrate (TYT) as an example of veterinary binary mixture. These methods based on the relation between two points on the scanned or manipulated spectra (derivative, ratio). The methods using the absorbance difference between two wavelengths namely, dual wavelength (DW), induced dual wavelength (IDW), absorption correction (AC) and advanced absorbance subtraction (AAS) or amplitude difference namely, ratio difference (RD), amplitude subtraction namely, amplitude correction (PC) and advanced amplitude modulation (AAM) as well as amplitude addition namely, derivative ratio (DD¹). Calibration graphs are direct relation in the range of (5-40) μg/mL for doxycycline hydrochloride and (5-45) μg/mL for tylosin tartrate. The suggested methods was successfully applied for evaluate the potency of their veterinary medicine that has direct affecting human health. The method has been validated according to the guideline of international conference on Harmonization and parameters like linearity, range, accuracy and precision have been studied. The outcomes were matched statistically with those of the authorized systems; Student's t-test, F-test, and One-way ANOVA, presenting acceptable values and no momentous change with accuracy. The procedures can be considered useful for the quantitative analysis.

Comparative study of eco-friendly spectrophotometric methods for accurate quantification of Mebendazole and Quinfamide combination; Content uniformity evaluation

Development and validation of accurate and selective spectrophotometric methods were carried out for determination of a new combination of Mebendazole and Quinfamide in bulk powder and pharmaceutical formulation. Extended ratio subtraction coupled with isoabsorptive point methods were used for determination of the binary mixture. A comparative study was carried out between the newly developed methods; simultaneous ratio subtraction, absorbance subtraction, and dual wavelength spectrophotometric methods were applied as well. The developed methods were validated in accordance with the ICH guidelines. The developed methods were successfully carried out for determination of Quinfamide and Mebendazole in Vermox Plus® tablets. Upon statistical comparison of the results obtained by the developed methods with those obtained by the reported simultaneous equation spectrophotometric method, no significant difference was shown among them. Moreover, the introduced methods have the advantages of being more sensitive and have wider linearity ranges than other reported spectrophotometric methods.

UV spectrophotometric method for simultaneous estimation of betamethasone valerate and tazarotene with absorption factor method: Application for in-vitro and ex-vivo characterization of lipidic nanocarriers for topical delivery

The present study elucidates the development of an accurate, precise and simple simultaneous estimation method for the routine analysis of Betamethasone Valerate (BV) and Tazarotene (TZ). This combination is widely used in the treatment of psoriasis. No method has been reported so far for the simultaneous estimation of BV and TZ in topical dosage forms. The method proposed by this study for the quantification of BV and TZ is the Absorption factor method. The developed method was validated as per the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guideline. The validated method was found to be linear in a concentration range of 10-38 μg/mL and 4-14 μg/mL for BV and TZ respectively with a regression coefficient >0.990. The method was validated for accuracy and precision which revealed the recovery of >99.80% with RSD <2.0. The method was found to be precise with RSD <2% for inter and intraday. The developed method was employed for quantification of BV and TZ in lipid based nanocarriers formulation and their in-vitro drug release samples. Further, the developed method was successfully applied for the estimation of BV and TZ in the ex-vivo skin matrix. This showed that the method can sensitively determine the drugs in aqueous and biological samples.

Novel feature extraction approach for achieving potential spectral resolution: Green analytical application on zofenopril calcium and hydrochlorothiazide in their spectrally overlapping binary mixture

A novel and green spectrophotometric method, namely constant extraction, based on extracting a spectral feature value (constant ratio) has been developed and validated for simultaneous estimation of a binary mixture of zofenopril calcium (ZOF) and hydrochlorothiazide (HCT) in their bulk and marketable formulation. A comparative study between this newly developed method and four long-established ones; ratio difference, ratio subtraction coupled with constant multiplication, advanced amplitude modulation and absorbance subtraction has been carried out giving very promising results. Various analytical performance parameters like linearity, accuracy, precision, and robustness were investigated in accordance with ICH (Q2B). Satisfying optimized instrumental parameters; absorbance of ZOF and HCT were linearly increased for the previously mentioned methods in a concentration range 5.0-35.0 and 3.0-20.0 μg/mL, respectively showing correlation coefficients ≥0.9990. Moreover, specificity has been checked through analyzing synthetic mixtures of the studied analytes. Feasibility has been successfully assessed by simultaneous quantification of both analytes in the commercially available formulation. As well, validity was examined and no interference from common excipients was noticed. Observed data has been statistically compared with those of the published one concluding that no significant variations between both results have been indicated. Furthermore, greenness profile of these methods was assessed by analytical Eco-Scale and found superior to that of the reported HPLC method as an even greener approach for the simultaneous analysis of ZOF and HCT.

Smart spectrophotometric assessment of tamsulosin hydrochloride and tadalafil in their new pharmaceutical formulation for treatment of benign prostatic hyperplasia and erectile dysfunction

A novel combination of tamsulosin hydrochloride and tadalafil is recently available for treatment of benign prostatic hyperplasia and erectile dysfunction. For the first time, four simple, accurate, smart and robust spectrophotometric methods have been suggested for their simultaneous quantification. The methods, namely; first derivative, ratio difference, derivative ratio and mean centering of ratio spectra, successfully resolved the spectral overlap of their challenging binary mixture. Calibration curves were linear at 2.0-40.0 and 2.0-55.0 μg/mL for tamsulosin hydrochloride and tadalafil, respectively. The methods were validated according to ICH guidelines and statistically compared with the official ones, revealing no considerable difference with respect to accuracy and precision. Specificity of the developed methods was assessed by evaluating various laboratory prepared mixtures. Furthermore, the methods were successfully applied for the quantification of the two drugs in their combined dosage form.

Evaluation of the Efficiency of Smart Stability-Indicating Spectrophotometric Methods Based on Mathematical and Statistical Processing of the Obtained Results Via Different Manipulating Pathways

Background:

Smart different stability-indicating spectrophotometric methods have been established for the assay of chlordiazepoxide and clidinium bromide without the intervention of alkaline degradate of clidinium via various and different manipulating pathways without previous separation steps.

Objective:

The specificity of the established methods was inspected by analysing mixtures of cited drugs in the existence of the alkali-induced degradation product.

Methods:

These methods were employed either on scanned zero-order absorption spectra using absorbance subtraction, dual wavelength and Q-absorbance ratio or the amplitudes of the ratio spectra of zero-order absorption spectra like amplitude modulation and by derivative techniques to the ratio spectra as a derivative ratio method. In addition, the absorbance of the recovered zero-order absorption spectra was applied by successive ratio subtraction coupled with constant multiplication. Finally, the pathway depends on the amplitudes of the derivative spectra, successive derivative subtraction coupled with constant multiplication. The ranges of linearity were (1-12µg/mL) for chlordiazepoxide and (3- 12µg/mL) for clidinium bromide.

Results:

The outcomes achieved by the prospective methods were in consent with those of the official and reported methods when statistically compared using student’s t test, F-test and one-way ANOVA where no significant difference was detected with suitable precision, proving the absence of any important difference in accuracy and precision between them. They were confirmed in accordance with International Conference on Harmonization guidelines.

Conclusion:

The established methods can be considered as alternative methods for the routine determination of this fixed dose combination with minimum sample preparation.

Smart Spectral Processing of Data for the estimation of Commonly Used Over-the-counter (OTC) Co-formulated drug; Pseudoephedrine hydrochloride and Ibuprofen

Oral pharmaceutical preparation containing pseudoephedrine hydrochloride (PSE) and ibuprofen (IBU) is widely prescribed as over- the- counter (OTC) for treatment of common cold-sinus. Development of four precise and accurate spectrophotometric methods are established for the concurrent determination of (PSE) and (IBU)in this preparation exploiting zero and/or ratio spectra. Method I is a dual wavelength method (DW). method II is a ratio difference method (RD), method III is a constant multiplication coupled with spectrum subtraction method (CM-SS) and method IV is a constant center coupled with spectrum subtraction method (CC-SS). While, absorbance correction method (AC) is successfully established for the determination of (IBU) only exploiting zero order absorption spectra. The calibration curves are linear over the concentration range of 100.0-900.0 μg/mL for (PSE) and 200.0-1000.0 μg/mL for (IBU). No separation steps are required for the spectrophotometric procedures which augments their simplicity. Analyzing synthetic mixtures of the cited drugs evaluated the specificity of the applied methods. Validation of the analysis results have been statistically performed confirming the accuracy and reproducibility of the proposed method through recovery studies which were carried out by following ICH guidelines. Thus, the developed methods can be successfully applied routinely in quality control laboratory.

Novel univariate spectrophotometric determination of the recently released solid dosage form comprising dapagliflozin and saxagliptin via factorized response spectra: Assessment of the average content and dosage unit uniformity of tablets

Dapagliflozin (DPF) and saxagliptin (SXG) are currently co-formulated in a tablet dosage form which is prescribed to improve glycemic control. The absorption spectra of DPF and SXG were highly overlapped which completely hindered their simultaneous estimation at their λ_max 224 nm and 209 nm, respectively. Thus, in this work three smart and simple univariate spectrophotometric methods were originally established and validated for the first time in order to quantitatively estimate DPF and SXG in bulk forms and in combined pharmaceutical formulation without the requirement for any initial separation or treatment. These methods are; factorized zero order method (FZM), factorized derivative method (FDM) and factorized ratio difference method (FRM). These methods were capable of determining DPF and SXG over the range of 2.5-50.0 μg/mL and 2.5-60.0 μg/mL, respectively. All the developed methods are based on a novel and unique approach for the spectral recovery of unresolved spectra named; factorized response spectrum (FRS). The exclusivity of the FRS originates from its ability to completely resolve the cited drugs in the mixture and retrieve their original spectra. Selectivity of all proposed methods was assessed by comparing the obtained results of the mixture analysis with those of the pure powdered drugs. Validation of the newly developed methods was applied as recommended by the ICH demonstrating acceptable accuracy and precision. In general, these methods could be effectively employed for the routine quality control investigation of bulk materials and available market formulations.

Fingerprint Spectrophotometric Methods for the Determination of Co-Formulated Otic Solution of Ciprofloxacin and Fluocinolone Acetonide in Their Challengeable Ratio

Six spectrophotometric methods were developed to determine a new single-dose otic solution known as "Otovel®," which consists of two components: the major one is ciprofloxacin (CIP) and the minor is fluocinolone acetonide (FLU). The ratio of (CIP) and (FLU) in Otovel® is 12 : 1, which is considered a challengeable ratio for UV determination. Thus, spectrum addition as a sample enrichment technique was required for the analysis of (FLU) low concentration. All these methods were capable of resolving the spectra for each component in D 0 belonging to the fingerprint resolution technique. The former absorptivity centering (a-centering) method was recently developed in 2018; it was effectively applied for its solution of both binary components in Otovel®, while another method, ratio subtraction (RS), is considered as an original resolution method that could be applied to determine only one component in mixtures. However, the other four methods that are related to their original method (RS) were extended ratio subtraction (EXRS), constant multiplication (CM), unified constant subtraction (UCS), and spectrum subtraction (SS). They were also easily applied for completing the quantification of binary mixture drugs present in Otovel®. The linearity ranges were found to be 3.0-15.0 μg/mL for (CIP) and (FLU), respectively. All results acquired from the proposed methods were successfully estimated according to ICH criteria and were statistically compared with official ones where no differences were noticed.

Novel spectrophotometric methods for the determination of Leflunomide and Diacerein in binary mixtures

Two novel spectrophotometric methods were presented in this work using ethanol as a solvent. The first method was the ratio difference spectrophotometric method [RDSM], in which the amplitude difference between two selected wavelengths on the ratio spectra were recorded and used for estimation of each of Leflunomide LEF in mixture with its alkaline induced degradate DEG and also for Diacerein DIA determination in mixture with Aceclofenac ACEC without interference from the other component in the mixture. The second method is the ratio subtraction coupled with constant multiplication [RS-CM], where LEF was determined in its mixture with its alkaline degradate DEG at 261 nm which is considered as a stability indicating assay. In addition to simultaneous determination of Diacerein DIA and Aceclofenac ACEC in their mixtures at 257 and 277 nm, respectively, by the second method without previous separation. Linearity was shown over the concentration range of [1.5-15 μg/ml] for LEF, [1-11 μg/ml] for DIA and [2.5-25 μg/ml] for ACEC, by both proposed methods. Leflunomide was found to be completely degraded when subjected to alkaline degradation producing one alkaline product. Validation of the suggested methods was conducted according to ICH guidelines, concerning precision, accuracy, repeatability. The suggested spectrophotometric methods were statistically compared to reference methods showing no significant difference. The suggested spectrophotometric methods are considered to be simple, sensitive and could be easily applied in quality control laboratories instead of LC methods.

Developing spectral numerical factor technique for the determination of amlodipine besylate and the latest generation of statins in their new pharmaceutical combination

Spectral numerical factor techniques have been developed for quantification of a new pharmaceutical combination. Five simple, fast and accurate spectrophotometric methods using spectral factor manipulation have been tested and validated so as to determine quantitatively a new fixed-dose combination tablet containing both amlodipine besylate (ADB) and rosuvastatin calcium (ROS). Namely, these methods are induced dual wavelength, absorbance correction, absorbance subtraction, amplitude correction and advanced amplitude subtraction. Their corresponding spectral factors are equality, absorption, absorbance, amplitude and unity factor, respectively. Calibration curves of ADB and ROS were set up for all the previously mentioned methods under the optimum conditions in a concentration range of 3.0-21.0 μg/mL with correlation coefficients ≥0.9990. Selectivity was calculated by analyzing laboratory-prepared synthetic blends of the cited drugs. A comparative study between these methods and the reported ones has been carried out statistically forming a judgment that the difference between both results is totally insignificant. Actually, the suggested spectral factor technique is so effective for use in routine laboratory essay owing to its simplicity, rapidity and precision. Generally, the proposed factor procedures have the ability to run smoothly without any interference from additives that may deteriorate analysis efficiency of a pharmaceutical combination.

Study of efficiency and spectral resolution for mathematical filtration technique using novel unlimited derivative ratio and classical univariate spectrophotometric methods for the multicomponent determination-stability analysis

Six simple, sensitive and selective spectrophotometric methods based on mathematical filtration technique are presented for concurrent determination of aceclofenac (ACE) and paracetamol (PAR) in presence of their degradation products, namely; diclofenac sodium (DIC) and 4-aminophenol (4-AP), respectively without preliminary physical separation procedures. This technique consists of several consecutive steps applied on built-in spectrophotometer software utilizing zero and/or derivative and/or ratio spectra of the studied components. These methods, namely, dual wavelength (DW), induced dual wavelength (IDW), derivative subtraction (DS) coupled with constant multiplication (CM), ratio difference method (RD), constant center method (CC) and the novel introduced unlimited derivative ratio method (UDD). This novel method has a very powerful competence for the analysis of the challengeable mixtures lacking zero crossing point. The linearity, accuracy and precision ranges of these methods were determined and validated as per ICH guidelines. Moreover, the specificity was checked by analyzing synthetic mixtures of both drugs. These methods were applied for the determination of the cited drugs in pharmaceutical formulation and a statistical comparison of the obtained results was made with each other and with those of reported spectrophotometric method. The comparison of the results of pure powder form showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Spectrophotometric assessment of the brand new antiviral combination: Sofosbuvir and velpatasvir in their pure forms and pharmaceutical formulation

Sofosbuvir (SOF) and velpatasvir (VEL) are recently co-formulated together for the treatment of hepatitis C virus. Smart and robust spectrophotometric methods were first developed and validated for quantification of SOF and VEL in their pure forms and in their combined pharmaceutical formulation without preliminary separation. VEL has two UV maxima at 302.5 and 337.0 nm that allow its direct determination by zero-order spectrophotometric method (D°) without any interference from SOF in a linear range of 2.0-30.0 μg/mL. On the other hand, determination of SOF in presence of VEL was carried out by four smart spectrophotometric methods, developed for resolving the overlaid spectra of these binary mixture. These methods are dual wavelength (DW), ratio subtraction (RS), ratio difference (RD) and first derivative of ratio spectra method (¹DD). Linearity was checked and found to be in the range of 5.0-90.0 μg/mL for SOF by all of the aforementioned spectrophotometric methods. The developed methods were optimized and validated in accordance to the ICH guidelines. They were successfully utilized for estimating both SOF and VEL in their pure forms, laboratory prepared mixtures and in their pharmaceutical formulations with good recoveries. The methods can be easily applied for the routine analysis in quality control laboratories.

Testing the purity of spectral profiles: Finger-print resolution of complex matrices and extraction of absorbance signals

The application of spectrophotometric techniques has shown a tremendous development over the past few years, where it is possible to determine the concentrations of several components in complex matrix. A new feature will be introduced in this work where the application of spectrophotometric techniques will be enhanced to resolution and checking the purity of signals. The finger-print resolution "ratio subtraction method" (RSM) was coupled with the novel complementary method "unified constant subtraction" (UCS); in addition to the methods: extended ratio subtraction method (EXRSM), constant multiplication (CM) or "spectrum subtraction" (SS). These techniques were applied for the determination of the complex matrix of the binary mixture of chloramphenicol and dexamethasone. By applying official spectrophotometric methods, direct determination of the components was allowed with no need for validation procedures. The spectrophotometric techniques were successfully applied to the laboratory prepared mixtures and the combined dosage form where the purity of the extracted signals were tested by calculating the spectral contrast angle (θ) and the spectral ratio factor (SRF) where the results were compared to show the capability to recover pure spectral profiles and detect the presence of impurities. The proposed methods proved that spectrophotometric techniques can be used for identification and separation of signals, similar to chromatographic techniques.

Novel absorptivity centering method utilizing normalized and factorized spectra for analysis of mixtures with overlapping spectra in different matrices using built-in spectrophotometer software

A novel, simple, rapid, accurate, and economical spectrophotometric method, namely absorptivity centering (a-Centering) has been developed and validated for the simultaneous determination of mixtures with partially and completely overlapping spectra in different matrices using either normalized or factorized spectrum using built-in spectrophotometer software without a need of special purchased program. Mixture I (Mix I) composed of Simvastatin (SM) and Ezetimibe (EZ) is the one with partial overlapping spectra formulated as tablets, while mixture II (Mix II) formed by Chloramphenicol (CPL) and Prednisolone acetate (PA) is that with complete overlapping spectra formulated as eye drops. These procedures do not require any separation steps. Resolution of spectrally overlapping binary mixtures has been achieved getting recovered zero-order (D⁰) spectrum of each drug, then absorbance was recorded at their maxima 238, 233.5, 273 and 242.5 nm for SM, EZ, CPL and PA, respectively. Calibration graphs were established with good correlation coefficients. The method shows significant advantages as simplicity, minimal data manipulation besides maximum reproducibility and robustness. Moreover, it was validated according to ICH guidelines. Selectivity was tested using laboratory-prepared mixtures. Accuracy, precision and repeatability were found to be within the acceptable limits. The proposed method is good enough to be applied to an assay of drugs in their combined formulations without any interference from excipients. The obtained results were statistically compared with those of the reported and official methods by applying t-test and F-test at 95% confidence level concluding that there is no significant difference with regard to accuracy and precision. Generally, this method could be used successfully for the routine quality control testing.

Comparative study between different simple methods manipulating ratio spectra for the analysis of alogliptin and metformin co-formulated with highly different concentrations

Different simple spectrophotometric methods were developed for simultaneous determination of alogliptin and metformin manipulating their ratio spectra with successful application on recently approved combination, Kazano® tablets. Spiking was implemented to detect alogliptin in spite of its low contribution in the pharmaceutical formulation as low quantity in comparison to metformin. Linearity was acceptable over the concentration range of 2.5-25.0μg/mL and 2.5-15.0μg/mL for alogliptin and metformin, respectively using derivative ratio, ratio subtraction coupled with extended ratio subtraction and spectrum subtraction coupled with constant multiplication. The optimized methods were compared using one-way analysis of variance (ANOVA) and proved to be accurate for assay of the investigated drugs in their pharmaceutical dosage form.

Different applications of isosbestic points, normalized spectra and dual wavelength as powerful tools for resolution of multicomponent mixtures with severely overlapping spectra

Background

Analysis of complex mixture containing three or more components represented a challenge for analysts. New smart spectrophotometric methods have been recently evolved with no limitation. A study of different novel and smart spectrophotometric techniques for resolution of severely overlapping spectra were presented in this work utilizing isosbestic points present in different absorption spectra, normalized spectra as a divisor and dual wavelengths. A quaternary mixture of drotaverine (DRO), caffeine (CAF), paracetamol (PCT) and para-aminophenol (PAP) was taken as an example for application of the proposed techniques without any separation steps. The adopted techniques adopted of successive and progressive steps manipulating zero /or ratio /or derivative spectra. The proposed techniques includes eight novel and simple methods namely direct spectrophotometry after applying derivative transformation (DT) via multiplying by a decoding spectrum, spectrum subtraction (SS), advanced absorbance subtraction (AAS), advanced amplitude modulation (AAM), simultaneous derivative ratio (S¹DD), advanced ratio difference (ARD), induced ratio difference (IRD) and finally double divisor–ratio difference-dual wavelength (DD-RD-DW) methods.

Results

The proposed methods were assessed by analyzing synthetic mixtures of the studied drugs. They were also successfully applied to commercial pharmaceutical formulations without interference from other dosage form additives. The methods were validated according to the ICH guidelines, accuracy, precision, repeatability, were found to be within the acceptable limits.

Conclusion

The proposed procedures are accurate, simple and reproducible and yet economic. They are also sensitive and selective and could be used for routine analysis of complex most of the binary, ternary and quaternary mixtures and even more complex mixtures.

Development and validation of different methods manipulating zero order and first order spectra for determination of the partially overlapped mixture benazepril and amlodipine: A comparative study

Three simple, selective, and accurate spectrophotometric methods have been developed and then validated for the analysis of Benazepril (BENZ) and Amlodipine (AML) in bulk powder and pharmaceutical dosage form. The first method is the absorption factor (AF) for zero order and amplitude factor (P-F) for first order spectrum, where both BENZ and AML can be measured from their resolved zero order spectra at 238nm or from their first order spectra at 253nm. The second method is the constant multiplication coupled with constant subtraction (CM-CS) for zero order and successive derivative subtraction-constant multiplication (SDS-CM) for first order spectrum, where both BENZ and AML can be measured from their resolved zero order spectra at 240nm and 238nm, respectively, or from their first order spectra at 214nm and 253nm for Benazepril and Amlodipine respectively. The third method is the novel constant multiplication coupled with derivative zero crossing (CM-DZC) which is a stability indicating assay method for determination of Benazepril and Amlodipine in presence of the main degradation product of Benazepril which is Benazeprilate (BENZT). The three methods were validated as per the ICH guidelines and the standard curves were found to be linear in the range of 5-60μg/mL for Benazepril and 5-30 for Amlodipine, with well accepted mean correlation coefficient for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits.

Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product

Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D(1)), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.

Comparative study between recent methods manipulating ratio spectra and classical methods based on two-wavelength selection for the determination of binary mixture of antazoline hydrochloride and tetryzoline hydrochloride

A comparative study was developed between two classical spectrophotometric methods (dual wavelength method and Vierordt's method) and two recent methods manipulating ratio spectra (ratio difference method and first derivative of ratio spectra method) for simultaneous determination of Antazoline hydrochloride (AN) and Tetryzoline hydrochloride (TZ) in their combined pharmaceutical formulation and in the presence of benzalkonium chloride as a preservative without preliminary separation. The dual wavelength method depends on choosing two wavelengths for each drug in a way so that the difference in absorbance at those two wavelengths is zero for the other drug. While Vierordt's method, is based upon measuring the absorbance and the absorptivity values of the two drugs at their λ(max) (248.0 and 219.0 nm for AN and TZ, respectively), followed by substitution in the corresponding Vierordt's equation. Recent methods manipulating ratio spectra depend on either measuring the difference in amplitudes of ratio spectra between 255.5 and 269.5 nm for AN and 220.0 and 273.0 nm for TZ in case of ratio difference method or computing first derivative of the ratio spectra for each drug then measuring the peak amplitude at 250.0 nm for AN and at 224.0 nm for TZ in case of first derivative of ratio spectrophotometry. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. All methods were applied successfully for the determination of the selected drugs in their combined dosage form proving that the classical spectrophotometric methods can still be used successfully in analysis of binary mixture using minimal data manipulation rather than recent methods which require relatively more steps. Furthermore, validation of the proposed methods was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that the methods can be competitively applied in quality control laboratories.

Application and validation of superior spectrophotometric methods for simultaneous determination of ternary mixture used for hypertension management

Telmisartan (TL), Hydrochlorothiazide (HZ) and Amlodipine besylate (AM) are co-formulated together for hypertension management. Three smart, specific and precise spectrophotometric methods were applied and validated for simultaneous determination of the three cited drugs. Method A is the ratio isoabsorptive point and ratio difference in subtracted spectra (RIDSS) which is based on dividing the ternary mixture of the studied drugs by the spectrum of AM to get the division spectrum, from which concentration of AM can be obtained by measuring the amplitude values in the plateau region at 360nm. Then the amplitude value of the plateau region was subtracted from the division spectrum and HZ concentration was obtained by measuring the difference in amplitude values at 278.5 and 306nm (corresponding to zero difference of TL) while the total concentration of HZ and TL in the mixture was measured at their isoabsorptive point in the division spectrum at 278.5nm (Aiso). TL concentration is then obtained by subtraction. Method B; double divisor ratio spectra derivative spectrophotometry (RS-DS) and method C; mean centering of ratio spectra (MCR) spectrophotometric methods. The proposed methods did not require any initial separation steps prior the analysis of the three drugs. A comparative study was done between the three methods regarding their; simplicity, sensitivity and limitations. Specificity was investigated by analyzing the synthetic mixtures containing different ratios of the three studied drugs and their tablets dosage form. Statistical comparison of the obtained results with those found by the official methods was done, differences were non-significant in regard to accuracy and precision. The three methods were validated in accordance with ICH guidelines and can be used for quality control laboratories for TL, HZ and AM.

Simultaneous determination of mebeverine hydrochloride and chlordiazepoxide in their binary mixture using novel univariate spectrophotometric methods via different manipulation pathways

Smart, sensitive, simple and accurate spectrophotometric methods were developed and validated for the quantitative determination of a binary mixture of mebeverine hydrochloride (MVH) and chlordiazepoxide (CDZ) without prior separation steps via different manipulating pathways. These pathways were applied either on zero order absorption spectra namely, absorbance subtraction (AS) or based on the recovered zero order absorption spectra via a decoding technique namely, derivative transformation (DT) or via ratio spectra namely, ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), spectrum subtraction (SS), constant multiplication (CM) and constant value (CV) methods. The manipulation steps applied on the ratio spectra are namely, ratio difference (RD) and amplitude modulation (AM) methods or applying a derivative to these ratio spectra namely, derivative ratio (DD(1)) or second derivative (D(2)). Finally, the pathway based on the ratio spectra of derivative spectra is namely, derivative subtraction (DS). The specificity of the developed methods was investigated by analyzing the laboratory mixtures and was successfully applied for their combined dosage form. The proposed methods were validated according to ICH guidelines. These methods exhibited linearity in the range of 2-28μg/mL for mebeverine hydrochloride and 1-12μg/mL for chlordiazepoxide. The obtained results were statistically compared with those of the official methods using Student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

Comparative study of novel versus conventional two-wavelength spectrophotometric methods for analysis of spectrally overlapping binary mixture

Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision.

A comparative study between three stability indicating spectrophotometric methods for the determination of diatrizoate sodium in presence of its cytotoxic degradation product based on two-wavelength selection

Three sensitive, selective, and precise stability indicating spectrophotometric methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA) in the presence of its acidic degradation product (highly cytotoxic 3,5-diamino metabolite) and in pharmaceutical formulation, were developed and validated. The first method is ratio difference, the second one is the bivariate method, and the third one is the dual wavelength method. The calibration curves for the three proposed methods are linear over a concentration range of 2-24 μg/mL. The selectivity of the proposed methods was tested using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

Simultaneous determination of binary mixture of amlodipine besylate and atenolol based on dual wavelengths

Four, accurate, precise, and sensitive spectrophotometric methods are developed for simultaneous determination of a binary mixture of amlodipine besylate (AM) and atenolol (AT). AM is determined at its λmax 360 nm ((0)D), while atenolol can be determined by four different methods. Method (A) is absorption factor (AF). Method (B) is the new ratio difference method (RD) which measures the difference in amplitudes between 210 and 226 nm. Method (C) is novel constant center spectrophotometric method (CC). Method (D) is mean centering of the ratio spectra (MCR) at 284 nm. The methods are tested by analyzing synthetic mixtures of the cited drugs and they are applied to their commercial pharmaceutical preparation. The validity of results is assessed by applying standard addition technique. The results obtained are found to agree statistically with those obtained by official methods, showing no significant difference with respect to accuracy and precision.

Smart manipulation of ratio spectra for resolving a pharmaceutical mixture of Methocarbamol and Paracetamol

Two smart, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for simultaneous determination of Methocarbamol (METH) and Paracetamol (PAR) in their combined pharmaceutical formulation without preliminary separation. Method A, is an extended ratio subtraction one (EXRSM) coupled with ratio subtraction method (RSM), which depends on subtraction of the plateau values from the ratio spectrum. Method B is a ratio difference spectrophotometric one (RDM) which measures the difference in amplitudes of ratio spectra between 278 and 286 nm for METH and 247 and 260 nm for PAR. The calibration curves are linear over the concentration range of 10-100 μg mL(-1) and 2-20 μg mL(-1) for METH and PAR, respectively. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. Both methods were applied successfully for the determination of the selected drugs in their combined dosage form. Furthermore, validation was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that both methods can be competitively applied in quality control laboratories.

Comparative study of spectrophotometric methods manipulating ratio spectra: an application on pharmaceutical binary mixture of cinnarizine and dimenhydrinate

Four simple, specific, accurate and precise spectrophotometric methods are developed and validated for simultaneous determination of cinnarizine (CIN) and dimenhydrinate (DIM) in a binary mixture with overlapping spectra, without preliminary separation. The first method is dual wavelength spectrophotometry (DW), the second is a ratio difference spectrophotometric one (RD) which measures the difference in amplitudes between 250 and 270 nm of ratio spectrum, the third one is novel constant center spectrophotometric method (CC) and the fourth method is mean centering of ratio spectra (MCR). The calibration curve is linear over the concentration range of 4-20 and 10-45 μg/ml for CIN and DIM, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. The validity of results was assessed by applying standard addition technique. The results obtained were found to agree statistically with those obtained by a reported method, showing no significant difference with respect to accuracy and precision.

Novel spectrophotometric methods for simultaneous determination of Amlodipine, Valsartan and Hydrochlorothiazide in their ternary mixture

This work represents a comparative study of two smart spectrophotometric techniques namely; successive resolution and progressive resolution for the simultaneous determination of ternary mixtures of Amlodipine (AML), Hydrochlorothiazide (HCT) and Valsartan (VAL) without prior separation steps. These techniques consist of several consecutive steps utilizing zero and/or ratio and/or derivative spectra. By applying successive spectrum subtraction coupled with constant multiplication method, the proposed drugs were obtained in their zero order absorption spectra and determined at their maxima 237.6 nm, 270.5 nm and 250 nm for AML, HCT and VAL, respectively; while by applying successive derivative subtraction they were obtained in their first derivative spectra and determined at P230.8-246, P261.4-278.2, P233.7-246.8 for AML, HCT and VAL respectively. While in the progressive resolution, the concentrations of the components were determined progressively from the same zero order absorption spectrum using absorbance subtraction coupled with absorptivity factor methods or from the same ratio spectrum using only one divisor via amplitude modulation method can be used for the determination of ternary mixtures using only one divisor where the concentrations of the components are determined progressively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. Moreover comparative study between spectrum addition technique as a novel enrichment technique and a well established one namely spiking technique was adopted for the analysis of pharmaceutical formulations containing low concentration of AML. The methods were validated as per ICH guidelines where accuracy, precision and specificity were found to be within their acceptable limits. The results obtained from the proposed methods were statistically compared with the reported one where no significant difference was observed.

Novel spectrophotometric determination of chloramphenicol and dexamethasone in the presence of non labeled interfering substances using univariate methods and multivariate regression model updating

Smart and novel spectrophotometric and chemometric methods have been developed and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and dexamethasone sodium phosphate (DSP) in presence of interfering substances without prior separation. The first method depends upon derivative subtraction coupled with constant multiplication. The second one is ratio difference method at optimum wavelengths which were selected after applying derivative transformation method via multiplying by a decoding spectrum in order to cancel the contribution of non labeled interfering substances. The third method relies on partial least squares with regression model updating. They are so simple that they do not require any preliminary separation steps. Accuracy, precision and linearity ranges of these methods were determined. Moreover, specificity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied for analysis of both drugs in their pharmaceutical formulation. The obtained results have been statistically compared to that of an official spectrophotometric method to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision.

A comparative study of smart spectrophotometric methods for simultaneous determination of a skeletal muscle relaxant and an analgesic in combined dosage form

Six simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the analgesic drug; paracetamol (PARA) and the skeletal muscle relaxant; dantrolene sodium (DANT). Three methods are manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and mean centering (MC). The other three methods are utilizing the isoabsorptive point either at zero order namely; absorbance ratio (AR) and absorbance subtraction (AS) or at ratio spectrum namely; amplitude modulation (AM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and capsules. The obtained results were statistically compared with each other and with those of reported spectrophotometric ones. The comparison showed that there is no significant difference between the proposed methods and the reported methods regarding both accuracy and precision.

Evaluating the efficiency of spectral resolution of univariate methods manipulating ratio spectra and comparing to multivariate methods: an application to ternary mixture in common cold preparation

Simple, accurate, and selective methods have been developed and validated for simultaneous determination of a ternary mixture of Chlorpheniramine maleate (CPM), Pseudoephedrine HCl (PSE) and Ibuprofen (IBF), in tablet dosage form. Four univariate methods manipulating ratio spectra were applied, method A is the double divisor-ratio difference spectrophotometric method (DD-RD). Method B is double divisor-derivative ratio spectrophotometric method (DD-RD). Method C is derivative ratio spectrum-zero crossing method (DRZC), while method D is mean centering of ratio spectra (MCR). Two multivariate methods were also developed and validated, methods E and F are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods have the advantage of simultaneous determination of the mentioned drugs without prior separation steps. They were successfully applied to laboratory-prepared mixtures and to commercial pharmaceutical preparation without any interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with the official methods where no significant difference was observed regarding both accuracy and precision.

A comparative study of novel spectrophotometric resolution techniques applied for pharmaceutical mixtures with partially or severely overlapped spectra

Simultaneous determination of mixtures of lidocaine hydrochloride (LH), flucortolone pivalate (FCP), in presence of chlorquinaldol (CQ) without prior separation steps was applied using either successive or progressive resolution techniques. According to the concentration of CQ the extent of overlapping changed so it can be eliminated from the mixture to get the binary mixture of LH and FCP using ratio subtraction method for partially overlapped spectra or constant value via amplitude difference followed by ratio subtraction or constant center followed by spectrum subtraction spectrum subtraction for severely overlapped spectra. Successive ratio subtraction was coupled with extended ratio subtraction, constant multiplication, derivative subtraction coupled constant multiplication, and spectrum subtraction can be applied for the analysis of partially overlapped spectra. On the other hand severely overlapped spectra can be analyzed by constant center and the novel methods namely differential dual wavelength (D(1) DWL) for CQ, ratio difference and differential derivative ratio (D(1) DR) for FCP, while LH was determined by applying constant value via amplitude difference followed by successive ratio subtraction, and successive derivative subtraction. The spectra of the cited drugs can be resolved and their concentrations are determined progressively from the same ratio spectrum using amplitude modulation method. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures and were successfully applied for the analysis of pharmaceutical formulations containing the cited drugs with no interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the official or reported methods; using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

A study of selective spectrophotometric methods for simultaneous determination of Itopride hydrochloride and Rabeprazole sodium binary mixture: Resolving sever overlapping spectra

Itopride hydrochloride (IT) and Rabeprazole sodium (RB) are co-formulated together for the treatment of gastro-esophageal reflux disease. Three simple, specific and accurate spectrophotometric methods were applied and validated for simultaneous determination of Itopride hydrochloride (IT) and Rabeprazole sodium (RB) namely; constant center (CC), ratio difference (RD) and mean centering of ratio spectra (MCR) spectrophotometric methods. Linear correlations were obtained in range of 10-110μg/μL for Itopride hydrochloride and 4-44μg/mL for Rabeprazole sodium. No preliminary separation steps were required prior the analysis of the two drugs using the proposed methods. Specificity was investigated by analyzing the synthetic mixtures containing the two cited drugs and their capsules dosage form. The obtained results were statistically compared with those obtained by the reported method, no significant difference was obtained with respect to accuracy and precision. The three methods were validated in accordance with ICH guidelines and can be used for quality control laboratories for IT and RB.

A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

Spectrophotometric methods manipulating ratio spectra for simultaneous determination of binary mixtures with sever overlapping spectra: a comparative study

Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44μg/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.69±0.504 for method A, 99.83±0.483 for (B) and 100.31±0.499 for (C), respectively, and that of DP were 99.52±0.474 for method A, 100.12±0.505 for (B) and 100.16±0.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories.