Developed and Validated for the Estimation of Bupropion and Dextromethorphan in a Fixed Dose Combination of the Tablet.

Objectives: The aim of this study was to develop a simple, accurate, and precise method for the estimation of bupropion and dextromethorphan in a fixed-dose combination of tablets and robust high-performance liquid chromatography for assay analysis of such a fixed combination. Materials and Methods: Chromatographic analysis was performed and separations were achieved on a Denali C18 150 × 4.6 mm, 5 micron using a mobile phase composition of ortho-phosphoric acid and acetonitrile in the ratio of 600:400 (v/v), flow rate of 1.0 mL/min, injection volume is 10 µL and run time of 6 min in isocratic elution. Ultraviolet (UV) detection was performed at a wavelength of 221 nm. The temperature was maintained at 30 °C. Well-resolved peaks were observed with a high number of theoretical plates, lower tailing factor, and reproducible relative retention time. The method was validated, and all validation parameters were found to be within the acceptance limits. Results: A simple, accurate, and precise method has been developed for estimating bupropion and dextromethorphan in a fixed dose combination of tablets. The optimized method included the following parameters: column temperature of 30 °C, 40% acetonitrile as the mobile phase, and flow rate of 1.0 mL/min. Retention times were 2.25 min and 3.12 min for bupropion and dextromethorphan, respectively. The method was found to be linear in the range of 17.5-105 µg/mL [for R2 < 0.999) and 7.5-45 µg/mL (for R2 > 0.999] for bupropion and dextromethorphan, respectively. Both active pharmaceutical ingredients dissolved more than 90% within 5 min. Conclusion: The current study describes a new, simple, reliable, and economical elution reversed-phase high performance liquid chromatography method for estimating bupropion and dextromethorphan in a fixed combination tablet dosage form. The forced degradation studies were conducted using several degradation conditions such as acidic, alkali, oxidation, thermal, UV, and neutral conditions; the proposed method was effectively employed from the resolution of sample peaks. To the best of our knowledge, no such detailed and stability-indicating method has been reported for a fixed tablet dosage form.

Novel RP-HPLC method for estimation of a newly developed combination of tizanidine and etoricoxib in rat plasma: Eight criteria for greens evaluation.

A novel environmentally friendly reversed-phase high-performance liquid chromatography (RP-HPLC) method has been effectively validated for simultaneously measuring a prospective conjunction of tizanidine (TIZ) and etoricoxib (ETC), the combined medicine, in rat plasma. The technique employs diclofenac potassium as the internal standard, guaranteeing dependable and precise outcomes. This study aimed to assess the impact of the suggested combination therapy on treating inflammation resulting from rheumatoid arthritis (RA) in a rat model. The procedure was performed using an Agilent series 1200 model HPLC apparatus. The chromatographic conditions consist of isocratic elution mode, C18 column with dimensions of 150 mm × 4.6 mm × 5 µm, flow rate of 1.5 mL/min, wavelength of 230 nm, temperature of 50°C, and injection volume of 10 µL. The elution was performed using a mobile phase consisting of a phosphate buffer with a pH of 3.5 and acetonitrile in a ratio of 80:20 v/v. Calibration curves were conducted for TIZ and ETC within the 1-50 µg/mL range, demonstrating linear trends with R2 values over 0.999. The effectiveness and eco-friendliness of the proposed method were evaluated using eight separate environmentally conscious metrics. The addition of TIZ and ETC to arthritic rodents amplified these effects significantly. Furthermore, TIZ and ETC significantly reduced serum levels in arthritic rodents, and safety investigations revealed normal complete blood count, liver, and renal functions. TIZ and ETC appear to have antiarthritic, anti-inflammatory, and safe combinations, making them viable future treatment options for RA that are also safe and efficacious. Following validation by United States Food and Drug Administration (US-FDA) rules, all goods met the criteria.

Development of chromatographic methods to determine multivitamins formulation depending on their solubility and polarity: comparative study using three greenness assessment tools.

High performance liquid chromatography is one of the techniques of choice for the separation and quantitative determination of drugs in mixture form. Ipriflavone, ascorbic acid, pyridoxine, vitamin D3, and lysine are formulated together as an adjuvant combination in osteoporosis. In this work, we developed and validated two complementary high performance liquid chromatographic methods to determine the five compounds in their pharmaceutical dosage form. The first method (method A) was capable of determining ipriflavone, ascorbic acid, pyridoxine, and vitamin D3 in their bulk and combined pharmaceutical formulation. The method is based on Liquid Chromatographic separation with UV detection at 254 nm using Agilent Eclipse XDB-C18 column with a mobile phase consisting of 25 mM ammonium acetate buffer (pH 4.2): methanol in gradient mode. Due to the high polarity of lysine, it was difficult to achieve satisfactory retention on reversed phase columns. So, we separated it on a strong cation exchange column (Exsil 100 SCX) without derivatization with a mobile phase consisting of 10 mM sodium dihydrogen phosphate and 200 mM sodium chloride (pH 6) with UV detection at 210 nm (method B). Validation of the proposed methods was performed according to ICH guidelines Q2(R1). The proposed methods proved to be valid for selective analysis of the stated drugs in their bulk and combined pharmaceutical formulation. Greenness assessment of the developed methods was evaluated using three assessment tools: ESA, GAPI and the most recently developed tool AGREE, showing a satisfactory comprehensive guide of the greenness of the developed methods.

Computational quality-by-design strategy to validate high-performance liquid chromatography method for the estimation of meloxicam in bulk dosage forms and milk samples.

Bovine clinical mastitis has significant repercussions for farmers across the globe. Meloxicam, a COX-2 inhibitor, attenuates mastitis symptoms and is also approved for veterinary use. An RP-HPLC (Reverse Phase-High Performance Liquid Chromatography) method development and validation is essential in the pharmaceutical industry to assess API (Active Pharmaceutical Ingredient) quantity present in the pharmaceutical dosage forms. RP-HPLC method of meloxicam was developed and optimized with the aid of QbD (Quality by Design) using Box-Behnken design (BBD). The pH of the aqueous mobile phase, acetonitrile (ACN) percentage, and column temperature were chosen as influence variables, and retention time (RT) and tailing factor (Tf) were selected as response variables. The optimum experimental conditions were selected as pH ~ 3 of the aqueous mobile phase, 65% v/v ACN, and 30˚C as column temperature. The drug was eluted at 6.02 min RT with 1.18 as Tf. The method was subjected to validation for accuracy, linearity, precision, range, sensitivity, and robustness and was found to comply with ICH Q2 (R1) guidelines. The in vitro bioequivalent studies were performed in hydrochloric acid, pH ~ 1.2; acetate buffer, pH ~ 4.5; and phosphate buffer, pH ~ 6.8 for two veterinary brands of meloxicam tablets, and their release profiles were compared by mathematical models. Both the brands, brand 1 and 2 exhibited significant (Unpaired t-test, P < 0.05) differences in dissolution efficiency (DE) and mean dissolution time (MDT) except DE at pH 1.2. However, brands 1 and 2 showed similarity (f2 > 50) in terms of release of meloxicam except at pH 6.8 (f2 = 47.01). The in vitro release of meloxicam followed Peppas kinetics except for brand 2 at pH 6.8, where it followed the Higuchi model. Moreover, the recovery of meloxicam extracted with ACN in the milk sample was estimated to be 99.67 ± 0.58% significantly (Unpaired t-test, P < 0.05) higher than 90.34 ± 6.77% extracted with methanol. In conclusion, the optimized and validated RP-HPLC method of meloxicam may further be used for the analysis of drug content in pharmaceutical dosage forms in addition to biological fluids.

Implementation of Quality by Design Approaches for Development and Validation of Reverse-Phase High-Performance Liquid Chromatography Assay Method for Determination of Glycyrrhizin in Nanoformulation.

Glycyrrhizin (GL) is the principal constituent of Glycyrrhiza glabra, having antiallergic, anticancer, anti-inflammatory, and antimicrobial action. The reverse-phase high-performance liquid chromatography (RP-HPLC) analytical method was used to quantitatively estimate GL in a nanoformulation and validated as per International Conference on Harmonization Q2 (R1) standards. A stationary phase of the C18-HL reversed-phase column and a mobile phase of acetonitrile and water were used for effective elution. The chromatographic conditions of RP-HPLC were optimized utilizing a quality-by-design approach to accomplish the required chromatographic separation of GL from its nanoformulation with minimal experimental runs. Optimized RP-HPLC conditions for the assay method consist of acetonitrile (41%) and water, pH 1.8, balanced with phosphoric acid (0.1%) as a mobile phase with a flow rate of 1 mL/min. The retention time was found at 7.25 min, and method validation confirmed its sensitivity, preciseness, accuracy, and robustness.

Stability-indicating method development and validation for quantitative estimation of organic impurities of the antidiabetic drug glipizide in drug substance and pharmaceutical dosage form using HPLC.

Glipizide is an antidiabetic drug used for the treatment of type 2 diabetes. A simple, reliable and robust reverse-phase liquid chromatographic method (RP-HPLC) was developed and validated as per International Conference on Harmonization Q2(R1) for estimating the impurities of glipizide in pharmaceutical formulations. The chromatographic separation was carried out on a Phenomenex Luna C18 (2), 250 × 4.6 mm, 5 µm with a binary solvent delivery system [MP-A, a homogenous mixture of water and acetonitrile in a ratio of 90:10 (v/v) and 1 ml of orthophosphoric acid; and MP-B, a homogenous mixture of water and acetonitrile in a ratio of 10:90 (v/v) and 1 ml of orthophosphoric acid] with a detection wavelength of 225 nm, a column temperature of 30°C, a flow rate of 1.5 ml/min, and an injection volume of 20 µl. All process, degradant and unknown impurities were separated well with a resolution >2.2 and were estimated accurately without any interference. The recovered values and regression values were 98.7-100.5% and R2 > 0.9999, respectively. The recovery and linearity studies covered the quantitation limit to 150% of the specification limit. The stability-indicating properties of the developed RP-HPLC method was assessed from the forced degradation studies. The developed method was successfully applied for real-time sample analysis of the glipizide dosage form.

Identification and structural characterization of major stress degradation products of halcinonide by liquid chromatography-high-resolution mass spectrometry.

Halcinonide is a topical corticosteroid approved by the US Food and Drug Administration (FDA), known for its anti-inflammatory and antipruritic properties. The therapeutic benefits of halcinonide have rendered it an effective treatment regimen for various dermatological conditions such as psoriasis, dermatitis, and eczema. However, stability of the drug substance is a prerequisite in determining the therapeutic efficacy and plays a crucial role during formulation development and long-term storage. As corticosteroids are highly susceptible to degradation, the current study aims to expose halcinonide to different stress conditions and understand its stability behavior. An HPLC method was developed for the separation of halcinonide and its degradation products. Separation was accomplished in gradient mode using an Eclipse Plus C18 column (250 × 4.5 mm, 5 µm) with ammonium formate (10 mM, pH 6.5) and acetonitrile as the mobile phases. LC-Q-TOF/MS/MS studies were conducted on halcinonide, which led to the identification of degraded products using optimized mass parameters. A potential mechanistic degradation pathway for halcinonide, along with the major identified degradation products has been established. The chromatographic method that was developed has been validated in compliance with the Q2(R1) guideline of the International Council for Harmonization. ProTox-II was used to perform in silico toxicity studies in order to evaluate the toxicity potential of both halcinonide and the identified degradation products.

Stability-indicating method development and validation for quantitative estimation of assay and organic impurities of antiviral drug baloxavir marboxil in drug substance and pharmaceutical dosage form using HPLC and LC-MS methods.

Baloxavir marboxil (BXM) is a polymerase acidic endonuclease inhibitor used as an antiviral drug. A simple, reliable, and robust liquid chromatographic method was developed and validated per International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) for estimating the assay and impurities of BXM in drug substance and pharmaceutical formulations. The chromatographic separation was carried out on C18 (100 × 4.6 mm, 5 µm) with binary solvent delivery system (A:0.1% trifluoroacetic acid in water; B:0.1% trifluoroacetic-acid in acetonitrile) along with detection wavelength of 260 nm, column temperature of 57°C, flow of 1.2 mL/min and injection volume of 10 µL. All five known impurities and unknown impurities were separated well with resolution >1.7 and were estimated accurately without any interference. Recovered values and regression value were 99.5%-101.2% and R2  > 0.999, respectively. The recovery and linearity studies covered from 50% to 150% for assay, and quantitation limit, 120% for five BXM impurities. Stability-indicating property of the HPLC developed method was assessed from the forced degradation studies. The mass spectral data of unknown impurity formed under oxidation stress condition were discussed. The developed method was also successfully utilized for stability sample analysis of drug substance and tablet dosage form.

Optimization of HPLC method using central composite design for estimation of Torsemide and Eplerenone in tablet dosage form

Abstract A simple, precise, accurate and robust high performance liquid chromatographic method has been developed for simultaneous estimation of Torsemide and Eplerenone in tablet dosage form. Design of experiment was applied for multivariate optimization of the experimental conditions of RP-HPLC method. A Central composite design was used to study the response surface methodology and to analyse in detail the effects of these independent factors on responses. Total eleven experiments along with 3 center points were performed. Two factors were selected to design the matrix, one factor is variation in ratio of Acetonitrile and the second factor is flow rate (mL/min). Optimization in chromatographic conditions was achieved by applying Central composite design. The optimized and predicted data from contour diagram comprised mobile phase (acetonitrile, water and methanol in the ratio of 50: 30: 20 v/v/v respectively), at a flow rate of 1.0 ml/min and at ambient column temperature. Using these optimum conditions baseline separation of both drugs with good resolution and run time of less than 5 minutes were achieved. The optimized assay conditions were validated as per the ICH guidelines (2005). Hence, the results showed that the Quality by design approach could successfully optimize RP-HPLC method for simultaneous estimation of Torsemide and Eplerenone.

Effect of light, oxygen and temperature on the stability of artepillin C and p-coumaric acid from Brazilian green propolis.

Brazilian Green Propolis (BGP) is an important bee product, which displays important biological activities, making it valuable in the international market. The major prenylated phenolic compound in BPG is (E)-artepillin C, along with its precursor (E)-p-coumaric acid, both contributing to the biological effects of BGP. Taking that into account, it was evaluated the effect of light, temperature and air oxygen in their content to establish the best storage and transport conditions for crude BGP and the pure compounds. For that, (E)-artepillin C and (E)-p-coumaric acid were initially submitted to degradation for five days under sunlight and high temperature (50 °C), furnishing three major (E)-Artepillin C isomers and one from (E)-p-coumaric acid. Then, it was developed and validated a Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for quantifying these compounds in crude BGP and in its extracts. In the stability studies, it was used a Full Factorial and Central Composite Design to establish the desirable storage conditions. (E)-Artepillin C, both pure and in BGP should be kept protected from light and storage below -2.5 °C. (E)-p-Coumaric acid can be stored at room temperature. Therefore, the best storage and transport conditions to keep the content of both compounds in BGP are protection from light at low temperatures.

Development and validation of a RP-HPLC method for the simultaneous detection and quantification of simvastatin's isoforms and coenzyme Q10 in lecithin/chitosan nanoparticles.

Hybrid nanocapsules constituted of phospholipids and polysaccharides have been proposed as colloidal systems for the delivery of drugs via non-parenteral administration routes, due their capacity of high drug loading, controlled drug release and targeted delivery to the specific organ. Moreover, nanoparticles systems offer the possibility of co-encapsulation of drugs in the same drug delivery system and, consequently, the simultaneous administration of compounds. Characterization of nanoparticles properties, specifically involves quantification of the active pharmaceutical ingredients and is pivotal in the development of innovative nanomedicines. Therefore, this study has proposed and validated a new RP-HPLC-UV method for the simultaneous determination of simvastatin and coenzyme Q10 in hybrid nanoparticles systems. A reversed phase (RP) C8 column and a gradient elution of water: methanol at flow rate of 1.5 ml/min was used. Simvastatin (SVT), simvastatin hydroxyacid isoform (SVA) and coenzyme Q10 were identified by dual wavelength-UV detection at 238 nm (statins) and 275 nm, respectively. The proposed method was selective and linear in the range of 0.5-25 µg/ml (r2 > 0.999), precise, with values of relative standard deviation (RSD) lower than 2%, robust and accurate (recovery values of 100 ±â€¯5%), satisfying FDA guidelines. Furthermore, low detection (LOD <0.2 µg/ml) and quantification limits (LOQ <0.4 µg/ml) were suitable for the application of the method for the in vitro study of release kinetics of simvastatin and coenzyme Q10 co-encapsulated in lecithin/chitosan nanoparticles. The proposed method represents, to our knowledge, the only method for the simultaneous quantification of simvastatin, coenzyme Q10 and of the hydrolysed hydroxyacid isoform of the statin in nanoparticles.

Development and Validation of Stability-Indicating RP-HPLC Method for Simultaneous Determination of Metformin HCl and Glimepiride in Fixed-Dose Combination.

A simple reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of Metformin hydrochloride (MET) and Glimepiride (GLM) in combination and estimation of their principal degradation products. The separation was achieved using JASCO Finepak SIL (250 mm × 4.6 mm i.d. 5 µm) at ambient temperature. The optimized mobile phase composed of an aqueous phase (20 mM phosphate buffer, adjusted to pH 3.0) and an organic phase (methanol:acetonitrile; 62.5:37.5) in the ratio of 80:20. The flow rate was 1 mL/minute, and the analytes were detected at 230 nm. The developed method was validated for accuracy, precision, specificity, linearity, and sensitivity. The chromatographic analysis time was approximately six minutes with the complete resolution of MET (Rt = 2.75 minutes) and GLM (Rt = 5.87 minutes). The method exhibited good linearity over the range of 5-30 µg/mL for MET and 1-10 µg/mL for GLM. The drugs in combination were subjected to various stress degradation studies as per the International Conference Harmonization (ICH) guidelines. Results obtained from the stress degradation studies revealed that the developed method is applicable for stability studies.

Development and Validation of Stability-indicating HPLC Method for Simultaneous Estimation of Cefixime and Linezolid.

A stability-indicating reverse phase high performance liquid chromatography method was developed and validated for cefixime and linezolid. The wavelength selected for quantitation was 276 nm. The method has been validated for linearity, accuracy, precision, robustness, limit of detection and limit of quantitation. Linearity was observed in the concentration range of 2-12 µg/ml for cefixime and 6-36 µg/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 µm column using phosphate buffer (pH 7):methanol (60:40 v/v) as mobile phase with flow rate 1 ml/min. The retention time of cefixime and linezolid were found to be 3.127 min and 11.986 min, respectively. During force degradation, drug product was exposed to hydrolysis (acid and base hydrolysis), H2O2, thermal degradation and photo degradation. The % degradation was found to be 10 to 20% for both cefixime and linezolid in the given condition. The method specifically estimates both the drugs in presence of all the degradants generated during forced degradation study. The developed methods were simple, specific and economic, which can be used for simultaneous estimation of cefixime and linezolid in tablet dosage form.

Selective separation, detection of zotepine and mass spectral characterization of degradants by LC-MS/MS/QTOF.

A simple, precise, accurate stability-indicating gradient reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the quantitative determination of zotepine (ZTP) in bulk and pharmaceutical dosage forms in the presence of its degradation products (DPs). The method was developed using Phenomenex C18 column (250 mm×4.6 mm i.d., 5 µm) with a mobile phase containing a gradient mixture of solvents, A (0.05% trifluoroacetic acid (TFA), pH=3.0) and B (acetonitrile). The eluted compounds were monitored at 254 nm; the run time was within 20.0 min, in which ZTP and its DPs were well separated, with a resolution of >1.5. The stress testing of ZTP was carried out under acidic, alkaline, neutral hydrolysis, oxidative, photolytic and thermal stress conditions. ZTP was found to degrade significantly in acidic, photolytic, thermal and oxidative stress conditions and remain stable in basic and neutral conditions. The developed method was validated with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness as per ICH guidelines. This method was also suitable for the assay determination of ZTP in pharmaceutical dosage forms. The DPs were characterized by LC-MS/MS and their fragmentation pathways were proposed.

RP-HPLC analysis of manool-rich Salvia officinalis extract and its antimicrobial activity against bacteria associated with dental caries

In this paper we screened the dichloromethane extract from the aerial parts of Salvia officinalis L., Lamiaceae, against a representative panel of microorganisms that cause caries, conducted a bioassay-guided fractionation to establish themselves the most active metabolite (manool) and determined the Salvia officinalis fraction with the manool highest concentration to be used to activate an ingredient in oral care products such as toothpastes and mouthwashes. Both manool and S. officinalis extract showed very promising minimal inhibitory concentration values (between 6.24 and 31.36 µg.ml-1) and time kill curves against the primary causative agents of dental caries (Streptococcus mutans) revealed that, at twice its minimal bactericidal concentration (12.48 µg.ml-1), manool required 6 h to completely kill the bacteria. Salvia officinalis extract at twice its minimal bactericidal concentration (31.36 µg.ml-1 ) needed 12 h. The results achieved with Salvia officinalis extract motivated us to develop and validate an analytical RP-HPLC method to detect and determine manool in this extract. The validation parameters were satisfactorily met and evaluated allows us to consider the developed method suitable for use in different labs. In conclusion, our results evidenced that the manool-rich S. officinalis extract can be considered an analytically validated alternative to develop novel and effective antimicrobial agents against the main bacteria responsible for dental caries.

Analytical method development and validation of prasugrel in bulk and its pharmaceutical formulation using the RP-HPLC method.

PURPOSE: This study was designed to develop and validate a simple, sensitive, precise, and specific reverse phase high-performance liquid chromatographic (HPLC) method for the determination of prasugrel in bulk and its tablet dosage forms. MATERIALS AND METHODS: The HPLC separation was carried out by reverse phase chromatography on an inertsil ODS-3V column (5 µm; 250 × 4.6mm(2)) with a mobile phase composed of 0.02 M potassium dihydrogen orthophosphate, 0.02 M dipotassium hydrogen orthophosphate in water:acetonitrile (30:70 v/v) in isocratic mode at a flow rate of 1 ml/min. The detection was monitored at 210 nm. RESULTS: The calibration curve for prasugrel was linear from 100 to 600 µg/ml. The inter-day and intra-day precision was found to be within limits. The proposed method has adequate sensitivity, reproducibility, and specificity for the determination of prasugrel in bulk and its tablet dosage forms. The limit of detection and limit of quantification for prasugrel were found to be 0.25 µg/ml and 0.75 µg /ml, respectively. Accuracy (recoveries: 99.8-101.2%) and reproducibility were found to be satisfactory. CONCLUSION: The proposed method is simple, fast, accurate, and precise for the simultaneous quantification of prasugrel in the dosage form, bulk drugs as well as for routine analysis in quality control.

Simultaneous HPLC determination of butenafine hydrochloride and betamethasone in a cream formulation.

A fast, specific, accurate and precise reverse phase high performance liquid chromatographic method was developed for the simultaneous determination of butenafine hydrochloride and betamethasone in cream formulation. The determination was carried out on licrocart licrosphere RP-select B (250x4.6 mm, 5 mu) column in isocratic mode, the mobile phase consisting of 50 mM ammonium acetate buffer and acetonitrile in the ratio of 60:40, adjusted to pH 4.5 +/- 0.1 with glacial acetic acid. The flow rate was 2.0 ml/min and eluent was monitored at 254 nm. The retention times of butenafine hydrochloride and betamethasone were 4.70 min and 7.76 min, respectively, and the resolution factor was greater than 4.0. Linearity of butenafine hydrochloride and betamethasone were in the range of 100-300 mug/ml and 5-15 mug/ml, respectively. The proposed method is also found to be precise and robust for the simultaneous determination of butenafine hydrochloride and betamethasone in cream formulation.

A Validated RP-HPLC Method for Simultaneous Estimation of Nebivolol and Hydrochlorothiazide in Tablets.

A simple, selective, rapid, precise and economical reverse phase high pressure liquid chromatographic method has been developed for the simultaneous estimation of nebivolol and hydrochlorthiazide from pharmaceutical formulation. Phenomenex Gemini C(18) (25 cm×4.6 mm i.d., 5 µ) column with a mobile phase consisting of acetonitrile: 50mM ammonium acetate (adjusted to pH 3.5 using orthophosphoric acid) (70:30 v/v) at a flow rate of 1.0 ml/min was used. Detection was carried out at 254 nm. Probenecid was used as an internal standard. The retention times of probenecid, nebivolol and hydrochlorthiazide were 13.05, 3.32 and 4.25 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms.