Recent Applications of Quantum Dots in Pharmaceutical Analysis.

Nanotechnology has emerged as one of the most potential areas for pharmaceutical analysis. The need for nanomaterials in pharmaceutical analysis is comprehended in terms of economic challenges, health and safety concerns. Quantum dots (QDs)or colloidal semiconductor nanocrystals are new groups of fluorescent nanoparticles that bind nanotechnology to drug analysis. Because of their special physicochemical characteristics and small size, QDs are thought to be promising candidates for the electrical and luminescent probes development. They were originally developed as luminescent biological labels, but are now discovering new analytical chemistry applications, where their photo-luminescent properties are used in pharmaceutical, clinical analysis, food quality control and environmental monitoring. In this review, we discuss QDs regarding properties and advantages, advances in methods of synthesis and their recent applications in drug analysis in the recent last years.

Probing the potential toxicity of trimetazidine by characterizing its interaction with human serum albumin.

The small molecular drugs pharmacodynamics and pharmacokinetics could be affected by human serum albumin (HSA) transport, so we studied the interaction between HSA and the widely used anti-ischemic agent, trimetazidine (TMZ), using different approaches. As shown by synchronous fluorescence spectroscopy, the interaction affects the microenvironment confirmation around tyrosine residues. The site-competitive experiments showed that TMZ had an affinity toward subdomain III A (site II) of HSA. The enthalpy and entropy changes (ΔH and ΔS), which were 37.75 and 0.197 K J mol-1, respectively, showed that the predominant intermolecular interactions are hydrophobic forces. According to FTIR research, the interaction between HSA and TMZ caused polypeptide carbonyl-hydrogen bonds to rearrange. The HSA esterase enzyme activity was decreased with TMZ. Docking analysis confirmed the site-competitive experiments and thermodynamic results. This study demonstrated that TMZ interacted with HSA, and the structure and function of HSA were influenced by TMZ. This study could aid in understanding the pharmacokinetics of TMZ and provide basic data for safe use.

Co-delivery of gentiopicroside and thymoquinone using electrospun m-PEG/PVP nanofibers: In-vitro and In vivo studies for antibacterial wound dressing in diabetic rats.

Nanofibers (NFs) provide several delivery advantages like their great flexibility and similarity with extracellular matrix (ECM) which qualify them to be the unique model of a wound dressing. NFs could create mats of polymeric matrix loaded with an active agent enhancing its solubility and stability. In our study, Gentiopicroside (GPS) and Thymoquinone (TQ) loaded in NFs polymeric mats composed of coblended polyvinyl pyrrolidine (PVP) and methyl ether Polyethylene glycol (m-PEG) were fabricated via electrospinning technique. A morphological study using Scanning Electron Microscopy (SEM) was performed for all formulae as well as in vitro release study using High-performance Liquid chromatography (HPLC) for sample analysis. The optimized formula (F3) was chosen for further assays using Fourier-Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). Study of the antibacterial effect, and in vivo healing action for diabetic infected wounds to quantify Tumor necrosis factor-alpha and Cyclooxygenase-2 were also investigated. F3 achieved the highest % cumulative release (99.79 ± 6.47 for GPS and 96.89 ± 6.87 for TQ) at 60 min, and a smaller diameter (200 nm) showing significant anti-bacterial effects with well-organized skin architecture demonstrating great healing signs. Our results revealed that m-PEG/PVP NFs mats loaded with GPS and TQ could be considered an optimal wound care dressing.

Multi-spectroscopic, thermodynamic and molecular docking studies to investigate the interaction of eplerenone with human serum albumin.

The binding of small molecular drugs with human serum albumin (HSA) has a crucial influence on their pharmacokinetics. The binding interaction between the antihypertensive eplerenone (EPL) and HSA was investigated using multi-spectroscopic techniques for the first time. These techniques include ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared (FTIR), native fluorescence spectroscopy, synchronous fluorescence spectroscopy and molecular docking approach. The fluorescence spectroscopic study showed that EPL quenched HSA inherent fluorescence. The mechanism for quenching of HSA by EPL has been determined to be static in nature and confirmed by UV absorption and fluorescence spectroscopy. The modified Stern-Volmer equation was used to estimate the binding constant (Kb ) as well as the number of bindings (n). The results indicated that the binding occurs at a single site (Kb = 2.238 × 103 L mol-1 at 298 K). The enthalpy and entropy changes (∆H and ∆S) were 58.061 and 0.258 K J mol-1 , respectively, illustrating that the principal intermolecular interactions stabilizing the EPL-HSA system are hydrophobic forces. Synchronous fluorescence spectroscopy revealed that EPL binding to HSA occurred around the tyrosine (Tyr) residue and this agreed with the molecular docking study. The Förster resonance energy transfer (FRET) analysis confirmed the static quenching mechanism. The esterase enzyme activity of HSA was also evaluated showing its decrease in the presence of EPL. Furthermore, docking analysis and site-specific markers experiment revealed that EPL binds with HSA at subdomain IB (site III).

Carbon quantum dots as a sensitive fluorescent probe for quantitation of pregabalin; application to real samples and content uniformity test.

A novel optical nano-sensor for the detection of pregabalin (PG) in its pharmaceutical (Lyrica®) capsules and biological samples was reported. For the fabrication of highly fluorescent carbon quantum dots (CQDts), a simple green hydrothermal approach was described, and ascorbic acid (AA) was used as a carbon source. The obtained CQDts were confirmed by spectroscopic characterization such as transmission electron microscopy (TEM) and Fourier-transform infrared (FTIR) spectra. The synthesized CQDts were capped by alcohol to form yellow emitters, showing strong fluorescent emission at 524 nm, and excitation at 356 nm. The method is based on fluorescence quenching of CQDts in the presence of PG. The proposed analytical method was validated according to ICH guidelines. PG was successively assayed in the concentration range of 4.0 to 100 µg/ml). The detection and quantitation limits were 1.12 and 3.39 µg/ml, respectively. The proposed method could be used in both quality control and pharmacokinetic research for the studied drug.

One-pot synthesis of fluorescent nitrogen and sulfur-carbon quantum dots as a sensitive nanosensor for trimetazidine determination.

Water-soluble and highly stable N,S-doped CQDs (N,S-CQDs) were synthesized using a low-cost strategy with citric acid and thiosemicarbazide in one step for use as a fluorescent nanosensor. The achieved N,S-CQDs produced strong emission at 446 nm upon excitation at 370 nm and a high quantum yield of 58.5%. The quenching effect on the prepared N,S-CQDs was utilized for determination of trimetazidine (TMZ) spectrofluorimetrically over a wide linear range 0.04-0.5 µM (0.0106-0.133 µg ml-1 ) and a low limit of detection of 0.01 µM (0.002 µg ml-1 ). Furthermore, CDs were used as a simple and rapid fluorescent probe to determine TMZ in its pharmaceutical formulations as well as in human plasma. The method was tested in compliance with International Council for Harmonisation guidelines. The results obtained were compared statistically with those given for a reported method showing no significant variation regards accuracy and precision.

Determination and Pharmacokinetics of Omeprazole Enantiomers in Human Plasma and Oral Fluid Utilizing Microextraction by Packed Sorbent and Liquid Chromatography-Tandem Mass Spectrometry.

In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase. OME enantiomers were determined utilizing a triple quadrupole tandem mass spectrometer in positive ion mode (ESI+) monitoring mass transitions: m/z 346.3 ⟶ 198.0 for OME and m/z 369.98 ⟶ 252.0 for internal standard. The limits of detection and quantification of the present method for both enantiomers were 0.1 and 0.4 ng/mL, respectively. The method validation provided good accuracy and precision. The matrix effect factor was less than 5%, and no interfering peaks were observed. The interday precision values ranged from 2.2 to 7.5 (%RSD), and the accuracy of determinations varied from -9.9% to 8.3%. In addition, the pharmacokinetics (PK) of omeprazole enantiomers in healthy subjects after a single oral dose was investigated. (S)-Enantiomers showed higher levels than (R)-enantiomers throughout 24 h. It was found that the mean maximum concentrations of (R)- and (S)-omeprazole in plasma samples were about two times higher than in oral fluid.

In Vitro and In Vivo Antitumor Activity of Indolo[2,3-b] Quinolines, Natural Product Analogs from Neocryptolepine Alkaloid.

Neocryptolepine (5-methyl-5H-indolo[2,3-b] quinoline) analogs were synthesized and evaluated in vitro and in vivo for their effect versus Ehrlich ascites carcinoma (EAC). The analogs showed stronger cytotoxic activity against EAC cells than the reference drug. The in vivo evaluation of the target compounds against EAC-induced solid tumor in the female albino Swiss mice revealed a remarkable decrease in the tumor volume (TV) and hepatic lipid peroxidation. A noticeable increase of both superoxide dismutase (SOD) and catalase (CAT) levels was reported (p < 0.001), which set-forth proof of their antioxidant effect. In addition, the in vitro antioxidant activity of the neocryptolepine analogs was screened out using the DPPH method and showed promising activities activity. The histopathological investigations affirmed that the tested analogs have a remarkable curative effect on solid tumors with minimal side-effect on the liver. The study also includes illustrated mechanism of the antitumor activity at the cell level by flow cytometry. The cell cycle analysis showed that the neocryptolepine analogs extensively increase the aggregation of tumor cells in three phases of the cell cycle (G0/G1, S and G2/M) with the emergence of a hypo-diploid DNA content peak (sub-G1) in the cell cycle experiments, which is a clear-cut for the apoptotic cell population. Furthermore, the immunological study manifested a significant elevation in splenic lymphocyte count (p < 0.001) with the elevation of the responsiveness of lymphocytes to phytohemagglutinin (PHA). These results indicate that these naturally-based neocryptolepine alkaloids exhibit marked antitumor activity in vivo and represent an important lead in the development of natural-based anticancer drugs.

A Novel Eplerenone Ecofriendly Fluorescent Nanosensor Based on Nitrogen and Sulfur-Carbon Quantum Dots.

In this work, a novel ecofriendly optical nanosensor for detection of Eplerenone (EPL) in biological samples was reported. Highly luminescent water-soluble nitrogen and sulfur doped carbon quantum dots (N, S-CQDs) have been prepared successfully. The synthesis was based on the reaction of thiosemicarbazide (TS) as source of N and S and citric acid (CA) as source of carbon in one-step aqueous base reflux treatment. The produced N, S-CQDs have a small particle size in the range of 4.7 nm with a high quantum yield (58.5%) and high emission intensity at 446 nm under excitation wavelength of 370 nm. The unique properties of N, S-CQDs make them useful tool as a nano fluorescent probe for sensitive determination of EPL. EPL has been found to decrease the fluorescence of S, N-CDs significantly through static quenching according to the Stern - Volmer plot. The decreased intensity of S, N-CDs fluorescence was proportional to EPL in the 0.2-3.0 µM range. The limit of detection and quantitation were 0.05 and 0.15 µM, respectively. The assay of EPL by this approach was successfully done in drug formulations and in spiked human serum samples.

Application of MEKC and UPLC with Fluorescence Detection for Simultaneous Determination of Amlodipine Besylate and Bisoprolol Fumarate.

OBJECTIVE: Two chromatographic methods were described for simultaneous determination of the antihypertensive drugs amlodipine besylate (AML) and bisoprolol fumarate (BIS). METHODS: Method I applies micellar electrokinetic capillary chromatography using a deactivated fused silica capillary (25 cm effective length × 50 µm internal diameter). The background electrolyte consisted of 0.01 M borate buffer (pH 9.2) containing 0.025 M sodium dodecyl sulphate and methanol in the ratio of 80:20 (v/v). Valsartan (VAL) was used as an internal standard. Diode array detector was set at 238, 224, and 210 nm for measuring AML, BIS, and VAL, respectively. Method II involves using ultra-performance liquid chromatography with fluorescence detection. Zorbax SB-C8 column (2.1 × 100 mm, 1.8 µm particle size) was used with isocratic elution of the mobile phase composed of 0.1% trifluoroacetic acid, acetonitrile, and methanol in the ratio of 55:35:10 (v/v) at a flow rate of 0.6 mL/min. Fluorescence detection was done using excitation wavelengths 230 and 370 nm and emission wavelengths 305 and 450 nm for BIS and AML, respectively. Validation parameters were carefully studied including linearity, ranges, precision, accuracy, robustness, detection, and quantification limits. RESULTS: Method I showed good linearity over the range 10-100 µg/mL for both dugs. Method II's linear ranges were 0.001-0.1 and 0.02-1 µg/mL for BIS and AML, respectively. CONCLUSION: The proposed methods were successfully validated and applied for assay of the studied drugs in their fixed-dose combination tablets. HIGHLIGHTS: To the best of our knowledge, this study suggests the first electro-chromatographic and LC with fluorescence detection methods for simultaneous determination of amlodipine and bisoprolol.

New liquid chromatography assays for simultaneous quantification of antihypertensives atenolol and valsartan in their dosage forms.

Nowadays, various single-pill combinations are used as the best choice in hypertension management. However, these pills made a high challenge to analysts in terms of quality control assays. We have developed three sensitive, selective, fast, simple, green, accurate, precise, and robust isocratic high-performance liquid chromatography methods for simultaneous determination of valsartan and atenolol in dosage forms. To find the appropriate high-performance liquid chromatography conditions for the separation of the examined drugs, various columns, isocratic mobile phase systems were tried, and successful attempts were performed. The used columns proved to be indispensably applicable and gave a shorter analysis time and peak symmetries. This reduction in total run time leads to low solvent consumption and makes all methods more economical. The linearity, accuracy, and precision remained within the acceptable limits. Therefore, all developed methods are suitable for the routine quality control analysis of any pharmaceutical preparation containing the two tested drugs with the proposed chromatographic methods advantages for checking quality during stability studies of their pharmaceutical preparations.

The use of green spectroscopy with multivariate calibration models for simultaneous analysis of ternary drug mixture in combined oral antidiabetic pill.

In this work, different chemometric calibration models were developed and validated for the purpose of determining of ternary mixture of oral antidiabetic drugs; vildagliptin (VDG), saxagliptin (SAX) and sitagliptin phosphate (STG). The used models were Partial least squares (PLS) and Artificial Neural Networks (ANN). However, on these various models the impact of genetic algorithm (GA) as a form of variable selection was also investigated. The UV spectral data was used as basis in the quantitative study of the drugs analyzed in bulk and product formulations. The concentration range of the calibration curves of VDG, SAX and STG were 10-22 µg mL-1, 24-40 µg mL-1 and 82-130 µg mL-1, respectively. The calibration set included nineteen mixtures and the others six were used as a validation set to test the predictability of the developed multivariate models. The validation parameters of the evaluated methods were statistically determined. For the analysis of drugs studied in laboratory-prepared mixtures and their dosage forms, PLS-1, GA-PLS-1, ANN, and GA-ENN were successfully employed. The results obtained by the developed methods were compared to those given by a reported method and there were no statistically significant differences regarding accuracy and precision.

Fluorescence spectroscopy for determination of dapagliflozin in pure form and its tablets formulation; Application to content uniformity testing.

A new, valid method was developed for quantitative spectrofluorimetric analysis of dapagliflozin (DGF) in its pure form and its commercially available tablets (Farxiga®). The proposed analytical method based on measurement of fluorescence intensity for DGF at 303 nm after excitation at 278 nm. Various experimental parameters influencing the fluorescence of DGF were examined to produce the optimal conditions. DGF was successively assayed in concentration range of (100-1000 ng mL-1) with lower detection limit (LOD) of 26.49 and quantitation limit (LOQ) was 79.48 ng mL-1. The suggested method was validated according to ICH guidelines for the estimation of DGF in its pure form and its new dosage form with percent recovery of 100.43 ±â€¯1.15. The proposed method was adapted to examine DGF in content uniformity testing according to United States Pharmacopeia guidelines. This method can be used in routine analysis of DGF in quality control lab.

New spectrofluorimetric analysis of empagliflozin in its tablets and human plasma using two level full factorial design.

An efficient, accurate and sensitive spectrofluorimetric method was developed for analysis of empagliflozin (EGF) in pure form, dosage form and human plasma. The proposed procedure was based on formation of yellow fluorescent product between benzofurazan reagent and empagliflozin in slightly alkaline medium that is measured at 521 nm, when excitation at 455 nm. The present study was validated according to ICH guidelines and bioanalytical validated according to US-FDA guidance. The fluorescence intensity-concentration plot was linear over the range of 50-1000 ng ml-1 with limit of detection (LOD) and quantitation (LOQ) of 15.55 and 46.63 ng ml-1, respectively. The correlation (r) and determination (r2) coefficient was 0.9998 and 0.9997, respectively. Due to high sensitivity and selectivity of the proposed method, it is successfully used for analysis of empagliflozin in its dosage form and human plasma with good recoveries of 98.89% and 98.70%, respectively, without any interfering from matrix components. The corresponding regression equation, Y = 0.756X + 141.93, (r2 = 0.9994) for spiked plasma sample. Two level full factorial designs were used to study different experimental parameters that affect the reaction product and to get the optimum method conditions. The suggested method can be used in quality control lab as well as in pharmacokinetic studies of empagliflozin.

Second-derivative synchronous spectrofluorimetric assay of dapagliflozin: Application to stability study and pharmaceutical preparation.

A highly accurate, simple and sensitive spectrofluorimetric analytical method for dapagliflozin (DGF) quantitation was developed. The proposed method was successively applied to DGF analysis in both its pure and pharmaceutical dosage forms. This method was developed to investigate DGF stability in its degradation products, as laid out in International Council for Harmonisation (ICH) rules. Kinetics of alkaline degradation of DGF was also calculated. The half-life time (t1/2 ) of the reaction was 75.32 min. An alkaline degradation pathway was described. The present study involved measurement of the second-derivative synchronous fluorescence intensity of DGF at Δλ = 30 nm. Peak amplitude was measured at 322 nm. Linear range of the calibration curve was 0.1-1.0 µg ml-1 . Lower detection and quantitation limits were 0.023 and 0.071 µg ml-1 , respectively, and indicated good sensitivity of the proposed method. Mean per cent recovery was 99.78 ± 1.78%. The proposed analytical approach was successfully applied to DGF in the quality control laboratory and would be suitable as a stability-indicating assay.

New spectrofluorimetric analysis of dapagliflozin after derivatization with NBD-Cl in human plasma using factorial design experiments.

A new validated spectrofluorimetric method was proposed for dapagliflozin (DGF) analysis in bulk, plexin its commercially available tablets and in spiked human plasma. The proposed spectrofluorimetric method depended on the formation of a fluorescent complex soluble in organic liquids by a substitution reaction between 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) reagent and DGF in aqueous buffered solution at pH 7. The fluorescence intensity was measured at 522 nm after excitation at 453 nm. The high selectivity of the proposed method allowed analysis of DGF in dosage form and human plasma samples with average recovery values of 99.84 ± 1.38% and 98.71 ± 1.80%, respectively, without any interference from matrix components. The calibration range was 50-1000 ng ml-1 . The limit of detection (LOD) and limit of quantitation (LOQ) were 14.24 ng ml-1 and 43.14 ng ml-1 , respectively. The estimated relative standard deviation values were lower than 2.0%, this showed the excellent precision at both levels. Factorial design was used to get the optimum method conditions for the analysis of the resulting DGF fluorescence complex in different matrices. The proposed method could be used in routine analysis of DGF in quality control laboratories. Also, it could be used to assay DGF in human plasma and be applied for pharmacokinetic investigation of DGF.

Determination of Ibuprofen and Phenylephrine in Tablets by High-Performance Thin Layer Chromatography and in Plasma by High-Performance Liquid Chromatography with Diode Array Detection.

Two chromatographic methods (high performance thin layer chromatography (HPTLC) and high performance liquid chromatography-diode array detector (HPLC-DAD)), were addressed for the analysis of a mixture consisted of phenylephrine hydrochloride and ibuprofen in two forms bulk and their combined dosage form. This binary mixture is considered to be a challenging one as the two drugs differ greatly in their chemical and physical properties. Not only this affects their simultaneous analysis, but also hinders their simultaneous extraction from biological fluids as plasma. That is the reason the literature lacks any report for the simultaneous extraction and analysis of these drugs from biological fluids. The concentration ranges of both drugs were 0.1-2.5 µg/spot and 0.1-100 µg/mL by HPTLC and HPLC, respectively. Not only was the HPLC-DAD method applied to the investigated drugs determination in pharmaceutical preparations, but also in spiked human plasma. Extensive study was conducted to optimize their simultaneous extraction from plasma as it was a crucial step for the in vivo analysis. The results obtained by proposed methods and a reference one were statistically comparable by analysis of variance test. No significant difference was recorded between the mean percent levels determined by the proposed methods and the reference one.

Application of Capillary Zone Electrophoresis Coupled with a Diode Array Detector (CZE-DAD) for Simultaneous Analysis of Ibuprofen and Phenylephrine.

Background: A validated method based on capillary zone electrophoresis coupled with a diode array detector (CZE-DAD) was investigated for analyzing binary mixture of ibuprofen (IBU) and phenylephrine (PHE) in their bulk and combined dosage form. Objective: This binary mixture is a challenging one as IBU is acidic and PHE is alkaline, which may affect their simultaneous analysis using CZE. The literature lacks any CZE report for IBU and PHE simultaneous analysis. Methods: Fused silica capillary (85 cm × 75 µm id) was used, and the electrolyte was a 50 mM borate buffer adjusted to pH 11 with 0.5 M NaOH. Results: The concentration ranges were 5-200 and 5-100 µg/mL for IBU and PHE, respectively, using CZE. High efficiency was achieved (N > 92990). Reasonable migration time (tm) was attained (tm< 8.5 min). Conclusions: Although the results obtained by the proposed CZE method and reported HPLC method were statistically comparable, the proposed method showed lower linearity ranges, higher efficiency, and a more reasonable run time. Highlights: CZE-DAD was used for the analysis of IBU and PHE in bulk and tablets, as no report was found for their determination using CZE. Binary mixture is challenging due to differences in chemical and physical properties. A detailed discussion of electrophoretic parameters optimization is included. Confirmation of peak purity was attained using DAD.

Simple protein precipitation extraction technique followed by validated chromatographic method for linezolid analysis in real human plasma samples to study its pharmacokinetics.

Fast and sensitive HPLC method was developed, optimized and validated for quantification of linezolid (LNZ) in human plasma using guaifenesin as an internal standard (IS). Analyte and IS were extracted from plasma by simple protein precipitation extraction technique using methanol as the precipitating solvent. The pretreated samples were injected in a mobile phase formed of acetonitrile:water:methanol (20:70:10v/v/v) in an isocratic mode at a flow rate of 1.5mL/min with UV detection at 251nm. Separation was done using Aglient ODS C18. The method showed linearity in the range of 0.75-50µg/mL with correlation coefficients equals to 0.9991. Precision and accuracy were in conformity with the criteria normally accepted in bio-analytical method validation. The RSDs for intra- and inter-day assays were <3.56 and 4.63%, respectively. The intra- and inter-day accuracies were 94.67-98.28% and 91.25-96.18%, respectively. The mean absolute recoveries ranged from 92.56±1.78 to 95.24±2.84. According to stability results, LNZ was stable in human plasma during the storage and analysis. LNZ a pharmacokinetic behavior was studied by applying the proposed analytical method.

High-performance liquid chromatography with diode array detection method for the simultaneous determination of seven selected phosphodiesterase-5 inhibitors and serotonin reuptake inhibitors used as male sexual enhancers.

This work presents a simple, sensitive and generic high-performance liquid chromatography with diode array detection method for the simultaneous determination of seven drugs prescribed for the treatment of erectile dysfunction and premature ejaculation. Investigated drugs include the phosphodiesterase-5 inhibitors: sildenafil, tadalafil, and vardenafil, in addition to the selective serotonin reuptake inhibitors: dapoxetine, duloxetine, fluoxetine, and paroxetine. The drugs were separated using a Waters C8 column (4.6 × 250 mm, 5 µm) with the mobile phase consisting of phosphate buffer pH 3, acetonitrile and methanol in the ratio 60:33:7. The flow rate was 1.2 mL/min, and quantification was based on measuring peak areas at 225 nm. Peaks were perfectly resolved with retention times 3.3, 3.9, 6.4, 7.5, 9.5, 10.7, and 13.4 min for vardenafil, sildenafil, paroxetine, duloxetine, dapoxetine, fluoxetine, and tadalafil, respectively. The developed method was validated with respect to system suitability, linearity, ranges, accuracy, precision, robustness, and limits of detection and quantification. The proposed method showed good linearity in the ranges 5-500, 2-200, 2-200, 3-300, 1.5-150, 2-200, and 2-200 µg/mL for sildenafil, tadalafil, vardenafil, dapoxetine, duloxetine fluoxetine, and paroxetine, respectively. The limits of detection were 0.18-0.38 µg/mL for the analyzed compounds. The applicability of the proposed method to real life situations was assessed through the analysis of commercial tablets, and satisfactory results were obtained.