HPLC analysis of raloxifene hydrochloride and its application to drug quality control studies

Colorimetric detection for raloxifene based on Cu-PTs nanozyme with peroxidase-like activity

The amorphous Cu-containing phosphomolybdate (Cu-PTs) composite with high peroxidase (POD)-like activity at neutral conditions was explored as biosensors for raloxifene (RAF) detection. The strong attraction between negatively charged Cu-PTs and positively charged substrates 3,3',5,5'-tetramethylbenzidine (TMB), as well as the acceleration of the conversion of active Cu+/Cu2+ by the Cu/W bimetallic redox couples were demonstrated to play significant roles in POD-like activity in physiological environment. When RAF is presence, it can bind to the surface of Cu-PTs and changes the chemical signal on the material surface, leading to the decreased POD-like activity. Based on this, a colorimetric method was established for the sensitive assay of RAF with a lower limit of detection (LOD) of 0.025 mg/L and good recovery from 90.13% to 108.9%. This work paves a new way to design a POD-like colorimetric protocol for tracing RAF in pharmaceutical products and environmental samples.

Potentiality of raloxifene loaded melittin functionalized lipidic nanovesicles against pancreatic cancer cells

Pancreatic cancer (PC) frequency and incidence have grown rapidly in recent years. One of the most serious problems with PC is the existence of asymptotic manifestations, which frequently delays early detection, and until the diagnosis is established, tumor cells progress to the metastatic stage. Another significant concern with PC is the scarcity of well-defined pharmacotherapeutic drugs. The aim of this study was to develop an efficient nanocarrier system to augment the efficacy of raloxifene (RLX) against PC cells. As a result, the current investigation was carried out in order to give an effective treatment method, in which an optimum RLX loaded phospholipid-based vesicles with melittin (PL-MEL) was chosen using experimental design software, with particle size, zeta potential and entrapment efficiency % as dependent variables. Furthermore, anticancer activity against PANC1 cells was assessed. The optimized nanovesicle parameters were 172.5 nm for the measured size, zeta potential of -0.69 mV, and entrapment efficiency of 76.91% that were in good agreement with the expected ones. RLX-raw, plain formula, and optimized RLX-PL-MEL showed IC50 concentrations of 26.07 ± 0.98, 9.166 ± 0.34, and 1.24 ± 0.05 µg/mL, respectively. Furthermore, cell cycle analysis revealed that the nanovesicle was most effective in the G2-M phase, whereas Bax, and Bcl-2 estimates revealed that optimized RLX formula had the highest apoptotic activity among treatments investigated. However, as compared to RLX alone or plain formula alone, the optimized formula demonstrated higher expression of TNFα and Bax while a significant reduction of Bcl-2 and NF-κB expression was observed. mitochondrial membrane potential (MMP) analysis confirmed the apoptosis as well as the anticancer effect of the optimized formula. Thus, the present study results showed an improvement in the anti-PC effects of the RLX with phospholipid conjugated melittin, making it a novel treatment approach against PC.

Simultaneous Determination of Adulterants in Dietary Food Supplements Using Multivariate Data Analysis after Preconcentration with Novel Nanosorbents and Chromatographic Measurement

Background

The increasing popularity of dietary supplements and, consequently, related adulteration emphasizes the rising need to examine the association of food supplements with fraud. Intentional or unintentional fraud in food supplements by hazardous chemicals compounds is a problem that many countries are struggling with. Much effort have been made to effectively and reliably control the quality of food supplements.

Objective

Due to the importance of the subject, an analytical method for the simultaneous and reliable detection and quantitative determination of three key adulterants in dietary food supplements was developed. The proposed method benefits from analytical methods and multivariate calibration methods to progress the determination of adulterants in a complex matrix.

Methods

HPLC assisted by multivariate curve resolution-alternating least square (MCR-ALS) analysis was used to detect adulterants in real samples after separation and preconcentration using novel mesoporous carbon nanoparticles. Solid-phase extraction (SPE) optimization was accomplished by central composite design (CCD). In order to obtain the best results, the MCR-ALS model was compared with the parallel factor analysis 2 (PARAFAC2) model and validated by estimation of linearity, detection limits, and recovery.

Results

The detection limits and linear dynamics were calculated as 1.5, 4.27, and 4.77 µg/mL, and 1–50, 5–20, and 5–20 µg/mL for caffeine, ephedrine, and fluoxetine, respectively. Mean recovery for determination of caffeine, ephedrine, and fluoxetine using the developed method was reported as 101.75, 91.7, and 92.36, respectively.

Conclusion

The results showed that to avoid negative health outcomes associated with the excessive consumption of adulterated food supplements releasing such products should be carefully regulated. The developed method was validated using statistical factors and showed acceptable and reliable results.

Highlights

(1) The application of MCR-ALS coupled with HPLC-Diode-Array Detection data sets allowed the simultaneous identification and quantification of three key adulterants (caffeine, ephedrine, and fluoxetine) in dietary food supplements. (2) A small amount of the novel adsorbent was successfully used to preconcentrate the trace amounts of adulterants in samples. (3) This method benefits from the chemometrics tools and experimental design to significantly reduce the use of toxic solvents and complicated instruments to propose a less time-consuming method for quantification of multicomponents in the presence of uncalibrated interferents.

Enhancing the Bioavailability and Efficacy of Vismodegib for the Control of Skin Cancer: In Vitro and In Vivo Studies

Skin cancer is the most frequent cancer throughout the world. Vismodegib (VSD) is a hedgehog blocker approved for the prevention and treatment of skin cancer. VSD, however, is poorly bioavailable and has been linked to side effects. This work focused on designing a nano-invasome gel as a vehicle for enhancing the permeation, bioavailability, and efficacy of VSD. Additionally, the combined effect of terpenes and ethanol was studied on the permeation of VSD compared with liposomes. The prepared VSD-loaded invasomes (VLI) formulation included cineole (1%v/v), cholesterol (0.15%w/w), phospholipid (2%w/w), and ethanol (3%v/v) and displayed an entrapment efficiency of 87.73 ± 3.82%, a vesicle size of 188.27 ± 3.25 nm, and a steady-state flux of 9.83 ± 0.11 µg/cm²/h. The VLI formulation was vigorously stirred into a carbopol base before being characterized in vivo to investigate the permeation, bioavailability, and efficacy of VSD. The VLI gel enhanced the dermal permeation of VSD and, as a result, had 3.59 times higher bioavailability with excellent antitumor action as compared to oral VSD. In summary, as an alternative to oral administration for skin cancer treatment, invasomes are efficient carriers for delivering VSD and enhancing its transdermal flux into deep skin layers.

The Impact of Improving Dermal Permeation on the Efficacy and Targeting of Liposome Nanoparticles as a Potential Treatment for Breast Cancer

Breast cancer is the most frequent malignancy in women. This work focuses on developing deformable liposomes as a potential carrier for breast cancer treatment and studying the impact of improving dermal permeation on the efficacy and targeting of liposomes. Raloxifene (RXF), an oestrogen antagonist, was used as a model drug. Using Box-Behnken design, different formulations of RXF-loaded deformable liposome (RLDL) were prepared using different propylene glycol, phospholipid and cholesterol concentrations. The percentage of entrapment efficiency (Y₁), particle size (Y₂), zeta potential (Y₃) and steady-state flux (Y₄) of the prepared formulations were all evaluated. Y₁ and Y₄ were significantly increased and Y₂ and Y₃ were significantly decreased when the propylene glycol concentration was increased. The optimization was obtained and the optimum formulation was that including phospholipid (1.40% w/w), cholesterol (0.15% w/w) and propylene glycol (10% v/v). The selected optimum formulation displayed a % EE of 78.34 ± 1.04% with a steady-state flux of 4.21 ± 0.02 µg/cm²/h. In order to investigate bioavailability, antitumor effectiveness and permeation, the optimum formulation was selected and included in a carbopol gel. The optimum gel formulation had 2.77 times higher bioavailability and, as a result, considerable antitumor action as compared to oral RXF. In conclusion, optimum RLDL gel may be an effective breast cancer treatment.

Lipidic Nano-Sized Emulsomes Potentiates the Cytotoxic and Apoptotic Effects of Raloxifene Hydrochloride in MCF-7 Human Breast Cancer Cells: Factorial Analysis and In Vitro Anti-Tumor Activity Assessment

Raloxifene hydrochloride (RLX), an antiosteoporotic agent, has been utilized for guarding against breast cancer and recently, for the disease management owing to its estrogen antagonist activity. Nevertheless, RLX exhibits poor bioavailability that could be attributed to reduced water solubility and first pass metabolism. To overcome these challenges, this study aimed at formulating and optimizing RLX emulsomes (RLX-EMLs) to enhance the drug antitumor activity. A 4131 factorial design was employed for assessing the effect of lipoid: solid lipid ratio and solid lipid type on the emulsomes characteristics. The anticancer potential of the optimized formulation and apoptotic parameters were assessed. Vesicle size, entrapment, and release efficiency were significantly influenced by both variables, while zeta potential was influenced by lipoid: solid lipid at p < 0.05. The optimal formulation exhibited vesicle size of 236 ± 8.6 nm, zeta potential of -18.6 ± 0.7 mV, drug entrapment of 98.9 ± 4.9%, and release efficiency of 42.7 ± 1.8%. MTT assay showed concentration-dependent inhibition of MCF-7 cells viability. In addition, cells treated with RLX-EMLs showed significant arrest at G2/M phase associated with significant increase in apoptotic and necrotic cells. The enhanced cytotoxic and anti-proliferative effect of RLX-EMLs relative to raw drug was authenticated through increased Bax/Bcl-2 ratio, caspase-9 activation and depletion of mitochondrial membrane potential.

A matrix dispersion based on phospholipid complex system: preparation, lymphatic transport, and pharmacokinetics

Raloxifene hydrochloride (RH) suffers from low oral bioavailability due to its low water-solubility and first-pass metabolism. Therefore, a novel phospholipid complex of RH (RHPC) and a matrix dispersion based on phospholipid complex (RHPC-MD) were successfully prepared and optimized. Several methods were used to validate the formation of RHPC and RHPC-MD, such as differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, particle size, and zeta potential, meanwhile, their octanol-water partition coefficient, solubility, and dissolution in vitro were also evaluated. To investigate the absorption mechanism of RHPC in vivo, the RHPC was administered to the chylomicron flow blockage rat model. Interestingly, as we expected, a significant reduction in RHPC absorption (67%) (**p< .01) in presence of cycloheximide (CXI) inhibitor was observed, thus confirming the RHPC could be absorbed by lymphatic transport in vivo. Pharmacokinetic studies revealed that the relative oral bioavailability of RHPC as well as RHPC-MD was 223% and 329%, respectively, when comparing with the commercial RH tablets. These outcomes suggested that the current study provided an attractive formulation to enhance the oral bioavailability of RH and stimulated to further research the absorption mechanism of RHPC in vivo.

Folic acid-conjugated raloxifene hydrochloride carbon nanotube for targeting breast cancer cells

Breast cancer is one of the leading causes of mortality specifically for the women. The existing therapy is not sufficient due to the lack of target specificity and drug resistance. Carbon nanotubes (CNTs) are one of the promising formulation approaches that show a promising effect to target specifically the cancer cells, with better cellular internalization. CNTs were prepared based on the modified Staudenmaier process, where temperature and stirring speed were found to be the most influencing factor for particle size and entrapment of the drug raloxifene hydrochloride (RLX). The optimized formulation was produced with drug loading of about 74.2 ± 4.67% and the average particle size of 234.2 ± 1.7 nm. The surface of the CNTs was functionalized by folic acid (FA), which helps to deliver the drug on the site of the cancer cells only in a target-specific manner. in vitro drug-release studies indicated that the drug release was dependent on the pH of the system. Cytotoxicity study clearly indicated the efficacy of the FA physically conjugated CNTs with affectivity induces apoptosis in the cancer cell line with the IC50 value of 43.57305 μg/ml. The fluorescence imagining study showed higher cellular internalization of the RLX compared with the pure drug and the RLX-CNT formulation.

In situ misemgel as a multifunctional dual-absorption platform for nasal delivery of raloxifene hydrochloride: formulation, characterization, and in vivo performance

BACKGROUND

Raloxifene hydrochloride (RLX) is approved by the US Food and Drug Administration for the treatment and prevention of osteoporosis, in addition to reducing the risk of breast cancer in postmenopausal women. RLX has the disadvantages of low aqueous solubility, extensive presystemic intestinal glucuronidation, and first-pass metabolism, resulting in a limited bio-availability of only 2%. The aim of this work was to enhance the bioavailability of RLX via the formulation of an in situ nasal matrix (misemgel) comprising micelles made of vitamin E and D-α-tocopheryl polyethylene glycol 1000 succinate and nanosized self-emulsifying systems (NSEMS).

MATERIALS AND METHODS

Optimization of the RLX-loaded NSEMS was performed using a mixture design. The formulations were characterized by particle size and then incorporated into an in situ nasal gel. Transmission electron microscopy, bovine nasal mucosa ex vivo permeation, and visualization using a fluorescence laser microscope were carried out on the RLX in situ misemgel comparing with raw RLX in situ gel. In addition, the in vivo performance was studied in rats.

RESULTS

The results revealed improved permeation parameters for RLX misemgel compared with control gel, with an enhancement factor of 2.4. In vivo studies revealed a 4.79- and 13.42-fold increased bioavailability for RLX in situ misemgel compared with control RLX in situ gel and commercially available tablets, respectively. The obtained results highlighted the efficacy of combining two different formulations to enhance drug delivery and the benefits of utilizing different possible paths for drug absorption.

CONCLUSION

The developed in situ misemgel matrix could be considered as a promising multifunctional platform for nasal delivery which works based on a dual-absorption mechanism.

Mechanochemically induced solid state transformations: The case of raloxifene hydrochloride

Raloxifene hydrochloride is a benzothiophene derivative mainly used in the prevention and treatment of osteoporosis, but exhibits a low bioavailability hindered by its poor water solubility. In this study, a mechanochemical approach based on neat and liquid-assisted grinding was applied to produce new solid forms of raloxifene hydrochloride. The solids obtained were characterized by several solid-state techniques, such as powder X-ray diffraction, thermal analysis, infrared and Raman spectroscopy. These results showed that depending on the processing conditions solvated or amorphous forms can be produced. The thermal stability of the new forms was also investigated showing that the new forms convert back into the raw material form, as observed by Raman spectroscopy, which was successfully used to discriminate amorphous and crystalline forms, as well as, to monitor in situ the recrystallization process. Furthermore, the solubility of the new forms was evaluated, showing the clear advantage of the amorphous form, when compared with the currently marketed salt.

The Effectiveness of Raloxifene-Loaded Liposomes and Cochleates in Breast Cancer Therapy

Liposome (spherical vesicles) and cochleate (multilayer crystalline, spiral structure) formulations containing raloxifene have been developed having dimethyl-β-cyclodextrin (DM-β-CD) or sodium taurocholate (NaTC). Raloxifene was approved initially for the treatment of osteoporosis but it is also effective on breast tissue and endometrial cells. Raloxifene inhibits matrix metalloproteinase-2 (MMP-2) enzyme, which is known to be responsible for tumor invasion and the initiation of angiogenesis during the tumor growth. Therefore, raloxifene was selected as a model drug. A series of raloxifene-loaded liposome and cochleate formulations were prepared. In vitro release studies and in vivo tests were performed. Breast cancer cell lines (MCF-7) were also used to find the most effective formulation. Highest antitumor activity was observed, and MMP-2 enzyme was also found to be inhibited with raloxifene-loaded cochleates containing DM-β-CD. These developed formulations can be helpful for further treatment alternatives and new strategies for cancer therapy.

Development of alternative methods for the determination of raloxifene hydrochloride in tablet dosage form

<p>Three methods are proposed for the quantitative determination of raloxifene hydrochloride in pharmaceutical dosage form: ultraviolet method (UV) high performance liquid chromatography (HPLC) and micellar capillary electrophoresis (MEKC). These methods were developed and validated and showed good linearity, precision and accuracy. Also they demonstrated to be specific and robust. The HPLC and MEKC methods were tested in regards to be stability indicating methods and they showed to have this attribute. The UV method used methanol as solvent and optimal wavelength at 284 nm, obeying Lambert-Beer law in these conditions. The chromatographic conditions for the HPLC method included: NST column C18 (250 x 4.6 mm x 5 µm), mobile phase water:acetonitrile:triethylamine (67:33:0,3 v/v), pH 3.5, flow rate 1.0 mL min^-1, injection volume 20.0 µl, UV detection 287 nm and analysis temperature 30 °C. The MEKC method was performed on a fused-silica capillary (40 cm effective length x 50 µm i.d.) using as background electrolyte 35.0 mmol L^-1 borate buffer and 50.0 mmol L^-1 anionic detergent sodium dodecyl sulfate (SDS) at pH 8.8. The capillary temperature was 32°C, applied voltage 25 kV, UV detection at 280 nm and injection was perfomed at 45 mBar for 4 s, hydrodimanic mode. In this MEKC method, potassium diclofenac (200.0 µg mL^-1) was used as internal standard. All these methods were statistically analyzed and demonstrated to be equivalent for quantitative analysis of RLX in tablets and were successfully applied for the determination of the drug.</p>

Experimental design and optimization of raloxifene hydrochloride loaded nanotransfersomes for transdermal application

Raloxifene hydrochloride, a highly effective drug for the treatment of invasive breast cancer and osteoporosis in post-menopausal women, shows poor oral bioavailability of 2%. The aim of this study was to develop, statistically optimize, and characterize raloxifene hydrochloride-loaded transfersomes for transdermal delivery, in order to overcome the poor bioavailability issue with the drug. A response surface methodology experimental design was applied for the optimization of transfersomes, using Box-Behnken experimental design. Phospholipon^® 90G, sodium deoxycholate, and sonication time, each at three levels, were selected as independent variables, while entrapment efficiency, vesicle size, and transdermal flux were identified as dependent variables. The formulation was characterized by surface morphology and shape, particle size, and zeta potential. Ex vivo transdermal flux was determined using a Hanson diffusion cell assembly, with rat skin as a barrier medium. Transfersomes from the optimized formulation were found to have spherical, unilamellar structures, with a homogeneous distribution and low polydispersity index (0.08). They had a particle size of 134±9 nM, with an entrapment efficiency of 91.00%±4.90%, and transdermal flux of 6.5±1.1 μg/cm²/hour. Raloxifene hydrochloride-loaded transfersomes proved significantly superior in terms of amount of drug permeated and deposited in the skin, with enhancement ratios of 6.25±1.50 and 9.25±2.40, respectively, when compared with drug-loaded conventional liposomes, and an ethanolic phosphate buffer saline. Differential scanning calorimetry study revealed a greater change in skin structure, compared with a control sample, during the ex vivo drug diffusion study. Further, confocal laser scanning microscopy proved an enhanced permeation of coumarin-6-loaded transfersomes, to a depth of approximately160 μM, as compared with rigid liposomes. These ex vivo findings proved that a raloxifene hydrochloride-loaded transfersome formulation could be a superior alternative to oral delivery of the drug.

Measuring selective estrogen receptor modulator (SERM)-membrane interactions with second harmonic generation

The interaction of selective estrogen receptor modulators (SERMs) with lipid membranes has been measured at clinically relevant serum concentrations using the label-free technique of second harmonic generation (SHG). The SERMs investigated in this study include raloxifene, tamoxifen, and the tamoxifen metabolites 4-hydroxytamoxifen, N-desmethyltamoxifen, and endoxifen. Equilibrium association constants (Ka) were measured for SERMs using varying lipid compositions to examine how lipid phase, packing density, and cholesterol content impact SERM-membrane interactions. Membrane-binding properties of tamoxifen and its metabolites were compared on the basis of hydroxyl group substitution and amine ionization to elucidate how the degree of drug ionization impacts membrane partitioning. SERM-membrane interactions were probed under multiple pH conditions, and drug adsorption was observed to vary with the concentration of soluble neutral species. The agreement between Ka values derived from SHG measurements of the interactions between SERMs and artificial cell membranes and independent observations of the SERMs efficacy from clinical studies suggests that quantifying membrane adsorption properties may be important for understanding SERM action in vivo.

The effective encapsulation of a hydrophobic lipid-insoluble drug in solid lipid nanoparticles using a modified double emulsion solvent evaporation method

Raloxifene HCl (RH), a selective estrogen receptor modulator (SERM), is indicated for the prophylaxis or treatment of postmenopausal osteoporosis. RH shows extremely poor bioavailability due to limited solubility and an extensive intestinal/hepatic first-pass metabolism. Solid lipid nanoparticles (SLNs) are valuable carriers that can enhance drug bioavailability. However, in the case of RH, the encapsulation of the drug in SLNs remains a challenge because of its poor solubility in both water and lipids. In this study, a series of RH-containing SLNs (RH-SLNs) were generated using a modified double emulsion solvent evaporation (DESE) method. Briefly, RH with various drug/lipid ratios was solubilized in the inner core of a double emulsion using different water/organic solvent mixtures. Our best formulation was achieved with the formation of negatively charged nanoparticles, 180nm in diameter, with an encapsulation and loading efficiency of 85% and 4.5%, respectively. It also showed a Fickian mechanism of the drug release in the basic dissolution media. Thermal analysis revealed a distinct decrease in the crystallinity of lipids and RH in comparison with the unprocessed materials. The results of a cell viability assay also showed a better antiproliferative effect of the drug-loaded SLNs versus the free drug solution. Thus, these results indicated that the modified DESE method could be proposed for the effective encapsulation of RH in SLNs with appropriate physicochemical and biological properties.

Systematical approach in evaluation of LC method for determination of raloxifene hydrochloride and its impurities employing experimental design

Method validation presents a detailed investigation of analytical method and provision of the evidence that the method, when correctly applied, produces results that fit to the purpose. In order to achieve the method validation scope efficiently, experimental design presents a very useful tool. The greatest benefits of such approach could be seen in robustness testing through the provision of very useful data about the control of the chromatographic system during the routine application. In this paper, robustness testing of the LC method proposed for the determination of raloxifene hydrochloride and its four impurities was done employing Plackett-Burman design. Applying this design, the effect of five real factors (acetonitrile content, sodium dodecyl sulfate content, column temperature, pH of the mobile phase and flow rate) on the corresponding resolution factors was investigated through twelve experiments. Furthermore, the insignificance intervals for significant factors were calculated and the parameters for system suitability tests were defined. Eventually, the other validation parameters were tested and the effectiveness of the proposed analytical method with a high degree of accuracy was confirmed.

Electrochemistry of raloxifene on glassy carbon electrode and its determination in pharmaceutical formulations and human plasma

The electrochemical behavior of raloxifene (RLX) on the surface of a glassy carbon electrode (GCE) has been studied by cyclic voltammetry (CV). The CV studies were performed in various supporting electrolytes, wide range of potential scan rates, and pHs. The results showed an adsorption-controlled and quasi-reversible process for the electrochemical reaction of RLX, and a probable redox mechanism was suggested. Under the optimum conditions, differential pulse voltammetry (DPV) was applied for quantitative determination of the RLX in pharmaceutical formulations. The DPV measurements showed that the anodic peak current of the RLX was linear to its concentration in the range of 0.2-50.0μM with a detection limit of 0.0750μM, relative standard deviation (RSD %) below 3.0%, and a good sensitivity. The proposed method was successfully applied for determination of the RLX in pharmaceutical and human plasma samples with a good selectivity and suitable recovery.

Penetration of moxifloxacin into rat mandibular bone and soft tissue

OBJECTIVE

Based on its in vitro activity and spectrum of activity, the new 8-methoxyquinolone antibiotic moxifloxacin (MXF) seems suited for the antibiotic therapy of odontogenic infections. Penetration into the relevant tissue is another prerequisite for clinical efficacy. For this reason, the levels of MXF in plasma, soft tissue, and mandibular bone were determined in an animal model with Wistar rats.

MATERIAL AND METHODS

Samples of 49 rats were analyzed. Tissue samples were homogenized and proteins were precipitated. The pharmacokinetic evaluation was conducted based on non-compartmental analysis.

RESULTS

The concentration-time courses of tissues show a more plateau-shaped curve compared to plasma. Calculated AUC (area under the curve) ratios tissue:plasma were M. masseter:plasma = 2.64 and mandibles:plasma = 1.13.

CONCLUSIONS

Administration of antibiotics is considered an important part of therapy during and/or after surgical procedures in the maxillofacial area. Because of the good penetration into bone and muscle tissues demonstrated in Wistar rats, MXF might be an option for clinical application in this indication.

Gradient HPLC analysis of raloxifene hydrochloride and its application to drug quality control

A rapid, sensitive and selective method for the determination of raloxifene hydrochloride (RLX) in pure drug and in tablets was developed using gradient high performance liquid chromatography (HPLC). The devised method involved separation of RLX on a reversed phase Hypersil ODS column and determination with UV detection at 284 nm. The standard curve was linear (R = 0.999) over the concentration range of 50-600 microg mL-1 with a detection limit of 0.04 microg mL-1 and a quantification limit of 0.16 microg mL-1. Intra-day and inter-day precision and accuracy of the method were established according to the current ICH guidelines. Intra-day RSD values at three QC levels (250, 450 and 550 microg mL-1) were 0.2-0.5%, based on the peak area. The intra-day relative error (er) was between 0.2 and 0.5%. The developed method was successfully applied to the determination of RLX in tablets and the results were statistically compared with those obtained by a literature method. Accuracy, evaluated by means of the spike recovery method, was the excellent with percent recovery in the range 97.7-103.2 with precision in the range 1.6-2.2%. No interference was observed from the co-formulated substances. The method was economical in terms of the time taken and the amount of solvent used.

Development and validation of a liquid chromatography–tandem mass spectrometry assay for determination of raloxifene and its metabolites in human plasma

This paper describes the development and validation of a method for the detection of raloxifene (Ral) and its two glucuronide metabolites, raloxifene-6-glucuronide (M1) and raloxifene-4'-glucuronide (M2), in human plasma samples. Both glucuronides were synthesized enzymatically, purified and used as authentic standards. The assay involves a simple solid phase extraction (SPE) procedure of 0.5 mL of human plasma and subsequent analysis by LC-MS-MS. The recoveries were higher than 71% and chromatographic separation of all the analytes was accomplished in less than 7 min. Linear ranges (r(2)>0.99) were found from 0.200 to 340 microg/L, from 1.600 to 2720 microg/L and from 0.088 to 60.00 microg/L, for M1, M2 and Ral, respectively. The limits of detection achieved were 8, 11 and 6 ng/L for M1, M2 and Ral, respectively. The method presented was successfully applied to a genetic polymorphism study of 47 plasma samples from women taking Evista (raloxifene hydrochloride).

The determination of raloxifene in rat tissue using HPLC

We report a rapid and reliable HPLC-UV method for determination of raloxifene, a kind of selective estrogen receptor modulator (SERM), in rat tissue. Proteins were precipitated by adding 200 microL of acetonitrile and 50 microL of methanol to 100 microL of the tissue homogenates, following vortex mixing and centrifugation. Separation was carried out on a reversed-phase C(18) column (150 x 4.6 mm, 5 microm) with a mobile phase of acetonitrile:0.05 m ammonium acetate (pH 4.0 +/- 0.1; 33:67, v/v) at a flow rate of 1.0 mL/min. The UV detection wavelength was set at 289 nm and the temperature of column was kept at 23 degrees C, without interference from endogenous tissue compounds. The calibration curve was linear from 0.0125 to 10.0 microg/mL with correlation coefficient of over 0.994, while the limit of quantification was 0.008 microg/mL. The intra- and inter-day coefficients of variation were less than 10% (RSD). The recovery of assay was between 95.8 and 104.5%. Furthermore, the method was used to measure the concentration of raloxifene in rat tissue after a simple oral dose. The highest level was observed in liver, lung, spleen, then heart and kidney. The lowest level was found in brain. These results suggest that raloxifene distributes rapidly and moderately into tissues such as liver, lung and spleen.