Qualitative and quantitative analysis of PDE-5 inhibitors in counterfeit medicines and dietary supplements by HPLC–UV using sildenafil as a sole reference

Adulterated dietary supplements commercialized in Brazil: development of a screening method and a preliminary study of cytotoxicity

The high consumption of dietary supplements was a fundamental driver for the creation of the regulatory framework by the Brazilian governmental authorities. However, the regulatory agencies lack official low-cost methodologies to evaluate the quality of food supplements. A preliminary screening method by HPLC-DAD was proposed and validated for screening and quantification of adulterants in dietary supplements. The limits of detection and quantification were <0.11 and 0.37 µg.g-1, respectively. The method was applied for the investigation of ten unauthorized substances (spironolactone, hydrochlorothiazide, furosemide, clenbuterol, testosterone, testosterone propionate, yohimbine, vardenafil, tadalafil, and sildenafil) with a time of analysis of <5 min. Sixteen percent of the 44 samples analyzed had at least one adulterant at or above therapeutic concentrations. Subsequently, in vitro evaluations were performed of the potential cytotoxicity to evaluate the cell viability, DNA damage, determination of nitric oxide levels, and quantification of reactive oxygen species. Despite the necessity of further studies, the results indicate a relationship between the presence of adulterants in food supplements and a potential cytotoxic effect.

Detection of 94 PDE-5is and Their Analogs Including N-Desmethylthiosildenafil in Various Formulations of Dietary Supplements and Food Samples Using HPLC and LC-Q-TOF/MS

Consumption of foods and dietary supplements (DS) adulterated with unprescribed or non-permitted phosphodiesterase-5 inhibitors (PDE-5i) and their analogs can cause serious risk to human health. This study aims to analyze 93 PDE-5i and their analogs present in adulterated foods and DS using an established and validated method involving high-performance liquid chromatography (HPLC). The method was validated in solid and liquid samples, resulting in a limit of detection and quantitation of 0.03-0.5 and 0.08-1.6 μg/mL, respectively. Using the validated method, a total of 404 samples were screened. It was found that 32% of 404 samples were illegally adulterated with PDE-5i and their analogs; moreover, 16.9% of the adulterated samples were found to contain more than three compounds. HPLC-quadrupole-time-of-flight (TOF)/mass spectrometry (MS) analysis was conducted on all the samples to confirm the detected compounds accurately based on fragmentation ion patterns. In addition, sildenafil and tadalafil were detected from the capsule shells of DS unusually. Subsequently, the detected compounds were identified and quantified using HPLC at concentrations ranging from 0.007 to 370.0 mg/g. NMR analysis was carried out to confirm the accurate chemical structure of a compound found during the TOF/MS analysis, which did not match with the 93 reference standards.; it was identified to be N-desmethylthiosildenafil. In this study, various PDE-5i compounds and their analogs were detected from low to high concentrations in a sample. Therefore, the study sheds light on the misuse of PDE-5i and their analogs in consumable products, which pose a severe threat to public health.

HPLC/Fluorescence-Diode Array Detection for Rapid and Reliable Determination of Illegal Synthetic Drugs in Male Sexual Herbal and Honey Remedies: Comparative Study with UFLC–MS

Background

Nutraceuticals (NTCs), as honey and tablets with herbal extract are subjected to adulteration.

Objective

For NTCs claimed to enhance sexual performance, synthetic drugs (sildenafil, tadalafil, avanafil, vardenafil, and dapoxetine) are common adulterants, so they were selected to be simultaneously analyzed in the current study. Natural aphrodisiacs (icariin and yohimbine) are claimed to be present in many fake NTCs, so they were also included in the study.

Methods

In order to achieve the target of the current study, three liquid chromatographic methods with different unique detectors were developed and validated.

Results

High performance liquid chromatography (HPLC) with fluorescence detection enables rapid and reliable determination of natively fluorescent yohimbine, tadalafil vardenafil, and dapoxetine and it is the first report to analyze these compounds as adulterants in counterfeit NTC. Although the diode-array detector (DAD) enables the analysis of the seven adulterants, the fluorescence detector (FLD) shows better sensitivity and selectivity with lower LOQs and LODs. On the other hand, ultra-fast liquid chromatography–mass spectrometry (UFLC–MS) offers the advantages of peak identity confirmation, and it is of comparable sensitivity and selectivity to HPLC–FLD.

Conclusion

One or more of these synthetic drugs were found in the analyzed NTCs while natural aphrodisiacs were absent.

Highlights

Aphrodisiac nutraceuticals, NTCs, were analyzed for adulterants: five aphrodisiac synthetic drugs (adulterants) and two natural claimed aphrodisiacs. UFLC–MS and HPLC–DAD/FLD were compared for illicit NTCs analysis; all NTCs show the presence of synthetic aphrodisiacs and the absence of natural ones.

Lodenafil

Lodenafil is a class of drugs called an inhibitor of PDE5 which also include a wide range of other erectile medicines, such as sildenafil, tadalafil and vardenafil. It is part of a new generation of PDE5 inhibitors that includes udenafil and avanafil. Lodenafil is a prodrug manufactured in the form of lodenafil carbonate, the carbonate dimer that divides in the body into two active drug lodenafil molecules. The oral bioavailability of this formulation is higher than that of the parent drug. This article discusses, by a critical comprehensive review of the literature on lodenafil in terms of its description, names, formulae, elemental composition, appearance, and therapeutic uses. The article also discusses the methods for preparation of lodenafil, its physical-chemical properties, analytical methods for its determination, pharmacological-toxicological properties, and dosing information.

Assessment of Undeclared Synthetic Drugs in Dietary Supplements in an Analytical View: A Comprehensive Review

Dietary supplements have gained widespread attention globally as they are supposed to be healthier than synthetic pharmaceutical compounds with fewer side effects. Unlike common prescription drugs, dietary supplements are readily available to the general public. However, over the past few years, all kinds of legal and illegal drugs, have been detected in dietary supplements without labeling to defraud consumers, resulting in serious public health consequences. Due to the increasing number of drug frauds in dietary supplements, their consumption will undoubtedly risk consumers. Therefore; the importance of high-tech analytical methods in their assessment for controlling food quality seems undeniable. The current review examines the analytical techniques that focus on adulterating health products with undeclared pharmaceuticals, including registered and banned drugs. The present study referred to a survey from 2004 to 2021 based on articles in the Scopus database.

Facing Counterfeit Medications in Sexual Medicine. A Systematic Scoping Review on Social Strategies and Technological Solutions

Introduction

The counterfeit phenomenon is a largely under-reported issue, with potentially large burden for healthcare. The market for counterfeit drugs used in sexual medicine, most notably type 5 phosphodiesterase inhibitors (PDE5i), is rapidly growing.

Aims

To report the health risks associated with the use of counterfeit medications, the reasons driving their use, and the strategies enacted to contain this phenomenon.

Methods

A systematic scoping review of the literature regarding counterfeit PDE5i was carried between January and June 2021, then updated in August 2021.

Main Outcome Measure

We primarily aimed to clarify the main drivers for counterfeit PDE5i use, the health risks associated, and the currently available strategies to fight counterfeiters.

Results

One hundred thirty-one records were considered for the present scoping review. Production of fake PDE5i is highly lucrative and the lacking awareness of the potential health risks makes it a largely exploitable market by counterfeiters. Adulteration with other drugs, microbial contamination and unreliable dosages make counterfeit medications a cause of worry also outside of the sexual medicine scope. Several laboratory techniques have been devised to identify and quantify the presence of other compounds in counterfeit medications. Strategies aimed at improving awareness, providing antitampering packaging and producing non-falsifiable products, such as the orodispersible formulations, are also described.

Clinical implications

Improving our understanding of the PDE5i counterfeit phenomenon can be helpful to promote awareness of this issue and to improve patient care.

Strengths & Limitations

Despite the systematic approach, few clinical studies were retrieved, and data concerning the prevalence of counterfeit PDE5i use is not available on a global scale.

Conclusion

The counterfeit phenomenon is a steadily growing issue, with PDE5i being the most counterfeited medication with potentially large harmful effects on unaware consumers.

Sansone A, Cuzin B, and Jannini EA. Facing Counterfeit Medications in Sexual Medicine. A Systematic Scoping Review on Social Strategies and Technological Solutions. Sex Med 2021;9:100437.

Rapid Screening and Quantitative Determination of Illegal Phosphodiesterase Type 5 Inhibitors (PDE-5i) in Herbal Dietary Supplements

Phosphodiesterase type 5 inhibitors (PDE-5i) are the first-line medication for oral erectile dysfunction, which are used according to the prescription of doctors. However, these substances have been found illegally in supplementary foods. The quality and safety of dietary supplements for enhancing male sexual performance have been questioned, raising the need for continual development of analytical methods. Liquid chromatography coupled with high-resolution mass spectrometry has become one of the most effective methods to identify and measure PDE-5i concentration. In this research, we focused on (i) developing and validating an effective screening and quantitation method for more than 53 PDE-5i in ingredients and supplementary products using LC-Q-Exactive after a simple sample extraction and (ii) assessing PDE-5i content in natural-based supplementary products available in Vietnam market. The extraction method used a small amount of organic solvent, which makes it more environmentally friendly (greener). The developed method has a limit of detection of 0.4 mg/kg, a limit of quantitation of 1.2 mg/kg, recoveries from 80 to 110%, and repeatability lower than 15%. Ninety-two herbal supplementary foods and ingredients used for enhancement of male sexual performance available in Vietnamese markets were collected. Fourteen PDE-5i including conventional and novel analogous were detected and measured in eighteen food supplements and two formulation ingredient samples.

HPLC-UV and UPLC-MS/MS methods for the simultaneous analysis of sildenafil, vardenafil, and tadalafil and their counterfeits dapoxetine, paroxetine, citalopram, tramadol, and yohimbine in aphrodisiac products

In recent times, the counterfeiting of pharmaceuticals has been considered a serious trouble especially in developing countries that acquire poor inspection programs. Sildenafil, vardenafil and tadalafil (phosphodiesterase type 5 inhibitors) products have gained wide popularity in treating sexual disorders, for which they are subjected to counterfeiting. For this purpose, a simple, rapid, and novel HPLC method with ultraviolet detection has been simply developed for the simultaneous determination of vardenafil, sildenafil, and tadalafil, and their counterfeits (dapoxetine, paroxetine, citalopram, tramadol and yohimbine) in pharmaceutical dosage forms and counterfeit products such as instant coffee and honey. The separation was carried out on a C18 column, with acetonitrile and an aqueous 0.05% formic acid solution as the mobile phase with a gradient program and at a flow rate of 1 mL min-1. UV detection was accurately set at 230 nm. The total run time was 11 min for elution of these eight drugs. A UPLC-MS/MS method was also developed, by which compounds were separated in only 6 min, and it was used as a confirmatory tool for studied compounds by identification of their mass spectra. Proposed methods were validated by following ICH guidelines. Both methods were found to be linear, specific, precise and accurate, and they were efficiently applied to analyze 50 commercial products including honey sachets, instant coffee and pharmaceutical products marketed as aphrodisiacs and suspected to contain PDE5-inhibitors.

Application of Design Space, Uncertainty, and Risk Profile Strategies to the Development and Validation of UPLC Method for the Characterization of Four Authorized Phosphodiesterase Type 5 Inhibitors to Combat Counterfeit Drugs

BACKGROUND

Counterfeit medicines are an increasing scourge that are difficult to identify and they have become industrialized and widespread through highly organized illegal channels.

OBJECTIVE

This research aims to develop a robust method to determine four phosphodiesterase type-5 inhibitors in counterfeit drugs based on ultra-performance liquid chromatography.

METHOD

Experimental design methodology (DOE) and design space (DS) recommended by ICH Q8 were used side-by-side in the development phase to define the optimal parameters as well as the robustness of the chromatographic method. Moreover, both the uncertainty and risk profile derived from the β-content and γ-confidence tolerance interval were investigated during the validation phase to examine the performance of this method.

RESULTS

Successful chromatographic results, in a high resolution between the four active ingredients and an optimal analysis time of less than 1.6 min, were achieved at the end of the optimization phase. In addition, validation results show a low risk of future measurements outside acceptance limits set at 5%.

CONCLUSIONS

Our procedure was successfully applied in the routine phase to identify 23 illicit formulations of an erectile dysfunction drug.

HIGHLIGHTS

An efficient method for the characterization of 4 authorized phosphodiesterase in less than 1.6 min was established. A DS approach was applied to test the performance of this analytical method during analytical development. A risk profile was then carried out to approve the validity of the analytical method through the uncertainty profile approach.

A new approach to ion exchange chromatography with conductivity detection for adulterants investigation in dietary supplements

The extent of adulteration of dietary supplements has significantly increased in recent years. This situation worries health authorities and requires auxiliary analytical tools for the investigation of illegal substances purposely added. Ion exchange chromatography with conductivity detection is a consolidated analytical technique for the determination of inorganic compounds in various matrices. This technique has been applied to the pharmaceutical characterization of mainly impurities and degradation products. This work presents a new approach to ion exchange chromatography as a screening method to investigate the presence of amfepramone, femproporex, sibutramine, bisacodyl and amiloride in dietary supplements advertised for weight loss. The method was optimized and validated using a Metrosep C4 100/4.0 cation exchange column. The mobile phase consisted of 1.8 mm HNO₃ containing 2% acetonitrile (v/v), with a flow rate of 0.9 ml min^-1 , and nonsuppressed conductivity detection was applied. The limits of detection and quantification varied from 1.01 to 3.62 mg L^-1 and from 1.48 to 8.72 mg L^-1 , respectively. The proposed method was successful applied to 78 solid dietary supplement samples, in two of which adulterations were found. Moreover, ion exchange chromatography with conductivity detection could be easily used for quality control without prior complex sample pre-treatment.

Identification and Quantification of an Adulterant in a Dietary Supplement Marketed for Sexual Enhancement

In recent years, the consumption of dietary supplements (DS) has increased worldwide. In Argentina, approximately 14 million DS units were sold between 2015 and 2017. The adulteration of DS with active pharmaceutical ingredients or their analogues has been reported. This represents an alarming emerging risk to public health. The aim of this work was to detect the possible adulteration of a DS marketed in Argentina for the treatment of erectile dysfunction. Initially, thin layer chromatography analysis of the DS capsules content suggested the presence of a major compound. For the isolation and purification of this compound, an easy method consisted of a liquid-liquid extraction (water/CH2Cl2) followed by re-crystallisation from ethanol, is reported. Spectroscopic techniques such as mono- and bidimensional nuclear magnetic resonance, Fourier transform infrared spectroscopy and mass spectrometry allowed its identification as tadalafil. A rapid and reliable method was developed for the quantification of tadalafil in this DS by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS). The mean content of tadalafil per capsule was 21.2 mg which represents a slightly higher value than that found in approved products in Argentina (5 or 20 mg per tablet). In addition, an undeclared alga was identified in the DS by microscopic techniques.

Simultaneous analysis of 23 illegal adulterated aphrodisiac chemical ingredients in health foods and Chinese traditional patent medicines by ultrahigh performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

This paper presents an application of ultra high-performance liquid-chromatography-quadrupole-TOF high resolution mass spectrometry (UHPLC-Q-TOF HRMS) for simultaneous analysis of 23 illegal adulterated aphrodisiac type chemical ingredients in health foods and Chinese Traditional Patent Medicines (CTPMs). The mass spectrometer was operated in Information Dependent Acquisition (IDA) mode, which provides crucial information for the elemental composition analysis, structure elucidation and quantitative analysis simultaneously. Quantitative analysis was performed using the peak areas of the precursor ions in the XICs. The method validation included assessment of selectivity, sensitivity, calibration curve, accuracy, precision, recovery, matrix effect and stability. The results show good linear relationship with the concentrations of the analytes over wide concentration ranges (e.g., 0.05–10 μg/g for sildenafil) as all the fitting coefficients of determination r² are >0.9984. The detection limits (LODs) were in the range of 0.002–0.1 μg/g. The recoveries were able to reach 82.5–103.6%, while the matrix effects ranged from 87.7 to 109.3%. The intra- and inter-day accuracies were in the range of 82.3–113.8%, while the intra- and inter-day precision ranged from 0.4 to 13.6%. Among 40 batches of health foods and 32 batches of CTPMs (including 28 capsules, 32 tablets, 10 liquid and 2 pills) samples, 28 batches of heath foods were positive. The detected chemical ingredients involved sildenafil, tadalafil, aildenafil and sulfoaildenafil. This method can be used for the screening, identification and quantification of illegal adulterated aphrodisiac chemical ingredients in health foods and CTPMs. Moreover, the LC-Q-TOF MS is very useful to structural elucidation of unknown compound.

Sublingual Administration of Sildenafil Oro-dispersible Film: New Profiles of Drug Tolerability and Pharmacokinetics for PDE5 Inhibitors

Objective: Type 5 phosphodiesterase inhibitors (PDE5i) are efficient drugs used for treatment of erectile dysfunction (ED); however, a large discontinuation rate due to major side effects is reported. The aim of this study was to evaluate the possible improvement of sildenafil (Sild) pharmacokinetics associated to the sublingual administration of the new available oro-dispersible film (ODF), compared to both the oro-dispersible tablet (ODT) and the film-coated tablet (FCT) as original per os formulation.

Methods:In vitro disaggregation test, dissolution test, and permeation test in specific devices to estimate the trans-mucosal absorption. In vivo analysis of serum Sild levels, by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), was performed in 20 patients with psychogenic ED receiving alternatively per os FCT or sublingual ODT or ODF, at an equal dosage (50 mg). Pharmacokinetic parameters of Sild and adverse drug reactions experienced after the dosing of each formulation were compared.

Results:In vitro, ODF showed the highest time to disaggregation and an increased rate of permeation compared to both ODT and FCT (P = 0.017 and P = 0.008, respectively). In vivo, compared to both FCT and ODT, ODF showed a faster increase of serum Sild levels (serum levels at 15 min from dosing, respectively: 2.24 ± 1.4 ng/ml FCT, 0.5 ± 0.3 ng/ml ODT, and 13.5 ± 9.1 ng/ml ODF; P < 0.01 and P < 0.05 vs. ODF) together with a higher drug bioavailability within 60 min from dosing (relative AUC_60min vs. FCT, respectively: 100.0 ± 44.9% FCT, 183.8 ± 75.4% ODT, and 304.2 ± 156.0% ODF). A trend toward lower peak serum levels was observed for ODF. Finally, ODF showed a lower prevalence of headache compared to FCT (1 vs. 35%; P < 0.05) and improved pattern of flushing and nasal congestion.

Conclusion: Sublingual Sild ODF improves the drug tolerability through a likely modified pharmacokinetic, suggesting a possible implication also in the clinical efficacy profile. Sublingual administration of oro-dispersible formulations may represent a strategy to ameliorate the adherence to therapy with PDE5i, particularly in patients discouraged by side effects.

Estimating the Effect of Health Insurance on Personal Prescription Drug Importation

Personal prescription drug importation occurs in the United States because of the high cost of U.S. medicines and lower cost of foreign equivalents. Importation carries a risk of exposure to counterfeit (i.e., falsified, fraudulent), adulterated, and substandard drugs. Inadequate health insurance may increase the risk of importation. We use inverse probability weighted marginal structural models and data on 87,494 individuals from the 2011-2013 National Health Interview Survey to estimate the marginal association between no health insurance and importation within U.S. subpopulations. The marginal prevalence difference [95% confidence limits] for those without (prevalence = 0.031) versus those with health insurance was 0.016 [0.011, 0.021]. The prevalence difference was higher among persons who were Hispanic, born in Latin America, Russia, or Europe, traveled to developing countries, and did not use the Internet to fill prescriptions or to find health information. Health insurance coverage may effectively reduce importation, especially among particular subpopulations.

Testing of complementarity of PDA and MS detectors using chromatographic fingerprinting of genuine and counterfeit samples containing sildenafil citrate

Counterfeit medicines are a global threat to public health. High amounts enter the European market, which is why characterization of these products is a very important issue. In this study, a high-performance liquid chromatography-photodiode array (HPLC-PDA) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) method were developed for the analysis of genuine Viagra®, generic products of Viagra®, and counterfeit samples in order to obtain different types of fingerprints. These data were included in the chemometric data analysis, aiming to test whether PDA and MS are complementary detection techniques. The MS data comprise both MS1 and MS2 fingerprints; the PDA data consist of fingerprints measured at three different wavelengths, i.e., 254, 270, and 290 nm, and all possible combinations of these wavelengths. First, it was verified if both groups of fingerprints can discriminate between genuine, generic, and counterfeit medicines separately; next, it was studied if the obtained results could be ameliorated by combining both fingerprint types. This data analysis showed that MS1 does not provide suitable classification models since several genuines and generics are classified as counterfeits and vice versa. However, when analyzing the MS1_MS2 data in combination with partial least squares-discriminant analysis (PLS-DA), a perfect discrimination was obtained. When only using data measured at 254 nm, good classification models can be obtained by k nearest neighbors (kNN) and soft independent modelling of class analogy (SIMCA), which might be interesting for the characterization of counterfeit drugs in developing countries. However, in general, the combination of PDA and MS data (254 nm_MS1) is preferred due to less classification errors between the genuines/generics and counterfeits compared to PDA and MS data separately.

Adulteration of Dietary Supplements by the Illegal Addition of Synthetic Drugs: A Review

In the last few years, the consumption of dietary supplements, especially those having plants as ingredients, has been increasing due to the common idea that they are natural products posing no risks to human health. In the European Union and the United States, dietary supplements are legally considered as foods/special category of foods, thus are not being submitted to any safety assessment prior to their commercialization. Among the issues that can affect safety, adulteration by the illegal addition of pharmaceutical substances or their analogs is of major concern since unscrupulous producers can falsify these products to provide for quick effects and to increase sales. This review discusses the various classes of synthetic drugs most frequently described as being illegally added to dietary supplements marketed for weight loss, muscle building/sport performance and sexual performance enhancement. Information regarding regulation and consumption is also presented. Finally, several conventional and advanced analytical techniques used to detect and identify different adulterants in dietary supplements and therefore also in foods, with particular emphasis on plant food supplements, are critically described. This review demonstrates that dietary supplement adulteration is an emerging food safety problem and that an effective control by food regulatory authorities is needed to safeguard consumers.

Development of a comprehensive spectral library of sildenafil and related active analogues using LC-QTOF-MS and its application for screening counterfeit pharmaceuticals

The abuse or misuse of forged erectile-dysfunction drugs, containing phosphodiesterase type 5 inhibitors (e.g. sildenafil), is a serious issue globally. Therefore, the detection of sildenafil and related active analogues in counterfeit pharmaceuticals or the differentiation between counterfeit and authentic drugs has been performed with a variety of analytical techniques. Recently, a liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS)-based in-house library, consisting of accurate mass ion fragmentation information and retention times, was effectively applied to screen a large number of compounds in field of forensic toxicology. However, a comprehensive LC-QTOF-MS spectral library of sildenafil and related active analogues has not yet been reported. In the present study, a spectral library of 40 compounds of sildenafil and related analogues was developed with accurate mass spectra and retention times using LC-QTOF-MS, and applied to screen nine marketed counterfeit products. The in-house library successfully identified sildenafil, dimethylsildenafil, hydroxyhomosildenafil, demethylhongdenafil, pseudovardenafil and vardenafil in the samples. Our LC-QTOF-MS-based spectral library search is considered a powerful approach for identifying sildenafil and related active analogues in counterfeit pharmaceuticals.

Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma

A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λem 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4-40 and 10-250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test.