Simple and universal HPLC-UV method to determine cimetidine, ranitidine, famotidine and nizatidine in urine: application to the analysis of ranitidine and its metabolites in human volunteers

Carbon Dots Employed for the Detection of Ranitidine and Elaborating the Detecting Mechanism

Carbon dots (CDs) has been widely utilized in multiple fields, especially towards kinds of drug analyses, owing to its superior optical properties and satisfactory stability. Herein, we rapidly synthesized one kind of soluble bright-blue fluorescent CDs through a facile microwave method, while disodium ethylenediaminetetraacetic acid and phosphoric acid served as the raw materials. Importantly, introducing ranitidine into these CDs resulted in its decreased fluorescence, and thus an innovative method of detecting ranitidine was successfully established, which showed the favorable selectivity and anti-interference ability. With the optimal conditions, the standard curve diagram of F0/F against concentration of ranitidine was linear in the range of 6-2000 µM with a correlation coefficient of 0.9833, and the limit of detection (LOD) was calculated to be 4.2 µM. Meanwhile, we also explored the detecting mechanism of ranitidine by CDs, and elaborated that as the internal filtration effect. Consequently, we may broaden the avenues of detecting ranitidine on the basis of CDs.

GC Analysis of Metformin, Ranitidine and Famotidine from Pharmaceuticals and Human Serum

A method has been designed based on gas chromatography with flame ionization detection (FID) for the separation and analyses of ranitidine, famotidine and metformin after pre-column derivatization with trifluoroacetylacetone and ethyl chloroformate. DB-1 (30 m × 0.32 mm id) column with film thickness 0.25 μm was used for the separation at an initial temperature of column was 100°C for 2 min, and ramping at 20°C/min up to 250°C, with a hold time of 3 min. The rate of nitrogen flow was 2.5 mL/min and FID was used for detection. Complete separation was obtained between all the three drugs including excess of derivatization reagents. Linear calibration curves and detection limits were obtained in the ranges 0.1-30 μg/mL and 0.011-0.015 μg/mL. The procedure was repeatable in terms of peak heights/peak areas and retention time (n = 5) for derivatization, quantitation and separation with relative standard deviations (RSDs) within 2.0-3.0%. The approach was examined for the analyses of drug products and serum after the intake of the drugs by healthy volunteers, and recoveries were obtained within 95-98% with RSDs 2.4-3.1%.

Deciphering the human urine matrix: a new approach to simultaneously quantify the main ions and organic compounds by ion chromatography/mass spectrometry (IC-MS)

Analyzing the composition of (human) urine plays a major role in the fields of biology and medicine. Organic molecules (such as urea, creatine) and ions (such as chloride, sulfate) are the major compounds present in urine, the quantification of which allows for the diagnosis of a subject's health condition. Various analytical methods have been reported for studying urine components and validated on the basis of known and referenced compounds. The present work introduces a new method able to simultaneously determine both major organic molecules and ions contained in urine, by combining ion chromatography using a conductimetric detector with mass spectroscopy. The analysis of organic and ionized compounds (anionic and cationic) was achieved in double injections. For quantification, the standard addition method was used. Human urine samples were pre-treated (diluted and filtered) for IC-CD/MS analysis. The analytes were separated in 35 min. Calibration ranges (0-20 mg.L-1) and correlation coefficients (> 99.3%) as well as detection (LODs < 0.75 mg.L-1) and quantification (LOQs < 2.59 mg.L-1) limits were obtained for the main organic molecules (lactic, hippuric, citric, uric, oxalic acids, urea, creatine, and creatinine) and ions (chloride, sulfate, phosphate, sodium, ammonium, potassium, calcium, and magnesium) contained in urine. The intra- and inter-day accuracies of the analytes consistently ranged from 0.1 to 5.0%, and the precision was within 4.0%. For all analytes, no significant matrix effects were observed, and recoveries ranged from 94.9 to 102.6%. Finally, quantitative results of analytes were obtained from 10 different human urine samples.

Design of a Sensitive Fluorescent Zn-Based Metal-Organic Framework Sensor for Cimetidine Monitoring in Biological and Pharmaceutical Samples

A new highly fluorescent zinc-organic framework [Zn₂(btca)(DMSO)₂]_n (Zn-MOF) was prepared via in situ ligand formation by the solvothermal reaction of Zn(NO₃)₂·6H₂O and pyromellitic dianhydride (PMDA) in DMSO solvent. During the solvothermal reaction, PMDA was gradually hydrolyzed to a pyromellitic acid, 1,2,4,5-benzene tetracarboxylic acid (H₄btca), to provide a tetracarboxylic acid as a linker in the reaction medium. Single-crystal X-ray diffraction analysis exhibits a 3D porous structure with open tetragonal channels running along the crystallographic c-axis. The Zn-MOF was explored as an on-mode fluorescent sensor for tracing cimetidine in biological fluids and pharmaceutical samples in the presence of interfering species. The results show a quick response in a short time range. The characteristics of this sensor were investigated by field-emission scanning electron microscopy, dynamic light scattering, energy-dispersive X-ray analysis, powder X-ray diffraction, Fourier transform infrared and UV-vis spectroscopy as well as thermogravimetric, and elemental analyses.

Column Classification/Characterisation of Strong Cation Exchange Phases for the Liquid Chromatographic Analysis of Small Molecular Weight Bases

A simple, rapid and robust protocol for the characterisation of strong cation exchange columns for the analysis of small molecular weight bases is described. A range of ten different phases were characterised, and the resultant selectivity and retention factors analysed using Principal Component Analysis. The score plots for the first and second principal components described 83% of the variability within the dataset. Score plots highlighted the large chromatographic differences observed between the phases, the validity of which was established using a larger range of bases. All the strong cation exchange materials demonstrated a synergistic mixed mode (i.e. ion exchange and hydrophobic) retention mechanism. Principal Component Analysis also highlighted the potential difficulty in locating suitable strong cation exchange “back-up” columns for the analysis of small molecular weight bases in that the characterised columns all displayed very different selectivities. The robustness of the protocol was confirmed by a factorial design experiment.

Sex-Dependence in the Effect of Pharmaceutical Excipients: Polyoxyethylated Solubilising Excipients Increase Oral Drug Bioavailability in Male but not Female Rats

It is known that males and females respond differently to medicines and that differences in drug behaviour are due to inter-individual variability and sex specificity. In this work, we have examined the influence of pharmaceutical excipients on drug bioavailability in males and females. Using a rat model, we report that a portfolio of polyoxyethylated solubilising excipients (polyethylene glycol 2000, Cremophor RH 40, Poloxamer 188 and Tween 80) increase ranitidine bioavailability in males but not in females. The in vivo sex and excipient effects were reflected in vitro in intestinal permeability experiments using an Ussing chamber system. The mechanism of such an effect on drug bioavailability is suggested to be due to the interaction between the excipients and the efflux membrane transporter P-glycoprotein (P-gp), whose expression in terms of gene and protein levels were inhibited by the solubilising agents in male but not in female rats. In contrast, the non-polyoxyethylated excipient, Span 20, significantly increased ranitidine bioavailability in both males and females in a non-sex-dependent manner. These findings have significant implications for the use of polyoxyethylated solubilising excipients in drug formulation in light of their sex-specific modulation on the bioavailability of drugs that are P-gp substrates. As such, pharmaceutical research is required to retract from a ‘one size fits all’ approach and to, instead, evaluate the potential impact of the interplay between excipients and sex on drug effect to ensure effective pharmacotherapy.

Ultrasensitive chemiluminescence assay for cimetidine detection based on the synergistic improving effect of Au nanoclusters and graphene quantum dots

A novel and sensitive chemiluminescence (CL) procedure based on the synergetic catalytic effects of gold nanoclusters (Au NCs) and graphene quantum dots (GQDs) was developed for the reliable measurement of cimetidine (CM). The initial experiments showed that the KMnO₄ -based oxidation of alkaline rhodamine B (RhoB) generated a very weak CL emission, which was intensively enhanced in the simultaneous presence of Au NCs and GQDs. CL intermediates can be adsorbed and gathered on the surface of Au NCs, becoming more stable. GQDs participate in the energy transferring processes and facilitate them. These improving effects were simultaneously obtained by adding both Au NCs and GQDs into the RhoB-KMnO₄ reaction. Consequently, the increasing effect of the Au NCs/GQDs mixture was more than that of pure Au NCs or GQDs, and a new nano-assisted powerful CL system was achieved. Furthermore, a marked quenching in the emission of the introduced CL system was observed in the presence of CM, so the system was examined to design a sensitive sensor for CM. After optimization of influencing parameters, the linear lessening in CL emission intensity of KMnO₄ -RhoB-Au NCs/GQDs was verified for CM concentrations in the range 0.8-200 ng ml^-1 . The limit of detection (3S_b /m) was 0.3 ng ml^-1 . Despite being a simple CL method, good sensitivity was obtained for CM detection with reliable results for CM determination in human urine samples.

Colorimetric sensor for cimetidine detection in human urine based on d-xylose protected gold nanoparticles

A simple, novel, and rapid colorimetric sensor for cimetidine (Cim) detection based on d-xylose protected gold nanoparticles (d-x@AuNPs) has been developed for the first time.

Application of Micellar Extraction for Isolation of Famotidine from Aqueous Samples Prior to its Chromatographic Determination

Micellar extraction was applied to isolate famotidine from aqueous samples. This drug is an H₂ receptor antagonist used for the treatment of stomach diseases. The process was performed with a mixture of anionic sodium dodecylsulfate and nonionic Triton X-114 surfactants. The effect of different parameters on the efficiency of the micellar extraction such as electrolyte and surfactant concentration, pH of sample, temperature, shaking and centrifugation time was investigated. The influence of foreign substances on a studied process was tested. The elaborated procedure was applied for HPLC–UV determination of famotidine in natural water samples. The calibration graph was recorded in the range 1.35–37.12 μg mL⁻¹ of the studied compound. The repeatability of the method was equal to 7.4%. The limit of detection and quantification values for the determination of famotidine by using the proposed method amounted to 0.40 and 1.25 μg mL⁻¹, respectively.

An Efficient Ion-Pair Liquid Chromatographic Method for the Determination of Some H2 Receptor Antagonists

A simple, efficient and reliable ion-pair chromatography (IPC) method was developed and validated for the determination of some H2 receptor antagonists including ranitidine (RAN), nizatidine (NIZ) and famotidine (FAM). The use of IPC separations provided improved peak resolution with good peak shape in short analysis time and augmented method selectivity compared with the frequently used RP-C18 methods. A simple isocratic mode with mobile phase containing acetonitrile and 20 mM acetate buffer (50 : 50, v/v) containing 20 mM sodium dodecyl sulfate was used for separation. The flow rate was set at 1.0 mL min(-1), and the effluent was monitored by UV detector at 280 nm FAM and 320 nm for NIZ and RAN. The method was validated in accordance with International Conference on Harmonization guidelines and shown to be suitable for intended applications. The limits of detections and quantitations were 0.008-0.011 and 0.025-0.033 µg mL(-1), respectively. The proposed IPC method was successfully applied for the determination of pharmaceutical dosage forms without prior need for separation. Additionally, the developed method was applied for the determination of RAN in rabbit plasma using NIZ as the internal standard. The method entailed direct injection of the plasma samples after deproteination using methanol. Finally, the proposed IPC method was applied successfully in a pharmacokinetic study for RAN in rabbits after a single oral dose of RAN.

Spectrofluorimetric analysis of famotidine in pharmaceutical preparations and biological fluids by derivatization with benzoin

A sensitive and simple spectrofluorimetric method has been developed for the analysis of famotidine, from pharmaceutical preparations and biological fluids after derivatization with benzoin. The reaction was carried out in alkaline medium with measurement of fluorescence intensity at 446 nm with excitation wavelength at 286 nm. Linear calibration was obtained with 0.5-15 μg/ml with coefficient of determination (r(2)) 0.997. The factors affecting the fluorescence intensity were optimized. The pharmaceutical additives and amino acid did not interfere in the determination. The mean percentage recovery (n=4) calculated by standard addition from pharmaceutical preparation was 94.8-98.2% with relative standard deviation (RSD) 1.56-3.34% and recovery from deproteinized spiked serum and urine of healthy volunteers was 98.6-98.9% and 98.0-98.4% with RSD 0.34-0.84% and 0.29-0.87% respectively.

HPLC fluorescence method for the determination of nizatidine in human plasma and its application to pharmacokinetic study

A sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of nizatidine in human plasma. Nizatidine was derivatized by 4-fluoro-7-nitrobenzofurazan (NBD-F). Chromatographic separation was performed on a Inertsil C18 column (150 mm × 4.6 mm, 5 µm) using isocratic elution by a mobile phase consisting of methanol/water (55:45) at a flow rate of 1.2 mL/min. Amlodipine was used as the internal standard (IS). Fluorescence detector was used operated at 461 nm (excitation) and 517 nm (emission), respectively. The calibration curve was linear over the range of 50-2000 ng/mL. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of nizatidine.

A novel method for ranitidine hydrochloride determination in aqueous solution based on fluorescence quenching of functionalised CdS QDs through photoinduced charge transfer process: spectroscopic approach

A novel method for the quantitative determination of ranitidine hydrochloride (RNH) based on the fluorescence quenching of functionalised CdS quantum dots (QDs) by RNH in aqueous solution was proposed. The method is simple, rapid, specific and highly sensitive with good precision. The thioglycolic acid (TGA)-capped CdS QDs were synthesized from cadmium nitrate and sodium sulfide in alkaline solution. Under the optimal conditions, the Stern-Volmer calibration plot of F(0)/F against concentration of RNH was linear in the range of 0.50-15.0 μg mL(-1) with a correlation coefficient of 0.996. The limit of detection (LOD) was 0.38 μg mL(-1). The method was satisfactorily applied to the direct determination of RNH in pharmaceutical formulations with no significant interference from excipients. The results were found to be in good agreement with those obtained by the reference method and the claimed value. The accuracy and reliability of the method were further ascertained by recovery studies via the standard-addition method, with percentage recoveries in the range of 98.47 to 102.30%. The possible fluorescence quenching mechanism for the reaction was also discussed.

Spectrofluorimetric determination of famotidine in pharmaceutical preparations and biological fluids. Application to stability studies

A simple, economic, selective, and stability indicating spectrofluorimetric method was developed for the determination of famotidine (FMT); is based on its reaction with 9, 10-phenanthraquinone in alkaline medium to give a highly fluorescent derivative measured at 560 nm after excitation at 283 nm. The fluorescence intensity-concentration plot was rectilinear over the concentration range of 50-600 ng/ml with minimum quantification limit (LOQ) of 13.0 ng/ml and minimum detection limit (LOD) of 4.3 ng/ml. The factors affecting the development of the fluorescence intensity of the reaction product were carefully studied and optimized. The method was applied for the determination of FMT in its dosage forms. The stability of the compound was studied, and the proposed method was found to be stability indicating one. The results obtained were in good agreement with those obtained by the official method. Furthermore, the method was applied for the determination of FMT in spiked and real human plasma. The mean % recovery (n = 4) was found to be 99.94 +/- 0.24, and 105.13 +/- 0.64 for spiked and real human plasma, respectively. The composition of the reaction product as well as its stability constant was also investigated. Moreover, the method was utilized to investigate the kinetics of both alkaline and oxidative induced degradation of the drug. The apparent first order rate constant and half life time of the degradation product was calculated. A proposal of the reaction pathway was postulated.

Polyethylene glycol 400 enhances the bioavailability of a BCS class III drug (ranitidine) in male subjects but not females

PURPOSE

The aim of this study was to investigate the effects of different doses of polyethylene glycol 400 (PEG 400) on the bioavailability of ranitidine in male and female subjects.

METHOD

Ranitidine (150 mg) was dissolved in 150 ml water with 0 (control), 0.5, 0.75, 1, 1.25 or 1.5 g PEG 400 and administered to 12 healthy human volunteers (six males and six females) in a randomized order. The cumulative amount of ranitidine and its metabolites excreted in urine over 24 h was determined for each treatment using a validated HPLC method.

RESULTS

In the male volunteers, the mean cumulative amount of ranitidine excreted in the presence of 0, 0.5, 0.75, 1, 1.25 and 1.5 g PEG 400 were 35, 47, 57, 52, 50 and 37 mg respectively. These correspond to increases in bioavailability of 34%, 63%, 49%, 43% and 6% over the control treatment. In the female subjects, the mean cumulative quantity of ranitidine excretion in the absence and presence of increasing amounts of PEG 400 were 38, 29, 35, 33, 33 and 33 mg, corresponding to decreases in bioavailability of 24%, 8%, 13%, 13% and 13% compared to the control. The metabolite excretion profiles followed a similar trend to the parent drug at all concentrations of PEG 400.

CONCLUSIONS

All doses of PEG 400 enhanced the bioavailability of ranitidine in male subjects but not females, with the most pronounced effect in males noted with the 0.75 g dose of PEG 400 (63% increase in bioavailability compared to control, p < 0.05). These findings have significant implications for the use of PEG 400 in drug development and also highlight the importance of gender studies in pharmacokinetics.