Development of an HPLC method for the determination of ranitidine and cimetidine in human plasma following SPE

A microchip device based liquid-liquid-solid microextraction for the determination of permethrin and cypermethrin in water samples

In this work, for the first time, a microchip device integrating liquid-liquid-solid phase microextraction is presented. As a novel approach to microchip systems, liquid-liquid-solid microextraction was performed in a sandwiched microchip device. The microchip device consisted of three poly(methyl methacrylate) layers along with a double "Y"-shaped microchannel. As the stationary phase, polyacrylonitrile-C18 was synthesized and immobilized in the upper channel, while the beneath channel was used as a reservoir for the stagnant volume ratio of sample-to-extraction solvent phase. In this way, analytes were extracted from an aqueous sample through an organic phase into the stationary phase. The analytes were finally desorbed with a minimum amount of acetonitrile as the desorption solvent. Permethrin and cypermethrin were selected as the model analytes for extraction and subsequent analysis by gas chromatography-flame ionization detection. Under optimum conditions (extraction solvent; n-hexane, sample -to-extraction solvent volume ratio; 2:1, extraction time; 20 min, desorption solvent; acetonitrile, desorption volume; 200 μL, and desorption time; 15 min) detection limits were 3.5 and 6.0 ng mL^-1 for permethrin and cypermethrin, respectively. Relative standard deviations for intra- and inter-day reproducibility were below 8.3%. Device-to-device precision was in the range of 8.1-9.6%. The proposed microchip device was successfully applied to determine permethrin and cypermethrin in water samples with recoveries in the range of 73-96%.

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.

An Overview of Analytical Determination of Diltiazem, Cimetidine, Ranitidine, and Famotidine by UV Spectrophotometry and HPLC Technique

This review article recapitulates the analytical methods for the quantitative determinations of diltiazem and three H2receptor antagonists (cimetidine, ranitidine, and famotidine) by one of the spectroscopic technique (UV spectrophotometery) and separation technique such as high-performance liquid chromatography (HPLC). The clinical and pharmaceutical analysis of these drugs requires effective analytical procedures for quality control, pharmaceutical dosage formulations, and biological fluids. An extensive survey of the literature published in various analytical and pharmaceutical chemistry-related journals has been compiled in its review. A synopsis of reported spectrophotometric and high-performance liquid chromatographic methods for individual drug is integrated. This appraisal illustrates that majority of the HPLC methods reviewed are based on the quantitative analysis of drugs in biological fluids, and they are appropriate for therapeutic drug monitoring purpose.

Gastrokinetic activity of Morinda citrifolia aqueous fruit extract and its possible mechanism of action in human and rat models

AIMS OF THE STUDY

This study was to investigate the gastrokinetic activity of Morinda citrifolia aqueous fruit extract (AFE) in human subjects by examining the GI absorption of ranitidine, a putative indicator of GI motility and to elucidate its possible gastrokinetic mechanism of action in rats.

MATERIALS AND METHODS

The single-dose, randomized, open-label and 2-period crossover study was performed on 20 Thai healthy volunteers with a washout period of 14 day between the doses. AFE or drinking water was administered orally 30 min prior to a single oral administration of ranitidine (300 mg). Blood samples were collected over a 12 h period after drug administration and the pharmacokinetic parameters of ranitidine were calculated. The gastrokinetic mechanism of action of AFE was elucidated by measurement of its contractile response on the isolated rat gastric fundus strip.

RESULTS

The area under the plasma ranitidine concentration-time curve and the maximal plasma ranitidine concentration were significantly increased after pretreatment with AFE (p=0.001). The plasma ranitidine concentrations were significantly greater at 30-120 min after its administration. AFE produced a definite contractile response of a rat gastric fundus strip with a dose dependency. Scopoletin at the same equivalent dose present in AFE elicited a concentration-dependent contraction that amounted to 45% of the maximal response to AFE. The contractile response of both AFE and scopoletin was mediated through the 5-HT(4) receptor.

CONCLUSION

AFE has a unique gastrokinetic activity in enhancement of the rate and the extent of ranitidine absorption. The underlying mechanism can be attributed, at least in part, to the ability of its active component: scopoletin to stimulate the 5-HT(4) receptor.

A validated stability-indicating liquid-chromatographic method for ranitidine hydrochloride in liquid oral dosage form

A selective, specific and stability-indicating gradient reverse phase high-performance liquid chromatographic (HPLC) method was developed for the determination of Ranitidine in presence of its impurities, forced degradation products and placebo substances such as saccharide and parabens. Ultraviolet detection was performed at 230 nm. Separate portions of the drug product and ingredients were exposed to stress conditions to induce oxidative, acidic, basic, hydrolytic, thermal and photolytic degradation. Ranitidine was found to degrade significantly at acidic, basic and oxidative stress conditions but was stable at heat and humidity. The developed method was validated as per International Conference on Harmonization (ICH) guidelines. The method was validated over this range for (i) system suitability (ii) specificity, (iii) precision, (iv) limit of detection and limit of quantification, (v) linearity, (vi) accuracy, (vii) robustness. The method was found to be precise, accurate, linear and robust. The proposed method was successfully employed for estimation of Ranitidine impurities in pharmaceutical preparations.

An environmentally friendly reflectometric method for ranitidine determination in pharmaceuticals and human urine

This paper describes an environmentally friendly method for quantitative determination of ranitidine using diffuse reflectance spectroscopy. This method is based on the reflectance measurements of the colored product produced from the spot test reaction between ranitidine and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using filter paper as solid support. Experimental design methodologies were used to optimize the optimal conditions. All reflectance measurements were carried out at 590 nm and the linear range was from 1.42x10(-3) to 3.42x10(-2) mol L(-1), with a correlation coefficient of 0.997. The limit of detection was estimated to be 1.09x10(-3) mol L(-1) (R.S.D.=1.9%). The proposed method was successfully applied to the determination of ranitidine in commercial brands of pharmaceuticals and no interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those obtained by an official procedure at 95% confidence level. Additionally, the method was also applied to the determination of ranitidine in human urine showing excellent recoveries (99.6-100.3%).

OCT2 polymorphisms and in-vivo renal functional consequence: studies with metformin and cimetidine

PURPOSE

Genetic polymorphisms of organic cation transporter 2 (OCT2) have been recently described, but their genotype-phenotype relationship in humans is unknown. We performed this study to (i) characterize genetic variations of the OCT2 gene in the Chinese population and (ii) investigate the potential functional significance of OCT2 polymorphisms using metformin (an OCT2 substrate) alone or in the presence of its transport inhibitor (cimetidine).

METHOD

Direct sequencing of all OCT2 exons and the surrounding introns was performed using genomic DNA from 112 healthy Chinese participants. To evaluate the potential functional change of a common 808G>T variant (Ala270Ser) identified in this population, 15 healthy participants with different 808G>T mutation status were recruited in a pharmacokinetic study of metformin with or without cimetidine.

RESULTS

A total of 14 genetic variants were identified and 13 had frequency more than 1%. The renal tubular clearance (CLt) of metformin averaged 8.78+/-1.75, 7.68+/-0.672, and 6.32+/-0.954 ml/min/kg for participants with GG (n=6), GT (n=5), and TT (n=4) genotypes, respectively (P=0.037, one-way analysis of variance). In the presence of cimetidine, metformin CLt was decreased in all participants, but the decrease was significantly lower in TT than GG group (18.7 vs. 48.2%, P=0.029).

CONCLUSION

Our study results demonstrated for the first time the existence of genetic polymorphisms of OCT2 in the Chinese population, and further showed that the 808G>T polymorphism is associated with a reduced metformin renal or tubular clearance. Moreover, the inhibition of metformin renal tubular secretion by cimetidine also appeared to be dependent on this mutation.

Convenient and rapid determination of cimetidine in human plasma using perchloric acid-mediated plasma protein precipitation and high-performance liquid chromatography

This study demonstrates the analysis of cimetidine in human plasma with HPLC using a simplified sample preparation by protein precipitation with perchloric acid. Plasma cimetidine concentration was determined by plotting peak height ratio of cimetidine to ranitidine (internal standard, IS) against cimetidine concentrations in plasma. The cimetidine and ranitidine peaks were completely separated and no interference from plasma was observed. The lower limit of quantification (LLOQ) of the method was established at 0.1 microg/mL with a precision of 4.3% and a relative error of 1.9%. The average analytical recovery was >90% over the range of cimetidine concentrations (0.1-15.0 microg/mL). The linearity of calibration curve was excellent (r(2) > 0.999). The within- and between-day precision and accuracy, expressed as the coefficients of variation and relative error, were found to be less than 5%. Compared with previously reported methods, the analytical technique for cimetidine determination in human plasma presented here demonstrates comparable accuracy and precision, an acceptable analysis time, shorter and simpler sample preparation, and a reduced need for complicated equipment. The method presented here is simple and rapid, and the precision and sensitivity are appropriate for the determination of cimetidine in plasma in pharmacokinetic studies.

A new sensitive flow-injection chemiluminescence method for the determination of H2-receptor antagonists

Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K(3)Fe(CN)(6)]-rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow-injection chemiluminescence (FI-CL) method has been developed, validated and applied for the determination of three kinds of H(2)-receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 x 10(-9)-7.0 x 10(-5) g/ml for CIMT, 1.0 x 10(-9)-5.0 x 10(-5) g/mL for RANT hydrochloride and 5.0 x 10(-9)-7.0 x 10(-5) g/mL for FAMT. During 11 repeated measurements of 1.0 x 10(-6) g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 x 10(-10) g/mL for CIMT, 8.69 x 10(-10) g/mL for RANT hydrochloride and 2.35 x 10(-9) g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H(2)-receptor antagonists in pharmaceuticals.

Pharmacokinetics and bioequivalence of ranitidine and bismuth derived from two compound preparations

AIM: To evaluate the bioequivalence of ranitidine and bismuth derived from two compound preparations.

METHODS: The bioavailability was measured in 20 healthy male Chinese volunteers following a single oral dose (equivalent to 200 mg of ranitidine and 220 mg of bismuth) of the test or reference products in the fasting state. Then blood samples were collected for 24 h. Plasma concentrations of ranitidine and bismuth were analyzed by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The non-compartmental method was used for pharmacokinetic analysis. Log-transformed C_max, AUC_(0-t) and AUC_(0-∞) were tested for bioequivalence using ANOVA and Schuirmann two-one sided t-test. T_max was analyzed by Wilcoxon’s test.

RESULTS: Various pharmacokinetic parameters of ranitidine derived from the two compound preparations, including C_max, AUC_(0-t), AUC_(0-∞), T_max and T_1/2, were nearly consistent with previous observations. These parameters derived from test and reference drug were as follows: C_max (0.67 ± 0.21 vs 0.68 ± 0.22 mg/L), AUC_(0-t) (3.1 ± 0.6 vs 3.0 ± 0.7 mg/L per hour), AUC_(0-∞) (3.3 ± 0.6 vs 3.2 ± 0.8 mg/L per hour), T_max (2.3 ± 0.9 vs 2.1 ± 0.9 h) and T_1/2 (2.8 ± 0.3 vs 3.1 ± 0.4 h). In addition, double-peak absorption profiles of ranitidine were found in some Chinese volunteers. For bismuth, those parameters derived from test and reference drug were as follows: C_max (11.80 ± 7.36 vs 11.40 ± 6.55 μg/L), AUC_(0-t) (46.65 ± 16.97 vs 47.03 ± 21.49 μg/L per hour), T_max (0.50 ± 0.20 vs 0.50 ± 0.20 h) and T_1/2 (10.2 ± 2.3 vs 13.0 ± 6.9 h). Ninety percent of confidence intervals for the test/reference ratio of C_max, AUC_(0-t) and AUC_(0-) derived from both ranitidine and bismuth were found within the bioequivalence acceptable range of 80%-125%. No significant difference was found in T_max derived from both ranitidine and bismuth.

CONCLUSION: The two compound preparations are bioequivalent and may be prescribed interchangeably.

Sensitive determination of G-protein-coupled receptor binding ligands by solid phase extraction–electrospray ionization–mass spectrometry

High affinity Histamine H2-receptor binding ligands were assayed by automated solid phase extraction (SPE) coupled via electrospray ionization with a Quadrupole-Time-of-Flight mass spectrometer (Q-ToF-MS). The mass spectrometric behavior of these analytes was tested in aqueous solutions with several (nine) volatile salts, in different pH, and with various methanol contents. Out of the high amount of available ligands, three fluorescent-labeled molecules (5706, 5707, and 5708) were studied in detail. The limits of detection (LODs) for all three compounds obtained in mass spectrometric detection was 1 fmol (absolute) in continuous flow and FIA (flow injection analysis) measurements. The results obtained with FIA-fluorescence detection gave LODs a factor 10-100 times higher. A systematic investigation of sample solving conditions, loading flow conditions, and elution flow conditions made the automated SPE-MS coupling efficient. Ideally, the ligands were dissolved in MeOH-25 mM phosphate buffer (30:70 v/v; pH 11), the SPE loading flow comprised MeOH-25 mM phosphate buffer (30:70 v/v; pH 11) and the SPE elution flow contained MeOH-100 mM ammonium formate solution (90:10 v/v; pH 3). Using this method on a C18-modified silica cartridge (C18, 5 microm, 100 A, 300 microm i.d. x 5 mm, LC Packings) assures high recovery and achieved LODs for all three compounds of 5 fmol (absolute). As an absolute amount of ligands specifically bound on H2-receptors in biochemical experiments is, as will be published elsewhere, between 10 and 100 fmol, the SPE-MS method for the basic compounds can be directly applied for these Histamine H2-receptors.

A novel gradient HPLC method for simultaneous determination of ranitidine, methylparaben and propylparaben in oral liquid pharmaceutical formulation

A selective and accurate high-performance liquid chromatographic method has been developed and validated for the simultaneous determination of ranitidine, methylparaben (MP) and propylparaben (PP) in oral liquids. Samples were purified by solid-phase extraction (SPE) using a copolymeric [poly(divinylbenzene-co-N-vinylpyrrolidone)] sorbent. The chromatographic separation was achieved by HPLC using a mixture of ammonium acetate solution (0.5 M), acetonitrile and methanol as the mobile phase with gradient elution, a Nucleosil C18 column and UV detection at 254 nm. The method was validated with respect to linearity, precision, accuracy, selectivity, and robustness. All the parameters examined met the current recommendations for bioanalytical method validation. The method was found to be applicable to routine analysis (assays and stability tests) of active compound (ranitidine) and preservatives (MP and PP).