Rapid determination of ranitidine in human plasma by high-performance liquid chromatography without solvent extraction

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.

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.

Simultaneous determination of amoxicillin and ranitidine in rat plasma by high-performance liquid chromatography

A high-performance liquid chromatography method using ultraviolet detection at 230 nm for the simultaneous determination of amoxicillin and ranitidine in rat plasma has been validated. Plasma samples after pretreatment with acetonitrile to effect deproteinization were dried under N2 and reconstituted with water. The standard calibration curves for amoxicillin and ranitidine were linear (r2=0.9999) over the concentration range of 0.2-20 microg ml-1 and 0.03-6 microg ml-1 in rat plasma, respectively. The intra- and inter-day assay variability range for amoxicillin was 2.4-8.5% and 3.2-11.7%, and for ranitidine was 1.7-9.0% and 4.5-10.1%, respectively. This method has been successfully applied to a pharmacokinetic study after oral coadministration of amoxicillin and ranitidine to rats.

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.

Measurement of unbound ranitidine in blood and bile of anesthetized rats using microdialysis coupled to liquid chromatography and its pharmacokinetic application

To investigate the pharmacokinetics of unbound ranitidine in rat blood and bile, multiple microdialysis probes coupled to a liquid chromatographic system were developed. This study design was parallel in the following groups: the control-group of six rats received ranitidine alone (10 and 30 mg/kg, i.v.), the treated-group rats were co-administered with ranitidine and cyclosporine (P-glycoprotein (P-gp) inhibitor) or quinidine (both organic cation transport (OCT) and P-gp inhibitors) in six individual rats. Microdialysis probes were inserted into the jugular vein and the bile duct for blood and bile fluids sampling, respectively. Ranitidine in the dialysate was separated by a reversed-phase C18 column (Zorbax, 150 mm x 4.6 mm i.d.; 5 microm) maintained at ambient temperature. Samples were eluted with a mobile phase containing acetonitrile-methanol-tetrahydrofuran-20 mM K2HPO4 (pH 7.0) (24:20:10:946, v/v), and the flow rate of the mobile phase was 1 ml/min. The optimal UV detection for ranitidine was set at wavelength 315 nm. Between 20 and 30 min after drug administration (10 or 30mg/kg), the ranitidine reached the maximum concentration in the bile. The bile-to-blood distribution ratio (AUC(bile)/AUC(blood)) was 9.8 +/- 1.9 and 13.9 +/- 3.8 at the dosages of 10 and 30 mg/kg, respectively. These studies indicate that ranitidine undergoes hepatobiliary excretion which against concentration gradient from bile-to-blood. In addition, the AUC of ranitidine in bile decreased in the treatment of cyclosporine or quinidine, which suggests that the hepatobiliary excretion of ranitidine was partially regulated by P-glycoprotein or organic cation transporter.

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).

Simultaneous determination of ranitidine and metronidazole in human plasma using high performance liquid chromatography with diode array detection

The development and validation of a simple method for the simultaneous determination of ranitidine and metronidazole in human plasma is described. Plasma samples (250 microL) were deproteinized by precipitation with 60% perchloric acid, centrifuged and the supernatant directly injected into the HPLC. Separation was achieved in isocratic mode with a Shimpak C(18) column and a mobile phase consisting of 10mM potassium dihydrogen phosphate pH 3.5:acetonitrile (90:10, v/v) with UV detection at 315 nm. The method showed good selectivity and sensitivity. Good and consistent recovery for metronidazole and ranitidine was obtained: 96.22+/-3.52 and 95.00+/-4.50% for ranitidine (25-1000 ng/mL) and metronidazole (60-10,000 ng/mL), respectively (n=3). With this one-step sample preparation method, both ranitidine and metronidazole could be quantified simultaneously in human plasma with good precision (R.S.D.<15%) and accuracy (bias values below 15%). The limit of quantification for ranitidine and metronidazole were 20 and 40 ng/mL plasma, respectively.

Ion-Selective Electrodes for Potentiometric Determination of Ranitidine Hydrochloride, Applying Batch and Flow Injection Analysis Techniques

New ranitidine hydrochloride (RaCl)-selective electrodes of the conventional polymer membrane type are described. They are based on incorporation of ranitidine-tetraphenylborate (Ra-TPB) ion-pair or ranitidine-phosphotungstate (RaPT) ion-associate in a poly(vinyl chloride) (PVC) membrane plasticized with dioctylphthalate (DOP) or dibutylphthalate (DBP). The electrodes are fully characterized in terms of the membrane composition, solution temperature, and pH. The sensors showed fast and stable responses. Nernstian response was found over the concentration range of 2.0 x 10(-5) M to 1.0 x 10(-2) M and 1.0 x 10(-5) M to 1.0 x 10(-2) M in the case of Ra-TPB electrode and over the range of 1.03 x 10(-5) M to 1.00 x 10(-2) M and 1.0 x 10(-5) M to 1.0 x 10(-2) M in the case of Ra-PT electrode for batch and FIA systems, respectively. The electrodes exhibit good selectivity for RaCl with respect to a large number of common ions, sugars, amino acids, and components other than ranitidine hydrochloride of the investigated mixed drugs. The electrodes have been applied to the potentiometric determination of RaCl in pure solutions and in pharmaceutical preparations under batch and flow injection conditions with a lower detection limit of 1.26 x 10(-5) M and 5.62 x 10(-6) M at 25 +/- 1 degrees C. An average recovery of 100.91% and 100.42% with a relative standard deviation of 0.72% and 0.53% has been achieved.

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

A selective, sensitive and accurate high-performance liquid chromatographic method has been developed, validated and applied for the determination of ranitidine and cimetidine in plasma samples. The effects of mobile phase composition, buffer concentration, mobile phase pH and concentration of organic modifiers on retention of investigated drugs were investigated. Sample preparation was carried out by adding an internal standard, famotidine, and the clean-up procedure was accomplished using solid-phase extraction (SPE). This method uses ultraviolet detection, the separation used a Lichrocart Lichrospher 60 RP-select B column and the mobile phase consisted of 0.2% triethylamine (TEA), 0.04 mol l(-1) KH2PO4 at pH 6.8 and 14% acetonitrile. The recovery, selectivity, linearity, precision and accuracy of the method were evaluated from spiked human plasma. The method has been implemented to monitor ranitidine levels in clinical samples.