A novel method for fast determination of ranitidine in its pharmaceutical formulations by fast continuous cyclic voltammetry.

INTRODUCTION: A novel method for the determination of Ranitidine in flow injection systems was developed. METHODS: Some investigations were also done to find the effects of various parameters on the sensitivity of the method. The conditions producing optimal performance were a pH value of 2, a scan rate value of 100 V/s, accumulation potential of (-100) mV, and accumulation time of 0.4 s. Some of the advantages of the proposed method are as follows: the removal of oxygen from the test solution is not required any more, the detection limit of the method is sub-nanomolar and finally, the method is fast enough for determination of compounds in a wide variety of chromatographic methods. We also introduce a special computer based numerical method, for calculation of the analyte signal and noise reduction. After subtracting the background current from noise, the electrode response was calculated, based on partial and total charge exchanges at the electrode surface. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, to obtain a sensitive determination. The waveform potential was continuously applied on an Au disk microelectrode (12.5 microm in radius). RESULTS: The detection limit of the method for Ranitidine was found to be 25 pg/ml. For 8 runs, the relative standard deviation of the method at 1.1 x 10(-8) M was 2.1%. DISCUSSION: The method was successfully applied for fast determination of Ranitidine in its pharmaceutical formulations. Being very simple, precise, accurate, time saving and economical this method has many advantages compared to all previously reported methods.

Development of a rapid HPLC method for determination of famotidine in human plasma using a monolithic column.

A rapid and sensitive HPLC method using a monolithic column has been developed for quantification of famotidine in plasma. The assay enables the measurement of famotidine for therapeutic drug monitoring with a minimum detectable limit of 5 ngml(-1). The method involves simple, one-step extraction procedure and analytical recovery was complete. The separation was carried out in reversed-phase conditions using a Chromolith Performance (RP-18e, 100 mm x 4.6 mm) column with an isocratic mobile phase consisting of 0.03 M disodium hydrogen phosphate buffer-acetonitrile (93:7, v/v) adjusted to pH 6.5. The wavelength was set at 267 nm. The calibration curve was linear over the concentration range 20-400 ngml(-1). The coefficients of variation for inter-day and intra-day assay were found to be less than 8%.

Validation of a liquid chromatographic method for the determination of ranitidine hydrochloride residues on surfaces in the manufacture of pharmaceuticals.

A liquid chromatographic method for determination of the residues of ranitidine hydrochloride on various surfaces employed in drug manufacture is described. Cotton swabs, moistened with a methanol-water (1:1, v/v) mixture were used to remove any residues of drugs from glass, vinyl, and stainless steel surfaces, and gave recoveries of 85%, 78% and 90%, respectively. Residues were determined by high-performance liquid chromatography on a C18 column at 25 degrees C with methanol-ammonium acetate (40:60 v/v) pH 6.7 as the mobile phase and detection at 320 nm. The method was validated over a concentration range of 20-10 000 ng/ml and had a detection limit of 2 ng/ml.

Solid state assay of ranitidine HCl as a bulk drug and as active ingredient in tablets using DRIFT spectroscopy with artificial neural networks.

PURPOSE: A new, simple, sensitive and rapid method was developed to analyse the polymorphic purity of crystalline ranitidine-HCI as a bulk drug and from a tablet formulation. METHODS: Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was combined with Artificial Neural Networks (ANNs) as a data modelling tool. A standard feed-forward network, with backpropagation rule and with single hidden layer architecture was chosen. Reduction and transformation of the spectral data enhanced the ANN performance and reduced the complexity of the ANNs model. Spectral intensities from 1738 wavenumbers were reduced into 173 averaged spectral values. These 173 values were used as inputs for the ANN. Following a sensitivity analysis the number of inputs was reduced to 30, or 35, these being the input windows which had most effect on the output of the ANN. RESULTS: For the bulk drug assay, the ANN model had 30 inputs selected from a sensitivity analysis, one hidden layer, and two output neurons, one for the percentage of each ranitidine hydrochloride crystal form. The model could simultaneously distinguish between crystal forms and quantify them enabling the physical purity of the bulk drug to be checked. For the tablet assay, the ANN model had 173 averaged spectral values as the inputs, one hidden layer and five output neurons, two for the percentage of the two ranitidine hydrochloride crystal forms and three more outputs for tablet excipients and additives. The ANN was able to solve the problem of overlapping peaks and it successfully identified and quantified all components in tablet formulation with reasonable accuracy. CONCLUSIONS: Some of the advantages over conventional analytical methods include simplicity, speed and good selectivity. The results from DRIFT spectral quantification study show the benefits of the neural network approach in analysing spectral data.

Single-dose intravenous H2 blocker prophylaxis against aspiration pneumonitis: assessment of drug concentration in gastric aspirate.

This placebo-controlled trial compared the effects of preoperative, intravenous cimetidine (300 mg) or ranitidine (50 mg) on gastric pH and gastric volume in 31 adult patients requiring general anesthesia. The elapsed time from drug administration to initial gastric sampling did not differ significantly between ranitidine (45 minutes), cimetidine (48 minutes), or placebo (52 minutes) treated patients. Ranitidine, but not cimetidine, significantly (P = 0.02) increased gastric pH when compared with placebo. Gastric pH correlated (r = 0.7, P = 0.01) with cimetidine concentration in gastric fluid at induction. Gastric pH was directly proportional to ranitidine concentration in gastric fluid at induction, but the correlation was weak (r = 0.54, P = 0.1). The H2 blockers did not significantly alter gastric volume when compared with placebo. The number of patients with gastric pH less than = 2.5 and gastric volume = greater than 25 ml did not differ significantly between cimetidine (8%), ranitidine (10%), and placebo (22%). No clinical evidence of aspiration pneumonitis was found in our study patients.