Determination of some antiemetic drugs through its native fluorescence or fluorescence quenching of cerrous ammonium sulphate

The manuscript describes two fluorimetric methods for the determination of some antiemetic drugs namely granisetron HCl, ondansetron HCl and tropisetron HCl, used in the management of nausea and vomiting induced by cytotoxic chemotherapy and radiotherapy. Granisetron HCl solution exhibits a native fluorescence, which can be applied for its determination at 365 nm upon excitation at 305 nm. The method was applied for the determination of granisetron HCl in drug substance, drug product as well as in presence of its acid induced degradation products. The quantum yield was calculated. The second proposed method is based on measuring the quenching effect induced by ondansetron HCl or tropisetron HCl on the fluorescence intensity of cerrous ammonium sulphate at λ_em 348 nm upon excitation at 250 nm in acidic medium. The analysis of quenching data showed that quenching of cerrous ammonium sulphate induced by ondansetron HCl or tropisetron HCl is mainly through dynamic quenching. Various variables affecting fluorescence response were studied and optimized. The obtained results were found to be statistically agreed with those obtained from the official or reported ones. Moreover, the validity of the methods was assessed according to ICH guidelines.

Validated Analytical Methods for the Determination of Drugs Used in the Treatment of Hyperemesis Gravidarum in Multiple Formulations

Quantitative multicomponent analysis is considered an analytical goal to save time and cost in analysis. Hence, this work aimed to provide sensitive and selective UV-spectrophotometric, chemometric manipulation, and ultra-performance LC (UPLC) methods for the determination of well-known coformulated antiemetics used in pregnancy, namely pyridoxine HCl (PYR), meclozine HCl, and cyclizine. The developed UV-spectrophotometric methods are dual wavelength in ratio spectra and first derivative of the ratio spectra with which PYR was determined selectively at 290.8 nm, whereas the other drugs in a ternary mixture were determined from their ratio spectra using a spectrum of PYR as a divisor in 0.1 M HCl. An ecofriendly partial least-squares regression chemometric method was applied to raw UV absorbance data for the determination of the ternary mixture in a 218-355 nm range using a three-factor, three-level design with water as the green solvent. A gradient UPLC method was developed and successfully resolved the ternary mixture within 5 min. Different ratios of water (adjusted to pH 3 with phosphoric acid) and methanol were delivered at 0.5 mL/min as the mobile phase into a Hypersil Gold C18 column (50 × 2.1 mm, 1.9 µm). The developed methods were successfully applied to different pharmaceutical formulations containing the aforementioned drugs and validated according to the International Conference on Harmonization guidelines. The results obtained were reproducible and reliable and can be applied for routine analysis and QC in laboratories.

Ginger-Mechanism of action in chemotherapy-induced nausea and vomiting: A review

Despite advances in antiemetic therapy, chemotherapy-induced nausea and vomiting (CINV) still poses a significant burden to patients undergoing chemotherapy. Nausea, in particular, is still highly prevalent in this population. Ginger has been traditionally used as a folk remedy for gastrointestinal complaints and has been suggested as a viable adjuvant treatment for nausea and vomiting in the cancer context. Substantial research has revealed ginger to possess properties that could exert multiple beneficial effects on chemotherapy patients who experience nausea and vomiting. Bioactive compounds within the rhizome of ginger, particularly the gingerol and shogaol class of compounds, interact with several pathways that are directly implicated in CINV in addition to pathways that could play secondary roles by exacerbating symptoms. These properties include 5-HT3, substance P, and acetylcholine receptor antagonism; antiinflammatory properties; and modulation of cellular redox signaling, vasopressin release, gastrointestinal motility, and gastric emptying rate. This review outlines these proposed mechanisms by discussing the results of clinical, in vitro, and animal studies both within the chemotherapy context and in other relevant fields. The evidence presented in this review indicates that ginger possesses multiple properties that could be beneficial in reducing CINV.

Development of normalized spectra manipulating spectrophotometric methods for simultaneous determination of Dimenhydrinate and Cinnarizine binary mixture

Simultaneous determination of Dimenhydrinate (DIM) and Cinnarizine (CIN) binary mixture with simple procedures were applied. Three ratio manipulating spectrophotometric methods were proposed. Normalized spectrum was utilized as a divisor for simultaneous determination of both drugs with minimum manipulation steps. The proposed methods were simultaneous constant center (SCC), simultaneous derivative ratio spectrophotometry (S(1)DD) and ratio H-point standard addition method (RHPSAM). Peak amplitudes at isoabsorptive point in ratio spectra were measured for determination of total concentrations of DIM and CIN. For subsequent determination of DIM concentration, difference between peak amplitudes at 250 nm and 267 nm were used in SCC. While the peak amplitude at 275 nm of the first derivative ratio spectra were used in S(1)DD; then subtraction of DIM concentration from the total one provided the CIN concentration. The last RHPSAM was a dual wavelength method in which two calibrations were plotted at 220 nm and 230 nm. The coordinates of intersection point between the two calibration lines were corresponding to DIM and CIN concentrations. The proposed methods were successfully applied for combined dosage form analysis, Moreover statistical comparison between the proposed and reported spectrophotometric methods was applied.

Study on the interactions of antiemetic drugs and 12-tungstophosphoric acid by absorption and resonance Rayleigh scattering spectra and their analytical applications

In 0.1 mol L(-1) HCl medium, antiemetic drugs (ATM), such as granisetron hydrochloride (GS) and tropisetron hydrochloride (TS), reacted with H(3)PW(12)O(40)·nH(2)O and formed 3:1 ion-association complex of [(ATM)(3)PW(12)O(40)], then self-aggregated into nanoparticles-[(ATM)(3)PW(12)O(40)](n) with an average size of 100 nm. The reaction resulted in the enhancement of resonance Rayleigh scattering (RRS) and the absorption spectra. The increments of scattering intensity (ΔI(RRS)) and the change of absorbance (ΔA) were both directly proportional to the concentrations of ATM in certain ranges. Accordingly, two new RRS and spectrophotometric methods were proposed for ATM detection. The detection limits (3σ) of GS and TS were 3.2 ng mL(-1) and 4.0 ng mL(-1)(RRS method), 112.5 ng mL(-1) and 100.0 ng mL(-1)(spectrophotometric method). These two methods were applied to determine GS in orally disintegrating tablets and the results were in good agreement with the official method. The ground-state geometries and electronic structures of GS and TS were optimized by the hybrid density functional theory (DFT) method and the shape of [(ATM)(3)PW(12)O(40)](n) was characterized by atomic force microscopy (AFM). Take the RRS method with higher sensitivity as an example, the reaction mechanism and the reasons for enhancement of scattering were discussed.

Iridoids as chemical markers of false ipecac (Ronabea emetica), a previously confused medicinal plant

ETHNOPHARMACOLOGICAL RELEVANCE

Several roots or rhizomes of rubiaceous species are reportedly used as the emetic and antiamoebic drug ipecac. True ipecac (Carapichea ipecacuanha) is chemically well characterized, in contrast to striated or false ipecac derived from the rhizomes of Ronabea emetica (syn. Psychotria emetica). Besides its previous use as substitute of ipecac, the latter species is applied in traditional medicine of Panama and fruits of its relative Ronabea latifolia are reported as curare additives from Colombia.

MATERIALS AND METHODS

Compounds of Ronabea emetica were isolated using standard chromatographic techniques, and structurally characterized by NMR spectroscopy and mass spectrometry. Organ specific distribution in Ronabea emetica as well as in Ronabea latifolia was further assessed by comparative HPLC analysis.

RESULTS

Four iridoid-glucosides, asperuloside (1), 6α-hydroxygeniposide (2), deacetylasperulosidic acid (3) and asperulosidic acid (4) were extracted from leaves of Ronabea emetica. Rhizomes, used in traditional medicine, were dominated by 3. HPLC profiles of Ronabea latifolia were largely corresponding. These results contrast to the general tendency of producing emetine-type and indole alkaloids in species of Psychotria and closely related genera and merit chemotaxonomic significance, characterizing the newly delimited genus Ronabea.

CONCLUSIONS

The aim of the work was to resolve the historic problem of adulteration of ipecac by establishing the chemical profile of Ronabea emetica, the false ipecac, as one of its less known sources. The paper demonstrates that different sources of ipecac can be distinguished by their phytochemistry, thus contributing to identifying adulterations of true ipecac.

Development and validation of a high performance liquid chromatographic method for the separation of exo and endo isomers of granatamine (9-methyl-9-azabicyclo[3.3.1]nonan-3-amine); a key intermediate of granisetron

A simple and accurate high-performance liquid chromatographic method was developed for the determination of exo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine in endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine, commercially known as grantamine and used as a key intermediate in the preparation of granisetron bulk drug. Chromatographic separation of the exo and endo isomers of 9-methyl-9-azabicyclo[3.3.1]nonan-3-amine was achieved on an Inertsil C8 column using a mobile phase containing 0.3% trifluoroacetic acid. The resolution between the two isomers was found to be more than 4. The limit of detection (LOD) and limit of quantification (LOQ) of exo isomer were 0.8 and 2.5 microg x mL(-1) respectively, for a 10 microL injection volume. The percentage recovery of exo-isomer ranged from 99 to 102% w/w in the endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine sample. The test solution and mobile phase were observed to be stable up to 48 h after preparation. The validated method yielded good results for precision, linearity, accuracy, robustness and ruggedness. The proposed method was found to be suitable and accurate for the quantitative determination of exo-isomer in bulk samples of endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine.

High-performance thin-layer chromatographic determination of rabeprazole sodium and domperidone in combined dosage form

A new, simple, high-performance thin-layer chromatographic method for determination of rabeprazole sodium (RAB) and domperidone (DOM) in combined tablet dosage form has been developed and validated. The mobile phase was toluene-acetone-methanol (4.5 + 4.5 + 0.5, v/v/v) with UV detection at 285 nm. The retention factors for RAB and DOM were found to be 0.53 +/- 0.12 and 0.32 +/- 0.20. The method was validated with respect to linearity, accuracy, precision, and robustness. Beer's law was obeyed in the concentration range of 50-800 ng/band for both RAB and DOM. The method has been successfully applied for the analysis of drugs in a pharmaceutical formulation.

Second derivative synchronous fluorescence spectroscopy for the simultaneous determination of metoclopramide and pyridoxine in syrup and human plasma

A rapid, simple, and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous determination of metoclopramide (MT) and pyridoxine (PY) in a binary mixture. The method is based on measurement of the native fluorescence of these drugs at delta lambda = 80 nm in methanol. The different experimental parameters affecting the native fluorescence of the drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges of 0.02-0.4 and 0.1-2 microg/mL for MT and PY, respectively. The limits of detection were 0.003 and 0.007 microg/mL and the limits of quantification were 0.008 and 0.02 microg/mL for MT and PY, respectively. The proposed method was successfully applied to the determination of MT and PY in synthetic mixtures and in commercial syrup. The results were in good agreement with those obtained with a reported method. The high sensitivity attained by the proposed method allowed the determination of MT in spiked and real human plasma samples. The mean percent recoveries of MT from spiked and real human plasma (n = 3) were 93.72 +/- 3.15 and 89.72 +/- 2.19 respectively.

Residue Analysis of Metoclopramide in Bovine and Swine Tissues by HPLC and Administration Experiment

A reversed-phase ion-pair HPLC method with ultraviolet detection has been developed for determination of metoclopramide (MCP) in bovine and swine muscle, liver, kidney, fat and intestine. MCP was extracted from samples with acetonitrile, and the extracts were cleaned up on an Oasis HLB cartridge (60 mg) after liquid-liquid extraction. The limit of detection of MCP was 0.002 microg/g and the limit of quantitation was 0.007 microg/g. Recoveries of MCP spiked at 0.03 ppm ranged from 74.1 to 93.3% for bovine tissues and from 86.1 to 92.7% for swine tissues. The present method was used for the analysis of bovine and swine tissues 1 day after withdrawal following drug administration. The MCP concentrations in all tissues were lower than the Japanese provisional MRLs.

Stability and characterization of perphenazine aerosols generated using the capillary aerosol generator

Perphenazine (a potent antiemetic) was aerosolized using capillary aerosol generator to generate respirable condensation aerosols from drug in propylene glycol (PG) solutions, by pumping the liquids through a heated capillary tube. The study characterized the stability of perphenazine during and following aerosol generation. The stability-indicating HPLC method (C-8 column with a mobile phase of 52% 0.01 M pH 3.0 acetate buffer+48% acetonitrile) also enabled the study of perphenazine stability in solution under acidic, basic, oxidizing and photolysing conditions. An LC-MS (ESI+) method was used to characterize the degradation products. Perphenazine was found to be stable in acidic and basic conditions, while perphenazine sulfoxide was the major product formed in dilute peroxide solutions. Two photo-degradation products were formed in PG that were tentatively identified by LC-MS; one of these was synthesized and confirmed to be 2-[4-(3-phenothiazin-10-yl-propyl)-piperazino]-ethanol. Both photolysis products showed that aromatic dechlorination had occurred and one appeared to also result from interaction with the solvent. Within an aerosolization energy window of 84-95 J, fine particle aerosols were generated from perphenazine PG formulations with no significant degradation. Small amounts of degradation products were produced in all samples during aerosolization at elevated (non-optimal) energies. These were largely consistent with those seen to result from oxidation and photolysis in solution, showing that oxidation and dehalogenation appeared to be the main degradation pathways followed when the CAG system was overheated.

“Determination of domperidone in tablet dosage form by anodic differential pulse voltammetry”

A differential pulse voltammetric method was described for the determination of domperidone. The method was based on the anodic oxidation of domperidone on a glassy carbon electrode at +0.64 V vs. SCE in Britton-Robinson buffer solution of pH 2.3. The reversibility of the oxidation was tested by cyclic voltammetry; the electrode process is irreversible and diffusion-adsorption controlled. Calibrations are linear over the range 1.0 x 10(-6)-2.0 x 10(-5) M of domperidone with a detection limit of 4.0 x 10(-7) M. The method was applied, without any interference from the excipients, to the determination of the drug in a tablet dosage form.

Square wave anodic stripping voltammetric determination of metoclopramide in tablet and urine at carbon paste electrode

A simple, reliable and selective square wave anodic stripping (SWAS) voltammetric method at carbon paste electrode (CPE) of metoclopramide hydrochloride (MCP) in pharmaceutical dosage forms (tablet) and in biological fluids (spiked and real urine samples) has been developed and evaluated. Different parameters such as medium, supporting electrolyte, pH, accumulation potential, scan rate, accumulation time and ionic strength, were tested to optimize the conditions for the determination of MCP. The adsorbed form is oxidized irreversibly under optimal conditions, viz., 0.4M HCl-sodium acetate buffer (pH approximately 6.2), 0.2M KCl, a linear concentration ranges from 0.067 to 0.336, 0.067 to 0.269 and 0.067 to 0.269 ng/mL of MCP, at accumulation times 60, 120 and 180 s, respectively, can be determined successfully. The interferences of some common excipients and some metal ions were studied. The standard addition method was used to determine the MCP in pure solutions, tablets and in biological fluids with satisfactory results. The data obtained are compared with the standard official method.

Individual and Simultaneous Spectrophotometric Determination of Dapsone and Metoclopramide HCl in Pharmaceutical Dosage Forms and Synthetic Binary Mixtures

A rapid, sensitive and selective spectrophotometric method has been developed for the quantitative determination of dapsone (DAP) and metoclopramide hydrochloride (MCP) in both pure and dosage forms. Individual and simultaneous methods are based on the diazo coupling reaction of these drugs with benzoylacetone (BAC) in alkaline medium. The resulting azo dyes exhibit maximum absorption at 437 and 411 nm with a molar absorptivity of 4.14x10(4) and 2.97x10(4) l mol-1 cm-1 for DAP and MCP, respectively. Simultaneous determination of DAP and MCP was developed utilizing first-order digital derivative spectrophotometry. All variables have been optimized. No interferences were observed from drug excipients and the validity of the methods was tested against reference methods.

A capillary zone electrophoresis (CZE) method for the determination of cyclizine hydrochloride in tablets and suppositories

Current compendial methods of assay for the analysis of cyclizine tablets involve the use of UV spectrophotometry. Since this is a non-selective technique its application to more complex dosage forms, such as suppositories, is unlikely to be appropriate. There is therefore a need for the development of a highly specific quantitative analytical method, such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE). The latter technique was chosen in view of some specific advantages over HPLC, such as the use of relatively non-toxic aqueous buffers, as opposed to organic solvents, which obviates the use of expensive HPLC grade solvents making CE more cost effective. Cyclizine was analyzed in 50mM phosphate buffer (pH 2.3) and run at an applied voltage 25 kV. Detection sensitivity was enhanced by using a wavelength of 200 nm and samples were loaded hydrodynamically onto an uncoated fused-silica capillary (60 cm x 50 mm i.d.). Chlorcyclizine was used as the internal standard and resolution of both compounds was achieved in less than 7 min. Stress testing was undertaken in order to investigate the appearance of breakdown products. The method has the requisite accuracy, selectivity, sensitivity and precision to assay cyclizine in tablets and suppositories. Degradation products resulting from the stress studies did not interfere with the detection of cyclizine and the assay is thus stability-indicating.

Spectrophotometric methods for the determination of anti-emetic drugs in bulk and in pharmaceutical preparations

Four rapid, simple, reproducible and sensitive methods (A-D) for assaying domperidone (I) and metoclopramide (II) in a bulk sample and in dosage forms were investigated. The first and second methods, A and B, are based on the oxidation of I and/or II by Fe3+ in the presence of o-phenanthroline (o-phen) or bipyridyl (bipy). The formation of tris-complex upon reactions with Fe3+-o-phen and/or Fe3+-bipy mixture in an acetate buffer solution of the optimum pH-values was demonstrated. Methods C and D involve the addition of excess Ce4+ and the determination of unreacted oxidant by a decrease of the red color of chromotrope 2R (C2R) at a suitable lambda(max) of 528 nm for method C, or a decrease in the orange pink color of Rhodamine 6G (Rh6G) at a suitable lambda(max) value of 525 nm for method D. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.2-5.8 microg ml(-1). The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. For a more accurate analysis, the Ringbom optimum concentration ranges are 0.35-5.6 microg ml(-1). The developed methods were successfully applied to the determination of domperidone and metoclopramide in bulk and pharmaceutical preparations without any interference from common excipients.

PVC matrix membrane sensor for potentiometric determination of metoclopramide hydrochloride in some pharmaceutical formulations

The construction and characteristic performance of metoclopramide (MCP)-polyvinyl chloride (PVC) membrane sensor are described. The sensor is based on the use of MCP-tetraiodomercurate ion pair as electroactive material in PVC matrix in presence of dioctylphthalate (DOP) as solvent mediator. MCP membrane sensor shows a stable, near Nernstian response over the concentration range 1 x 10(-2)-6 x 10(-5) M of MCP at 25 degrees C in the pH range 3-7 with cationic slope of 53.0+/-0.5. The detection limit of 4 x 10(-5) M and the response time of 30-60 s have been attained. Selectivity coefficient data for some common ions show negligible intereferences. Direct potentiometric determination of 15-3540 microg/ml MCP show an average recovery of 98.5% and a mean relative standard deviation (R.S.D.) of 1.6% at 100.0 microg/ml. The determination of MCP in Primperan tablets, injection, and syrup gave results that compare favorably with those obtained by the British pharmacopoeia method. Precipitation titrations involving MCP as titrant are monitored with the MCP sensor for some potentiometric precipitation reaction, e.g. sodium tetraphenylborate (STPB) and phosphomolybdic acid (PMA).

Application of LC-NMR for the study of the volatile metabolite of MK-0869, a substance P receptor antagonist

LC-NMR was applied to identify the polar volatile metabolite of MK-0869. MK-0869, a morpholine-based compound containing a triazolone ring, is a very potent NK(1) receptor antagonist. Currently, it is in development as an anti-emesis agent in chemotherapy treatments. The primary metabolites of MK-0869, M1 and M2, are non-polar and lack the triazolone ring. Incubation of [14C]M1 with liver microsomes from male rats produced a very polar and volatile metabolite, M3. Analysis was not possible by LC-MS or by conventional NMR because of poor ionization, small molecular weight and volatility, leaving chemical derivatization and LC-NMR as alternative methods. Reduction of M3 with NaBH(4) resulted in a derivative that had the same retention time as p-fluorophenylethylene glycol on HPLC. A small aliquot of the solution containing M3 was passed through the LC of the LC-NMR system, which was connected on-line with a radioactivity detector. The simultaneous UV and radioactivity chromatograms thus identified the chromatographic UV peak that was associated with the metabolite. Analysis was carried out by stop-flow on another portion of this fraction. From the chemical derivatization and the analysis by LC-NMR, M3 is shown to be p-fluoro-alpha-hydroxyacetophenone. Further studies using LC-NMR showed that M3 could be generated from both M1 and M2 in NADPH-dependant reactions catalyzed by microsomes containing recombinant human CYP2C19, CYP1A2 or CYP3A4.

Simultaneous determination of domperidone maleate and cinnarizine in a binary mixture using derivative ratio spectrophotometry and classical least squares calibration

This work is concerned with the simultaneous determination of domperidone maleate (DOM) and cinnarizine (CINN) in a binary mixture form without previous separation by two different methods. The first method is the application of derivative ratio spectrophotometry where the linearity range was 2.5-30 micro g/ml, 2.5-25 micro g/ml for DOM and CINN, respectively, and percentage recoveries were 100.26+/-1.308 and 99.86+/-0.939 for DOM and CINN, respectively, in their laboratory prepared mixtures. The second method depends on the application of classical least squares (CLS) calibration model. Two training sets were constructed and the best model was used for the prediction of the concentrations of both drugs. The proposed procedures were successfully applied for the simultaneous determination of both drugs in laboratory prepared mixtures and in commercial tablet preparations. The validity of the proposed methods was assessed by applying the standard addition technique where the percentage recovery of the added standard was found to be 99.83+/-1.861 and 98.38+/-0.871 for DOM and CINN, respectively, using the derivative ratio method and 99.53+/-0.916 and 99.39+/-0.599 for DOM and CINN, respectively, using the CLS method. The proposed procedures are rapid, simple, require no preliminary separation steps and can, therefore, be used routine analysis of both drugs in quality control laboratories.

Spectrophotometric determination of meclozine HCl and papaverine HCl in their pharmaceutical formulations

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of meclozine and papaverine hydrochlorides using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of meclozine HCl and into methylene chloride in case of papaverine HCl. The ion-associates exhibit absorption maxima at 536 and 524 nm for C2B and C2R with meclozine HCl and at 540 and 528 nm with papaverine HCl, respectively. Meclozine can be determined up to 4.0 and 2.6 mg ml(-1), using C2B and C2R, respectively, while papaverine can be determined up to 1.68 and 1.37 mg ml(-1), respectively. The effect of acidity, reagent concentration, time, solvent and stoichiometric ratio of the ion-associates were studied. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. The method was applied to the determination of the drugs in their pure state or pharmaceutical preparations with mean recovery values of 99.63-100.80 and 99.75-100.08% and coefficient of variation 0.945-2.210 and 1.020-1.268 for meclozine HCl and papaverine HCl, respectively.

Determination of some aminobenzoic acid derivatives: glafenine and metoclopramide

Simple, sensitive and accurate spectrophotometric methods for the determination of glafenine and metoclopramide hydrochloride are described. The first method is based on the oxidation of glafenine with iodic acid in strong acid medium to give a coloured diphenylbenzidine derivative and subsequent measurement of the coloured product at 509 nm. Beer's law is obeyed over the concentration range 2.5-20 microg ml(-1). The second method depends on the interaction of metoclopramide hydrochloride with p-dimethylaminocinnamaldehyde, to give a red coloured schiffs base with an absorbance maximum at 548 nm. Obedience to Beer's law is achieved over the concentration range 5-30 microg ml(-1). First-derivative method is used to overcome the slight interference of p-dimethylaminocinnamaldehyde reagent blank at the wavelength of measurement. Linearity between the peak heights at 576 nm versus concentration range 5-25 microg ml(-1) metoclopromide hydrochloride is obtained. The proposed methods have been successfully applied to the determination of these drugs in commercial products without interference. The validity of the methods is assessed by applying the standard addition technique, the relative standard deviation is less than 1%. The proposed methods are compared with reference methods with good agreement.

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.

Equipment for drug release testing of medicated chewing gums

An apparatus was specially designed and constructed for release testing of medicated chewing gums. The adjustable instrumental settings such as temperature, chewing frequency, chewing time, volume of test medium, distance between the jaws and twisting angle increased the versatility of the apparatus. Selection of the test medium was also an important parameter. Each sample was kneaded mechanically in separate test chambers and the drug release was followed by sampling and HPLC analysis. Different gum formulations were tested and the obtained results demonstrated satisfactory release curves for a variety of formulations and active ingredients. The tested gum formulations comprised nicotine, meclizine, dimenhydrinate and xylitol. The apparatus proved to be suitable in product control of commercial batches but also a useful tool in the research and development of medicated gum formulations.

Determination of domperidone in human serum and human breast milk by high-performance liquid chromatography-electrospray mass spectrometry

A sensitive and selective method for the determination of domperidone in human breast milk and serum has been developed. The same method may be successfully applied to both matrices to a lower limit of quantitation of 0.5 ng/ml. Samples are processed by a liquid-liquid extraction, and analyzed by LC-ESI-MS in positive ion mode. There was no interference, on the domperidone quantitation, from over 30 drugs. Samples from patients, at various times post-dose, were analyzed and a large number showed significant levels of domperidone in the breast milk as well as in the serum.

Cleaning level acceptance criteria and a high pressure liquid chromatography procedure for the assay of Meclizine Hydrochloride residue in swabs collected from pharmaceutical manufacturing equipment surfaces

A method using pharmacologically based and visual limit of detection criteria to determine the acceptable residue level for Meclizine Hydrochloride (MH) on pharmaceutical manufacturing equipment surfaces after cleaning is described. A formula was used in order to determine the pharmacologically safe cleaning level for MH. This level was termed as specific residual cleaning Level (SRCL) and calculated to be 50 microg 100 cm(-2). The visual limit of detection (VLOD) was determined by spiking different levels of MH on stainless steel plates and having the plates examined by a group of observers. The lowest level that could be visually detected by the majority of the observers, 62.5 microg 100 cm(-2), was considered as the VLOD for MH. The lower of the SRCL and VLOD values, i.e. 50 microg 100 cm(-2), was therefore chosen as the cleaning acceptance criterion. A sensitive reversed-phase HPLC method was developed and validated for the assay of MH in swabs used to test equipment surfaces. Using this method, the mean recoveries of MH from spiked swabs and '180-Grit' stainless steel plates were 87.0 and 89.5% with relative standard deviations (RSD) of +/- 3.3 and +/- 2.4%, respectively. The method was successfully applied to the assay of actual swab samples collected from the equipment surfaces. The stability of MH on stainless steel plates, on cleaning swabs and in the extraction solution was investigated.

A rapid assay of granisetron in biological fluids from cancer patients

A convenient high-performance liquid chromatography (HPLC) was developed for the rapid assay of granisetron (GRN) in biological fluids, such as serum, urine, and pleural effusion, from cancer patients. Extrelut-1 was used for the solid-phase extraction. HPLC was carried out using a LiChroCART cartridge column packed with Lichrospher 100 CN and a mobile phase consisting of 0.1 M acetate buffer (pH 3.5) and acetonitrile (7:3). A fluorescence detector of 290 nm for excitation and 365 nm for emission was used. The standard curve was linear over the range of 2 to 100 ng/ml of GRN. Assay precision, expressed as a coefficient of variation (C.V.), was in the range of 0.9-5.4% in the within-day assay and 2.5-6.9% in the between-day assay, respectively. GRN was well separated on the HPLC chromatogram from drugs such as etoposide, metclopramide, ondansetron, and domperidone which are often used together with GRN. It was suggested that the present method is useful for the rapid monitoring of GRN in the serum, urine, and pleural effusion of patients undergoing cancer chemotherapy.

[Determination of Ondansetron in injection by high performance capillary zone electrophoresis]

Ondansetron is a kind of drug which is used for the treatment of nausea and vomiting induced by cytotoxic chemotherapy and radiotherapy. In this paper, a method to determine Ondansetron in injection by high performance capillary zone electrophoresis is discussed. The injection was directly introduced into the capillary employing 40 mmol/L phosphate at pH 4.03 as buffer. The capillary used was 75 microns in i.d. and 47 cm in length. UV detection was set at 254 nm. The calibration curve showed good linearity. The recovery of Ondansetron ranged from 95%-98% with a coefficient of variation of 1.05%(n = 4). This method is simple, rapid and reliable.

Enzyme-linked immunosorbent assay for ondansetron captured from airborne samples

A simple and relatively rapid enzyme-linked immunosorbant assay method for the anti-emetic drug ondansetron has been developed for its quantitation in solution. This has been optimised for use with samples that have been obtained following extraction of filters after the drug's capture from air samples in the workplace. The assay has the sample throughput (40 duplicate samples in 3 h), specificity, sensitivity (LOD of 10.5 ng drug ml-1) and precision (RSD < 11%) necessary for its use in determining airborne concentrations of ondansetron in such samples as part of an occupational health and hygiene monitoring programme.

Micellar electrokinetic chromatography of scopolamine-related anticholinergics

A simple micellar electrokinetic chromatography (MEKC) method is described for the separation of scopolamine N-oxide hydrobromide (SO), scopolamine hydrobromide (SH), scopolamine N-methylbromide (SM) and scopolamine N-butylbromide (SB), and for the quantitation of SH, SM and SB (using SO as an internal standard). The analysis of these drugs was performed in a phosphate buffer (30 mM; pH 7.00) with sodium dodecyl sulfate (SDS) (30 mM) as an anionic surfactant. Several parameters affecting the separation of the drugs were studied, including the concentrations of the buffer and SDS. The stability of the drugs in the phosphate buffer (pH 7.00) was also examined. Partial application of the method to the determination of scopolamine N-butylbromide in tablets proved to be feasible.

Compatibility and stability of fentanyl admixtures in polypropylene syringes

OBJECTIVE

To determine the physicochemical stability of fentanyl in combination with midazolam and either hyoscine butylbromide or metoclopramide, and stored in 30 ml polypropylene syringes.

METHODS

Solutions containing approximately 40 microg/ ml of fentanyl in combination with midazolam (approximately 600 microg/ml) and either metoclopramide (approximately 700 microg/l) or hyoscine (approximately 850 microg/ml) were prepared from commercial ampoules of the drugs. The solutions were stored, in triplicate, in the dark at 32 degrees C (to simulate usage conditions) for 10 days, and the concentration of each constituent drug was periodically determined using a stability-indicating high-performance liquid chromatography assay.

RESULTS

The combinations were relatively stable, with all drugs maintaining over 90% of their initial chemical potency for at least 1 week. There were no evident changes in either the physical appearance or pH values of the solutions over the course of the study.

CONCLUSIONS

On the basis of physicochemical stability, polypropylene syringes containing fentanyl with midazolam and either hyoscine butylbromide or metoclopramide can be safely prepared and stored at or below 32 degrees C for periods of up to 1 week prior to use by palliative care patients receiving the drugs via a portable subcutaneous infusion device.

Partial least-squares regression for the quantitation of pharmaceutical dosages in control analyses

A spectrophotometric method for the simultaneous determination of the active principle and a flavouring agent in syrups containing additional excipients is proposed. The calibration matrix must include all the variability expected in the samples and this is achieved using laboratory-made mixtures and production samples in order to ensure correct results. The optimum number of principal components for the regression model was selected by using various procedures. The proposed method was used to quantify samples from different production batches. The results are compared with those provided by HPLC.

Application of packed capillary liquid chromatography/mass spectrometry with electrospray ionization to the study of the human biotransformation of the anti-emetic drug dolasetron

Packed capillary liquid chromatography/mass spectrometry (LC/MS) using electrospray ionization (ESI) was used to study the human biotransformation of the anti-emetic drug dolasetron. Urine from subjects given a single 100 mg intravenous dose, containing 14C-labeled dolasetron (50 microCi), was de-salted and concentrated for LC/MS with minimal loss of radioactivity (97% recovery). Aliquots of the de-salted material were injected directly onto a C8 packed capillary column (25 cm x 0.32 mm i.d.) and eluted with an acetonitrile-water gradient, buffered with 1% acetic acid, at a flow rate of 2 microliters min-1. Five metabolites were detected by LC ESI-MS which, yielded molecular mass information but no fragmentation. The identity of each metabolite was confirmed in a subsequent analysis using product ion scans in conjunction with collisionally induced dissociation. Precursor ion scanning was also employed and did not reveal any new biotransformation products. In addition to defining the major routes of biotransformation, the data obtained were compared with a 14C radioprofile prepared in a separate experiment. Qualitative agreement in the two chromatographic profiles enabled the major clusters of radioactivity to be assigned to specific metabolites of dolasetron. An important observation in this comparison was that the signal obtained by ESI did not provide an accurate assessment of the quantity of each metabolite. This was especially true for acidic conjugates (i.e. glucuronides, sulfates), which in the case of dolasetron can exist as zwitterions (no net charge). The results demonstrate the power of packed capillary LC ESI-MS for use in drug biotransformation studies and suggest that caution should be exercised when interpreting relative metabolite abundances from ESI data in the absence of actual reference standards.

Retention behaviour of anti-emetic serotonin antagonists in reversed phase high performance liquid chromatography

Granisetron, Ondansetron and Tropisetron, three 5-HT3 antagonists showing anti-emetic activity, were analysed by HPLC on lipophilic stationary phases. The addition of an amine or quaternary ammonium salt to the eluents was a powerful tool in the analysis of these basic substances. The influence on chromatographic parameters of pH, ionic strength and various counter-ions in the aqueous phase as well as of different organic modifiers is discussed. Some of the proposed experimental conditions allow a more strictly partition-based separation mechanism and can produce chromatographic parameters suitable for structure-activity studies. These experimental conditions are also suitable for analysis of the considered compounds in pharmaceutical dosage forms or in biological fluids.

Thermospray liquid chromatography-mass spectrometry for the characterisation of sulphate ester conjugates

Formation of polar conjugates is a well documented metabolic pathway for xenobiotics containing phenolic hydroxyl groups. This paper describes the analysis of two sulphate ester conjugates by fast atom bombardment mass spectrometry and thermospray liquid chromatography-mass spectrometry. Thermospray liquid chromatography-mass spectrometry proved the more successful technique for obtaining the molecular weight of the intact conjugate, but only by removal of the buffer from the high-performance liquid chromatography eluent.

Quantitation of a novel antiemetic (ADR-851) in plasma and urine by reversed-phase high-performance liquid chromatography with fluorescence detection

A sensitive and specific bioanalytical method for quantitation of a novel antiemetic (ADR-851) in plasma and urine has been developed and validated. The drug and internal standard (metoclopramide) are extracted from the plasma matrix by solid-phase extraction on cyanopropyl bonded-phase columns. After extraction, samples are separated by isocratic reversed-phase high-performance liquid chromatography. The parent drug, internal standard and a yet unidentified metabolite are detected by fluorescence. The method requires 1.0 ml of plasma or 0.1 ml of urine and has a lower limit of quantitation of 2 ng/ml with 10.9% relative standard deviation (R.S.D.). Method linearity has been established over a 2-800 ng/ml range when 1.0 ml of plasma is used. The intra- and inter-day imprecisions for the method are typically better than 6% and 11% R.S.D., respectively, in both plasma and urine over the entire dynamic range. The pooled estimate of bias is less than 5% and attests to the excellent accuracy.

Drug level monitoring: chromatography of some minor groups of drugs

Some important facts about the chromatographic separation of a number of selected categories of drugs are summarized. The data refer to the chromatographic method of choice, stationary phase, mobile phase (carrier gas), detection procedure and (where available) method sensitivity. Also, fundamental instrumental parameters, namely injector, column and detector temperature, carrier gas and mobile phase flow-rate and gradient set-up are reported here. In all cases also the source material used for analysis is specified. The data are presented in table form, each table dealing with a particular category of drugs. The following categories of drugs are being dealt with: anthelmintics, antiarteriosclerotics, antibacterials, anticholinergics and cholinergics, anticoagulants, antidiabetics, antiemetics, antimycotics, antihistamines, antimalarials, antiparasitics, antiparkinsonics, antitussives, antiulcer drugs, antiviral compounds, appetite depressants and immunosuppressives.

Analysis of solid-state Carbon-13 NMR spectra of polymorphs (benoxaprofen and nabilone) and pseudopolymorphs (cefazolin)

The solid-state 13C-NMR spectra of the polymorphs of benoxaprofen, nabilone, and cefazolin are reported using the cross-polarization/magic-angle spinning (CP/MAS) technique. In general, the spectra of the different crystal forms are different. In favorable cases the spectra of the drug in a pharmaceutical granulation can be discerned. These results provide a preliminary indication that solid-state NMR spectroscopy is a useful technique for the investigation of drug polymorphs and drugs in their dosage forms.

Rapid microchemical identification of four phenothiazine antiemetics with gold bromide and iodine-potassium iodide reagents: collaborative study

A microchemical method was developed for the rapid identification of 4 phenothiazine antiemetics. Perphenazine, promethazine, thiethylperazine, and triflupromazine were positively identified and differentiated with the aid of a gold bromide reagent and an iodine-potassium iodide reagent. Only promethazine and triflupromazine yielded microcrystalline derivatives with gold bromide; only perphenazine and thiethylperazine reacted with iodine-potassium iodide. For each pair of positive reactions, the crystalline products were morphologically distinguishable under a microscope. The 2 tests were collaboratively studied by 7 independent laboratories and found to be simple, rapid, and effective for identifying the phenothiazines of interest. The method has been adopted official first action.

[Hydrolysis of the antiemetic alizapride]

First order rate constants of the hydrolysis of N-[(1-allyl-2-pyrrolidinyl)-methyl]-6-methoxy-1H-benzotriazole-5-carboxa mide (alizapride, Vergentan) in acid and alkaline medium were determined. The activation energy observed in alkaline solution was 60.3 kJ X mol-1. The substance was not hydrolized in vitro by esterase, liver homogenate and plasma.

High-performance liquid chromatographic determination of alizapride, a new antiemetic compound, and its application to a dose-dependent pharmacokinetic study

An assay was developed to measure alizapride (a new antiemetic compound) in biological specimens. The method involved reversed-phase high-performance liquid chromatography and fluorescence detection. The detection limit was 5 ng/ml in plasma or urine samples. The value of the assay was demonstrated with a dose-dependent pharmacokinetic study. It showed a two-phase decrease in plasma concentrations, after intravenous injection, with half-lives of 7.5-min and 2.5-hr, respectively. From plasma and urine results, pharmacokinetic parameters remained constant in the dose range of 50-200 mg.

Rapid thin-layer chromatographic photodensitometric method for the determination of metoclopramide and clebopride in the presence of some of their metabolic products

Metoclopramide and its newly developed analogue clebopride, together with some of their metabolic products are quantitated, following extraction from biological tissues and fluids, and subsequent separation on silica gel thin-layer chromatographic plates. Diazotisation, followed by coupling with N-(1-naphthyl)ethylenediammonium dichloride, carried out on the thin-layer plate, is utilised for visualisation. The intensity of the spots is measured by photodensitometric analysis. The effect of variation of various experimental conditions is studied. The method has proven to be satisfactory for the measurement of 20 ng/ml of these compounds in biological material; the results are well within the accepted limits of deviation.