Biomedical subjects

Erwin Adams

Publications and source records attributed to Erwin Adams.

12 recordsLinked to original sources

PubMed2006

Evaluation of an International Pharmacopoeia method for the analysis of nelfinavir mesilate by liquid chromatography.

A gradient LC method for the determination of related substances in nelfinavir mesilate (NFVM) has been recently published in the International Pharmacopoeia. The method uses a base deactivated reversed phase C18 column (25 cm x 4.6 mm I.D.), 5 microm kept at a temperature of 35 degrees C. The mobile phases consist of acetonitrile, methanol, phosphate buffer pH 3.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 225 nm. A system suitability test (SST) is described to govern the quality of the separation. The separation towards NFVM components was investigated on 18 C18 columns and correlation was made with the column classification system developed in our laboratory. The method was evaluated using a Hypersil BDS C18 column (25 cm x 4.6 mm I.D.), 5 microm. A two level fractional factorial design was applied to examine the robustness of the method. The method shows good selectivity, precision, linearity and sensitivity. Seven commercial samples were examined using this method.

Chromatography, Liquid↗

PubMed2006

Application of an improved column characterisation system to evaluate the within and between batch variability.

The selection of a reversed-phase liquid chromatographic column with suitable selectivity for a particular separation is difficult if the brand name of the column is not known. A project to develop a chromatographic test procedure to characterize reversed-phase liquid chromatography C18 columns was started earlier and resulted in a fast, simple, repeatable and reproducible test procedure using four column parameters. Here, this procedure is used to evaluate the diversity of columns originating from the same batch as well as from different batches. The determination of one of the parameters, the retention factor of 2,2'-dipyridyl, was improved and a simplified test procedure is proposed.

2,2'-Dipyridyl↗

PubMed2006

Evaluation of an International Pharmacopoeia method for the analysis of saquinavir (mesilate) bulk drugs by liquid chromatography.

A single gradient LC method for the determination of related substances in both saquinavir (SQV), saquinavir mesilate (SQVM) has been published in a consultation document of the International Pharmacopoeia, WHO Drug Information. The method uses a base deactivated reversed phase C18 column (25 cm x 4.6 mm i.d.), 5 microm kept at a temperature of 30 degrees C. The mobile phases consist of acetonitrile, methanol, phosphate buffer pH 3.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) is described to govern the quality of the separation. The separation towards SQV(M) components was investigated on 18 C18 columns and correlation was made with the column classification system developed in our laboratory. The method was evaluated using a Hypersil BDS C18 column (25 cm x 4.6 mm i.d.), 5 microm. A central composite design was applied to examine the robustness of the method. The method shows good precision, linearity, sensitivity and robustness. SQV(M) commercial samples of bulk drugs were examined using this method.

Algorithms↗

PubMed2006

Analysis of unknown compounds in gentamicin bulk samples with liquid chromatography coupled with ion trap mass spectrometry.

Six unknown compounds present in bulk gentamicin samples have been identified by ion-pairing reversed-phase liquid chromatography coupled with ion trap mass spectrometry. The structures of these unknown compounds were deduced by comparison of their fragmentation patterns with those of the available related substances and gentamicin reference substances. Seven other unknown components were partially identified.

Anti-Bacterial Agents↗

PubMed2006

Application of liquid chromatography/ion trap mass spectrometry to the characterization of the related substances of clarithromycin.

A selective reversed-phase liquid chromatography/mass spectrometry (LC/MS(n)) method was developed for the characterization of components of the semi-synthetic macrolide clarithromycin. Mass spectral data were acquired online on a LCQ ion trap mass spectrometer equipped with an electrospray ionization source operated in the positive ion mode. One unknown compound was structurally elucidated and two other unknowns were characterized using the MS/MS and MS(n) collision-induced dissociation spectra of reference substances as interpretative templates, combined with knowledge of the nature of functional group fragmentation behaviour. Given the importance attached to the identification of impurities of unknown identity in pharmaceutical substances, this study is useful for companies producing clarithromycin.

Chromatography, Liquid↗

PubMed2005

Investigation of degradation products in a topical gel containing erythromycin and benzoyl peroxide by liquid chromatography-mass spectrometry.

Benzamycin, combining benzoyl peroxide and erythromycin, is a topical gel used in the treatment of acne vulgaris. Because of the reactivity of benzoyl peroxide, preparations containing both erythromycin and benzoyl peroxide might be unstable and degradation products could be formed. To investigate and identify these latter products, a gradient-based liquid chromatographic method using volatile mobile phase constituents was developed. Mass spectrometry data were acquired on solutions containing erythromycin and benzoyl peroxide and on freshly prepared, 2-month-old and 18-month-old samples of Benzamycin. With the reference spectra as interpretative templates, it was concluded that erythromycin undergoes oxidation, followed by benzoylation.

Benzoyl Peroxide↗

PubMed2005

Facilitated column selection in pharmaceutical analyses using a simple column classification system.

In this paper, the performance of a previously developed classification system applied to pharmaceutical chromatographic analyses, is investigated. The separation of seven different drug substances from their respective impurities was studied. The chromatographic procedure for acetylsalicylic acid, clindamycin hydrochloride, buflomedil hydrochloride, chloramphenicol sodium succinate, nimesulide and phenoxymethylpenicillin was performed according to the corresponding European Pharmacopoeia (Ph. Eur.) monograph. The separation of dihydrostreptomycin sulphate was performed according to the literature. It is shown that the column ranking system is a helpful tool in the selection of a suitable column in these analyses.

Aspirin↗

PubMed2004

Identification of impurities in erythromycin by liquid chromatography-mass spectrometric detection.

A simple, isocratic liquid chromatographic (LC) method using volatile mobile phase constituents for the identification of related substances in erythromycin samples is described. For method development, evaporative light scattering detection (ELSD) was used. An XTerra RP18 column was used at 70 degrees C with a mobile phase consisting of acetonitrile-isopropanol-0.2M ammonium acetate pH 7.0-water (165:105:50:680). Mass spectral data were acquired on an ion trap mass spectrometer equipped with an electrospray interface operated in the positive ion mode. First, a library was created using MS/MS and MS(n) spectra of reference substances available in the laboratory. Using these reference spectra as interpretative templates, eight novel related substances in erythromycin samples were identified: N-demethylerythromycin E, erythromycin E N-oxide, anhydroerythromycin C, N-demethylerythromycin B, anhydro-N-demethylerythromycin A, pseudoerythromycin E enol ether, EF lacking the neutral sugar and EA lacking the neutral sugar.

Chromatography, Liquid↗

PubMed2004

Characterisation of reversed-phase liquid-chromatographic columns by chromatographic tests comparing column classification based on chromatographic parameters and column performance for the separation of acetylsalicylic acid and related compounds.

Selection of RP-LC columns with suitable selectivity for a given analysis is difficult. For example, the European Pharmacopoeia (Ph. Eur.) and other official compendia for drug analysis only give a general description of the stationary phase in the operating procedure of a liquid chromatographic method. The need for a general test method to characterise RP-LC columns has been rising since the 1970s. A project to define a chromatographic procedure characterising RP-LC columns was started earlier. A procedure to measure test parameters was introduced and a classification of the columns, based on a minimal number of parameters, was obtained. This paper focuses on correlating the column classification with the selectivity obtained for a real separation. The separation of acetylsalicylic acid (aspirin) and related compounds was performed according to the Ph. Eur. monograph on the stationary phases previously characterised chromatographically. It was examined whether the classes of columns, determined using test parameter results, contain either suitable or unsuitable supports for the aspirin separation. The system suitability test prescribed by the Ph. Eur. in order to distinguish between suitable or unsuitable columns for this separation was also evaluated.

Aspirin↗

PubMed2004

Application of liquid chromatography-ion trap mass spectrometry to the characterization of the 16-membered ring macrolide josamycin propionate.

Coupled liquid chromatography and ion trap mass spectrometry (LC/MS) was used for the characterization of the semi-synthetic 16-membered ring macrolide josamycin propionate. On-line identification of impurities in this antibiotic complex was performed with an ion trap mass spectrometer without recourse to time-consuming isolation and purification procedures. Ion trap mass spectrometry is ideally suited to identification of impurities because it provides MSn capability, enabling multiple stages of mass spectrometry to obtain the maximum amount of structural information for a given molecule. The ion trap was used with an electrospray ionization source operated in the positive ion mode or with an atmospheric pressure chemical ionization source operated in the negative ion mode. The identity of the unknown compounds was deduced using the MS/MS and MSn collision-induced dissociation spectra of reference substances or structural analogs as interpretative templates, combined with knowledge about the nature of functional group fragmentation behavior. Given the importance attached to the identification of impurities of unknown identity in pharmaceutical substances, this study is useful for companies producing josamycin propionate. The knowledge of the fragmentation behavior is also of importance in further research on other 16-membered macrolides.

Chromatography, Liquid↗

PubMed2003

Sequencing of bacitracin A and related minor components by liquid chromatography/electrospray ionization ion trap tandem mass spectrometry.

A selective reversed-phase liquid chromatography/mass spectrometry (LC/MS(n)) method is described for the characterization of related compounds in commercial bacitracin samples. Mass spectral data for these polypeptide antibiotics were acquired on a LCQ ion trap mass spectrometer equipped with an electrospray ionization probe operated in the positive and negative ion mode. The LCQ ion trap is ideally suited for the sequencing of those linear side-chain cyclized peptides because it provides on-line LC/MS(n) capability. Using this method bacitracin A, 1-epibacitracin A, bacitracins B(1), B(2), B(3) and bacitracin F were sequenced and previous sequencing was confirmed. Bacitracins C(1), C(2), C(3), D, H(2) and H(3) were resolved chromatographically and their ring portion was sequenced for the first time. Four components not described in the literature (1-epibacitracin B(1), 1-epibacitracin B(2), 1-epibacitracin C(1) and H(4)) were sequenced completely for the first time. The main advantage of this hyphenated LC/MS(n) technique is the characterization of the related substances without time-consuming isolation and purification procedures.

Amino Acid Sequence↗

PubMed2002

Scaling-up of a lactose wet granulation process in Mi-Pro high shear mixers.

The high shear wet granulation upscaling possibilities of a Pro-C-epT Mi-Pro 250 ml with a batch size of 40 g were investigated by down-scaling an alpha-lactose monohydrate wet granulation process from a Collette Gral 10 (8 l batch size) to a Pro-C-epT Mi-Pro with different bowl volumes of 5 l, and 1900, 900 and 250 ml. The wet granulation process was optimised in the Gral 10, next an octagonal design was build around the central point. Two process parameters, the impeller tip speed and the water content, were varied at three levels, which resulted in a two-factor three-level experimental design. alpha-Lactose monohydrate 200 M was granulated using a polyvinylpyrollidone K 30 (2.5% on dry material) binder solution. The granules were dried at 25 degrees C for 24 h, sieved and characterised. The granules were compressed to tablets. In all mixer volumes the used impeller tip speed range did not influence the granule or tablet properties. In all bowl volumes the influence of water concentration on actual yield, particle size distribution and granule friability was similar. All batch sizes resulted in tablets of similar quality. For the selected formulation the lab scale Mi-Pro high shear mixers with different bowl volumes could be used to determine the optimal process parameters and to scale up to the Collette Gral 10 pilot scale.

Lactose↗