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Raju CBVN, Sharma HK, Rao CS, Rao GN. RP-HPLC method for analysis of related substances in amoxicillin drug substance. ACTA CHROMATOGR 2009. [DOI: 10.1556/achrom.21.2009.1.5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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2
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Itoh T, Tanno M, Li YH, Yamada H. Transport of phenethicillin into rat intestinal brush border membrane vesicles: role of the monocarboxylic acid transport system. Int J Pharm 1998. [DOI: 10.1016/s0378-5173(98)00196-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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Valvo L, Ciranni E, Alimenti R, Alimonti S, Draisci R, Giannetti L, Lucentini L. Development of a simple liquid chromatographic method with UV and mass spectrometric detection for the separation of substances related to amoxicillin sodium. J Chromatogr A 1998. [DOI: 10.1016/s0021-9673(97)00952-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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4
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Itoh T, Watanabe N, Ishida M, Tsuda Y, Koyano S, Tsunoi T, Shimada H, Yamada H. Stereoselective disposition of sulbenicillin in humans. Antimicrob Agents Chemother 1998; 42:325-31. [PMID: 9527780 PMCID: PMC105408 DOI: 10.1128/aac.42.2.325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Stereoselective disposition of sulbenicillin (SBPC) epimers in healthy human volunteers was studied in order to clarify the differences in pharmacokinetic behavior between the epimers. Stereospecific high-performance liquid chromatography was used for the determination of SBPC epimers. Plasma protein binding was measured in vitro with an ultrafiltration method. The binding was stereoselective, with the unbound fraction (fu) of the R-epimer being approximately 1.3-fold greater than that of the S-epimer. SBPC was administered intravenously to human volunteers, and concentrations of SBPC in plasma and urinary excretion rates were measured. Renal clearance (CLR) for the unbound drug (approximately 400 ml/min) was greater than the glomerular filtration rate (GFR) (approximately 109 ml/min) for both epimers, suggesting that both epimers are secreted at the renal tubules. Renal tubular secretion appeared to be greater for the S-epimer. When probenecid was coadministered, the CLR values of both epimers were significantly reduced and were approximately equal to the GFR values. CLR was greater for the S-epimer (37.5 and 49.8 ml/min for R-SBPC and S-SBPC, respectively), which was simply due to the greater fu of the S-epimer in plasma. In contrast, total body clearance was greater for the R-epimer (67.8 and 56.3 ml/min for R-SBPC and S-SBPC, respectively) because of the stereoselective degradation of the R-epimer in plasma. It was revealed that stereoselective degradation in the body had significant influence on the disposition of SBPC epimers.
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Affiliation(s)
- T Itoh
- Department of Pharmacokinetics and Biopharmaceutics, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
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Li YH, Itoh T, Tsuda Y, Ishida M, Watanabe N, Shimada H, Yamada H. Determination of ticarcillin epimers in plasma and urine with high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 694:145-52. [PMID: 9234857 DOI: 10.1016/s0378-4347(97)00123-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A high-performance liquid chromatogaphic method was developed for determining the concentrations of ticarcillin (TIPC) epimers in human plasma and urine. Samples were prepared for HPLC analysis with a solid-phase extraction method and the concentrations of TIPC epimers were determined using reversed-phase HPLC. The mobile phase was a mixture of 0.005 M phosphate buffer (pH 7.0) and methanol (12:1, v/v) with a flow-rate of 1.0 ml/min. TIPC epimers were detected at 254 nm. Baseline separation of the two epimers was observed for both plasma and urine samples with a detection limit of ca. 1 microg/ml with a S/N ratio of 3. No peaks interfering with either of the TIPC epimers were observed on the HPLC chromatograms for blank plasma and urine. The recovery was more than 80% for both plasma and urine samples. C.V. values for intra- and inter-day variabilities were 0.9-2.1 and 1.1-6.4%, respectively, at concentrations ranging between 5 and 200 microg/ml. The present method was used to determine the concentrations of TIPC epimers in plasma and urine following intravenous injection of TIPC to a human volunteer. It was found that both epimers were actively secreted into urine and that the secretion of TIPC was not stereoselective. Plasma protein binding was also measured, which revealed stereoselective binding of TIPC in human plasma.
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Affiliation(s)
- Y H Li
- Department of Pharmacokinetics and Biopharmaceutics, School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
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Itoh T, Yamada H. Diastereomeric beta-lactam antibiotics. Analytical methods, isomerization and stereoselective pharmacokinetics. J Chromatogr A 1995; 694:195-208. [PMID: 7719465 DOI: 10.1016/0021-9673(94)00932-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Stereospecific HPLC methods for the determination of various diastereomeric beta-lactam antibiotics are reviewed. Stereoselectivity in the absorption, distribution and excretion of several diastereomeric beta-lactams is summarized. The isomerization of beta-lactam isomers and its influence on the pharmacokinetics and pharmacodynamics are discussed.
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Affiliation(s)
- T Itoh
- Department of Pharmacokinetics and Biopharmaceutics, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
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La Follette G, Jayewardene AL, Seneviratne AK, Lin ET, Gambertoglio JG. Determination of ticarcillin in human plasma and in urine by reversed-phase LC. J Pharm Biomed Anal 1995; 13:159-64. [PMID: 7766723 DOI: 10.1016/0731-7085(94)00137-q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A liquid chromatographic assay for ticarcillin (ticar.) in plasma and urine is described. For analysis, the internal standard cefoperazone (cfp) is dissolved in acetonitrile, which is used for precipitating the protein. The supernatant is evaporated, reconstituted in running mobile phase and injected directly onto the reversed-phase C18 column, with detection at 205 nm. The mobile phase is composed of water-acetonitrile-o-phosphoric acid-tetramethylammonium chloride (TMA). Coefficients of variation for reproducibility were in the range of 2.2-15.5% for extra-low, low, medium and high controls. Limits of detection were 0.5 microgram ml-1 for plasma and 1 microgram ml-1 for urine. No interference from other cephalosporins or other antibiotics was noted. This liquid chromatographic assay is simple, accurate, requires no extraction and overcomes previous problems related to the drug's peak splitting due to isomerization.
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Affiliation(s)
- G La Follette
- Division of Clinical Pharmacy, School of Pharmacy, University of California, San Francisco 94143-0622, USA
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8
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Naidong W, Dzerk AM, Lee JW. Development and validation of an LC method for the quantitation of carbenicillin in human serum. J Pharm Biomed Anal 1994; 12:845-50. [PMID: 7918788 DOI: 10.1016/s0731-7085(94)80026-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
An LC method for the quantitation of carbenicillin in human serum has been developed and validated. After protein precipitation with acetonitrile and evaporation, the residue was taken up by citric acid at pH 1.9. Carbenicillin and the internal standard (I.S.), piperacillin, were extracted with ethyl acetate, evaporated to dryness and reconstituted with a buffer solution. The separation of carbenicillin,, the I.S., and matrix peaks was achieved on a Microsorb C18, 3 microns column with a mobile phase of acetonitrile-tetrabutylammonium-phosphate buffer (pH* 6.6). The detection was by UV at 208 nm. The run time was 8 min. The established linearity range was 0.25-20 microgram ml-1 (r2 > 0.99) with a limit of quantitation of 0.25 microgram ml-1. Interday precision (RSD) and bias over the entire range were 1.1-6.9% and -1.83 to +2.80%, respectively. The interday precision (RSD) and bias for the QC samples at 0.75, 3.0 and 12 micrograms ml-1 were 5.9-7.9% and -2.80 to +2.30%, respectively. Stabilities of on-system, bench top, freeze-thaw cycles and sample storage were established.
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Affiliation(s)
- W Naidong
- Harris Laboratories, Inc., Lincoln, NE 68501
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Roets E, Beirinckx P, Quintens I, Hoogmartens J. Quantitative analysis of tylosin by column liquid chromatography. J Chromatogr A 1993; 630:159-66. [PMID: 8445000 DOI: 10.1016/0021-9673(93)80452-e] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A column liquid chromatographic method suitable for the quality control of tylosin A is described. The determination can be carried out on different C8 or C18 columns, using a mobile phase containing acetonitrile, 0.2 M tetrabutylammonium hydrogensulphate, 0.2 M phosphoric acid and water. The flow-rate is 1 ml/min and detection is performed at 280 nm. The method shows good selectivity towards the major components tylosin A, B, C and D and demycinosyltylosin. Minor degradation products, mainly observed in solutions, are also separated. The compositions of several standards are compared and results for a number of commercial samples are presented.
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Affiliation(s)
- E Roets
- Katholieke Universiteit Leuven, Laboratorium voor Farmaceutische Chemie, Belgium
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11
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Paesen J, Claeys P, Roets E, Hoogmartens J. Evaluation of silanol-deactivated silica-based reversed phases for liquid chromatography of erythromycin. J Chromatogr A 1993. [DOI: 10.1016/0021-9673(93)80446-f] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Cachet T, Delrue M, Paesen J, Busson R, Roets E, Hoogmartens J. Analysis of erythromycin estolate by liquid chromatography. J Pharm Biomed Anal 1992; 10:851-60. [PMID: 1298393 DOI: 10.1016/0731-7085(91)80091-m] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A method is described for the determination of erythromycin estolate by liquid chromatography. A C18 reversed-phase column (25 x 0.46 cm i.d.) was used with acetonitrile-tetrabutylammonium sulphate (pH 6.5, 0.2 M)-phosphate buffer (pH 6.5, 0.2 M)-water [x:5:5:(90-x), v/v/v/v] as mobile phase. The proportion of acetonitrile (x) has to be adapted to the type of stationary phase used. For RSil C18 LL 42.5% (v/v) was used. The column was heated at 35 degrees C, the flow rate was 1.5 ml min-1 and UV detection was performed at 215 nm. The main component, erythromycin A propionate, was separated from all other components which were present in commercial samples. The impurities most frequently observed were the propionate ester of erythromycin C and the amide N-propionyl-N-demethyl-erythromycin A. Erythromycin A was shown to be present in specialties.
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Affiliation(s)
- T Cachet
- Katholieke Universiteit Leuven, Laboratorium voor Farmaceutische Chemie, Instituut voor Farmaceutische Wetenschappen, Belgium
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13
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Naidong W, Vermeulen K, Quintens I, Roets E, Hoogmartens J. Evaluation of analytical methods. Analysis of minocycline by liquid chromatography. Chromatographia 1992. [DOI: 10.1007/bf02262248] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cachet T, Lannoo P, Paesen J, Janssen G, Hoogmartens J. Determination of erythromycin ethylsuccinate by liquid chromatography. J Chromatogr A 1992; 600:99-108. [PMID: 1400845 DOI: 10.1016/0021-9673(92)85443-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A method is described for the determination of erythromycin ethylsuccinate by liquid chromatography. A C18 reversed-phase column (25 cm x 4.6 mm I.D.) was used with acetonitrile-0.2 M tetrabutylammonium sulphate (pH 6.5)-0.2 M phosphate buffer (pH 6.5)-water [x:5:5:(90-x)] as mobile phase. The proportion of acetonitrile (x) has to be adapted to the type of stationary phase used. For RSil C18 LL, 42.5% was used. The column was heated at 35 degrees C, the flow-rate was 1.5 ml/min and UV detection was performed at 215 nm. The main component, erythromycin A ethylsuccinate, was separated from all other components which were present in commercial samples. The main impurities were erythromycin A and the ethylsuccinate esters of erythromycin B and C. The amide N-ethylsuccinyl-N-demethylerythromycin A was shown to be present in all the samples examined. The method was successfully applied to the analysis of specialities.
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Affiliation(s)
- T Cachet
- Katholieke Universiteit Leuven, Laboratorium voor Farmaceutische Chemie, Belgium
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Kelly JW, Stewart JT. Separation of Selected Beta Lactam Antibiotic Epimers on Gamma Cyclodextrin, Ion Exchange Ethylvinylbenzene/Divinylbenzene/Copolymer and Poly(Styrene-Divinylbenzene) Copolymer Stationary Phases. ACTA ACUST UNITED AC 1991. [DOI: 10.1080/01483919108049687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Cachet T, Quintens I, Paesen J, Roets E, Hoogmartens J. Improved Separation of Erythromycin on aged Reversed-Phase Columns. II. ACTA ACUST UNITED AC 1991. [DOI: 10.1080/01483919108049313] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Cachet T, de Turck K, Roets E, Hoogmartens J. Quantitative analysis of erythromycin by reversed-phase liquid chromatography using column-switching. J Pharm Biomed Anal 1991; 9:547-55. [PMID: 1817675 DOI: 10.1016/0731-7085(91)80176-a] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A column-switching technique is described for LC of erythromycin. The method allows, in about 1 h, the separation of erythromycin A from all its known potential impurities, except erythromycin D, which is a minor impurity. The switching technique combines two columns (7.5 cm x 4.6 mm and 25.0 cm x 4.6 mm) both packed with RSil C 18 LL 10 microns. The mobile phase is acetonitrile-tetrabutylammonium sulphate (0.2 M, pH 6.0)-ammonium phosphate buffer (0.2 M, pH 6.0)-water (24:5:5:66, v/v/v/v). Temperature was 35 degrees C, flow rate was 1.5 ml min-1, detection was by UV at 210 nm. Results for a number of commercial samples of various origin are reported.
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Affiliation(s)
- T Cachet
- Katholieke Universiteit Leuven, Instituut voor Farmaceutische Wetenschappen, Belgium
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Khan NH, Roets E, Hoogmartens J, Vanderhaeghe H. Quantitative analysis of chlortetracycline and related substances by high-performance liquid chromatography. J Pharm Biomed Anal 1989; 7:339-53. [PMID: 2488635 DOI: 10.1016/0731-7085(89)80101-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Isocratic high-performance liquid chromatography on Zorbax C8 7 microns allows quantitative determination of chlortetracycline, 4-epichlortetracycline, tetracycline, demethylchlortetracycline and isochlortetracycline using a mobile phase containing dimethylsulphoxide, 1 M perchloric acid and water (35:5:60). The minor impurities anhydrochlortetracycline and 4-epianhydrochlortetracycline, which are more strongly retained can be determined using a second isocratic system with a mobile phase containing more organic modifier. The method has been used for the comparison of official standards and for the analysis of a number of commercial samples.
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Affiliation(s)
- N H Khan
- Katholieke Universiteit Leuven, Instituut voor Farmaceutische Wetenschappen, Belgium
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Cachet T, Kibwage IO, Roets E, Hoogmartens J, Vanderhaeghe H. Optimization of the separation of erythromycin and related substances by high-performance liquid chromatography. J Chromatogr A 1987; 409:91-100. [PMID: 3693497 DOI: 10.1016/s0021-9673(01)86786-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An improved high-performance liquid chromatographic method for analysis of erythromycin is described. The separation can be performed under mild conditions of pH (6.5) and temperature (35 degrees C) on C8 and C18 silica-based reversed-phase materials of different origins. The mobile phase, with a flow-rate of 1.5 ml/min, contained various amounts of acetonitrile (25-40%, v/v), 5% (v/v) 0.2 M ammonium phosphate buffer pH 6.5, 20% (v/v) 0.2 M tetramethylammonium phosphate and water. UV detection at 215 nm allows quantitation of erythromycins A, B and C, N-demethylerythromycin A, erythromycin A enol ether and anhydroerythromycin A. The column history plays a major role, older columns often giving better separations.
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Affiliation(s)
- T Cachet
- Katholieke Universiteit Leuven, Instituut voor Farmaceutische Wetenschappen, Belgium
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22
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Verstraeten A, Roets E, Hoogmartens J. Quantitative determination by high-performance liquid chromatography of acetylsalicylic acid and related substances in tablets. J Chromatogr A 1987; 388:201-16. [PMID: 3558647 DOI: 10.1016/s0021-9673(01)94480-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
High-performance liquid chromatography on a Zorbax C8 7-micron column (25 cm X 0.46 cm I.D.) with methanol-water-1 M phosphoric acid (59:36:5) as the mobile phase has been used for the analysis of several naturally aged batches of fourteen brands of acetylsalicyclic acid tablets. The extraction solvent is methanol, containing 2% v/v of formic acid. Salicylic acid is the main impurity. Acetylsalicylsalicylic acid is the second most important impurity, and the corresponding salicylsalicylic acid is rarely present. Buffered or dispersible tablets contain relatively more of the latter two impurities and eventually also the corresponding higher oligomers. Acetylsalicylic anhydride is always a minor impurity. Comparison is made with classical spectrophotometric methods, which are observed to be selective for salicylic acid.
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Haginaka J, Wakai J. Liquid chromatographic determination of amoxicillin and its metabolites in human urine by postcolumn degradation with sodium hypochlorite. JOURNAL OF CHROMATOGRAPHY 1987; 413:219-26. [PMID: 3558671 DOI: 10.1016/0378-4347(87)80229-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A high-performance liquid chromatographic method has been developed for the determination of amoxicillin and its metabolites [(5R,6R)-amoxicilloic acid, the (5S,6R) epimer, and the (2R)-piperazine-2',5'-dione] in human urine. They were separated from the background components of urine on a reversed-phase C18 column using sodium heptylsulphonate as an ion-pairing agent and methanol as an organic mobile phase modifier. The eluent was led to the postcolumn degradation with 1.5 M sodium hydroxide plus 0.02% sodium hypochlorite solution at ambient temperature. The degradation product(s) of each compound was detected at 270 nm. The proposed method permits detection of I, II, III, and IV down to 1 microgram/ml in neat urine samples. At a concentration of 5 micrograms/ml of each compound, within- and between-run precisions (relative standard deviation) were 1.12-5.79 and 0.80-2.70%, respectively. The urinary levels of I and its metabolites were determined by the proposed method after administration of I to humans.
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Van Schepdael A, Roets E, Hoogmartens J, Vanderhaeghe H. Separation of ampicillin esters and their diastereoisomers by reversed-phase liquid chromatography. J Chromatogr A 1986. [DOI: 10.1016/s0021-9673(00)94683-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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De Pourcq P, Hoebus J, Roets E, Hoogmartens J, Vanderhaeghe H. Quantitative determination of amoxicillin and its decomposition products by high-performance liquid chromatography. J Chromatogr A 1985; 321:441-9. [PMID: 3988846 DOI: 10.1016/s0021-9673(01)90462-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Amoxicillin, amoxicilloates, amoxicillin oligomers and amoxicillin piperazine-2,5-dione are separated by reversed-phase (C8) high-performance liquid chromatography with gradient elution. Quantitative results are reported for a number of samples. Amoxicillin trihydrate samples mostly contain amoxicilloate as the main impurity. Samples of the sodium salt also contain the piperazine-2,5-dione and the dimer. Higher oligomers such as the trimer and tetramer were not present in significant amounts. Several samples were also analysed by a mercurimetric titration method.
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Kibwage I, Janssen G, Roets E, Hoogmartens J, Vanderhaeghe H. Isolation of erythromycins and related substances from fermentation residues of streptomyces erythreus by high-performance liquid chromatography on silica gel. J Chromatogr A 1985. [DOI: 10.1016/s0021-9673(00)90517-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hashimoto N, Tanaka H. Epimerization kinetics of moxalactam, its derivatives, and carbenicillin in aqueous solution. J Pharm Sci 1985; 74:68-71. [PMID: 3981422 DOI: 10.1002/jps.2600740118] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The mechanism of the epimerization of moxalactam was studied by measuring the rate of epimerization after deuteration of the C-7 side-chain chiral carbon, introduction of different substituents on the side chain, and variation of the ring system. Deuteration slowed the epimerization rate considerably. The rate was also influenced by the choice of the ring system and the substituent on the C-7 side-chain chiral carbon. When the penicillin ring system with the 2-carboxy-2-phenyl-acetamide was studied, the epimerization rate decreased indicating that the same ring system needed to be used throughout the epimerization studies. Thus, experiments were conducted with different substituents replacing the phenolic group at the C-7 side-chain chiral carbon of moxalactam. The epimerization rate decreased in the substituent order thienyl, phenyl, 4-hydroxyphenyl, the ionized form of 4-hydroxyphenyl, and ethyl. These results showed that dehydrogenation of the chiral carbon seems to be the rate-determining step and that the stronger the electron-donating effect of the substituent, the slower the epimerization rate becomes.
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Fong GW, Martin DT, Johnson RN, Kho BT. Determination of degradation products and impurities of amoxicillin capsules using ternary gradient elution high-performance liquid chromatography. J Chromatogr A 1984; 298:459-72. [PMID: 6092403 DOI: 10.1016/s0021-9673(01)92743-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A specific high-performance liquid chromatography method has been developed for the determination of amoxicillin penicilloic acids (PA), p-hydroxyphenylglycine (p-HPG), 6-aminopenicillanic acid (6-APA) and unidentified materials in amoxicillin capsules. The accuracy of the measurements was demonstrated by the standard addition technique on actual capsule samples. Within-day and between-day precision studies gave coefficients of variation of 3.15 and 1.70% for PA, 4.75 and 3.81% for p-HPG, and 5.59 and 32.23% for 6-APA, respectively. Typical calibration and expanded linearity of response curves for these components show no curvature over the range of interest. The detection limits for PA, p-HPG and 6-APA are 0.7, 0.2 and 0.6 micrograms/ml of sample extract and are considered adequate for the intended use of the method. These levels correspond to 0.35, 0.10, 0.30 mg per 500-mg Amoxil capsule, respectively.
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Selectivity of reversed-phase packing materials in high-performance liquid chromatography of cephalosporins. J Chromatogr A 1984. [DOI: 10.1016/s0021-9673(00)95007-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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