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Ouchaou K, Maire F, Salo O, Ali H, Hankemeier T, van der Marel GA, Filippov DV, Bovenberg RAL, Vreeken RJ, Driessen AJM, Overkleeft HS. A Mutasynthesis Approach with aPenicillium chrysogenumΔroqAStrain Yields New Roquefortine D Analogues. Chembiochem 2015; 16:915-23. [DOI: 10.1002/cbic.201402686] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 11/08/2022]
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Rahimi M, Mobedi H, Behnamghader A. Aqueous stability of leuprolide acetate: effect of temperature, dissolved oxygen, pH and complexation with β-cyclodextrin. Pharm Dev Technol 2014; 21:108-15. [PMID: 25331295 DOI: 10.3109/10837450.2014.971377] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In the present research, the aqueous stability of leuprolide acetate (LA) in phosphate buffered saline (PBS) medium was studied (pH = 2.0-7.4). For this purpose, the effect of temperature, dissolved oxygen and pH on the stability of LA during 35 days was investigated. Results showed that the aqueous stability of LA was higher at low temperatures. Degassing of the PBS medium partially increased the stability of LA at 4 °C, while did not change at 37 °C. The degradation of LA was accelerated at lower pH values. In addition, complexes of LA with different portions of β-cyclodextrin (β-CD) were prepared through freeze-drying procedure and characterized by Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) analyses. Studying their aqueous stability at various pH values (2.0-7.4) showed LA/β-CD complexes exhibited higher stability when compared with LA at all pH values. The stability of complexes was also improved by increasing the portion of LA/β-CD up to 1/10.
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Affiliation(s)
- Mehdi Rahimi
- a Department of Biomedical Engineering, Science and Research Branch , Islamic Azad University , Tehran , Iran
| | - Hamid Mobedi
- b Department of Novel Drug Delivery Systems , Iran Polymer and Petrochemical Institute , Tehran , Iran , and
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Stevenson CL, Leonard JJ, Hall SC. Effect of peptide concentration and temperature on leuprolide stability in dimethyl sulfoxide. Int J Pharm 1999; 191:115-29. [PMID: 10564838 DOI: 10.1016/s0378-5173(99)00289-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of temperature and concentration on leuprolide degradation in dimethyl sulfoxide (DMSO) were explored. Leuprolide degradation products were analyzed by reverse phase high-performance liquid chromatography (RP-HPLC), size exclusion chromatography (SEC) and structurally characterized by mass spectrometry. Leuprolide solution stability in DMSO was characterized at 50, 100, 200, 400 mg/ml at 37-80 degrees C for 2 months to 3 years. Leuprolide degradation products were identified by mass spectrometry and could generally be attributed to isomerization, hydrolysis, oxidation, or aggregation. The hydrolytic degradation products consisted primarily of backbone cleavage C-terminal to Trp(3), Ser(4), Tyr(5), Leu(6) and Leu(7), and oxidation of Trp(3) and beta-elimination of Ser(4) were identified. Leuprolide degradation at 50 degrees C, 65 degrees C and 80 degrees C proceeded in an exponential fashion (E(a)=22. 6+/-1.2 kcal/mol); however, leuprolide degradation plateau'd after approximately 6 months at 37 degrees C. Upon closer examination, degradation product peak areas were seen to vary with temperature. For example, aggregation products did not increase with time at 37 degrees C, but aggregation peak intensities increased sharply with time at 80 degrees C. Increasing the temperature also increased the proportion of leuprolide degrading via isomerization/hydrolytic pathways, and decreased the proportion degrading via oxidation. These variations suggested that solvent dielectric, free H(+) in an aprotic solvent, oxygen solubility, impurities and residual moisture may play a role. Leuprolide solubilized in DMSO yields adequate stabililty for a 1 year implantable osmotic delivery system, where use of a dry aprotic solvent results in conditions similar to solid state stability.
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Affiliation(s)
- C L Stevenson
- Biopharmaceutical R & D, ALZA Corporation, 950 Page Mill Road, Palo Alto, CA 94303, USA.
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Hall SC, Tan MM, Leonard JJ, Stevenson CL. Characterization and comparison of leuprolide degradation profiles in water and dimethyl sulfoxide. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1999; 53:432-41. [PMID: 10406221 DOI: 10.1034/j.1399-3011.1999.00069.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effect of solvent on the rate of leuprolide degradation and on the structure of the degradation products was explored. Leuprolide solutions (370 mg/mL) were prepared in water and dimethyl sulfoxide (DMSO) for delivery in DUROS osmotic implants. Both solvent systems demonstrated better than 90% stability after 1 year at 37 degrees C, where the DMSO formulation afforded better stability than the aqueous formulation and was used in subsequent clinical trials. The rate of leuprolide degradation in DMSO was also observed to accelerate with increasing moisture content, indicating that the aprotic solvent minimized chemical degradation. Interestingly, leuprolide degradation products varied with formulation vehicle. The proportions of leuprolide degradation products observed to form in water and DMSO at 37 degrees C were hydrolysis > aggregation > isomerization > oxidation and aggregation > oxidation > hydrolysis > isomerization, respectively. Specifically, more N-terminal hydrolysis and acetylation were observed under aqueous conditions, and increased Trp oxidation and Ser beta-elimination were seen under non-aqueous conditions. Furthermore, the major chemical degradation pathway changed with temperature in the DMSO formulation (decreasing oxidation with increasing temperature), but not in the aqueous formulation.
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Affiliation(s)
- S C Hall
- Biopharmaceutical R&D, Alza Corporation, Palo Alto, CA 94303, USA
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Tan MM, Corley CA, Stevenson CL. Effect of gelation on the chemical stability and conformation of leuprolide. Pharm Res 1998; 15:1442-8. [PMID: 9755898 DOI: 10.1023/a:1011914007940] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The purpose of this study was to characterize the conformation, aggregation, and stability of leuprolide on gelation. METHODS Infrared spectra (FTIR) of leuprolide solutions and gels were collected in water, propylene glycol (PG), dimethyl sulfoxide (DMSO), and trifluoroethanol (TFE). Leuprolide solution and gel stability data were obtained by SEC and RP-HPLC. RESULTS Leuprolide was induced to gel with increasing peptide concentration, introduction of salts, and gentle agitation. Leuprolide dissolved in water (400 mg/ml) demonstrated FTIR spectra consisting of two major bands of equal intensity at 1615 cm(-1) and 1630 cm(-1), similar to inter- and intra-molecular beta-sheet structure in proteins. When samples were gently agitated for 24 hours at 25 degrees C, the formulation was observed to change from a viscous liquid to an opaque gel with a concomitant shift in infrared spectra from the equal intensity bands to mostly 1630 cm(-1), indicating a shift to a preferred beta-sheet structure. Incubation of leuprolide with 20-200 mM salts at 25 degrees C and 37 degrees C also produced gels ranging from clear to cloudy and stringy white precipitates. The gel and precipitate were marked by a shift of the predominant beta-sheet band to 1630 cm(-1) and 1615 cm(-1), respectively. Leuprolide was also observed to gel and/or precipitate in mixtures of water, PG or TFE, but not in DMSO. CONCLUSIONS Birefringence was noted in many of the firmer gels. Both solutions and gels demonstrated minimal dimer or trimer formation, with no larger order aggregates detected. The chemical stability profile of gelled leuprolide was similar to that of the non-gelled water formulation by RP-HPLC.
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Affiliation(s)
- M M Tan
- Biopharmaceutical R & D, ALZA Corporation, Palo Alto, California 94303, USA
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Hoitink MA, Beijnen JH, Boschma MU, Bult A, van der Houwen OA, Wiese G, Underberg WJ. Degradation kinetics of three gonadorelin analogues: developing a method for calculating epimerization parameters. Pharm Res 1998; 15:1449-55. [PMID: 9755899 DOI: 10.1023/a:1011966024778] [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: 11/12/2022]
Abstract
PURPOSE To develop a method for calculating epimerisation parameters, find out if the kinetics of the independent reactions can be established, and elucidate primary structure-chemical degradation relationships in the degradation kinetics of three gonadorelin analogues. METHODS The influences of pH, temperature, and buffer concentration on the degradation of the three gonadorelin analogues buserelin, goserelin, and triptorelin were investigated using RP-HPLC. A method was developed to calculate epimerisation and hydrolysis rate constants independently. RESULTS Explicit structure-degradation mechanism relations were found in the degradation of all three compounds. The L-serine residue was found to be involved in both a solvent-catalysed backbone hydrolysis and a hydroxyl-catalysed epimerisation whereas, the O-tertiary butyl D-serine residue was only involved in proton-catalysed ether hydrolysis. The kinetics of identical reactions in different analogues were generally comparable. CONCLUSIONS The degradation of the gonadorelin analogues is located at a relatively small number of chemical residues and prediction of the degradation mechanisms and kinetics of other peptides with similar structural elements appears to be possible.
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Affiliation(s)
- M A Hoitink
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, The Netherlands.
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Hoitink MA, Beijnen JH, Boschma MUS, Bult A, Hop E, Nijholt J, Versluis C, Wiese G, Underberg WJM. Identification of the Degradation Products of Gonadorelin and Three Analogues in Aqueous Solution. Anal Chem 1997. [DOI: 10.1021/ac970634x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marnix A. Hoitink
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Jos H. Beijnen
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Marcel U. S. Boschma
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Auke Bult
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Ed Hop
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Jack Nijholt
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Cees Versluis
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Gerard Wiese
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
| | - Willy J. M. Underberg
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands
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Hoitink MA, Beijnen JH, Bult A, van der Houwen OA, Nijholt J, Underberg WJ. Degradation kinetics of gonadorelin in aqueous solution. J Pharm Sci 1996; 85:1053-9. [PMID: 8897270 DOI: 10.1021/js9601187] [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: 02/02/2023]
Abstract
The degradation kinetics of gonadorelin were investigated systematically with reversed-phase high-performance liquid chromatography. The stability-indicating properties of this system were checked with photodiode array detection and by comparison with capillary zone electrophoretic analysis. Influences of gonadorelin concentration, pH, temperature, buffer ions, and ionic strength on the degradation kinetics were studied. The pH-log Kobs profile can be divided into three parts, a proton, a solvent, and a hydroxyl-catalyzed section, with different degradation products. These degradation products were characterized by mass using LC-MS. Gonadorelin is most stable at pH 5-5.5 with a half-life of 70 days at 70 degrees C. The overall degradation rate constant as a function of the temperature under acidic and alkaline conditions obeys the Arrhenius equation. The gonadorelin concentration and the concentrations of acetate, phosphate, borate, and carbonate buffer have no influence on the decomposition rate of the analyte. Increasing ionic strength led to higher Kobs at pH 2 and lower Kobs at pH 9, but influences were relatively small.
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Affiliation(s)
- M A Hoitink
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, Utrecht University, The Netherlands
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Powers ME, Adjei A, Lu MYG, Manning MC. Solution behavior of leuprolide acetate, an LHRH agonist, as determined by circular dichroism spectroscopy. Int J Pharm 1994. [DOI: 10.1016/0378-5173(94)90415-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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