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Kostrzębska A, Junka A, Brożyna M, Musiał W. The Assessment of Physicochemical and Antimicrobial Properties of Hydrophilic Gels Containing Tetracycline Hydrochloride and Various Concentrations of Ethanol. Pharmaceutics 2024; 16:830. [PMID: 38931950 PMCID: PMC11207367 DOI: 10.3390/pharmaceutics16060830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 06/10/2024] [Accepted: 06/15/2024] [Indexed: 06/28/2024] Open
Abstract
The high prevalence of acne, which affects nearly 85% of adolescents and young adults, underscores the importance of exploring new therapeutic solutions. The aim of the present study was to design a stable hydrogel formulation containing tetracycline hydrochloride (TC) in the presence of ethanol at various concentration levels. The antibiotic stability was assessed over a period of 84 days using the HPLC method. The rheological properties of the formulations and their microbiological activity were also evaluated. Hydrogels without ethanol and those containing 5% and 25% alcohol showed similar rheological properties and high stability of the antibiotic throughout the observation period. The formulation with the highest ethanol content of 50% differed significantly from the others in terms of rheological properties. Although the flow and viscosity curves were like those of the other formulations, the viscosity values were significantly lower. The stability of tetracycline in this formulation was also significantly lower, and by the 84th day of observation, the concentration of the drug had decreased to almost 45% of its initial content. The formulations containing the highest concentration of ethanol displayed the highest activity against the biofilm of the acne-causing agent, Cutibacterium acnes. The study demonstrated the possibility of developing stable and antimicrobial effective hydrogel formulations with tetracycline and ethanol as a substance enhancing drug penetration into the hair follicles.
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Affiliation(s)
- Agnieszka Kostrzębska
- Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland;
| | - Adam Junka
- Platform for Unique Models Application P.U.M.A., Department of Pharmaceutical Microbiology and Parasitology, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland
| | - Malwina Brożyna
- Platform for Unique Models Application P.U.M.A., Department of Pharmaceutical Microbiology and Parasitology, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland
| | - Witold Musiał
- Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland;
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Effect of Hydrogel Substrate Components on the Stability of Tetracycline Hydrochloride and Swelling Activity against Model Skin Sebum. Int J Mol Sci 2023; 24:ijms24032678. [PMID: 36768998 PMCID: PMC9916833 DOI: 10.3390/ijms24032678] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023] Open
Abstract
Due to its high instability and rapid degradation under adverse conditions, tetracycline hydrochloride (TC) can cause difficulties in the development of an effective but stable formulation for the topical treatment of acne. The aim of the following work was to propose a hydrogel formulation that would ensure the stability of the antibiotic contained in it. Additionally, an important property of the prepared formulations was the activity of the alcoholamines contained in them against the components of the model sebum. This feature may help effectively cleanse the hair follicles in the accumulated sebum layer. A series of formulations with varying proportions of anionic polymer and alcoholamine and containing different polymers have been developed. The stability of tetracycline hydrochloride contained in the hydrogels was evaluated for 28 days by HPLC analysis. Formulations containing a large excess of TRIS alcoholamine led to the rapid degradation of TC from an initial concentration of about 10 µg/mL to about 1 µg/mL after 28 days. At the same time, these formulations showed the highest activity against artificial sebum components. Thanks to appropriately selected proportions of the components, it was possible to develop a formulation that assured the stability of tetracycline for ca. one month, while maintaining formulation activity against the components of model sebum.
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Evaluation of the Influence of a Hydrogel Containing AMPD on the Stability of Tetracycline Hydrochloride. Pharmaceutics 2021; 13:pharmaceutics13091381. [PMID: 34575457 PMCID: PMC8468035 DOI: 10.3390/pharmaceutics13091381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/18/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022] Open
Abstract
Tetracyclines, as beneficial antimicrobial factors in both local and systemic therapy, are characterized by high instability. The aim of the study was the development of the influence of hydrogel formulation on the tetracycline hydrochloride (TC) level under varying storage conditions. The HPLC, XPRD as well as SEM and macroscopic observations were involved in the study. The TC concentration decreased within ca. two months from 9.37 µg/mL to 4.41 µg/mL in the case of the photoprotected TC solution stored at 23 °C, whereas the decrease in storage temperature did not improve the final level of TC. In the presence of AMPD, the TC level in aqueous solution decreased drastically to ca. 1 µg/mL. Application of a polyacrylic acid derivative enabled conservation of the TC level through the ca. two months. Thus, the use of alcoholamine in the preparation of the TC hydrogel may result in the development of a therapeutic product with a dual action against acne, including antimicrobial activity and saponification of free fatty acids deposited in the follicles.
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Rapid Raman Spectroscopic Analysis of Stress Induced Degradation of the Pharmaceutical Drug Tetracycline. Molecules 2020; 25:molecules25081866. [PMID: 32316681 PMCID: PMC7221697 DOI: 10.3390/molecules25081866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/14/2022] Open
Abstract
Stress factors caused by inadequate storage can induce the unwanted degradation of active compounds in pharmaceutical formulations. Resonance Raman spectroscopy is presented as an analytical tool for rapid monitoring of small concentration changes of tetracycline and the metabolite 4˗epianhydrotetracycline. These degradation processes were experimentally induced by changes in temperature, humidity, and irradiation with visible light over a time period of up to 23 days. The excitation wavelength λexc = 413 nm was proven to provide short acquisition times for the simultaneous Raman spectroscopic detection of the degradation of tetracycline and production of its impurity in small sample volumes. Small concentration changes could be detected (down to 1.4% for tetracycline and 0.3% for 4-epianhydrotetracycline), which shows the potential of resonance Raman spectroscopy for analyzing the decomposition of pharmaceutical products.
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Li Y, Liu Y, Gao H, Helmy R, Wuelfing WP, Welch CJ, Cooks RG. Accelerated Forced Degradation of Pharmaceuticals in Levitated Microdroplet Reactors. Chemistry 2018; 24:7349-7353. [PMID: 29653016 DOI: 10.1002/chem.201801176] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Indexed: 11/12/2022]
Affiliation(s)
- Yangjie Li
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette IN 47907 USA
| | - Yong Liu
- Department of Analytical Sciences, MRLMerck & Co., Inc. West Point PA 19446 USA
| | - Hong Gao
- Department of Analytical Research & Development, MRLMerck & Co., Inc. Rahway NJ 07065 USA
| | - Roy Helmy
- Department of Analytical Sciences, MRLMerck & Co., Inc. West Point PA 19446 USA
| | - W. Peter Wuelfing
- Department of Analytical Sciences, MRLMerck & Co., Inc. West Point PA 19446 USA
| | - Christopher J. Welch
- Department of Analytical Research & Development, MRLMerck & Co., Inc. Rahway NJ 07065 USA
| | - R. Graham Cooks
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette IN 47907 USA
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Adams ML, Sharma V, Gokhale M, Huang Y, Stefanski K, Su C, Hussain MA. Dehydration and Stabilization of a Reactive Tertiary Hydroxyl Group in Solid Oral Dosage Forms of BMS-779788. J Pharm Sci 2016; 105:1478-88. [DOI: 10.1016/j.xphs.2015.12.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/30/2015] [Accepted: 12/18/2015] [Indexed: 11/25/2022]
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Mojica ERE, Nguyen E, Rozov M, Bright FV. pH-Dependent Spectroscopy of Tetracycline and Its Analogs. J Fluoresc 2014; 24:1183-98. [DOI: 10.1007/s10895-014-1399-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 04/23/2014] [Indexed: 10/25/2022]
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Schmitt MO, Schneider S. Novel Insight into the Protonation–Deprotonation Equilibria of Tetracycline, Sancycline and 10-Propoxy-Sancycline in Aqueous Solution. I. Analysis of the pH-Dependent UV/vis Absorption Spectra by the SVD Technique. Z PHYS CHEM 2009. [DOI: 10.1524/zpch.2006.220.4.441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Summary
The UV/vis absorption spectra recorded during titration experiments (pH2 ↔ pH11, ΔpH ∼ 0.33) were subjected to a principal component analysis. The aim was to determine by means of the program SPECFIT the number of significant components and to reduce the noise in the spectra. The attempt to achieve a global fit of the “noise-reduced” data was in general successful if 5 or more independent species were considered. The necessity to include a larger number of species than the 4 occuring within the simple protonation-deprotonation scheme of a triprotic acid provides strong evidence for conformational heterogeneity at various levels of protonation. Only if this heterogeneity is taken into account, the analysis yields the correct pK
a-values. For tetracycline, slow conformational changes are suggested to occur in the neutral state. Consequently, tetracycline adopts conformation 2 in alkaline solution if the pH is raised slowly up to pH11, whereas if it is dissolved directly in buffer solution at pH2 or pH11 it adopts conformation 1 (like in the crystal). In this conformation, tetracycline degrades rapidly in a methanol–water mixture around pH11 probably by methylation of the 11,12-β-carbonyl group. Sancycline and 10-propoxy-sancycline are stable at any pH, the conformational changes are proposed to occur preferentially in the anionic state. Because of these conformational changes, the pK
a-values derived from forward and backward titration can differ up to 0.4 pH units. In addition, there is evidence that C10-OH does not dissociate at pH less than 11.
In contrast to a widely accepted hypothesis, 4-epi-tetracycline also changes its conformation in the anionic form. This shows that CD spectra are not suited to draw conclusions on molecular geometry if the total net charge changes.
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Electroanalytical procedure to resolve a sample solution containing tetracycline and its toxic degraded product: Anhydrotetracycline. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hon JYC, Murray LR. Determination of Tetracycline and Related Compounds by High-Performance Liquid Chromatography. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/01483918208062867] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Fernández R, Dassie S. Transfer of tetracyclines across the H2O|1,2-dichloroethane interface: Analysis of degraded products in strong acid and alkaline solutions. J Electroanal Chem (Lausanne) 2005. [DOI: 10.1016/j.jelechem.2005.08.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Søeborg T, Ingerslev F, Halling-Sørensen B. Chemical stability of chlortetracycline and chlortetracycline degradation products and epimers in soil interstitial water. CHEMOSPHERE 2004; 57:1515-1524. [PMID: 15519396 DOI: 10.1016/j.chemosphere.2004.09.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2003] [Revised: 09/08/2004] [Accepted: 09/10/2004] [Indexed: 05/24/2023]
Abstract
Tetracyclines and tetracycline degradation products and epimers end up in the environment. In order to predict the persistence of the potential dominating species of the chlortetracyclines in the environment, the chemical stability of chlortetracycline (CTC) and four major CTC degradation products and epimers (iso-CTC, 4-epi-CTC, anhydro-CTC, and 4-epi-anhydro-CTC) was studied in milliQ water and soil interstitial water (SIW) under environmentally relevant conditions (oxygen, light, pH (3-9), and temperature (6 degrees C and 20 degrees C)). The chemical stability of the compounds was evaluated by following the decrease in amount of parent compound over time. In order to compare the results obtained under the varying conditions, apparent pseudo-first-order rate constants (k(obs)) for the disappearance of the parent compound and corresponding apparent half-lives were calculated. A statistical evaluation of the data showed that the chemical stability of the chlortetracyclines was generally dependent on photolysis, temperature, and matrix. The presence or absence of oxygen did not influence on the chemical stability. The presence of calcium and magnesium ions in SIW is believed to account for the significant differences in half-lives between milliQ water and SIW, although numerous of other factors are believed to influence as well. Generally, the five compounds were more persistent at pH 3-4 than at pH above 5.
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Affiliation(s)
- Tue Søeborg
- Section of Environmental Chemistry, Department of Analytical Chemistry, Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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Schwach-Abdellaoui K, Monti A, Barr J, Heller J, Gurny R. Optimization of a novel bioerodible device based on auto-catalyzed poly(ortho esters) for controlled delivery of tetracycline to periodontal pocket. Biomaterials 2001; 22:1659-66. [PMID: 11374468 DOI: 10.1016/s0142-9612(00)00327-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Local delivery of antimicrobial agents in inflamed periodontal pocket has been shown to be effective in reducing periodontopathic microorganisms. This research focuses on developing and characterizing bioerodible formulations based on auto-catalyzed poly(ortho esters) (POExLAy) for modulated release of tetracycline over 2 weeks. POExLAy are a new versatile family of POE-containing lactoyl lactyl dimers in the polymer backbone. By modifying the proportion of lactic acid in the polymer, viscous or solid materials having different degradation rate can be produced. The formulations can be either injected or placed as a solid device directly into the periodontal pocket. Tetracycline-free base incorporated into these materials was released within 10-14 days depending on polymer structure. Increase in lactic acid content in the polymer tended to increase the drug release rate and to reduce the initial lag time. Tetracycline release from such bioerodible delivery system occurs predominantly by surface erosion of the polymeric matrix, leading to kinetics which can be zero order. This periodontal drug delivery system is designed to be used as an adjunct in the treatment of periodontal diseases. Clinical studies are currently in progress.
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Tavares MF, McGuffin VL. Separation and characterization of tetracycline antibiotics by capillary electrophoresis. J Chromatogr A 1994. [DOI: 10.1016/s0021-9673(94)89014-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Neuzil J, Novotná J, Vancurová I, Bĕhal V, Hostálek Z. A direct-injection reversed-phase liquid chromatographic micromethod for studying the kinetics of terminal reactions of tetracycline biosynthesis. Anal Biochem 1989; 181:125-9. [PMID: 2817372 DOI: 10.1016/0003-2697(89)90404-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A new micromethod for measuring enzyme-catalyzed reactions was developed. The method involves a number of consecutive direct injections of aliquots of the reaction mixture onto a microbore column and permits the determination of the time dependence of the decrease of substrate or increase of product concentrations. The reactions proceed in a microvial placed in the autosampler, and as the starting volume can be as low as 10 microliters, the requirement for the amount of enzyme is very low. The autosampler backed by the liquid chromatographic software allows automation of the analyses including data processing and easy quantitation of the enzymatic reaction(s). The method was applied to a system of two consecutive terminal reactions of tetracycline biosynthesis in Streptomyces aureofaciens, catalyzed by anhydrotetracycline oxygenase and tetracycline dehydrogenase. The usage of a diode-array detector facilitated the quantification of the reactions as the product and substrate could be monitored at their optimal wavelengths.
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Affiliation(s)
- J Neuzil
- Institute of Microbiology, Czechoslovak Academy of Sciences, Prague, Czechoslovakia
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Neužil J, Novotná J, Vančurová I, Běhal V, Hošťálek Z. High-Performance Liquid Chromatography of Derivatives Involved in the Terminal Steps of Tetracycline Biosynthesis inStreptomyces Aureofaciens. ACTA ACUST UNITED AC 1988. [DOI: 10.1080/01483918808076761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Vancurová I, Volc J, Flieger M, Neuzil J, Novotná J, Vlach J, Bĕhal V. Isolation of pure anhydrotetracycline oxygenase from Streptomyces aureofaciens. Biochem J 1988; 253:263-7. [PMID: 3138982 PMCID: PMC1149284 DOI: 10.1042/bj2530263] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Anhydrotetracycline oxygenase was purified to homogeneity from Streptomyces aureofaciens, a producer of tetracycline. The enzyme was purified 60-fold in a 40% yield by a two-step procedure using a combination of hydrophobic chromatography and ion-exchange h.p.l.c. Purified anhydrotetracycline oxygenase was homogeneous according to SDS/polyacrylamide-gel electrophoresis, isoelectric focusing, ion-exchange h.p.l.c. on a Mono Q HR 5/5 column and size-exclusion h.p.l.c. on a TSK G 3000 SW column. The enzyme consists of two subunits of Mr 57,500, as determined by SDS/polyacrylamide-gel electrophoresis.
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Affiliation(s)
- I Vancurová
- Institute of Microbiology, Czechoslovak Academy of Sciences, Prague
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Sabharwal S, Kishore K, Moorthy PN. Determination of tetracycline hydrochloride in presence of anhydrotetracycline by differential pulse polarography. J Pharm Sci 1988; 77:78-80. [PMID: 3346827 DOI: 10.1002/jps.2600770115] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A differential pulse polarographic method is described for the determination of the antibiotic tetracycline HCl in the presence of its degradation product anhydrotetracycline. The method utilizes the large difference in their differential pulse polarograms at a peak potential of -1.39 V in 0.1 M phosphate buffer as the base electrolyte (pH 6.8). The assay was evaluated using synthetic mixtures and applied to the analysis of commercial tetracycline HCl samples. The results obtained with this method are in close agreement with those from the spectrophotometric absorbance ratio method.
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Affiliation(s)
- S Sabharwal
- Bhabha Atomic Research Centre, Nuclear Research Laboratory, Kashmir, India
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Grobben-Verpoorten A, Dihuidi K, Roets E, Hoogmartens J, Vanderhaeghe H. Determination of the stability of tetracycline suspensions by high performance liquid chromatography. PHARMACEUTISCH WEEKBLAD. SCIENTIFIC EDITION 1985; 7:104-8. [PMID: 4022761 DOI: 10.1007/bf01968711] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
High performance liquid chromatography was used to examine the stability of tetracycline suspensions, prepared according to the Formulary of the Dutch Pharmacists and the National Formulary v (Belgium). The influence of the nature of the buffer salt, of the pH, and of the temperature and time of storage are discussed. At slightly acid pH (4 to 5.5) and at room temperature suspensions are stable for at least three months.
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Tetracycline Hydrochloride. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0099-5428(08)60204-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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Jochsberger T, Cutie AJ, Wang HY, Mary NY. Differential pulse polarography of some degradation products of tetracycline. J Pharm Sci 1982; 71:1284-5. [PMID: 7175724 DOI: 10.1002/jps.2600711124] [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: 01/23/2023]
Abstract
In an attempt to develop a more rapid, convenient, and precise method for the direct detection and analysis of the degradation products of tetracycline, a study of those products utilizing differential pulse polarography was initiated. The investigation was concentrated on the subject of the kinetics of the epimerization of anhydrotetracycline to 4-epianhydrotetracycline in acetate buffer. The reaction was followed at 25 and 50 degrees. Duplicate experiments were run at each temperature. The apparent rate constants obtained were 4.17 +/- 0.13 X 10(-1)/hr (25 degrees) and 6.97 +/- 1.00 X 10(-2)/hr (50 degrees).
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Dihuidi K, Roets E, Hoogmartens J, Vanderhaeghe H. Influence of temperature on the stability of solid tetracycline hydrochloride, measured by high-performance liquid chromatography. J Chromatogr A 1982. [DOI: 10.1016/s0021-9673(00)95877-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Anhydrotetracycline oxygenase activity and biosynthesis of tetracyclines in streptomyces aureofaciens. Biotechnol Lett 1979. [DOI: 10.1007/bf01388144] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Brown JR, Ireland DS. Structural requirements for tetracycline activity. ADVANCES IN PHARMACOLOGY AND CHEMOTHERAPY 1978; 15:161-202. [PMID: 358803 DOI: 10.1016/s1054-3589(08)60483-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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27
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Yuen PH, Sokoloski TD. Kinetics of concomitant degradation of tetracycline to epitetracycline, anhydrotetracycline, and epianhydrotetracycline in acid phosphate solution. J Pharm Sci 1977; 66:1648-50. [PMID: 21284 DOI: 10.1002/jps.2600661143] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The concentrations of tetracycline, epitetracycline, anhydrotetracycline, and epianhydrotetracycline in pH 1.5 phosphate solution were followed as a function of time at four temperatures. Separation and quantification of all four species were accomplished using high-pressure liquid chromatography. Through nonlinear regression analysis, rate constants for the reversible first-order epimerization of tetracycline and anhydrotetracycline and for the first-order dehydration of tetracycline and epitetracycline were obtained. Solutions to the differential equations obtained through Laplace transforms successfully predict concentrations found experimentally. The energy of activation for each reaction step was calculated and ranged from 15 to 27 kcal/mole. The rate constants for tetracycline and epitetracycline dehydration conform with those of earlier studies that used different experimental methods. The study shows that epimerization of tetracycline and anhydrotetracycline can take place at a low pH.
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Sokoloski TD, Mitscher LA, Yuen PH, Juvarkar JV, Hoener B. Rate and proposed mechanism of anhydrotetracycline epimerization in acid solution. J Pharm Sci 1977; 66:1159-65. [PMID: 19615 DOI: 10.1002/jps.2600660829] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pathway through which the toxic tetracycline degradation product epianhydrotetracycline forms in solution was studied using high-performance liquid chromatography and circular dichroism, taking advantage of the large difference in ellipticity between the reactant and the product at 285 nm. The epimerization of anhydrotetracycline followed a reversible first-order process, and both analytical methods yielded the same rate constants. The rate constants indicate that anhydrotetracycline epimerization is faster than tetracycline epimerization. The equilibrium favored anhydrotetracycline, and the activation energies for the forward and reverse rates were almost the same as those for tetracycline epimerization. The epimerization was catalyzed by phosphate. Activation energies in 0.1 and 1 M phosphate were essentially the same. The equilibrium constants for both anhydrotetracycline and tetracycline favored the natural configuration rather than the epi series. Possible rationalization based on conformational and hydrogen bonding effects is presented.
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