Doxycycline methods

Nells and DeLeenheer (67) described a method for determining doxycycline in human tissues. 

The incidence of tetracycline residues in turkeys has been also studied recently (13). During meat inspection, suspicious flocks were identified by fluorescence detection in bones. A total of 85 flocks showed significant fluorescence in bones. When bones, liver, kidney, and muscle of these animals were analyzed for tetracyclines, residues of tetracycline, chlortetracycline, oxytetracycline, or doxycycline were found in 83 flocks. These results suggest that the detection of fluorescence in bones might be a useful screening method for tetracycline residues in poultry carcasses. 

Some antibacterials that do not induce liver enzymes (e.g. ampi-cillin and doxycycline) have the potential to reduce the concentration of EE as a result of their effect on gut flora, which impairs enterohepatic circulation. Therefore, additional contraceptive methods should be advised for short courses (less than three weeks) as the efficacy of CHCs may be reduced [3,11]. The efficacy of progestogen-only methods is not... 

Cherlet et al. [44] reported the determination of TC, chlor-TC, oxy-TC, and doxycycline and their 4-epimers, in edible pig tissue. The compounds are extracted with a sodium succinate solution. After protein precipitation with trifluoroacetic acid (TEA) and paper filtration, the extract was purified on an Oasis HLB SPE cartridge, prior to LC-ESI-MS analysis. The limit of quantification (LOQ) was 50 pg/kg, which is 50% of the MRL in the EU. A similar method was applied by Andersen et al. [45] for the analysis in shrimp and whole milk. 

Several studies have employed chemometric designs in CZE method development. In most cases, central composite designs were selected with background electrolyte pH and concentration as well as buffer additives such as methanol as experimental factors and separation selectivity or peak resolution of one or more critical analyte pairs as responses. For example, method development and optimization employing a three-factor central composite design was performed for the analysis of related compounds of the tetracychne antibiotics doxycycline (17) and metacychne (18). The separation selectivity between three critical pairs of analytes were selected as responses in the case of doxycycline while four critical pairs served as responses in the case of metacychne. In both studies, the data were htted to a partial least square (PLS) model. The factors buffer pH and methanol concentration proved to affect the separation selectivity of the respective critical pairs differently so that the overall optimized methods represented a compromise for each individual response. Both methods were subsequently validated and applied to commercial samples. 

Among the multi-class methods reported in the literature, a procedure that involves sample dissolution with EDTA under mildly acidic conditions (pH 4.0) followed by SPE with Oasis HLB cartridges has been applied for the simultaneous analysis of macroiides, tetracyclines, quinolones, and sulfonamides in honey samples Separation and determination by UPLC-MS/MS enabled the analysis of 17 compounds in <5 min. Mean recoveries ranged from 70% to 120%, except for three compounds (doxycycline, erythromycin, and tilmicosin), which had recoveries of >50%. Application of the method to the analysis of honey samples obtained from different beekeepers and local supermarkets... 

Cinquina A, Longo F, Anastasi G, et al., Validation of a high performance liquid chromatography method for the determination of oxytetracycline, tetracycline, chlortetracycline and doxycycline in bovine milk and muscle, J. Chromatogr. A 2003 987 227-233. 

Pharmacokinetic data show that the progestogen component (levonorg-estrel, norethisterone) of combined oral contraceptives is not affected by ampicillin, clarithromycin, doxycycline, metronidazole, moxi-floxacin, or tetracycline. There is no reason to expect that the contraceptive efficacy of the various progestogen-only methods (tablets, implants, injections, lUDs) would be affected by antibacterials that alter gut flora and do not induce liver enzymes. 

Ambroxol and doxycycline First derivative of ratio sp>ectra method was applied for simultaneous determination of both analytes in pharmaceutical formulations and in laboratory-made mixtures. 28... 

Ramipril concentration was determined by the optical sensor Sm +-Doxycycline (Sm -DC) complex doped in the sol-gel matrix. The method depends on the quenching of the luminescence intensity of the optical sensor in the presence of different concentrations of Ramipril, especially at 645 nm band [55]. 

M.S. Attia, A.M. Othman, M. M. Aboaly and M. S. A. Abdel-Mottaleb, Novel spectrofluorimetric method for measuring the activity of the enzyme r-L-fucosidase using the nano composite optical sensor samarium(III)-doxycycline complex doped in sol-gel matrix. Anal. Chem., ACS, 82,6230-6236,2010. 

Tetracyclines including doxycycline (DC) and oxytetracycline (OTC) and degradation products, like 4-epitetracycline (ETC), chlortetracycline (CTC), 4-epianhydro-tetracycline (EATC), anhydro-tetracycline (ATC), can also be separated on silica gel HPTLC plates (Merck), that have been predeveloped with a saturated aqueous Na2EDTA solution, dried at room temperature for Ih and activated at 130°C for 2h (47). In this method, 100 nl of the reference solutions (10 mg/ml methanol) were applied. The following solvents are used ... 

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