Metal-Acid Complexes with Members of the Tetracycline Family III: Summary of Blood Level Studies

Chemical-structural properties of tetracycline derivatives. 2. Coordination and conformational aspects of oxytetracycline metal ion complexation

“…zwitterionic oxytetracycline with those reported for the crystalline zwitterionic free base molecules in the preceding paper,27 the ligand in general, and the BCD chromophore in particular, is virtually unaltered by the formation of the observed complex. This is consistent with our observations concerning the uv absorption spectra below pH 7 and provides evidence that complex formation utilizing only the tricarbonylmethane moiety of the A ring will not account for the increased acidity of the BCD chromophore displayed by the other complexes investigated.…”

“…Three reference reflections, which were monitored after each 63 data were collected, remained constant to within 2% of their initial intensities. Of the 3998 unique data measured, sin /\ < 0.70 A-1, 3227 were classified as subjectively observed, I > 2 (7). Lorentz, polarization, and absorption corrections, for which the range of the calculated absorption coefficients was 1.17-2.03, were applied to the data.…”

“…As with the mercuric chloride complex, all crystallographic data were measured with a crystal, in this case enclosed in a thin-walled capillary tube, cooled to approximately -150 °C. The crystals display space-group symmetry C222¡ for which refined lattice parameters, a = 13.472 (2), b = 23.724 (6), and c = 19.643 (4) A, were obtained from automatically centered 26 values for 44 reflections within the angular range 22.0°< 26 < 35.4°; there is one formula unit, K2C22H22N2O9.2H2O.2CH3OH, per asymmetric unit.…”

“…Diffraction intensities, for a 0.20 X 0.10 X 0.25 mm parallelepiped crystal, were measured as described above with the exception that the scan range was reduced to 0.80°and the three reference reflections were monitored after each 129 data were measured; they remained constant to within 3% of their initial intensities and there was no indication of crystal decomposition; of the 3084 unique data measured, sin 6/ < 0.60, 2028 were classified as observed [7 > 3 (7)]. Lorentz and polarization corrections were applied to the data; absorption corrections were not considered necessary (µ = 3.6 cm-1).…”

Aluminum in the Environment and Human Health

“…Oral administration of Al silicate has been shown to decrease the absorption rate of chloramphenicol (669). Al gluconate and Al orthophosphate complexes of the tetracyclines have also been shown to decrease the absorption rate of these compounds following oral administration (670). However, intramuscular (IM) or intravenous (IV) administration resulted in a prolonged elevation of blood levels.…”