Tetracycline formula

Common Name N-[[4-(2-Hydroxyethyl)-1-piperazinyl] methyl] tetracycline pipacycline Structural Formula ... 

Absorption of antimicrobial agents such as fluoroquinolones and tetracyclines that can be bound by divalent and trivalent cations potentially could be compromised by administration with EN formulas containing these cations. The fluoroquinolones (e.g., levofloxacin and ciprofloxacin) have been best studied in this regard, and results of studies are not consistent. Mechanisms for an interaction between fluoroquinolones and EN formulas other than chelation by cations have been postulated.40 Some institutions hold tube feedings for 30 to 60 minutes or more before and after enteral dosages of fluoroquinolones. Because ciprofloxacin absorption has been shown to be decreased with jejunal administration, this drug probably should not be given by jejunal tube.41... 

Name, Formula, Molecular Weight Tetracycline hydrochloride C22H25C1N2°8 480.90... 

The microorganism used for tetracycline are Staphylococcus aureus NCTC 6751 and Staphylococcus aureus ATCC 6538 P. The buffer solution with a pH of 4.5 and the incubation temperature between 35 - 37 °C are used (90, 91). Additives in TC formulations can influence the results obtained by microbiological methods (92). Comparison of the microbiological results has been made with those obtained through other methods (93, 94). Effects of certain tablet-formula-tion-additives such as starch, bentonite, veegum F, talc, liquid paraffin, stearic acid etc. on the antimicrobial activity of TC-HC1 has been investigated (95). 

The stereochemistry uf the tetracyclines is very complex. Carbon atoms 4. 4a.. S.. Na. 6. and 12a arc potentially chiral, depending on substitution. Oxytctracyclinc and doxycyclinc. each with a Sa-hydroxyl substituent, have six asymmetric centers the others, lacking chirality at C-. >. have only five. Determination of the complete, absolute stcreochemi.stry of the tetracyclines w.as a difficult problem. Detailed x-ray diffraction analysis c.siablished the stereochemical formula shown in Table 10-6 as the orientations found in the natural and semisynthetic tetracyclines. Tlic.se studies also confirmed that conjugated systems exist in the structure from C-10 through C-12 and from C-1 through C-.T and that the formula represents only one uf. several canonical forms exi.st-ing in those portions of the molecule. 

The X-ray diffraction studies reveal that the following stereochemical formula represents the orientations, as observed in the natural tetracyclines ... 

Structural Formula See tetracycline for formula of base Chemical Abstracts Registry No. —... 

Some of the bound keto groups may be reduced by pyridine nucleotide-dependent dehydrogenases (C 2.1, see the formation of 6-methylsalicylic acid, D 3.3.1), and some of the activated CHg-groups may be alkylated by S-adenosyl-L-meth-ionine (C 3.3, see the biosynthesis of tetracyclines, D 3.3.7), or may be substituted by dimethylaUyl pyrophosphate (D 6), see the formulas of lupulone and humulone, the bitter principles of hop cones used in brewing beer (F 1). 

Figure 2 illustrates the basic content of a Registry substance record. The substance is tetracycline. Included are the CAS Registry Number, the CA Index Name, some synonymous chemical names, the molecular formula, and a stereospecihc structural diagram. An integral part of the CAS Chemical Registry System is the Registry Nomenclature File which contains the CA Index Name, and other systematic, semisystematic, and common names encountered in the chemical literature. 

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