Chloramphenicol base

Absorption - Chloramphenicol base is absorbed rapidly from the intestinal tract and is 75% to 90% bioavailable. The inactive prodrug, chloramphenicol palmitate, is rapidly hydrolyzed to active chloramphenicol base. Bioavailability is approximately 80% for the palmitate ester. The bioavailability of the IV... 

The ability of liver to biotransform chloramphenicol has been also demonstrated in several fish species. In pertinent studies, various metabolic pathways were determined and chloramphenicol-glucuronide, chloramphenicol-base, chloramphenicol-alcohol, and chloramphenicol-oxamate were the main metabolites observed (34, 35). Following hepatic biotransformation, a large proportion of the administered dose was excreted in the urine. 

Results showed a total of 2.8% of the samples (n 2972) to be inhibitor positive by the Delvotest SP test further examination identified 1.7% as -lactam antibiotics, and 1.1 % as sulfonamides and dapsone. The percentage of chloramphenicol suspicious samples determined by the Charm II test was amazingly high however, tests for confirmation were not available and contamination of the samples by residues of the chloramphenicol-based preservative azidiol could not be excluded with certainty. Low concentrations of streptomycins were also detected in 5.7% of the samples (n 1221), but the MRL was not exceeded. Macrolide and tetracycline residues were not found in significant levels. Model trials with commercially applied yoghurt cultures confirmed how important the compliance to MRLs can be to dairy industry compared to antibiotic-free milk, a pH of 5.0 was reached with a delay of 15 min in the case of contamination with cloxacillin 30 min in the case of penicillin, spiramycin, and tylosin and 45 min in the case of oxytetracycline contamination. 

Optical detection of an antibiotic, chloramphenicol, based on competitive displacement of a chloramphenicol-methyl red conjugate bound to a chloramphenicol-imprinted polymer with free chloramphenicol has been demonstrated [40]. A flow injection system in conjunction with a 10 cm stainless steel column packed with the imprinted polymer and acetonitrile as a carrier solution containing chloramphenicol-methyl red conjugate was constructed. The dye conjugate released by displacement by free chloramphenicol was monitored at 460 nm. The signals were proportional to the concentration of free chloramphenicol injected, and the calibration range of this system included the therapeutic range of a chloramphenicol. This concept of flow displacement systems could be applicable not only for chloramphenicol determination but also for other template molecules. 

Other -NO2 containing metabolites such as the oxamic acid, chloramphenicol base and glucuronide could not be resolved by polarographic methods alone although it is probable that metabolite (X) could be determined by amperometric detection at a glassy carbon indicator electrode after HPLC separation. 

Names of compounds (a) bromamphenicol = D-/)u e (lf, 2/ )-l- )-nitrophenyl-2-b omoacctamido-l,3-propanediol (b) chloramphenicol base = D-[Pg.703]

Unlabeled bromamphenicol is prepared from bromoacetylbromide and chloramphenicol base m.p. = 132°. 

Glycylamphenicol Hydrochloride. To a solution of chloramphenicol base (545 mg, 2.2 mmoles) in 5 ml of chloroform and 0.3 ml of tri-ethylamine is added the iV-hydroxysuccinimide ester of A -fBoc-glycine (600 mg, 2.1 mmoles) in 5 ml of chloroform. After 2 hr at room temperature the solution is washed successively with 1 M sodium bicarbonate, water, 10% citric acid, and water, and dried over sodium sulfate. The solution is evaporated to a small volume and petroleum ether is added to precipitate the product. The tBoc group is removed by treatment with 1 N hydrochloric acid in acetic acid for 15 min at room temperature. The product is precipitated with diethyl ether. The yield is 510 mg. Thin-layer chromatography on silica gel with two solvent mixtures, n-butanol ... 

Camphor-10-sulfonic acid ( + )-form. Chloride, in C-00016 Chloramphenicol base, in A-00284... 

Ribosomal Protein Synthesis Inhibitors. Figure 5 Nucleotides at the binding sites of chloramphenicol, erythromycin and clindamycin at the peptidyl transferase center. The nucleotides that are within 4.4 A of the antibiotics chloramphenicol, erythromycin and clindamycin in 50S-antibiotic complexes are indicated with the letters C, E, and L, respectively, on the secondary structure of the peptidyl transferase loop region of 23S rRNA (the sequence shown is that of E. coll). The sites of drug resistance in one or more peptidyl transferase antibiotics due to base changes (solid circles) and lack of modification (solid square) are indicated. Nucleotides that display altered chemical reactivity in the presence of one or more peptidyl transferase antibiotics are boxed. 

Antibiotics may be classified by chemical structure. Erythromycin, chloramphenicol, ampicillin, cefpodoxime proxetil, and doxycycline hydrochloride are antibiotics whose primary structures differ from each other (Fig. 19). Figure 20 shows potential oscillation across the octanol membrane in the presence of erythromycin at various concentrations [23]. Due to the low solubility of antibiotics in water, 1% ethanol was added to phase wl in all cases. Antibiotics were noted to shift iiB,sDS lo more positive values. Other potentials were virtually unaffected by the antibiotics. On oscillatory and induction periods, there were antibiotic effects but reproducibility was poor. Detailed study was then made of iiB,sDS- Figure 21 (a)-(d) shows potential oscillation in the presence of chloramphenicol, ampicillin, cefpodoxime proxetil, and doxycycline hydrochloride [21,23]. Fb.sds differed according to the antibiotic in phase wl and shifted to more positive values with concentration. No clear relationship between activity and oscillation mode due to complexity of the antibacterium mechanism could be discovered but at least it was shown possible to recognize or determine antibiotics based on potential oscillation measurement. 

An important feature of the antibiotic chloramphenicol (9) is the presence of the dichloroacetamide function. Inclusion of this amide in a simpler molecule, teclozan (15), leads to a compound with antiamebic activity. Whether this is cause and effect or fortuitous is unclear. The synthesis begins with alkylation of the alkoxide derived from ethanolamine (10) with ethyl iodide to give the aminoether (11). Reaction of a,a -dibromo-p-xylene (12) with 2-nitropropane in the presence of base leads to dialdehyde (13). The reaction probably proceeds by O-alkylation on the nitropropyl anion... 

As in the case of chloramphenicol palmitate, it may be desirable to have the more soluble (less stable) polymorph of a drug. One method, based on thermo-... 

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