High-Performance Liquid Chromatographic Assay of Chloramphenicol in Serum

Zasshi 82: [342][343][344][345] 1962). Levels of serum bilirubin alone (4 to 6 mg/dl) resujted in apparent concentrations of chloramphenicol which appear to be in the therapeutic range. Concentrations of serum bilirubin greater than 8 mg/dl resulted in levels of apparent chloramphenicol associated with toxicity (>50 ,tg/ml). Small amounts of activated charcoal added to the isoamyl acetate extraction step of the assay eliminated this interference by bilirubin.Numerous authors have emphasized the necessity of monitoring serum concentrations of chloramphenicol in newborn and premature infants to achieve effective therapeutic concentrations and avoid concentrations associated with toxicity (1-3). The original chemical assay measures inactive metabolites as well as free chloramphenicol (4). In the modification of the chemical method by Kakemi et al., only the free chloramphenicol extracted into isoamyl acetate is measured, and the assay is unaffected by the presence of other antibiotics (7,11 Mock sample preparation. A concentrated bilirubin solution was prepared and added in different volumes to serum. The final total bilirubin concentration was measured by the method of Jacobson and Wennberg (6). Different amounts of chloramphenicol were then added to serum or distilled water to make samples of known concentration.Statistical methods. Statistical analysis was performed by using least mean squares linear regression or Student's t test. The percent error of the assay was calculated as described by Sabath et al. (14). RESULTSEffect of amount of charcoal on concentration of chloramphenicol. After extraction of chloramphenicol from 12 duplicate samples of normal human serum made to contain 35 ,ug of chloramphenicol per ml, different amounts of charcoal were added and the concentration of chloramphenicol was measured. There was no significant effect on the concentration of chloramphenicol when 5.7 to 37.5 mg of charcoal was added (P > 0.10).Reproducibility. A single sample of distilled water which contained 15 tg of chloramphenicol per ml and a single sample of ventricular cerebrospinal fluid from a child who was receiving chloramphenicol were assayed with and without charcoal treatment on 22 and 18 different occasions, respectively. The mean value recovered from the untreated distilled water samples was 16 Ag/ml (±1 ,ug/ml) and 15 ug/ml (+1 ,g/ml)

Section: Discussionmentioning

confidence: 99%

Modification of the Colorimetric Assay for Chloramphenicol in the Presence of Bilirubin

Mason

Kaplan

Baker

et al. 1979

“…After preliminary extraction of 0.1 ml of the sample with acetate containing an internal standard, chromatography was performed with a reversed-phase C18 microparticulate column with an acetonitrile-acetate buffer mobile phase, and detection was measured by ultraviolet absorbance at 270 nm (6).…”

Section: Antimicrob Agents Chemothermentioning

confidence: 99%

Comparison of cefamandole, cephalothin, ampicillin, and chloramphenicol in experimental Escherichia coli meningitis

Beam¹,

Allen²

1980

The activities of cefamandole, cephalothin, ampicillin, and chloramphenicol were compared in fulminant and temperate Escherichia coli meningitis in rabbits. Intensive dosing schedules were employed to achieve maximal therapeutic benefits with short-term treatment. In an 8-h schedule chloramphenicol was significantly more effective in sterilizing the cerebrospinal fluid and curing both fulminant and temperate infections than cefamandole or ampicillin. Cephalothin was without effect in fulminant meningitis. Cefamandole and ampicillin were equivalent in activity in this and longer (12-and 24-hr) fly needle, which cannulated a marginal ear vein, to a Harvard infusion/withdrawal pump (model 940; Harvard Apparatus, Millis, Mass.). Untreated controls had unlimited access to food and water; intakes were negligible after inoculation. Treated animals had access to water but no food. Except for the modifications summarized below, methods of procedure were those detailed previously (1).E. coli C13NK1, isolated from a neonate with meningitis, was provided for this study by George McCracken, Jr., University of Texas Health Science Center, Dallas. After overnight growth on Mueller-Hinton (MH) agar (Difco), a suspension of organisms in phosphate-buffered saline was prepared and adjusted with the help of nephelometry (Coleman 6A Spectrophotometer; Coleman Instruments, Maywood, Ill.) to a density of 7.0 x 107 to 8.0 x 107 colony-forming units (CFU)/ml. A cisternal puncture was performed with a 20-gauge needle and a 1.0-ml tuberculin syringe; 0.5 ml of CSF was withdrawn, and 0.5 ml of the bacterial suspension was injected. To produce fuhminant infections, 0.5-ml quantities of undiluted suspension were injected intracisternally; temperate infections were induced by injecting 0.5 ml of a 1:100 dilution. If visible blood contamination resulted, the animal was not included in the study. Gentle reaspiration and injection were performed to insure intracisternal inoculation. The needle was withdrawn, and the animal was returned to its cage for 14 h.Untreated controls were included every other week to insure constancy of virulence (11). Treated animals received an antibiotic in groups of four. Antibiotics were chosen in a nonrandom sequence before therapy. At the completion of therapy, rabbits with fulminant meningitis were sacrificed by an overdose of pentobarbital, at which time serum, CSF, and brain were obtained for assay. Pairs of treated rabbits with temperate meningitis were either sacrificed or anesthetized

“…In normal adults approximately 90% of an oral dose is excreted in urine within 24 h (8). Of this quantity, only 5 to 10% is excreted as unchanged drug (7).…”

mentioning

confidence: 99%

Chloramphenicol Pharmacokinetics in Hospitalized Patients

Koup

Lau

Brodsky

et al. 1979

Self Cite

The apparent body clearance of chloramphenicol was investigated in 21 hospitalized adult patients on 27 occasions. Apparent body clearance was found to be significantly lower (1.99 ± 1.49 ml/min per kg) in patients with total serum bilirubin concentrations of >1.5 mg/100 ml than in patients with serum bilirubin concentrations of c1.5 mg/100 ml (3.57 ± 1.72 ml/min per kg; P < 0.001). Serum protein binding of chloramphenicol was lower in cirrhotic patients (42.2 ± 6.8% bound) than in normal adults (53.1 ± 5.2% bound; P < 0.001). Low binding of chloramphenicol was also found in the serum of premature neonates (32.4 ± 8.2% bound; P < 0.001). Reduced binding in neonates implies the need for a lower therapeutic range of total chloramphenicol concentration (3.5 to 13.9 ,ug/ml) compared with the usual adult range (5 to 20 Ag/ml). Finally, three case reports are presented which demonstrate marked abnormalities and intrasubject variation in chloramphenicol clearance.As a result of the activity of chloramphenicol (CAP) against anaerobic organisms (5) and Haemophilus influenzae which are resistant to ampicillin (2), it has gained new popularity. Use of this agent is, however, coupled with serious potential toxicities. Idiosyncratic aplastic anemia is extremely rare (25) but must be weighed as a factor in the choice of this agent. Dose-related, and thus avoidable, toxicities include normocytic bone marrow suppression, which is associated with serum concentrations exceeding 25 yig/ml and prolonged courses of therapy (13,19,25), and a syndrome consisting of cardiovascular collapse, gastrointestinal distress, respiratory depression, and coma. This symptom complex, commonly referred to as the grey syndrome, has been reported in neonates (3,12,22,24), infants (4), and adults (11, 23) and is associated with serun CAP concentrations ranging from 40 to 200 ,ug/ml.CAP is extensively metabolized. In normal adults approximately 90% of an oral dose is excreted in urine within 24 h (8). Of this quantity, only 5 to 10% is excreted as unchanged drug (7). The principal metabolite is a glucuronide which is formed in the liver and is actively secreted by the kidney (6). It is reasonable to expect decreased clearance of the drug in patients with impaired liver function. McCurdy (13) and Suhrland and Weisberger (20) reported higher CAP serum concentrations in patients with cirrhosis of the liver compared with normal t Present address: