Pharmacokinetics of cefodizime in volunteers with normal or impaired renal function

Human variability in the renal elimination of foreign compounds and renal excretion-related uncertainty factors for risk assessment

Renal excretion is an important route of elimination for xenobiotics and three processes determine the renal clearance of a compound [glomerular filtration (about 120 ml/min), active renal tubular secretion (>120 ml/min) and passive reabsorption (<120 ml/min)]. Human variability in kinetics has been quantified using a database of 15 compounds excreted extensively by the kidney (>60% of a dose) to develop renal-excretion related uncertainty factors for the risk assessment of environmental contaminants handled via this route. Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [renal and total clearances, area under the plasma concentration time-curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was low for both routes of exposure, with coefficients of variation of 21% (oral) and 24% (intravenous) that were largely independent of the renal processes involved. Renal-excretion related uncertainty factors were below the default kinetic uncertainty factor of 3.16 for most subgroups analysed with the exception of the elderly (oral data) and neonates (intravenous data) for whom renal excretion-related factors of 4.2 and 3.2 would be required to cover up to 99% of these subgroups respectively.

Pharmacological properties of parenteral cephalosporins: rationale for ambulatory use

Parenteral cephalosporins are among the most frequently used antibiotics in hospital therapy. They are characterised by an extended spectrum of activity against gram-positive and gram-negative bacteria, and some also have good activity against anaerobes. They kill proliferating bacterial cells rapidly, and generally show only a low tendency to select resistant mutants. However, there are cephalosporin compounds which induce cephalosporinases very rapidly in certain microorganisms. Together with other beta-lactam antibiotics, parenteral cephalosporins interfere with bacterial cell wall synthesis by inhibiting peptidoglycan cross-linkage. Because of this specific target, they are nontoxic to mammalian cells, and have a very favourable adverse effect profile. The chemical stability of parenteral cephalosporins in aqueous solution is good. After intravenous injection, high concentrations of these agents are achieved in serum and tissue. Most cephalosporins are eliminated unchanged via the kidney, with a half-life of 1 to 2 hours. But there are also derivatives with a serum half-life of more than 2 and up to 8 hours, allowing 12- or 24-hour dosage intervals. Because of their reliable efficacy and low risk of adverse effects, the parenteral cephalosporins offer a high degree of tolerability even in the setting of outpatient antibiotic therapy. In particular, the derivatives of the third generation are characterised by unique pharmacological properties.

Cefodizime in skin suction blister fluid and serum following a single intravenous or intramuscular dose in adult patients

Cefodizime is a third generation cephalosporin for parenteral use. The pharmacokinetics of this cephem antibiotic were determined in serum and skin suction blister fluid (SBF) after intravenous (i.v.) or intramuscular (i.m.) administration of a single 1 g dose in 8 adult patients with normal renal and hepatic function who volunteered for the study. The concentration versus time curve showed a slower elimination rate from the extravascular compartment: the half-lives were 4.4+/-0.5 and 5.4+/-0.4 hours after i.v. and i.m. route respectively. The relatively long elimination half-life in SBF with a mean residence time of about 8 hours allows the use of cefodizime once-a-day for the treatment of infections due to sensitive pathogens.

Pharmacokinetic study of cefodizime and ceftriaxone in sera and bones of patients undergoing hip arthroplasty

The study was carried out to determine the concentrations of cefodizime (single 2-g intravenous [i.v.] dose) and ceftriaxone (single 2-g i.v. dose) in the sera and bones of 42 patients (18 women and 24 men) undergoing hip arthroplasty. The concentrations of cefodizime and ceftriaxone in cancellous and cortical bone appear to be related to the free levels in serum but not to the total levels in serum, so the concentrations of cephalosporins in bone must be compared with the free concentrations in serum. Both drugs diffuse well into bone, with concentrations exceeding the MIC at which 90% of the major pathogenic infecting organisms are inhibited.