Pharmacokinetic study of cefadroxil following single and repeated doses

Pharmacokinetics of cefixime after once-a-day and twice-a-day dosing to steady state

The pharmacokinetics of cefixime (CL 284,635; FK027), a new orally active broad-spectrum cephalosporin, were determined in 26 healthy volunteers, after multiple 200-mg twice-a-day (group 1; N = 13) or 400-mg once-a-day (group 2; N = 13) dosing for 15 days. On study days 1, 8, and 15, mean peak serum concentrations (Cmax) were 1.67, 1.75, and 1.87 micrograms/mL, respectively, for group 1 and 2.76, 3.04, and 2.67, respectively, for group 2. Over the 15-day period, mean trough serum concentrations were, on average, 0.40 and 0.08 microgram/mL for groups 1 and 2, respectively. Comparison (ANOVA) of serum and urinary excretion pharmacokinetic parameters for cefixime on days 1, 8, and 15 found no significant (P greater than .05) differences for either group except for a small but significantly (P less than .05) earlier time to reach Cmax and higher renal clearance on days 8 and 15 in group 1. These differences, however, are not clinically significant. On study days 1, 8, and 15, mean Cmax and AUC0-tau values for Group 2 were about 1.5 to 2.2 time those for Group 1. Urinary excretion of cefixime accounted for 11.9 to 14.5% and 9.9 to 12.4% of the dose in groups 1 and 2, respectively, over the 15-day study. Overall, there was no accumulation of cefixime in serum or urine nor was there a reduction in serum concentrations of urinary amounts over the 15-day dosing period when the drug was given either as a 200-mg twice-a-day or 400-mg once-a-day dosing regimen.

A pharmacokinetic comparison of cephalexin and cefadroxil using HPLC assay procedures

The pharmacokinetics of cephalexin and cefadroxil were compared following single 500 mg oral doses to 12 healthy male volunteers. Doses were administered after an overnight fast according to a crossover design. Plasma and urinary levels of both compounds were determined by HPLC procedures. Cephalexin was absorbed rapidly, achieving a mean peak plasma level of 17.5 micrograms ml-1 at 1 h, compared to 16 micrograms ml-1 at 1.8 h for cefadroxil. Elimination half-lives of cephalexin and cefadroxil were 0.7 and 1.1 h, respectively. The area under the cefadroxil plasma curve was significantly larger than that for cephalexin. However, after allowing for differences in elimination rate constants and assuming equal distribution volumes, plasma data indicated the compounds were equally well absorbed. Only 70 per cent of cefadroxil was recovered in urine compared to 87 per cent of cephalexin during the 12 h following drug administration. The therapeutic significance of the different pharmacokinetic characteristics of cephalexin and cefadroxil, if any, may be a function also of their pharmacologic activity and/or the sensitivity of the target organism.

Pharmacokinetics of cefotiam administered intravenously and intramuscularly to healthy adults

We studied the pharmacokinetics of cefotiam, a parenteral cephalosporin, at intravenous doses of 0.5, 1, and 2 g and intramuscular doses of 0.5 and 1 g in two groups of eight healthy adult volunteers. The concentrations of cefotiam in plasma were determined over a period of 5 or 6 h and in urine over 24 h, using high-pressure liquid chromatographic procedures. Plasma concentration-time data were fitted to a three-exponential equation for the intravenous administration, and after intramuscular administration, the data were analyzed by a two-compartment or a one-compartment open model. Over the above dosing range and routes of administration, cefotiam pharmacokinetics were essentially linear, with plasma clearances varying from 19.6 to 22.5 liters/h. No significant differences were observed with respect to the terminal half-life (1 h) and the area under the curve versus the dose. Intramuscularly injected cefotiam was 63 to 74% available. The fraction of dose excreted unchanged in urine (0.50 to 0.67) indicated a substantial nonrenal mechanism of elimination. The apparent volume of distribution (about 30 liters) was higher than those of other parenteral cephalosporins.