Pharmacokinetics of cefaclor in patients with end stage renal disease and during hemodialysis

Cefaclor into the millennium

We review the discovery and development of the cephalosporins and subsequently cefaclor. Cefaclor is active against a wide range of commonly encountered bacterial pathogens, acting by inhibiting cell wall synthesis. Its in vitro activity compares favourably with other beta-lactam antibiotics. Its pharmacokinetic properties indicate that an 8-hourly dosing schedule is appropriate. In addition a delayed release formulation allowing twice daily dosage has been developed. The efficacy of both formulations of cefaclor has been verified by many clinical trials. Cefaclor has been widely used in infections of the respiratory tract (including otitis media), urinary tract and soft tissues. The results of therapy are summarized. The low incidence of adverse events is highlighted and the beneficial influence of this on compliance is described. Finally, the pharmaco-economics of cefaclor are considered.

Pharmacokinetic study of an oral cephalosporin, cefdinir, in hemodialysis patients

The pharmacokinetics of cefdinir were investigated in six hemodialysis patients. For the present study, two tests were carried out, one with 4 h of hemodialysis and the other without hemodialysis. Cefdinir was given orally to each patient in a dose of 100 mg, and blood was collected serially for 48 h after dosing in the test without dialysis and for 72 h in the test with dialysis. In the test without dialysis, the maximum plasma concentration (Cmax) was 2.36 +/- 0.53 micrograms/ml (mean +/- standard deviation) and the time to Cmax was 9.00 +/- 2.45 h. The terminal elimination half-life (t1/2) and area under the concentration-time curve (AUC) were 16.95 +/- 1.20 h and 69.05 +/- 14.84 micrograms.h/ml, respectively. In the test with dialysis, t1/2 during hemodialysis decreased approximately to one-sixth of that obtained in the test without dialysis, although t1/2 in the latter elimination phase did not differ from that in the nondialysis test. AUC was reduced to 43% of that in the test without dialysis. The fractional removal of cefdinir by hemodialysis was 61%. These findings indicate that clearance of cefdinir is prolonged in patients with renal failure, and cefdinir is well removed by introduction of hemodialysis, although t1/2 (during hemodialysis) and AUC were two and eight times higher than the data previously reported for healthy volunteers, respectively. The pharmacokinetic data suggest that 100 mg of oral cefdinir once a day would result in a sufficient concentration in plasma in hemodialysis patients, but this remains to be confirmed by multiple-dose studies.

Clinical pharmacokinetics of antibiotics in patients with impaired renal function

Many antibiotics are eliminated renally and dosage adjustments are commonly made in patients with renal insufficiency. This is a critical review of antibiotic pharmacokinetics in patients with various degrees of renal function. Detailed information regarding pharmacokinetic alterations with specific antibiotics or antibiotic classes has been compiled and tabulated. From pharmacokinetic evidence, recommendations for dosage adjustments of antibiotics are supplied. The criteria used for assigning rating levels to specific pharmacokinetic articles as well as the grading system for dosage adjustments are outlined. In addition, a basic review of pharmacokinetic alterations in renal failure and factors affecting the removal of drugs by haemodialysis is included.

Pharmacokinetics of cefprozil in healthy subjects and patients with renal impairment

Cefprozil, a new broad-spectrum oral cephalosporin, is composed of cis and trans isomers in an approximate 90:10 ratio. The pharmacokinetics of a single oral 1000-mg dose of cefprozil were evaluated in 6 healthy subjects and 24 patients with various degrees of renal impairment. Six of these subjects were studied both while receiving hemodialysis and during an interdialytic period. Plasma, urine, and hemodialysate that were collected at predetermined times were analyzed for concentrations of the cis and trans isomers of cefprozil using reverse-phase HPLC assay with UV detection. The maximum plasma concentration of the cis isomer ranged from 12.3 micrograms/mL in subjects with normal renal function to 36.7 micrograms/mL in hemodialysis patients. Similarly the area under the plasma concentration-time curve and the elimination half-life increased from 46 micrograms.h/mL to 373 micrograms.h/mL and from 1.72 hours to 5.94 hours, respectively. Renal clearance of the cis isomer decreased from 198 mL/min in normal subjects to 19 mL/min in volunteers with creatinine clearances of less than or equal to 30 mL/min; there was a strong correlation (r2 greater than or equal to .93) between the renal clearance of the cis isomer and creatinine clearance. Urinary recovery of the cis isomer decreased from 57% in those with normal renal function to 24% in the group with a creatinine clearance of less than or equal to 30 mL/min. Hemodialysis decreased the half-life of the cis isomer to 2 hours and removed approximately 55% of it from the body during a 3-hour dialysis period (hemodialysis clearance equaled approximately 87 mL/min). The pharmacokinetics of the trans isomer were similar to those observed for the cis isomer and were affected similarly by declining renal function. A reduction in dosage is recommended in patients with a creatinine clearance of 30 mL/min or less. It may be necessary to administer a dose after hemodialysis to maintain therapeutic plasma concentrations.

Drug therapy in patients undergoing haemodialysis. Clinical pharmacokinetic considerations

Haemodialysis is utilised therapeutically as supportive treatment for end-stage renal disease (ESRD). In conjunction with haemodialysis therapy, ESRD patients frequently receive a large number of drugs to treat a multitude of intercurrent conditions. Because of the impaired renal function in ESRD patients, dosage reduction is often recommended to avoid adverse drug reactions, particularly for drugs and active metabolites with extensive renal excretion. On the other hand, if the removal of a drug by haemodialysis during concomitant drug therapy is significant, a dosage supplement would be required to ensure adequate therapeutic efficacy. Knowledge of the impact of haemodialysis on the elimination of specific drugs is therefore essential to the rational design of the dosage regimen in patients undergoing haemodialysis. This review addresses the clinical pharmacokinetic aspects of drug therapy in haemodialysis patients and considers: (a) the effects of ESRD on the general pharmacokinetics of drugs; (b) dialysis clearance and its impact on drug and metabolite elimination; (c) the definition of dialysability and the criteria for evaluation of drug dialysability; (d) pharmacokinetic parameters which are useful in the prediction of drug dialysability; and (e) the application of pharmacokinetic principles to the adjustment of dosage regimens in haemodialysis patients. Finally, drugs commonly associated with haemodialysis therapy are tabulated with updated pharmacokinetics and dialysability information.

Elimination of cefroxadine (CGP-9000) from patients undergoing dialysis

The pharmacokinetics of cefroxadine was studied in 17 patients with terminal renal impairment, 10 of whom were undergoing 5 h dialysis sessions. The antibiotic was administered as a single oral dose of 500 mg. Cefroxadine followed a single compartment open kinetic model. During the interdialysis period in patients with terminal renal impairment, an average Cmax of 26.59 micrograms/ml and a tmax of 3.65 h were reached, which are greater than in patients with normal renal function. The serum half-life was reduced from 23.55 h in the interdialysis periods to 3.40 h during the dialysis sessions. The average extraction coefficient was 0.249. It is recommended that a 500 mg dose cefroxadine should be administered at the end of each dialysis session if the interdialysis period is 48 h.

Cefaclor pharmacokinetic parameters: serum concentrations determined by a new high-performance liquid chromatographic technique

Pharmacokinetic parameters of cefaclor were studied in eight patients after an oral dose of 250 mg. Serum samples were obtained before and on 19 occasions after oral administration. Cefaclor serum concentrations were determined by a new high-performance liquid chromatographic technique.

Pharmacokinetics of ceforanide in patients with end stage renal disease on hemodialysis

The pharmacokinetics of ceforanide were evaluated in 11 patients with end stage renal disease (creatinine clearance less than 5 ml/min). A single intravenous dose of 750 mg/m2 produced peak plasma concentrations of 123 +/- 29 microgram/ml. The plasma half-life (T 1/2) of the drug was 19.1 +/- 2.5 h. A 5.5 h hemodialysis session removed 53% of the drug and reduced the T 1/2 to 5 +/- 0.7 h. Plasma concentrations greater than 10 microgram/m2 were maintained without adverse effects with a 1.5-g/m2 dose administered three times a week for 2 weeks.