Pharmacokinetic aspects during continuous ambulatory peritoneal dialysis: a literature review

Pharmacokinetics of antimicrobial agents in organ function impairment. A review

The pharmacokinetics of antimicrobial drugs in various types of organ function impairment are reviewed. The influence of renal function impairment on antimicrobial agents is well-known, although less is known about the accumulation of metabolites during renal failure. Fewer data are available on liver function impairment and more information is needed on highly metabolized agents. Pharmacokinetic studies in severely ill patients are urgently needed to investigate the influence of disease states on pharmacokinetics and to study the possibility of oral administration to seriously ill patients.

Pharmacokinetics of cefradine, sulfamethoxazole and trimethoprim and their metabolites in a patient with peritonitis undergoing continuous ambulatory peritoneal dialysis

Cefradine and co-trimoxazole pharmacokinetics were studied in a patient with peritonitis that complicated continuous ambulatory peritoneal dialysis (CAPD). Concentrations in the plasma reached after oral administration of 500 mg cefradine four times daily and 400/80 mg co-trimoxazole four times daily were for cefradine 100 micrograms/ml, for trimethoprim 15 micrograms/ml, and for sulfamethoxazole 100 micrograms/ml, respectively. In the dialysate concentrations were reached of 35-70 micrograms/ml cefradine, 2-5 micrograms/ml trimethoprim and 8-17 micrograms/ml sulfamethoxazole. The values for sulfamethoxazole are regarded too low to be clinically effective. Half-lives, protein binding values and CAPD clearances are presented. Low CAPD clearances were obtained during the night and high values during the day. The dosage yielded too high plasma trimethoprim concentrations, while sulfamethoxazole dialysate concentrations were too low. It seems questionable therefore whether co-trimoxazole can be used orally for the treatment of CAPD peritonitis.

Drug therapy in continuous ambulatory peritoneal dialysis patients

Transport of solutes across the peritoneal membrane in continuous ambulatory peritoneal dialysis (CAPD) is determined by patient-related factors (concentration gradient, membrane surface area, blood flow and membrane permeability) and by drug-related factors (charge on the molecule, protein binding, molecular weight, lipophilicity). On the basis of the chemical properties of a drug a prediction of the peritoneal clearance rate in CAPD patients is given, by the formula CLCAPD = 75 square root free fraction/molecular weight. The implications of this formula are discussed. It is concluded that usually it is not necessary to change the dose as compared with end-stage renal disease patients who are not treated with CAPD.

Toxicologic and pharmacokinetic evaluation of a case of vancomycin intoxication during continuous ambulatory peritoneal dialysis

The use of vancomycin is rapidly increasing due to the emergence of strains of staphylococci resistant to betalactam antibiotics. In this communication the pharmacokinetics of an overdose of vancomycin in a patient during continuous ambulatory peritoneal dialysis (CAPD) is reported. Brainstem auditory evoked potentials (BAEPs) are used to assess ototoxicity. It could be shown that by shortening the dwell time, the apparent CAPD flow was increased and the vancomycin clearance was also increased. This may explain in part the differences in the values of vancomycin t1/2 in this patient (21 h) as compared to other studies (60-120 h). The age of the patient (3.5 years) may also have influenced the t1/2. Using brainstem auditory evoked potentials as a parameter to assess ototoxicity, it was shown that this patient suffered no damage from the overdose.