Objectives
In the randomized controlled trial PANTHEM, the prophylactic effect of oral amoxicillin or clindamycin is investigated in patients receiving chronic haemodialysis (HD). However, data on plasma concentrations of these antibiotics during HD are sparse. This study aims to determine if the plasma concentration of amoxicillin and clindamycin is sufficient during HD after oral administration of amoxicillin and clindamycin at three different time intervals prior to the HD procedure.

Methods
Adult patients receiving chronic HD were investigated twice with an interval of at least 7 days starting with either a tablet of 500/125 mg amoxicillin/clavulanic acid or a tablet of 600 mg clindamycin. Patients were randomized to take the antibiotics either 30, 60 or 120 min prior to the HD procedure. Plasma antibiotic concentrations were measured at start, midway and at the end of HD. A lower threshold was set at 2.0 mg/L for amoxicillin and at 1.0 mg/L for clindamycin. In addition, a population pharmacokinetic (PK) analysis was performed, assessing PTA.

Results
In the amoxicillin cohort (n = 37), 84% of patients and 95% of all plasma amoxicillin concentrations were above or at the threshold throughout the dialysis procedure. In the clindamycin cohort (n = 33), all concentrations were above the threshold throughout the dialysis procedure. Further, in all patients, the mean plasma concentration of both amoxicillin and clindamycin across the HD period was well above the threshold. Finally, the PK model predicted a high PTA in the majority of patients.

Discussion
In patients on chronic HD, oral administration of amoxicillin/clavulanic acid (500/125 mg) or clindamycin (600 mg) within 30–120 min prior to HD leads to a sufficient prophylactic plasma concentration across the HD period.