Clinical pharmacokinetics of mitoxantrone after intraperitoneal administration

Summary The pharmacokinetics of intraperitoneally (i.p.) injected mitoxantrone was determined in plasma and peritoneal dialysate taken from five patients presenting with cancer confined to the peritoneal cavity over a sampling period of 1 week. The drug was given through a Tenckhoff catheter as a 15-min infusion and the peritoneal dialysate was removed after a dwell time of 4 h; the doses delivered varied between 20 and 50 mg/m². Dose-limiting local toxicity was moderate. The HPLC technique used for mitoxantrone determinations proved to be sensitive within the range of 0.3–4,000 ng/ml. Median values obtained for the pharmacokinetic parameters of mitoxantrone in peritoneal dialysate were:t _1/2 (distribution), 56.4 min (range, 16.8–235.8 min);t _1/2 (elimination), 128 h (range, 28.3–171.0 h); Vd_SS (volume of distribution at steady state), 24.8 l (range, 17.0–232.5 l); _ss (volume of distribution at steady state corrected for the body surface area in square meters), 14.4 l/m² (range, 10.6–129.2 l/m²); and clearance, 0.25 l/h (range, 0.16–0.59 l/h). For plasma the median values were:t _1/2 (absorption), 58.8 min (range, 45.6–87.0 min);t _1/2 (distribution), 2.5 h (range, 1.4–6.3 h);t _1/2 (elimination), 44.1 h (range, 9.1–91 h); Vd_SS, 2,152 l (range, 352–19,733 l); _ss, 1,345 l/m² (range, 220–11,606 l/m²); and clearance, 117 l/h (range, 51–1,609 l/h). After 168 h the median plasma concentration was 1 ng/ml. The median peak concentration in peritoneal dialysate was 490 ng/ml. Considering the moderate toxicity observed and the concentrations achieved in the peritoneal dialysate, removal of the dialysate after certain dwell times seems reasonable to be a reasonable approach for the optimization of i.p. treatment with mitoxantrone.