Biodistribution of doxorubicin-alkylated poly(L-lysine citramide imide) conjugates in an experimental model of peritoneal carcinomatosis after intraperitoneal administration.

Peritoneal spread is a common manifestation in ovarian and gastrointestinal cancer. Intraperitoneal (i.p.) chemotherapy after cytoreductive surgery is associated with high systemic or local toxicity. A macromolecular drug delivery system was evaluated with the aim of improving the therapeutic index of i.p. chemotherapy. Peritoneal carcinomatosis was generated in BDIX rats (n=55) by i.p. injection of 2 million DHDK12 cells. Fourteen days later, doxorubicin (DOX) and two DOX-alkylated poly(L-lysine citramide imide) conjugates bearing 9.5% and 20.5% (w/w) chemically bound drug, respectively, were given i.p. to rats at a single 2 mg DOX/kg dose. Free and polymer-bound DOX were assessed in plasma, peritoneal fluid, abdominal tissues and heart, 15 min, 2, 6, 24, 48 and 168 h after injection. According to pharmacokinetic profiles, the peritoneal fluid areas under the concentration versus time curves (AUCs) were 2 and 2.6 times greater for the conjugates (P-DOX20 and P-DOX10, respectively) than for the free drug, respectively. Conjugates crossed the peritoneal barrier slower than the free drug. For the tumor, AUCs were, respectively, 3 and 7 times higher for the conjugates than for free DOX. The elimination half-lives of the conjugates were higher than that calculated for the free drug. Only very small concentrations were detected in peripheral organs and in the heart. In contrast, significant retention and accumulation of the conjugates were found in abdominal organs, particularly in the tumor. There was no sign of macroscopic chemical peritonitis after injection of the polymer-DOX conjugates. In conclusion, the conjugates have higher elimination half-lives than free DOX and were preferentially retained in abdominal organs and in the peritoneal carcinomatosis. This feature is of clinical interest to target tumor deposits.