Poly(I) • poly(C), a potential drug carrier for the antitumor agent mitoxantrone: in vitro drug binding study

Coupling of mitoxantrone, a new antitumor agent, to a macromolecular carrier system may improve the drug's selectivity of action and pharmacokinetic properties. We have studied in vitro binding of mitoxantrone to poly(I).poly(C), a macromolecular, double-stranded homoribopolymer, by equilibrium dialysis and high-performance liquid chromatography (HPLC). Results showed high binding affinity for mitoxantrone to poly(I).poly(C) (Kd = 1.05 X 10(-6) M), the calculated number of mitoxantrone-binding sites is 60 per molecule poly(I).poly(C). In view of the good tolerance in clinical studies, poly(I).poly(C) may thus be a useful drug carrier for mitoxantrone. A mitoxantrone:poly(I).poly(C) ratio of 1:30 (w/w) is recommended for therapeutic studies.