Multivesicular liposomes containing 1-beta-D-arabinofuranosylcytosine for slow-release intrathecal therapy.

Optimal anticancer treatment with cell cycle-specific antimetabolites requires maintenance of a cytotoxic drug level for a prolonged period of time. We explored the use of multivesicular liposomes as a slow-release depot of 1-beta-D-arabinofuranosylcytosine for intrathecal administration. The intrathecal half-life of the liposome-encapsulated drug was 148 h, in contrast to the half-life of 2.7 h for the unencapsulated free drug, in a Sprague-Dawley rat model. The prolonged maintenance of a therapeutic drug level may increase efficacy, and the elimination of the very high peak level may decrease toxicity.