Phase I clinical trial and human pharmacokinetics of 2,4-diamino-5-adamantyl-6-methyl pyrimidine ethane sulfonate (DAMP-ES): a lipid-soluble antifolate.

A phase I and pharmacokinetic study of a novel lipid-soluble antifolate, 2,4 diamino-5-adamantyl-6-methyl pyrimidine ethane sulfonate (DAMP-ES) has been carried out on two schedules: I--daily x5; II--24-h continuous infusion. In schedule I, doses of 10-90 mg/m2 per day were evaluated. Dose-limiting toxicity was hematologic, but nausea and vomiting, skin rash, diarrhea, anorexia, alopecia, mucositis, and neurotoxicity were also noted. In schedule II, doses of 192 and 240 mg/m2 were evaluated. Dose-limiting toxicity was neurotoxicity, but hematologic toxicity was also marked. Recommended starting doses for phase II studies are 75 mg/m2 per day for 5 days or 192 mg/m2 by continuous infusion for 24 h. Pharmacokinetic studies indicated a beta-phase plasma half-life of 12.4-24 h and a large and variable volume of distribution.