PURPOSE: Heptaplatin, a new platinum analog, has favorable toxicity profiles and antitumor activity, comparable to those of cisplatin, in the treatment of gastric cancer. This study was designed to define the maximum tolerated dose (MTD), dose-limiting toxicity (DLT) and pharmacokinetics of heptaplatin administered by an intraperitoneal route in patients with resected advanced gastric cancer. MATERIALS AND METHODS: Seventeen patients with resected advanced gastric cancer were entered onto the study. After completion of a curative resection and an astomosis, heptaplatin was administered intraperiton eally in one liter of 5% dextrose solution. The starting heptaplatin dose was 400 mg/m2 of the body surface area, and was escalated in 200 mg/m2 increments, to cohorts of three patients. A pharmacokinetic analysis was carried out to determine the total and ultrafiltratable platinum concentrations in the plasma, peritoneal fluid, and urine. RESULTS: Patients were unable to tolerate a 1, 000 mg/m2 dose level, and at 800 mg/m2, reVersible Grade III toxic ities, including elevated creatinine, proteinuria, hypon- atremia, abdominal pain, and intraabdominal bleeding were noted. No significant toxicity was noted up to a 600 mg/m2 dose level. The ratio of the peak peritoneal to peak plasma drug concentrations were 19.4, 16.6 and 22.8 at doses of 400 mg/m2, 600 mg/m2 and 800 mg/m2, respectively. The pharmacological advantage, expressed as the peritoneal to plasma AUC ratio ranged from 4.3 to 7.0. CONCLUSION: Heptaplatin can be delivered by an intra peritoneal route, with both an acceptable toxicity profile and a major pharmacokinetic advantage for cavity exposure. The MTD of intraperitoneal heptaplatin was 800 mg/m2. The major DLTs were nephrotoxicity and intraabdominal bleeding. The recommended starting dose for a subsequent study would be 600 mg/m2.