HEMATOLOGIC AND SYSTEMIC TOXICOSES ASSOCIATED WITH CARBOPLATIN ADMINISTRATION IN CATS

Objective-To determine prevalence and severity of carboplatin-induced dose-limiting toxicoses in the cat. Animals-9 healthy, 6- to 7-month-o ld cats weighing 4.7 (range, 3.0 to 6.5) kg.Procedure-Cats were given a single IV bolus of carboplatin at a dosage of 150 (n = 3), 200 (n = 3), or 250 (n = 3) mg/m(2) of body surface area. Results-Dose-limiting neutropenia and thrombocytopenia were significant in all cats given c arboplatin at 200 or 250 mg/m(2). Weight loss, changes in appetite, an d evidence of respiratory difficulty, as well as vomiting, diarrhea, o r lethargy were not observed at any time during the 28-day period. At a highest dosage (250 mg/m(2)), the neutrophil nadir (560 +/- 303 neut rophils/mu l) was observed on day 17 and the platelet count nadir (96, 500 +/- 11,815 platelets/mu l) was observed on day 14 after carboplati n administration. Conclusions-Carboplatin appears to be safe and clini cally well-tolerated when given IV as a single bolus al a dosage of 20 0 mg/m(2) to clinically normal cats. The dose-limiting toxicity of a s ingle IV administered bolus is neutropenia. The nadir of a 200 mg/m(2) IV administered dose occurs on day 17 (1,110 +/- 165 neutrophils/mu l ) and neutropenia (< 2,000 neutrophils/mu l) lasts from day 14 through day 25 after carboplatin administration. Clinical Relevance-The fatal dose-related pulmonary toxicosis observed in cisplatin-treated cats w as inapparent in carboplatin-treated cats. To adequately determine the therapeutic role of carboplatin in tumor-bearing cats, a moderately t olerated dose of carboplatin of 200 mg/m(2) given IV once every 4 week s should be considered.