Hematologic and systemic toxicoses associated with carboplatin administration in cats

Abstract

Objective-To determine prevalence and severity of carboplatin-induced dose-limiting toxicoses in the cat. Animals-9 healthy, 6- to 7-month-old 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/m2 of body surface area. Results-Dose-limiting neutropenia and thrombocytopenia were significant in all cats given carboplatin at 200 or 250 mg/m2. Weight loss, changes in appetite, and evidence of respiratory difficulty, as well as vomiting, diarrhea, or lethargy were not observed at any time during the 28-day period. At a highest dosage (250 mg/m2), the neutrophil nadir (560 ± 303 neutrophils/μl) was observed on day 17 and the platelet count nadir (96,500 ± 11,815 platelets/μl) was observed on day 14 after carboplatin administration. Conclusions-Carboplatin appears to be safe and clinically well-tolerated when given IV as a single bolus at a dosage of 200 mg/m2 to clinically normal cats. The dose-limiting toxicity of a single IV administered bolus is neutropenia. The nadir of a 200 mg/m2 IV administered dose occurs on day 17 (1,110 ± 165 neutrophils/μl) and neutropenia (< 2,000 neutrophils/μl)lasts from day 14 through day 25 after carboplatin administration. Clinical Relevance-The fatal dose-related pulmonary toxicosis observed in cisplatin-treated cats was inapparent in carboplatin-treated cats. To adequately determine the therapeutic role of carboplatin in tumor-bearing cats, a moderately tolerated dose of carboplatin of 200 mg/m2 given IV once every 4 weeks should be considered.