Effects of lithium carbonate on carboplatin-induced thrombocytopenia in dogs

To describe the effects of lithium carbonate on thrombopoiesis in clinically normal dogs and in dogs treated with carboplatin.

18 young adult sexually intact female Beagles.

Dogs were assigned to each of 3 treatment groups (6 dogs/group). Group 1 received 150 mg of lithium carbonate (14 to 16 mg/kg), PO, every 12 hours on days 1 through 21. Group 2 received carboplatin (300 mg/m(2), IV) on day 0 and cephalexin (30 mg/kg, PO, q 12 h) on days 14 through 21. Group 3 received lithium, carboplatin, and cephalexin at the aforementioned doses and schedules. Plasma lithium and blood platelet concentrations were measured on days 0, 2, 4, 7, 9, 11, 14, 16, 18, and 21. Number of megakaryocytes in bone marrow specimens and the percentage of large unstained cells and CD34+ mononuclear cells in bone marrow aspirates were determined on days 0, 7, 14, and 21 by manual enumeration, automated hematologic analysis, and flow cytometric immunophenotyping, respectively.

Plasma lithium concentrations ranged from 0.12 to 2.41 mmol/L. All dogs given lithium achieved a concentration within the target interval of 0.5 to 1.5 mmol/L by days 4 to 7. Thrombopoiesis was increased in dogs receiving lithium alone. All dogs given carboplatin developed mild thrombocytopenia. There were no differences between group 2 and group 3 throughout the study.

Lithium stimulated thrombopoiesis in clinically normal dogs. Lithium administration at the doses and schedules used, with concurrent administration of cephalexin, did not prevent thrombocytopenia induced by carboplatin.