Neocyte Overdosage

In cancer patients receiving filgrastim as an adjunct to myelosuppressive chemotherapy, it is recommended to avoid the potential risks of excessive leukocytosis, that filgrastim therapy be discontinued if the ANC exceeds 10 x 10⁹/L after the chemotherapy-induced ANC nadir has occurred. Doses of filgrastim that increase the ANC beyond 10x 10⁹/L may not result in any additional clinical benefit.
The maximum tolerated dose of filgrastim has not been determined. Efficacy was demonstrated at doses of 4 to 8 mcg/kg body weight/day in a phase 3 study of nonmyeloablative chemotherapy. Patients in the bone marrow transplantation studies received up to 138 mcg/kg body weight/day without toxic effects, although there was a flattening of the dose response curve above daily doses of greater than 10 mcg/kg body weight/day.
In filgrastim clinical trials of cancer patients receiving myelosuppressive chemotherapy, white blood counts >100 x 10⁹/L have been reported in <5% of patients, but were not associated with any reported adverse clinical effects.
In cancer patients receiving myelosuppressive chemotherapy, discontinuation of filgrastim therapy usually results in a 50% decrease in circulating neutrophils within 1 to 2 days, with a return to pretreatment levels in 1 to 7 days.