%0 Journal Article %T The incidence and timing of leukocyte overshoot after pegfilgrastim administration %A Eiseki Usami %A Hiroki Asano %A Makiko Go %A Michio Kimura %A Mina Iwai %A Shino Adachi %A Shoya Takenaka %A Tomoaki Yoshimura %J Journal of Oncology Pharmacy Practice %@ 1477-092X %D 2019 %R 10.1177/1078155218769140 %X Pegfilgrastim is a PEGylated formulation of filgrastim with a long half-life. It is highly convenient and less burdensome for patients. However, white blood cell count may temporarily increase after administration; in particular, a leukocyte overshoot may be observed. The present study retrospectively examined the incidence and timing of leukocyte overshoot after pegfilgrastim administration. Fifty-five patients (118 occasions of pegfilgrastim) were evaluated. Leukocyte overshoot was defined as white blood cell count ¡Ý10,000/mm3 exceeding the reference value. Leukocyte overshoot was observed in 71.2% (84/118) occasions, in 76.4% (42/55) patients. The maximum white blood cell count ¡Ý30,000/mm3 was observed in 30.5% (36/118) occasions in 45.5% (25/55) patients and was observed in 39.3% (33/84) occasions on day 1 after pegfilgrastim administration and 26.2% (22/84) on day 2. Leukocyte overshoot has been observed in only 23.1% (9/39) patients administered with normal granulocyte colony-stimulating factor. However, there were no patients with white blood cell counts ¡Ý30,000/mm3. There was a higher frequency of occurrence of leukocyte overshoot in response to pegfilgrastim than in response to normal granulocyte colony-stimulating factor. High incidence of leukocyte overshoot was observed when blood was collected 1¨C2 days after administration of pegfilgrastim. It is important for patients to understand the characteristics of pegfilgrastim by conducting pharmaceutical guidance %K Pegfilgrastim %K granulocyte colony-stimulating factor %K leukocyte overshoot %K white blood cell counts %K timing %U https://journals.sagepub.com/doi/full/10.1177/1078155218769140