Suboptimal Dosing of Filgrastim is Acceptable for Treatment of Chemotherapy-Induced Neutropenia

TON - May 2018, Vol 11, No 2 - Side-Effects Management
Audrey Andrews

 

Orlando, FL—Because of the way the vials are packaged, patients receiving filgrastim who weigh 60 kg to 85 kg often receive lower-than-recommended doses, without evidence of its noninferiority to recommended doses. Based on research presented at the 2018 National Comprehensive Cancer Network (NCCN) Annual Conference, this practice is not only acceptable, but cost-saving.

The recommended dose of filgrastim is 5 µg/kg. The commercially available vials of the drug come in 2 strengths—300 µg and 480 µg. Because of these limitations in dosage formulations, ­clinicians frequently give a lower-than-recommended dose to patients weighing >60 kg in whom the ideal dose would be between 300 µg and 480 µg. In other words, some of the drug is wasted, explained Ahmed Elsayed, MD, MS, Hematology/Oncology, Joan C. Edwards School of Medicine, Edwards Comprehensive Cancer Center, Marshall University, Huntington, WV.

Suboptimal Dosing of Filgrastim Is Acceptable for Treatment of Chemotherapy-Induced Neutropenia

“It’s common practice in the oncology pharmacy community to use suboptimal dosing, but we do this without data to support it. Our analysis showed that for patients weighing up to 85 kg, it’s okay to give the ‘suboptimal’ dose….It’s ok to use one vial. But for patients over 85 kg, you should optimally dose,” Dr Elsayed said.

Lower-Dose Evaluation

Through chart review, Elsayed and colleagues identified 91 patients with chemotherapy-induced neutropenia who received 2 consecutive doses of filgrastim 300 µg. They divided the patients into 3 groups: low weight (<60 kg), medium weight (≥60 and <85 kg), and high weight (≥85 kg).

The researchers compared chemotherapy-induced neutropenia-related complications in patients with a higher weight (>60 kg), for whom 300 µg would be considered a suboptimal dose, versus patients weighing <60 kg, for whom a 300-µg dose would be recommended. The medium-weight and high-weight groups, who were presumably receiving subtherapeutic doses, were the cohorts of interest.

Outcomes and Cost-Savings

After administration of filgrastim, 98% of all patients had an increase in white blood cell count and 96% had an increased absolute neutrophil count. Similar responses for white blood cell and absolute neutrophil counts were observed among all 3 weight groups (Table).

Table Suboptimal Dosing of Filgrastim Is Acceptable for Treatment of Chemotherapy-Induced Neutropenia

The incidence of infections, delays in chemotherapy, and hospitalizations secondary to neutropenic fever were each approximately 5%. Meanwhile, chemotherapy dose reductions were necessary for 25% of patients. Patients in the medium-weight group did not have higher infection rates, but those in the high-weight group did have higher infection rates (5% vs 33%; P = .001).

“We showed that in patients [weighing] up to 85 kg, it’s okay to give the suboptimal dose, the one vial. Dosing filgrastim at 300 µg may be appropriate in this weight group,” Dr Elsayed concluded.

The investigators also concluded that this practice reduced the cost of treatment by 43%. Giving medium-weight patients 2 days of filgrastim at the lower dose (vs using the 480-µg vial) for 2 days translated into a savings of $147,274 in this one institution.

Related Items
Suboptimal Dosing of Filgrastim Is Acceptable for Treatment of Chemotherapy-Induced Neutropenia
Audrey Andrews
TOP - August 2018, Vol 11, No 2 published on August 3, 2018 in Side-Effects Management
Managing Immune Checkpoint Inhibitor Side Effects: Key Recommendations
Clark Westfield
TON - May 2018, Vol 11, No 2 published on May 15, 2018 in Side-Effects Management
The Challenges of Oral Cancer Drugs Use and Side-Effects Management
Meg Barbor, MPH
TON - March 2018, Vol 11, No 1 published on March 9, 2018 in ESMO, Drug Updates & News, Side-Effects Management
Project Aims to Prevent Future Infusion-Related Reactions
Audrey Andrews
TOP - May 2017, Vol 10, No 2 published on May 5, 2017 in NCCN News
Pharmacy-Led Intervention Improved Tyrosine Kinase Inhibitor Adherence and Monitoring
Audrey Andrews
TOP - May 2017, Vol 10, No 2 published on May 5, 2017 in NCCN News
Noncompliance with Granulocyte Colony-Stimulating Factor Guidelines Has Consequences
Audrey Andrews
TOP - May 2017, Vol 10, No 2 published on May 5, 2017 in NCCN News
New Survey Reveals How Pharmacies Manage Verification Processes
Audrey Andrews
TOP - November 2016, Vol 9, No 4 published on November 4, 2016 in Best Practices
Dose Modifications of Lenalidomide Lead to Good Outcomes in Myelodysplastic Syndrome
Audrey Andrews
TOP - November 2016, Vol 9, No 4 published on November 4, 2016 in Hematologic Cancers
Palliative Care Specialists Want More Involvement
Audrey Andrews
TON July 2016 Vol 9 No 4 published on July 18, 2016 in Conference Correspondent
Managing Dermatologic Toxicities
Audrey Andrews
TOP November 2015 Vol 8 No 4 published on December 2, 2015 in Conference Correspondent
Last modified: July 24, 2018