Incidence of ifosfamide induced encephalopathy in patients receiving concomitant fosaprepitant

INTRODUCTION

The incidence of Ifosfamide-induced encephalopathy (IIE) ranges from 5-30%. Aprepitant and fosaprepitant may increase the risk of IIE; however, data is limited. The objective of this study was to characterize the incidence of IIE in patients receiving concomitant fosaprepitant.

METHODS

This single-center, retrospective chart review included adult patients diagnosed with sarcoma who received at least one administration of high dose ifosfamide (≥1800mg/m²) and fosaprepitant between January 2017 and June 2018. The primary endpoint was the percentage of patient cycles in which IIE was experienced. Secondary endpoints included characterization of IIE management strategies, time to IIE resolution, and the incidence of IIE upon ifosfamide re-challenge. Subgroup analyses were performed to assess whether the following variables predisposed a patient to neurotoxicity: elevated serum creatinine, hypoalbuminemia, metabolic acidosis, hyperbilirubinemia, shorter infusion time, and higher body mass index. The role of CYP2B6 inhibitors and prior cisplatin use were also examined.

RESULTS

Fifty-one patients who received 215 total cycles of ifosfamide were included. Twenty (9.3%) patient cycles included documented evidence of IIE. The most common management strategies were to prolong the infusion time and administer methylene blue. The mean time to resolution of IIE was 2.58 days. The incidence of secondary IIE upon re-challenge was 26.3%. Baseline albumin <3.5 g/dL (p<0.001) was statistically associated with the development of IIE.

CONCLUSION

Co-administration of fosaprepitant and ifosfamide in sarcoma appears to be safe. Hypoalbuminemia was a notable risk factor confirmed in this study. Further research is needed to delineate IIE risk factors.

Aprepitant and fosaprepitant drug interactions: a systematic review

AIMS

Aprepitant and fosaprepitant, commonly used for the prevention of chemotherapy-induced nausea and vomiting, alter cytochrome P450 activity. This systematic review evaluates clinically significant pharmacokinetic drug interactions with aprepitant and fosaprepitant and describes adverse events ascribed to drug interactions with aprepitant or fosaprepitant.

METHODS

We systematically reviewed the literature to September 11, 2016, to identify articles evaluating drug interactions involving aprepitant/fosaprepitant. The clinical significance of each reported pharmacokinetic drug interaction was evaluated based on the United States Food and Drug Administration guidance document on conducting drug interaction studies. The probability of an adverse event reported in case reports being due to a drug interaction with aprepitant/fosaprepitant was determined using the Drug Interaction Probability Scale.

RESULTS

A total of 4377 publications were identified. Of these, 64 met inclusion eligibility criteria: 34 described pharmacokinetic drug interactions and 30 described adverse events ascribed to a drug interaction. Clinically significant pharmacokinetic interactions between aprepitant/fosaprepitant and bosutinib PO, cabazitaxel IV, cyclophosphamide IV, dexamethasone PO, methylprednisolone IV, midazolam PO/IV, oxycodone PO and tolbutamide PO were identified, as were adverse events resulting from an interaction between aprepitant/fosaprepitant and alcohol, anthracyclines, ifosfamide, oxycodone, quetiapine, selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitors and warfarin.

CONCLUSIONS

The potential for a drug interaction with aprepitant and fosaprepitant should be considered when selecting antiemetic therapy.