The safety and efficacy of methylnaltrexone in pediatric oncology patients: A single center experience.

INTRODUCTION: Peripherally acting µ-opioid receptor antagonists (PAMORAs) are used in the treatment of opioid induced constipation without impacting the actions of opioid analgesics. Subcutaneous methylnaltrexone was one of the first PAMORAs approved in April 2008 for the treatment of opioid induced constipation in adult patients. The safety and effectiveness of methylnaltrexone has not been established in pediatric patients. In this study, the use of subcutaneous methylnaltrexone in pediatric patients is analyzed and reviewed. The primary outcome is occurrence of a bowel movement within 24 h after methylnaltrexone (MNTX) administration and the number of bowel movements following treatment with methylnaltrexone. Secondary outcomes include safety in this patient cohort. METHODS: This is a retrospective study of 79 pediatric patients with opioid induced constipation. Patients were administered methylnaltrexone during their inpatient stay. Data on bowel activity after methylnaltrexone was obtained from the hospital information system. RESULTS: Out of the 79 patients who received methylnaltrexone, there were seven patients from whom data could not be analyzed. Of the 72 patients whose data was available, 38% (N = 27) were documented as having a bowel movement, 62% (N = 45) did not have a bowel movement. Reported adverse events were minimal with nausea (N = 3), vomiting (N = 1), and flatulence (N = 6). CONCLUSION: Methylnaltrexone appears safe in the pediatric population and produces bowel movements in more than a third of pediatric patients. It is a feasible and safe option for opioid induced constipation in pediatric patients.

Management of Patients with Acute Methotrexate Nephrotoxicity with High-Dose Leucovorin.

BACKGROUND: Acute kidney injury complicating high-dose methotrexate (HDMTX) therapy increases the risk for severe mucositis, myelosuppression, and death. It is unclear whether high-dose leucovorin and supportive therapy without the use of glucarpidase can reduce toxicity from HDMTX. STUDY DESIGN: The charts of all patients at Memorial Sloan Kettering Cancer Center whose methotrexate (MTX) drug levels at 48 or 72 hours after administration were 10 times or more the toxic level were reviewed between January 2000 and December 2011. RESULTS: Eighty-eight patients (median age 51 years, range 9-90 years) who received 100 courses of HDMTX were identified. Serum creatinine increased by 2-fold from baseline (median, range 1- to 10-fold), but all patients recovered kidney function. Serum levels of MTX were 69 µmol/L (median, range 2.2-400), 6.9 µmol/L (1.3-64), and 2.0 µmol/L (0.05-26) at 24, 48, and 72 hours, respectively, after administration. A statistically significant correlation existed between MTX levels at 48, 72, 96, and 120 hours after administration but not between 24 and 72 hours or subsequent time points. High-dose leucovorin was given in 81% of courses in accordance with institutional protocols in most cases. Myelosuppression was present in 42%; grade III or higher neutropenia in 29%, and thrombocytopenia in 25%. Infectious complications, oral mucositis, and diarrhea occurred in 21%, 17%, and 6% of patients, respectively. Five deaths occurred, none directly attributed to complications from MTX administration. Seven additional patients received glucarpidase at the discretion of a treating physician during the study period, and results are reported separately. CONCLUSION: Patients who had 100 episodes of HDMTX-associated acute kidney injury were treated with a strategy that only included usual supportive measures and high-dose leucovorin. No deaths were directly attributed to complications related to HDMTX. Glucarpidase, an expensive drug, may not be necessary for a significant number of patients.

Voriconazole Dosing in Children Younger Than 3 Years Undergoing Cancer Chemotherapy or Hematopoietic Stem Cell Transplantation.

There are limited pediatric population pharmacokinetic data for voriconazole dosing, particularly in younger children. In a cohort of 34 patients younger than 3 years receiving voriconazole, the majority (n = 23, 68%) had a low initial serum concentration <1 mg/L. Among 23 children <2 years old, 19 (83%) had an initial trough <1 mg/L. There was large intra- and interindividual variability in trough levels. Dosing also varied from 3.3 to 19.6 mg/kg per dose. Only 2 of 34 patients had a documented adverse drug reaction attributable to voriconazole. More data are needed to establish optimal dosing in very young children.

Retrospective Analysis of Posaconazole Suspension Dosing Strategies in a Pediatric Oncology Population: Single-Center Experience.

Limited data on optimal posaconazole dosing strategies for pediatric patients exist. In this study, we found that the median initial dose in patients who achieved a posaconazole plasma concentration of 0.7 µg/mL was 22.8 mg/kg per day whereas the median initial dose in those who did not reach the target concentration was 15.8 mg/kg per day; this result suggests that higher initial doses might be warranted.