Comparison of enteral and parenteral methods of urine alkalinization in patients receiving high-dose methotrexate.

Purpose Hyperhydration and urinary alkalinization is implemented with all high-dose (HD)-methotrexate infusions to promote excretion and prevent precipitation of methotrexate in the renal tubules. Our institution utilized enteral alkalinizing agents (sodium bicarbonate tablets and sodium citrate/citric acid solution) to alkalinize the urine of patients receiving HD-methotrexate during a parenteral sodium bicarbonate and sodium acetate shortage. The purpose of this study is to establish the safety and efficacy of the enteral route for urine alkalinization. Methods A single-center, retrospective, cohort study was conducted comparing cycles of HD-methotrexate using enteral alkalinizing agents to parenteral sodium bicarbonate. The primary objective was to compare the time, in hours, from administration of first inpatient administered dose of alkalinizing agent to time of achieving goal urine pH. Secondary objectives evaluated total dose of sodium bicarbonate required to achieve goal urine pH, time from start of urine alkalinizing agent until time of achieving methotrexate level safe for discharge, and toxicities associated with methotrexate and the alkalinizing agents. Results A total of 118 patients were included in this study, equally divided into two cohorts based on parenteral versus enteral routes of administration. No statistical difference was determined between the two cohorts regarding time to goal urine pH (6.5 h versus 7.9 h, P = 0.051) or regarding time to methotrexate level deemed safe for discharge (63.5 h versus 62.5 h, p = 0.835). There were no significant differences in methotrexate-induced toxicities. Conclusion Our study found enteral routes of urine alkalinization to be a viable alternative to the traditional parenteral sodium bicarbonate, especially during parenteral sodium bicarbonate and acetate shortages.

Autoinduction of voriconazole metabolism in a child with invasive pulmonary aspergillosis.

Inter- and intra-patient variability in voriconazole pharmacokinetics has been described in children as the result of age-specific differences in hepatic metabolism, saturable nonlinear pharmacokinetics, CYP450 2C19 polymorphisms, decreased bioavailability compared with adults, and drug-drug interactions. We introduce dose-dependent autoinduction of metabolism as another cause for altered voriconazole pharmacokinetics in children and summarize previously published literature on this phenomenon. A 10-year-old girl with severe aplastic anemia developed invasive pulmonary aspergillosis after high-dose cyclophosphamide therapy and required high doses of voriconazole for longer than 2 months. She initially achieved a therapeutic trough of 1.4 µg/ml on voriconazole 11 mg/kg/dose orally every 12 hours but required dose escalations to 9.3 mg/kg/dose orally every 8 hours to maintain a trough above 1 µg/ml. Because there were no changes in concomitant medications, route of administration, adherence, or oral intake, we conclude that the only plausible explanation for the precipitous drop in voriconazole troughs was autoinduction of metabolism, a phenomenon previously reported in adults receiving higher than usual doses or prolonged courses (longer than 2 months). These data highlight the need for continued therapeutic drug monitoring of voriconazole after initial therapeutic troughs are achieved because autoinduction of metabolism can lead to significant declines in subsequent voriconazole troughs, potentially leading to treatment failure.

A clinical algorithm identifies high risk pediatric oncology and bone marrow transplant patients likely to benefit from treatment of adenoviral infection.

BACKGROUND: Adenoviral infections cause morbidity and mortality in blood and marrow transplantation and pediatric oncology patients. Cidofovir is active against adenovirus, but must be used judiciously because of its nephrotoxicity and unclear indications. Therefore, before introducing cidofovir use during an adenoviral outbreak, we developed a clinical algorithm to distinguish low risk patients from those who merited cidofovir therapy because of significant adenoviral disease and high risk for death. OBJECTIVE: This study was conducted to determine whether the algorithm accurately predicted severe adenovirus disease and whether selective cidofovir treatment was beneficial. STUDY DESIGN: A retrospective analysis of a pediatric oncology/blood and marrow transplantation cohort prealgorithm and postalgorithm implementation was performed. RESULTS: Twenty patients with adenovirus infection were identified (14 high risk and 6 low risk). All low-risk patients cleared their infections without treatment. Before algorithm implementation, all untreated high-risk patients died, 4 out of 5 (80%), from adenoviral infection. In contrast, cidofovir reduced adenovirus-related mortality in the high-risk group postalgorithm implementation (9 patients treated, 1 patient died; RR 0.14, P<0.05) and all treated high-risk patients cleared their virus. CONCLUSIONS: The clinical algorithm accurately identified patients at high risk for severe fatal adenoviral disease who would benefit from selective use of cidofovir.

Intravenous pentamidine is effective as second line Pneumocystis pneumonia prophylaxis in pediatric oncology patients.

BACKGROUND: Pneumocystis jirovecii, formerly carinii, pneumonia (PCP) poses a life-threatening risk to oncology patients. The use of trimethoprim-sulfamethoxazole (TMP-SMZ) prophylaxis virtually eliminates the risk of infection; however, many patients cannot tolerate TMP-SMZ. We performed a retrospective analysis to determine the PCP breakthrough rate in pediatric oncology patients receiving intravenous pentamidine as second line PCP prophylaxis. PROCEDURE: We conducted a retrospective chart review of pediatric oncology patients who received intravenous pentamidine from 2001 to 2006 at our institution. The diagnosis, age and bone marrow transplant (BMT) status were determined. A subset of patients had review of their records to determine the justification for discontinuing TMP-SMZ. Children who developed symptoms of pneumonia with a clinical suspicion of PCP underwent bronchoscopy, allowing for identification of Pneumocystis. RESULTS: A total of 232 patients received 1,706 doses of intravenous pentamidine and no toxicities were identified. The main reasons for discontinuing TMP-SMZ were bone marrow suppression and drug allergy. Three children developed PCP, equating to a breakthrough rate of 1.3%. Two of these children had undergone BMT (1.9% breakthrough rate) and both were under the age of two (6.5% breakthrough rate). CONCLUSIONS: The use of intravenous pentamidine as PCP prophylaxis results in a breakthrough rate of 1.3%. TMP-SMZ is the first choice for PCP prophylaxis. However, when necessary, the use of intravenous pentamidine has an acceptably low failure rate, even in high-risk BMT patients. Other options should be considered for children less than 2 years of age.