Intravenous Pentamidine for Pneumocystis Carinii/Jiroveci Pneumonia (PCP) Prophylaxis

Background: Sulfamethoxazole/trimethoprim (SMX/TMP) is the current gold standard for PCP prophylaxis in hematopoietic stem cell transplant (HSCT) patients. There are several second line options for prophylaxis but many, including intravenous (IV) pentamidine, have not been proven to be as effective or as safe as SMX/TMP in the pediatric HSCT population. There is increasing use of IV pentamidine in the pediatric HSCT population, as it is easily given once monthly, with no issues regarding compliance or vomiting. However, there are limited published data to support safety and efficacy of this approach. This study was aimed to determine the safety and efficacy of IV pentamidine in preventing PCP infection in our pediatric HSCT patients.

Methods: A retrospective chart review was conducted with IRB approval to evaluate all HSCT patients at Cincinnati Children’s Hospital Medical Center (CCHMC) that received at least one dose of IV pentamidine from January 2010 to July 2013. The primary outcome, pentamidine efficacy, was evaluated through lack of breakthrough PCP infection. The secondary outcome, pentamidine safety, was evaluated by adverse events leading to pentamidine discontinuation.

 Results:Total of 285 HSCT patients received at least one dose of IV pentamidine and were included in the final analyses.  Median age of patients was 5 years (range: 0.2 to 32 years). Patients were on pentamidine prophylaxis for a median of 5 months (range 1-44 months). Only 1 patient developed breakthrough PCP infection while receiving IV pentamidine prophylaxis (0.35%). Two patients were diagnosed with toxoplasmosis while receiving pentamidine prophylaxis (0.7%). Twenty patients (7%) experienced an adverse event leading to discontinuation of pentamidine, with tachycardia being the most common adverse event leading to discontinuation of pentamidine. The rate of adverse effects seen with pentamidine is comparable to that seen in patients receiving SMX/TMP prophylaxis which is associated with adverse effects ranging from 3.1-59%.

Conclusion:In a three year time span only 1 patient (0.35%) receiving IV pentamidine prophylaxis had a breakthrough PCP infection. Although SMX/TMP is considered first line for PCP prophylaxis, based on the results of this study, IV pentamidine should be considered a safe and effective alternative in pediatric HSCT patients.  Of note, pentamidine does not provide toxoplasmosis suppression, a consideration for children considered at high risk of reactivation